深海游弋的鱼 – 第 48 页 – 智障儿童欢乐多

增加VBox显存到256M

Virtual Box supports up to 256 MB of video RAM. This can not be set using the slider of the Virtual Box Manager.

To make full use of all supported memory we can issue the following command in a terminal:

$ VBoxManage modifyvm "Name of VM" --vram 256

1	$ VBoxManage modifyvm "Name of VM" --vram 256

Before we change settings such as the video RAM a pre-existing virtual machine has to be shut down.

Note that for 3D video hardware acceleration from the guest addition’s video driver the physical RAM of the host graphics card will be passed through. The video RAM settings of the virtual machine will not affect this.

参考链接

增加VBox显存到256M

判断网页是通过PC端还是移动终端打开的

通过判断打开设备，跳转不同页面，可以根据 User-Agent 来区分：

if((navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i))) {
    window.location.href = "";     //手机
} else {
    window.location.href = "";        //电脑
}

if((navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i))) {

window.location.href = ""; //手机

} else {

window.location.href = ""; //电脑

}

也可以执行其他操作：

if((navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i))) {
    alert('您正在通过手机访问');
} else {
    alert("您在PC端访问");
}

if((navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i))) {

alert('您正在通过手机访问');

} else {

alert("您在PC端访问");

}

JS判断客户端是否是iOS或者Android手机移动端：

通过判断浏览器的 userAgent，用正则来判断手机是否是ios和Android客户端。代码如下：

<script type="text/javascript">
    var u = navigator.userAgent;
    var isAndroid = u.indexOf('Android') > -1 || u.indexOf('Adr') > -1; //android终端
    var isiOS = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/); //ios终端
    alert('是否是Android：'+isAndroid);
    alert('是否是iOS：'+isiOS);
</script>

var u = navigator.userAgent;

var isAndroid = u.indexOf('Android') > -1 || u.indexOf('Adr') > -1; //android终端

var isiOS = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/); //ios终端

alert('是否是Android：'+isAndroid);

alert('是否是iOS：'+isiOS);

</script>

下面一个比较全面的浏览器检查函数，提供更多的检查内容，你可以检查是否是移动端（Mobile）、ipad、iphone、微信、QQ等。

第一种：

<script type="text/javascript">
    //判断访问终端
    var browser={
        versions:function(){
            var u = navigator.userAgent, app = navigator.appVersion;
            return {
                trident: u.indexOf('Trident') > -1, //IE内核
                presto: u.indexOf('Presto') > -1, //opera内核
                webKit: u.indexOf('AppleWebKit') > -1, //苹果、谷歌内核
                gecko: u.indexOf('Gecko') > -1 && u.indexOf('KHTML') == -1,//火狐内核
                mobile: !!u.match(/AppleWebKit.*Mobile.*/), //是否为移动终端
                ios: !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/), //ios终端
                android: u.indexOf('Android') > -1 || u.indexOf('Adr') > -1, //android终端
                iPhone: u.indexOf('iPhone') > -1 , //是否为iPhone或者QQHD浏览器
                iPad: u.indexOf('iPad') > -1, //是否iPad
                webApp: u.indexOf('Safari') == -1, //是否web应该程序，没有头部与底部
                weixin: u.indexOf('MicroMessenger') > -1, //是否微信 （2015-01-22新增）
                qq: u.match(/\sQQ/i) == " qq" //是否QQ
            };
        }(),
        language:(navigator.browserLanguage || navigator.language).toLowerCase()
    }
    //使用方法：
    //判断是否IE内核
    if(browser.versions.trident){ alert("is IE"); }
    //判断是否webKit内核
    if(browser.versions.webKit){ alert("is webKit"); }
    //判断是否移动端
    if(browser.versions.mobile||browser.versions.android||browser.versions.ios){
        alert("移动端"); 
    }
</script>

//判断访问终端

var browser={

versions:function(){

var u = navigator.userAgent, app = navigator.appVersion;

return {

trident: u.indexOf('Trident') > -1, //IE内核

presto: u.indexOf('Presto') > -1, //opera内核

webKit: u.indexOf('AppleWebKit') > -1, //苹果、谷歌内核

gecko: u.indexOf('Gecko') > -1 && u.indexOf('KHTML') == -1,//火狐内核

mobile: !!u.match(/AppleWebKit.*Mobile.*/), //是否为移动终端

ios: !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/), //ios终端

android: u.indexOf('Android') > -1 || u.indexOf('Adr') > -1, //android终端

iPhone: u.indexOf('iPhone') > -1 , //是否为iPhone或者QQHD浏览器

iPad: u.indexOf('iPad') > -1, //是否iPad

webApp: u.indexOf('Safari') == -1, //是否web应该程序，没有头部与底部

weixin: u.indexOf('MicroMessenger') > -1, //是否微信（2015-01-22新增）

qq: u.match(/\sQQ/i) == " qq" //是否QQ

};

}(),

language:(navigator.browserLanguage || navigator.language).toLowerCase()

}

//使用方法：

//判断是否IE内核

if(browser.versions.trident){ alert("is IE"); }

//判断是否webKit内核

if(browser.versions.webKit){ alert("is webKit"); }

//判断是否移动端

if(browser.versions.mobile||browser.versions.android||browser.versions.ios){

alert("移动端");

}

</script>

检测浏览器语言

currentLang = navigator.language;   //判断除IE外其他浏览器使用语言
if(!currentLang){//判断IE浏览器使用语言
    currentLang = navigator.browserLanguage;
}
alert(currentLang);

currentLang = navigator.language; //判断除IE外其他浏览器使用语言

if(!currentLang){//判断IE浏览器使用语言

currentLang = navigator.browserLanguage;

}

alert(currentLang);

第二种：

if (/(iPhone|iPad|iPod|iOS)/i.test(navigator.userAgent)) {
    //alert(navigator.userAgent);  
    window.location.href ="iPhone.html";
} else if (/(Android)/i.test(navigator.userAgent)) {
    //alert(navigator.userAgent); 
    window.location.href ="Android.html";
} else {
    window.location.href ="pc.html";
};

if (/(iPhone|iPad|iPod|iOS)/i.test(navigator.userAgent)) {

//alert(navigator.userAgent);

window.location.href ="iPhone.html";

} else if (/(Android)/i.test(navigator.userAgent)) {

//alert(navigator.userAgent);

window.location.href ="Android.html";

} else {

window.location.href ="pc.html";

};

也可以通过这样来适配，然后直接转跳到移动端页面：

function mobile_device_detect(url){
  var thisOS=navigator.platform;
  var os=new Array("iPhone","iPod","iPad","android","Nokia","SymbianOS","Symbian","Windows Phone","Phone","Linux armv71","MAUI","UNTRUSTED/1.0","Windows CE","BlackBerry","IEMobile");
  for(var i=0;i<os.length;i++){
    if(thisOS.match(os[i])){
      window.location.href=url;
    }
  }
  if(navigator.platform.indexOf('iPad') != -1){
    window.location.href=url;
  }
  var check = navigator.appVersion;
  if( check.match(/linux/i) ){
    if(check.match(/mobile/i) || check.match(/X11/i)){
      window.location.href=url;
    }
  }
}

function mobile_device_detect(url){

var thisOS=navigator.platform;

var os=new Array("iPhone","iPod","iPad","android","Nokia","SymbianOS","Symbian","Windows Phone","Phone","Linux armv71","MAUI","UNTRUSTED/1.0","Windows CE","BlackBerry","IEMobile");

for(var i=0;i<os.length;i++){

if(thisOS.match(os[i])){

window.location.href=url;

}

if(navigator.platform.indexOf('iPad') != -1){

window.location.href=url;

}

var check = navigator.appVersion;

if( check.match(/linux/i) ){

if(check.match(/mobile/i) || check.match(/X11/i)){

window.location.href=url;

}

参考链接

判断网页是通过PC端还是移动终端打开的

CSS高度自适应铺满全屏

HTML:

<!DOCTYPE html>
<html>
 
<head>
    <meta charset="utf-8" />
    <title>dddd</title>
    <link rel="stylesheet" type="text/css" href="test.css" />
</head>
 
<body class="HolyGrail">
    <header>...</header>
    <div class="HolyGrail-body ">
        <main class="HolyGrail-content">...</main>
        <nav class="HolyGrail-nav">...</nav>
        <aside class="HolyGrail-ads">...</aside>
    </div>
    <footer>...</footer>
</body>

<!DOCTYPE html>

<html>

<head>

</head>

</div>

</body>

CSS:

.HolyGrail {
    display: flex;
    flex-direction: column;
    background-color: blueviolet;
}
 
header,
footer {
    height: 100px;
    background-color: aquamarine;
}
 
body {
    padding: 0;
    margin: 0;
    min-height: 100vh;
}
 
.HolyGrail-body {
    flex: 1;
    background-color: brown;
}

.HolyGrail {

display: flex;

flex-direction: column;

background-color: blueviolet;

}

header,

footer {

height: 100px;

background-color: aquamarine;

}

body {

padding: 0;

margin: 0;

min-height: 100vh;

}

.HolyGrail-body {

flex: 1;

background-color: brown;

}

这里需要注意的是设置body的min-height: 100vh;以及margin: 0;

vw和vh

vm、vh、vmin、vmax是一种视窗单位，也是相对单位。它相对的不是父节点或者页面的根节点。而是由视窗（Viewport）大小来决定的，单位 1，代表类似于 1%。视窗(Viewport)是你的浏览器实际显示内容的区域—，换句话说是你的不包括工具栏和按钮的网页浏览器。

具体描述如下：

vw：视窗宽度的百分比（1vw 代表视窗的宽度为 1%）
vh：视窗高度的百分比
vmin：取当前Vw和Vh中较小的那一个值
vmax：取当前Vw和Vh中较大的那一个值

vh和vw相对于视口的高度和宽度， 1vh 等于1/100的视口高度，1vw 等于1/100的视口宽度比如：浏览器高度900px，宽度为750px, 1 vh = 900px/100 = 9 px，1vw = 750px/100 = 7.5 px，很容易实现与同屏幕等高的框。

参考链接

spring boot设置favicon，favicon不生效，不成功，不起作用

Favicon配置

默认的Favicon图标

关闭默认图标
在application.properties中添加：

spring.mvc.favicon.enabled=false

1	spring.mvc.favicon.enabled=false

或者（我这个有效果）：

spring.favicon.enabled = false

1	spring.favicon.enabled = false

效果具体原因：https://jira.spring.io/browse/SPR-12851

spring boot设置favicon，favicon不生效，不成功，不起作用

springboot显示的是一片叶子，我们如何使用自己的favicon呢？

1.将favicon.icon放到resources目录下例如：/public,/static等等

2.完成上面的步骤还不能显示，还需在你的页面的head标签添加代码

<head>
    <meta charset="UTF-8">
    <title>登录</title>
    <link rel="shortcut icon" th:href="@{/favicon.ico}" type="image/x-icon"/>
    <link rel="icon" th:href="@{/favicon.ico}" type="image/x-icon"/>
    <link rel="bookmark" th:href="@{/favicon.ico}" type="image/x-icon"/>
</head>

<head>

</head>

3.注意我使用的thymeleaf所以是以上代码片段如果你不是请这样添加

<head>
    <meta charset="UTF-8">
    <title>登录</title>
    <link href="/favicon.ico" rel="shortcut icon" type="image/x-icon"/>
    <link href="/favicon.ico" rel="icon" type="image/x-icon"/>
    <link href="/favicon.ico" rel="bookmark" type="image/x-icon"/>
</head>

<head>

</head>

参考链接

spring boot设置favicon，favicon不生效，不成功，不起作用

fail2ban with OpenVPN(ubuntu 20.04)

This page describes how to set up fail2ban with OpenVPN 2.4.7 (tested on ubuntu 20.04)

Create /etc/fail2ban/filter.d/openvpn.conf containing:

# Fail2Ban filter for selected OpenVPN rejections
#
#

[Definition]

# Example messages (other matched messages not seen in the testing server's logs):
# Fri Sep 23 11:55:36 2016 TLS Error: incoming packet authentication failed from [AF_INET]59.90.146.160:51223
# Thu Aug 25 09:36:02 2016 117.207.115.143:58922 TLS Error: TLS handshake failed

failregex = ^ TLS Error: incoming packet authentication failed from \[AF_INET\]<HOST>:\d+$
            ^ <HOST>:\d+ Connection reset, restarting
            ^ <HOST>:\d+ TLS Auth Error
            ^ <HOST>:\d+ TLS Error: TLS handshake failed$
            ^ <HOST>:\d+ VERIFY ERROR

ignoreregex =

# Fail2Ban filter for selected OpenVPN rejections

[Definition]

# Example messages (other matched messages not seen in the testing server's logs):

# Fri Sep 23 11:55:36 2016 TLS Error: incoming packet authentication failed from [AF_INET]59.90.146.160:51223

# Thu Aug 25 09:36:02 2016 117.207.115.143:58922 TLS Error: TLS handshake failed

failregex = ^ TLS Error: incoming packet authentication failed from \[AF_INET\]<HOST>:\d+$

^ <HOST>:\d+ Connection reset, restarting

^ <HOST>:\d+ TLS Auth Error

^ <HOST>:\d+ TLS Error: TLS handshake failed$

^ <HOST>:\d+ VERIFY ERROR

ignoreregex =

Create /etc/fail2ban/jail.local containing:

# Fail2Ban configuration fragment for OpenVPN

[openvpn]
enabled  = true
port     = 1194
protocol = udp
filter   = openvpn
logpath  = /var/log/openvpn/openvpn.log
maxretry = 3

# Fail2Ban configuration fragment for OpenVPN

[openvpn]

enabled = true

port = 1194

protocol = udp

filter = openvpn

logpath = /var/log/openvpn/openvpn.log

maxretry = 3

To effect the configuration change:

$ service fail2ban restart

1	$ service fail2ban restart

To test the configuration change, check /var/log/fail2ban.log initially for service start messages and later for WARNING [openvpn] Ban and Unban messages.

参考链接

HOWTO fail2ban with OpenVPN

禁止macOS系统产生.DS_Store文件的方法

Mac经常会产生 .DS_Store 的隐藏文件，虽然在 Mac 上看不到，但是有时用了人家的 U 盘或把 U 盘拿到 Windows 系统上用，就会看到。

.DS_Store 是 Mac OS 保存文件夹的自定义属性的隐藏文件，如文件的图标位置或背景色，相当于Windows 的 desktop.ini。

禁止 .DS_Store 生成：
打开 “终端” ，复制黏贴下面的命令，回车执行，重启Mac即可生效。

$ defaults write com.apple.desktopservices DSDontWriteNetworkStores -bool TRUE

1

$ defaults write com.apple.desktopservices DSDontWriteNetworkStores -bool TRUE
恢复 .DS_Store 生成：

$ defaults delete com.apple.desktopservices DSDontWriteNetworkStores

1

$ defaults delete com.apple.desktopservices DSDontWriteNetworkStores

参考链接

JUnit中对Exception的判断

对于使用验证 Test Case 方法中抛出的异常，我起初想到的是一种比较简单的方法，但是显得比较繁琐：

    @Test
    public void testOldStyle() {
        try {
            double value = Math.random();
            if(value < 0.5) {
                throw new IllegalStateException("test");
            }
            Assert.fail("Expect IllegalStateException");
        } catch(IllegalStateException e) {
        }
    }

@Test

public void testOldStyle() {

try {

double value = Math.random();

if(value < 0.5) {

throw new IllegalStateException("test");

}

Assert.fail("Expect IllegalStateException");

} catch(IllegalStateException e) {

}

Google了一下，找到另外几种更加方便的方法：１，使用Test注解中的expected字段判断抛出异常的类型。2，使用ExpectedException的Rule注解。
个人偏好用Test注解中的expected字段，它先的更加简洁，不管读起来还是写起来都很方便，并且一目了然：

    @Test(expected = IllegalStateException.class)
    public void testThrowException() {
        throw new IllegalStateException("test");
    }
    
    @Test(expected = IllegalStateException.class)
    public void testNotThrowException() {
        System.out.println("No Exception throws");
    }

@Test(expected = IllegalStateException.class)

public void testThrowException() {

throw new IllegalStateException("test");

}

@Test(expected = IllegalStateException.class)

public void testNotThrowException() {

System.out.println("No Exception throws");

}

对Rule注解的使用（只有在JUnit4.7以后才有这个功能），它提供了更加强大的功能，它可以同时检查异常类型以及异常消息内容，这些内容可以只包含其中的某些字符，ExpectedException还支持使用hamcrest中的Matcher，默认使用IsInstanceOf和StringContains Matcher。在BlockJUnit4ClassRunner的实现中，每一个Test Case运行时都会重新创建Test Class的实例，因而在使用ExpectedException这个Rule时，不用担心在多个Test Case之间相互影响的问题：

    @Rule
    public final ExpectedException expectedException = ExpectedException.none();
    
    @Test
    public void testThrowExceptionWithRule() {
        expectedException.expect(IllegalStateException.class);
        
        throw new IllegalStateException("test");
    }
    
    @Test
    public void testThrowExceptionAndMessageWithRule() {
        expectedException.expect(IllegalStateException.class);
        expectedException.expectMessage("fail");
        
        throw new IllegalStateException("expect fail");
    }

@Rule

public final ExpectedException expectedException = ExpectedException.none();

@Test

public void testThrowExceptionWithRule() {

expectedException.expect(IllegalStateException.class);

throw new IllegalStateException("test");

}

@Test

public void testThrowExceptionAndMessageWithRule() {

expectedException.expect(IllegalStateException.class);

expectedException.expectMessage("fail");

throw new IllegalStateException("expect fail");

}

在stackoverflow中还有人提到了使用google-code中的catch-exception工程，今天没时间看了，回去好好研究一下。

地址是：http://code.google.com/p/catch-exception/

参考链接

JUnit中对Exception的判断

PBKDF2加密的实现

PBKDF2(Password-Based Key Derivation Function)

通过哈希算法进行加密。由于哈希算法是单向的，能够将不论什么大小的数据转化为定长的“指纹”，并且无法被反向计算。

另外，即使数据源仅仅修改了一丁点。哈希的结果也会全然不同。

这种特性使得它很适合用于保存password。由于我们须要加密后的password无法被解密，同一时候也能保证正确校验每一个用户的password。可是哈希加密能够通过字典攻击和暴力攻击破解。

password加盐。盐是一个加入到用户的password哈希过程中的一段随机序列。

这个机制可以防止通过预先计算结果的彩虹表破解。每一个用户都有自己的盐，这种结果就是即使用户的password同样。通过加盐后哈希值也将不同。

为了校验password是否正确，我们须要储存盐值。通常和password哈希值一起存放在账户数据库中。或者直接存为哈希字符串的一部分。

import java.math.BigInteger;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;

import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;

public class PasswordEncryption {

    public static final String PBKDF2_ALGORITHM = "PBKDF2WithHmacSHA1";

    /**
     * 盐的长度
     */
    public static final int SALT_BYTE_SIZE = 32 / 2;

    /**
     * 生成密文的长度
     */
    public static final int HASH_BIT_SIZE = 128 * 4;

    /**
     * 迭代次数
     */
    public static final int PBKDF2_ITERATIONS = 1000;

    /**
     * 对输入的password进行验证
     *
     * @param attemptedPassword 待验证的password
     * @param encryptedPassword 密文
     * @param salt              盐值
     * @return 是否验证成功
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */
    public static boolean authenticate(String attemptedPassword, String encryptedPassword, String salt)
            throws NoSuchAlgorithmException, InvalidKeySpecException {
        // 用同样的盐值对用户输入的password进行加密
        String encryptedAttemptedPassword = getEncryptedPassword(attemptedPassword, salt);
        // 把加密后的密文和原密文进行比較，同样则验证成功。否则失败
        return encryptedAttemptedPassword.equals(encryptedPassword);
    }

    /**
     * 生成密文
     *
     * @param password 明文password
     * @param salt     盐值
     * @return
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */
    public static String getEncryptedPassword(String password, String salt) throws NoSuchAlgorithmException,
            InvalidKeySpecException {

        KeySpec spec = new PBEKeySpec(password.toCharArray(), fromHex(salt), PBKDF2_ITERATIONS, HASH_BIT_SIZE);
        SecretKeyFactory f = SecretKeyFactory.getInstance(PBKDF2_ALGORITHM);
        return toHex(f.generateSecret(spec).getEncoded());
    }

    /**
     * 通过提供加密的强随机数生成器 生成盐
     *
     * @return
     * @throws NoSuchAlgorithmException
     */
    public static String generateSalt() throws NoSuchAlgorithmException {
        SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
        byte[] salt = new byte[SALT_BYTE_SIZE];
        random.nextBytes(salt);

        return toHex(salt);
    }

    /**
     * 十六进制字符串转二进制字符串
     *
     * @param hex the hex string
     * @return the hex string decoded into a byte array
     */
    private static byte[] fromHex(String hex) {
        byte[] binary = new byte[hex.length() / 2];
        for (int i = 0; i < binary.length; i++) {
            binary[i] = (byte) Integer.parseInt(hex.substring(2 * i, 2 * i + 2), 16);
        }
        return binary;
    }

    /**
     * 二进制字符串转十六进制字符串
     *
     * @param array the byte array to convert
     * @return a length*2 character string encoding the byte array
     */
    private static String toHex(byte[] array) {
        BigInteger bi = new BigInteger(1, array);
        String hex = bi.toString(16);
        int paddingLength = (array.length * 2) - hex.length();
        if (paddingLength > 0)
            return String.format("%0" + paddingLength + "d", 0) + hex;
        else
            return hex;
    }
}

100

101

102

103

104

105

106

107

import java.math.BigInteger;

import java.security.NoSuchAlgorithmException;

import java.security.SecureRandom;

import java.security.spec.InvalidKeySpecException;

import java.security.spec.KeySpec;

import javax.crypto.SecretKeyFactory;

import javax.crypto.spec.PBEKeySpec;

public class PasswordEncryption {

public static final String PBKDF2_ALGORITHM = "PBKDF2WithHmacSHA1";

/**

* 盐的长度

public static final int SALT_BYTE_SIZE = 32 / 2;

/**

* 生成密文的长度

public static final int HASH_BIT_SIZE = 128 * 4;

/**

* 迭代次数

public static final int PBKDF2_ITERATIONS = 1000;

/**

* 对输入的password进行验证

* @param attemptedPassword 待验证的password

* @param encryptedPassword 密文

* @param salt 盐值

* @return 是否验证成功

* @throws NoSuchAlgorithmException

* @throws InvalidKeySpecException

public static boolean authenticate(String attemptedPassword, String encryptedPassword, String salt)

throws NoSuchAlgorithmException, InvalidKeySpecException {

// 用同样的盐值对用户输入的password进行加密

String encryptedAttemptedPassword = getEncryptedPassword(attemptedPassword, salt);

// 把加密后的密文和原密文进行比較，同样则验证成功。否则失败

return encryptedAttemptedPassword.equals(encryptedPassword);

}

/**

* 生成密文

* @param password 明文password

* @param salt 盐值

* @return

* @throws NoSuchAlgorithmException

* @throws InvalidKeySpecException

public static String getEncryptedPassword(String password, String salt) throws NoSuchAlgorithmException,

InvalidKeySpecException {

KeySpec spec = new PBEKeySpec(password.toCharArray(), fromHex(salt), PBKDF2_ITERATIONS, HASH_BIT_SIZE);

SecretKeyFactory f = SecretKeyFactory.getInstance(PBKDF2_ALGORITHM);

return toHex(f.generateSecret(spec).getEncoded());

}

/**

* 通过提供加密的强随机数生成器生成盐

* @return

* @throws NoSuchAlgorithmException

public static String generateSalt() throws NoSuchAlgorithmException {

SecureRandom random = SecureRandom.getInstance("SHA1PRNG");

byte[] salt = new byte[SALT_BYTE_SIZE];

random.nextBytes(salt);

return toHex(salt);

}

/**

* 十六进制字符串转二进制字符串

* @param hex the hex string

* @return the hex string decoded into a byte array

private static byte[] fromHex(String hex) {

byte[] binary = new byte[hex.length() / 2];

for (int i = 0; i < binary.length; i++) {

binary[i] = (byte) Integer.parseInt(hex.substring(2 * i, 2 * i + 2), 16);

}

return binary;

}

/**

* 二进制字符串转十六进制字符串

* @param array the byte array to convert

* @return a length*2 character string encoding the byte array

private static String toHex(byte[] array) {

BigInteger bi = new BigInteger(1, array);

String hex = bi.toString(16);

int paddingLength = (array.length * 2) - hex.length();

if (paddingLength > 0)

return String.format("%0" + paddingLength + "d", 0) + hex;

else

return hex;

}

首先要生成一个盐值salt，再把原始password和salt加密得到密文。验证的时候，把用户输入的password和同样的盐值salt使用同样的加密算法得到一个密文，将这个密文和原密文相比較，同样则验证通过，反之则不通过。

public static void main(String[] args) {
    String password = "test";
    String salt;
    String ciphertext;
    try {
        salt = PasswordEncryption.generateSalt();
        ciphertext = PasswordEncryption.getEncryptedPassword(password, salt);
        boolean result = PasswordEncryption.authenticate(password, ciphertext, salt);

        System.out.println(password + "  " + password.length());
        System.out.println(salt + "  " + salt.length());
        System.out.println(ciphertext + "  " + ciphertext.length());
        if (result) {
            System.out.println("succeed");
        } else {
            System.out.println("failed");
        }
    } catch (NoSuchAlgorithmException e) {
        System.out.println("NoSuchAlgorithmException");
    } catch (InvalidKeySpecException e) {
        System.out.println("InvalidKeySpecException");
    }
}

public static void main(String[] args) {

String password = "test";

String salt;

String ciphertext;

try {

salt = PasswordEncryption.generateSalt();

ciphertext = PasswordEncryption.getEncryptedPassword(password, salt);

boolean result = PasswordEncryption.authenticate(password, ciphertext, salt);

System.out.println(password + " " + password.length());

System.out.println(salt + " " + salt.length());

System.out.println(ciphertext + " " + ciphertext.length());

if (result) {

System.out.println("succeed");

} else {

System.out.println("failed");

}

} catch (NoSuchAlgorithmException e) {

System.out.println("NoSuchAlgorithmException");

} catch (InvalidKeySpecException e) {

System.out.println("InvalidKeySpecException");

}

測试结果为：

test  4
3aca9ca3fa80158b765ece7d0a45f2e8  32
592cb30e95efc720c5accf425ed5f2fe46aa332d9980e6daa234797de49cda731c2c18e667b4dd71ba33797a3dcddd312ff9b03d802bf1cc09aacb2a176cf741  128
succeed

test 4

3aca9ca3fa80158b765ece7d0a45f2e8 32

592cb30e95efc720c5accf425ed5f2fe46aa332d9980e6daa234797de49cda731c2c18e667b4dd71ba33797a3dcddd312ff9b03d802bf1cc09aacb2a176cf741 128

succeed

参考链接

snapd进程持续写盘导致系统卡顿

系统使用一段时间后，莫名其妙出现卡顿现象。发现硬盘灯闪个不停。

经查，是snapd进程持续不停的往硬盘写入数据，同时也会占用CPU。

写入量不大，但是磁盘占用率出奇的高。

导致系统出现卡顿，这个问题从ubuntu18.04到20.04实测都有，更老的版本没有实测不妄加批评。

解决办法网上找了N圈也没有找到解决办法。所以，只好……

干掉它！

$ sudo apt purge snapd

1	$ sudo apt purge snapd

卸载后系统丝般顺滑。。

因为我暂时snap用的不多，加上也没别的办法，毕竟已经影响到系统的正常使用了，只好选择卸载。

有人说不能卸载，可以试试下面的命令：

$ sudo apt autoremove --purge snapd

1	$ sudo apt autoremove --purge snapd

卸载之后，继续重装一下，貌似也不再出现问题。

参考链接

Error 'Character set '#255' is not a compiled ch aracter set and is not specified in the '/usr/local/mariadb10/share/mysql/charse ts/Index.xml' file' on query. Default database: 'wordpress'. Query: 'BEGIN'

以前通过家里ADSL上网无固定外网IP的群晖NAS安全实现与公网MySQL服务器主从同步配置之后，群晖自带的 MariaDB 10.3.21 可以非常流畅的与服务器上的 MySQL 7.x 版本进行主从同步。

前两天系统从 ubuntu 18.04 升级到 ubuntu 20.04 (MySQL 8.x)之后，发现已经无法进行主从同步。

报告如下错误：

$ mysql -u root -p -e "show slave status\G;"
Enter password:
*************************** 1. row ***************************
                Slave_IO_State:
                   Master_Host: 10.8.0.1
                   Master_User: repl1
                   Master_Port: 3306
                 Connect_Retry: 60
               Master_Log_File: mysql-bin.001242
           Read_Master_Log_Pos: 8350259
                Relay_Log_File: mysqld10-relay-bin.000510
                 Relay_Log_Pos: 424
         Relay_Master_Log_File: mysql-bin.001222
              Slave_IO_Running: No
             Slave_SQL_Running: No
               Replicate_Do_DB:
           Replicate_Ignore_DB:
            Replicate_Do_Table:
        Replicate_Ignore_Table:
       Replicate_Wild_Do_Table:
   Replicate_Wild_Ignore_Table:
                    Last_Errno: 22
                    Last_Error: Error 'Character set '#255' is not a compiled character set and is not specified in the '/usr/local/mariadb10/share/mysql/charsets/Index.xml' file' on query. Default database: 'wordpress'. Query: 'BEGIN'
                  Skip_Counter: 0
           Exec_Master_Log_Pos: 125
               Relay_Log_Space: 137841279
               Until_Condition: None
                Until_Log_File:
                 Until_Log_Pos: 0
            Master_SSL_Allowed: Yes
            Master_SSL_CA_File: /var/packages/MariaDB10/etc/ssl/ca.pem
            Master_SSL_CA_Path: /var/packages/MariaDB10/etc/ssl
               Master_SSL_Cert: /var/packages/MariaDB10/etc/ssl/client-cert.pem
             Master_SSL_Cipher:
                Master_SSL_Key: /var/packages/MariaDB10/etc/ssl/client-key.pem
         Seconds_Behind_Master: NULL
 Master_SSL_Verify_Server_Cert: No
                 Last_IO_Errno: 0
                 Last_IO_Error:
                Last_SQL_Errno: 22
                Last_SQL_Error: Error 'Character set '#255' is not a compiled character set and is not specified in the '/usr/local/mariadb10/share/mysql/charsets/Index.xml' file' on query. Default database: 'wordpress'. Query: 'BEGIN'
   Replicate_Ignore_Server_Ids:
              Master_Server_Id: 1
                Master_SSL_Crl: /var/packages/MariaDB10/etc/ssl/ca.pem
            Master_SSL_Crlpath: /var/packages/MariaDB10/etc/ssl
                    Using_Gtid: No
                   Gtid_IO_Pos:
       Replicate_Do_Domain_Ids:
   Replicate_Ignore_Domain_Ids:
                 Parallel_Mode: conservative
                     SQL_Delay: 0
           SQL_Remaining_Delay: NULL
       Slave_SQL_Running_State:
              Slave_DDL_Groups: 0
Slave_Non_Transactional_Groups: 0
    Slave_Transactional_Groups: 0

$ mysql -u root -p -e "show slave status\G;"

Enter password:

*************************** 1. row ***************************

Slave_IO_State:

Master_Host: 10.8.0.1

Master_User: repl1

Master_Port: 3306

Connect_Retry: 60

Master_Log_File: mysql-bin.001242

Read_Master_Log_Pos: 8350259

Relay_Log_File: mysqld10-relay-bin.000510

Relay_Log_Pos: 424

Relay_Master_Log_File: mysql-bin.001222

Slave_IO_Running: No

Slave_SQL_Running: No

Replicate_Do_DB:

Replicate_Ignore_DB:

Replicate_Do_Table:

Replicate_Ignore_Table:

Replicate_Wild_Do_Table:

Replicate_Wild_Ignore_Table:

Last_Errno: 22

Last_Error: Error 'Character set '#255' is not a compiled character set and is not specified in the '/usr/local/mariadb10/share/mysql/charsets/Index.xml' file' on query. Default database: 'wordpress'. Query: 'BEGIN'

Skip_Counter: 0

Exec_Master_Log_Pos: 125

Relay_Log_Space: 137841279

Until_Condition: None

Until_Log_File:

Until_Log_Pos: 0

Master_SSL_Allowed: Yes

Master_SSL_CA_File: /var/packages/MariaDB10/etc/ssl/ca.pem

Master_SSL_CA_Path: /var/packages/MariaDB10/etc/ssl

Master_SSL_Cert: /var/packages/MariaDB10/etc/ssl/client-cert.pem

Master_SSL_Cipher:

Master_SSL_Key: /var/packages/MariaDB10/etc/ssl/client-key.pem

Seconds_Behind_Master: NULL

Master_SSL_Verify_Server_Cert: No

Last_IO_Errno: 0

Last_IO_Error:

Last_SQL_Errno: 22

Last_SQL_Error: Error 'Character set '#255' is not a compiled character set and is not specified in the '/usr/local/mariadb10/share/mysql/charsets/Index.xml' file' on query. Default database: 'wordpress'. Query: 'BEGIN'

Replicate_Ignore_Server_Ids:

Master_Server_Id: 1

Master_SSL_Crl: /var/packages/MariaDB10/etc/ssl/ca.pem

Master_SSL_Crlpath: /var/packages/MariaDB10/etc/ssl

Using_Gtid: No

Gtid_IO_Pos:

Replicate_Do_Domain_Ids:

Replicate_Ignore_Domain_Ids:

Parallel_Mode: conservative

SQL_Delay: 0

SQL_Remaining_Delay: NULL

Slave_SQL_Running_State:

Slave_DDL_Groups: 0

Slave_Non_Transactional_Groups: 0

Slave_Transactional_Groups: 0

网上查询很久，找到原因 MySQL 8.016 master with MariaDB 10.2 slave on AWS RDS, Character set '#255' is not a compiled character set

This could be a serious problem when replicating between MySQL 8.0 and MariaDB 10.x.

The default (for good technical reasons) COLLATION for the 8.0 is utf8mb4_0900_ai_ci. Note the "255" associated with it. MariaDB has not yet adopted the Unicode 9.0 collations.

Furthermore, Oracle (MySQL 8.0) did a major rewrite of the collation code, thereby possibly making collation tables incompatible.

A probable fix is to switch to the next best general-purpose collation, utf8mb4_unicode_520_ci (246) (based on Unicode 5.20). This would require ALTERing all the columns' collations. ALTER TABLE .. CONVERT TO .. might be the fastest way. Those could be generated via a SELECT .. information_schema.tables ....

大致原因就是MySql 8.0默认使用了最新的utf8mb4_0900_ai_ci字符集，然而MariaDB 10.3.x版本不支持这个字符集，导致无法同步。

8.0.17:

mysql> show collation like 'utf8mb4%';
+----------------------------+---------+-----+---------+----------+---------+---------------+
| Collation                  | Charset | Id  | Default | Compiled | Sortlen | Pad_attribute |
+----------------------------+---------+-----+---------+----------+---------+---------------+
| utf8mb4_0900_ai_ci         | utf8mb4 | 255 | Yes     | Yes      |       0 | NO PAD        |
| utf8mb4_0900_as_ci         | utf8mb4 | 305 |         | Yes      |       0 | NO PAD        |
| utf8mb4_0900_as_cs         | utf8mb4 | 278 |         | Yes      |       0 | NO PAD        |
| utf8mb4_0900_bin           | utf8mb4 | 309 |         | Yes      |       1 | NO PAD        |
| utf8mb4_bin                | utf8mb4 |  46 |         | Yes      |       1 | PAD SPACE     |
| utf8mb4_croatian_ci        | utf8mb4 | 245 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_cs_0900_ai_ci      | utf8mb4 | 266 |         | Yes      |       0 | NO PAD        |
| utf8mb4_cs_0900_as_cs      | utf8mb4 | 289 |         | Yes      |       0 | NO PAD        |
| utf8mb4_czech_ci           | utf8mb4 | 234 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_danish_ci          | utf8mb4 | 235 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_da_0900_ai_ci      | utf8mb4 | 267 |         | Yes      |       0 | NO PAD        |
| utf8mb4_da_0900_as_cs      | utf8mb4 | 290 |         | Yes      |       0 | NO PAD        |
| utf8mb4_de_pb_0900_ai_ci   | utf8mb4 | 256 |         | Yes      |       0 | NO PAD        |
| utf8mb4_de_pb_0900_as_cs   | utf8mb4 | 279 |         | Yes      |       0 | NO PAD        |
| utf8mb4_eo_0900_ai_ci      | utf8mb4 | 273 |         | Yes      |       0 | NO PAD        |
| utf8mb4_eo_0900_as_cs      | utf8mb4 | 296 |         | Yes      |       0 | NO PAD        |
| utf8mb4_esperanto_ci       | utf8mb4 | 241 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_estonian_ci        | utf8mb4 | 230 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_es_0900_ai_ci      | utf8mb4 | 263 |         | Yes      |       0 | NO PAD        |
| utf8mb4_es_0900_as_cs      | utf8mb4 | 286 |         | Yes      |       0 | NO PAD        |
| utf8mb4_es_trad_0900_ai_ci | utf8mb4 | 270 |         | Yes      |       0 | NO PAD        |
| utf8mb4_es_trad_0900_as_cs | utf8mb4 | 293 |         | Yes      |       0 | NO PAD        |
| utf8mb4_et_0900_ai_ci      | utf8mb4 | 262 |         | Yes      |       0 | NO PAD        |
| utf8mb4_et_0900_as_cs      | utf8mb4 | 285 |         | Yes      |       0 | NO PAD        |
| utf8mb4_general_ci         | utf8mb4 |  45 |         | Yes      |       1 | PAD SPACE     |
| utf8mb4_german2_ci         | utf8mb4 | 244 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_hr_0900_ai_ci      | utf8mb4 | 275 |         | Yes      |       0 | NO PAD        |
| utf8mb4_hr_0900_as_cs      | utf8mb4 | 298 |         | Yes      |       0 | NO PAD        |
| utf8mb4_hungarian_ci       | utf8mb4 | 242 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_hu_0900_ai_ci      | utf8mb4 | 274 |         | Yes      |       0 | NO PAD        |
| utf8mb4_hu_0900_as_cs      | utf8mb4 | 297 |         | Yes      |       0 | NO PAD        |
| utf8mb4_icelandic_ci       | utf8mb4 | 225 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_is_0900_ai_ci      | utf8mb4 | 257 |         | Yes      |       0 | NO PAD        |
| utf8mb4_is_0900_as_cs      | utf8mb4 | 280 |         | Yes      |       0 | NO PAD        |
| utf8mb4_ja_0900_as_cs      | utf8mb4 | 303 |         | Yes      |       0 | NO PAD        |
| utf8mb4_ja_0900_as_cs_ks   | utf8mb4 | 304 |         | Yes      |      24 | NO PAD        |
| utf8mb4_latvian_ci         | utf8mb4 | 226 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_la_0900_ai_ci      | utf8mb4 | 271 |         | Yes      |       0 | NO PAD        |
| utf8mb4_la_0900_as_cs      | utf8mb4 | 294 |         | Yes      |       0 | NO PAD        |
| utf8mb4_lithuanian_ci      | utf8mb4 | 236 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_lt_0900_ai_ci      | utf8mb4 | 268 |         | Yes      |       0 | NO PAD        |
| utf8mb4_lt_0900_as_cs      | utf8mb4 | 291 |         | Yes      |       0 | NO PAD        |
| utf8mb4_lv_0900_ai_ci      | utf8mb4 | 258 |         | Yes      |       0 | NO PAD        |
| utf8mb4_lv_0900_as_cs      | utf8mb4 | 281 |         | Yes      |       0 | NO PAD        |
| utf8mb4_persian_ci         | utf8mb4 | 240 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_pl_0900_ai_ci      | utf8mb4 | 261 |         | Yes      |       0 | NO PAD        |
| utf8mb4_pl_0900_as_cs      | utf8mb4 | 284 |         | Yes      |       0 | NO PAD        |
| utf8mb4_polish_ci          | utf8mb4 | 229 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_romanian_ci        | utf8mb4 | 227 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_roman_ci           | utf8mb4 | 239 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_ro_0900_ai_ci      | utf8mb4 | 259 |         | Yes      |       0 | NO PAD        |
| utf8mb4_ro_0900_as_cs      | utf8mb4 | 282 |         | Yes      |       0 | NO PAD        |
| utf8mb4_ru_0900_ai_ci      | utf8mb4 | 306 |         | Yes      |       0 | NO PAD        |
| utf8mb4_ru_0900_as_cs      | utf8mb4 | 307 |         | Yes      |       0 | NO PAD        |
| utf8mb4_sinhala_ci         | utf8mb4 | 243 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_sk_0900_ai_ci      | utf8mb4 | 269 |         | Yes      |       0 | NO PAD        |
| utf8mb4_sk_0900_as_cs      | utf8mb4 | 292 |         | Yes      |       0 | NO PAD        |
| utf8mb4_slovak_ci          | utf8mb4 | 237 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_slovenian_ci       | utf8mb4 | 228 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_sl_0900_ai_ci      | utf8mb4 | 260 |         | Yes      |       0 | NO PAD        |
| utf8mb4_sl_0900_as_cs      | utf8mb4 | 283 |         | Yes      |       0 | NO PAD        |
| utf8mb4_spanish2_ci        | utf8mb4 | 238 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_spanish_ci         | utf8mb4 | 231 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_sv_0900_ai_ci      | utf8mb4 | 264 |         | Yes      |       0 | NO PAD        |
| utf8mb4_sv_0900_as_cs      | utf8mb4 | 287 |         | Yes      |       0 | NO PAD        |
| utf8mb4_swedish_ci         | utf8mb4 | 232 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_tr_0900_ai_ci      | utf8mb4 | 265 |         | Yes      |       0 | NO PAD        |
| utf8mb4_tr_0900_as_cs      | utf8mb4 | 288 |         | Yes      |       0 | NO PAD        |
| utf8mb4_turkish_ci         | utf8mb4 | 233 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_unicode_520_ci     | utf8mb4 | 246 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_unicode_ci         | utf8mb4 | 224 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_vietnamese_ci      | utf8mb4 | 247 |         | Yes      |       8 | PAD SPACE     |
| utf8mb4_vi_0900_ai_ci      | utf8mb4 | 277 |         | Yes      |       0 | NO PAD        |
| utf8mb4_vi_0900_as_cs      | utf8mb4 | 300 |         | Yes      |       0 | NO PAD        |
| utf8mb4_zh_0900_as_cs      | utf8mb4 | 308 |         | Yes      |       0 | NO PAD        |
+----------------------------+---------+-----+---------+----------+---------+---------------+
75 rows in set (0.01 sec)

mysql> show collation like 'utf8mb4%';

+----------------------------+---------+-----+---------+----------+---------+---------------+

+----------------------------+---------+-----+---------+----------+---------+---------------+

| utf8mb4_0900_ai_ci | utf8mb4 | 255 | Yes | Yes | 0 | NO PAD |

| utf8mb4_0900_as_ci | utf8mb4 | 305 | | Yes | 0 | NO PAD |

| utf8mb4_0900_as_cs | utf8mb4 | 278 | | Yes | 0 | NO PAD |

| utf8mb4_0900_bin | utf8mb4 | 309 | | Yes | 1 | NO PAD |

| utf8mb4_bin | utf8mb4 | 46 | | Yes | 1 | PAD SPACE |

| utf8mb4_croatian_ci | utf8mb4 | 245 | | Yes | 8 | PAD SPACE |

| utf8mb4_cs_0900_ai_ci | utf8mb4 | 266 | | Yes | 0 | NO PAD |

| utf8mb4_cs_0900_as_cs | utf8mb4 | 289 | | Yes | 0 | NO PAD |

| utf8mb4_czech_ci | utf8mb4 | 234 | | Yes | 8 | PAD SPACE |

| utf8mb4_danish_ci | utf8mb4 | 235 | | Yes | 8 | PAD SPACE |

| utf8mb4_da_0900_ai_ci | utf8mb4 | 267 | | Yes | 0 | NO PAD |

| utf8mb4_da_0900_as_cs | utf8mb4 | 290 | | Yes | 0 | NO PAD |

| utf8mb4_de_pb_0900_ai_ci | utf8mb4 | 256 | | Yes | 0 | NO PAD |

| utf8mb4_de_pb_0900_as_cs | utf8mb4 | 279 | | Yes | 0 | NO PAD |

| utf8mb4_eo_0900_ai_ci | utf8mb4 | 273 | | Yes | 0 | NO PAD |

| utf8mb4_eo_0900_as_cs | utf8mb4 | 296 | | Yes | 0 | NO PAD |

| utf8mb4_esperanto_ci | utf8mb4 | 241 | | Yes | 8 | PAD SPACE |

| utf8mb4_estonian_ci | utf8mb4 | 230 | | Yes | 8 | PAD SPACE |

| utf8mb4_es_0900_ai_ci | utf8mb4 | 263 | | Yes | 0 | NO PAD |

| utf8mb4_es_0900_as_cs | utf8mb4 | 286 | | Yes | 0 | NO PAD |

| utf8mb4_es_trad_0900_ai_ci | utf8mb4 | 270 | | Yes | 0 | NO PAD |

| utf8mb4_es_trad_0900_as_cs | utf8mb4 | 293 | | Yes | 0 | NO PAD |

| utf8mb4_et_0900_ai_ci | utf8mb4 | 262 | | Yes | 0 | NO PAD |

| utf8mb4_et_0900_as_cs | utf8mb4 | 285 | | Yes | 0 | NO PAD |

| utf8mb4_general_ci | utf8mb4 | 45 | | Yes | 1 | PAD SPACE |

| utf8mb4_german2_ci | utf8mb4 | 244 | | Yes | 8 | PAD SPACE |

| utf8mb4_hr_0900_ai_ci | utf8mb4 | 275 | | Yes | 0 | NO PAD |

| utf8mb4_hr_0900_as_cs | utf8mb4 | 298 | | Yes | 0 | NO PAD |

| utf8mb4_hungarian_ci | utf8mb4 | 242 | | Yes | 8 | PAD SPACE |

| utf8mb4_hu_0900_ai_ci | utf8mb4 | 274 | | Yes | 0 | NO PAD |

| utf8mb4_hu_0900_as_cs | utf8mb4 | 297 | | Yes | 0 | NO PAD |

| utf8mb4_icelandic_ci | utf8mb4 | 225 | | Yes | 8 | PAD SPACE |

| utf8mb4_is_0900_ai_ci | utf8mb4 | 257 | | Yes | 0 | NO PAD |

| utf8mb4_is_0900_as_cs | utf8mb4 | 280 | | Yes | 0 | NO PAD |

| utf8mb4_ja_0900_as_cs | utf8mb4 | 303 | | Yes | 0 | NO PAD |

| utf8mb4_ja_0900_as_cs_ks | utf8mb4 | 304 | | Yes | 24 | NO PAD |

| utf8mb4_latvian_ci | utf8mb4 | 226 | | Yes | 8 | PAD SPACE |

| utf8mb4_la_0900_ai_ci | utf8mb4 | 271 | | Yes | 0 | NO PAD |

| utf8mb4_la_0900_as_cs | utf8mb4 | 294 | | Yes | 0 | NO PAD |

| utf8mb4_lithuanian_ci | utf8mb4 | 236 | | Yes | 8 | PAD SPACE |

| utf8mb4_lt_0900_ai_ci | utf8mb4 | 268 | | Yes | 0 | NO PAD |

| utf8mb4_lt_0900_as_cs | utf8mb4 | 291 | | Yes | 0 | NO PAD |

| utf8mb4_lv_0900_ai_ci | utf8mb4 | 258 | | Yes | 0 | NO PAD |

| utf8mb4_lv_0900_as_cs | utf8mb4 | 281 | | Yes | 0 | NO PAD |

| utf8mb4_persian_ci | utf8mb4 | 240 | | Yes | 8 | PAD SPACE |

| utf8mb4_pl_0900_ai_ci | utf8mb4 | 261 | | Yes | 0 | NO PAD |

| utf8mb4_pl_0900_as_cs | utf8mb4 | 284 | | Yes | 0 | NO PAD |

| utf8mb4_polish_ci | utf8mb4 | 229 | | Yes | 8 | PAD SPACE |

| utf8mb4_romanian_ci | utf8mb4 | 227 | | Yes | 8 | PAD SPACE |

| utf8mb4_roman_ci | utf8mb4 | 239 | | Yes | 8 | PAD SPACE |

| utf8mb4_ro_0900_ai_ci | utf8mb4 | 259 | | Yes | 0 | NO PAD |

| utf8mb4_ro_0900_as_cs | utf8mb4 | 282 | | Yes | 0 | NO PAD |

| utf8mb4_ru_0900_ai_ci | utf8mb4 | 306 | | Yes | 0 | NO PAD |

| utf8mb4_ru_0900_as_cs | utf8mb4 | 307 | | Yes | 0 | NO PAD |

| utf8mb4_sinhala_ci | utf8mb4 | 243 | | Yes | 8 | PAD SPACE |

| utf8mb4_sk_0900_ai_ci | utf8mb4 | 269 | | Yes | 0 | NO PAD |

| utf8mb4_sk_0900_as_cs | utf8mb4 | 292 | | Yes | 0 | NO PAD |

| utf8mb4_slovak_ci | utf8mb4 | 237 | | Yes | 8 | PAD SPACE |

| utf8mb4_slovenian_ci | utf8mb4 | 228 | | Yes | 8 | PAD SPACE |

| utf8mb4_sl_0900_ai_ci | utf8mb4 | 260 | | Yes | 0 | NO PAD |

| utf8mb4_sl_0900_as_cs | utf8mb4 | 283 | | Yes | 0 | NO PAD |

| utf8mb4_spanish2_ci | utf8mb4 | 238 | | Yes | 8 | PAD SPACE |

| utf8mb4_spanish_ci | utf8mb4 | 231 | | Yes | 8 | PAD SPACE |

| utf8mb4_sv_0900_ai_ci | utf8mb4 | 264 | | Yes | 0 | NO PAD |

| utf8mb4_sv_0900_as_cs | utf8mb4 | 287 | | Yes | 0 | NO PAD |

| utf8mb4_swedish_ci | utf8mb4 | 232 | | Yes | 8 | PAD SPACE |

| utf8mb4_tr_0900_ai_ci | utf8mb4 | 265 | | Yes | 0 | NO PAD |

| utf8mb4_tr_0900_as_cs | utf8mb4 | 288 | | Yes | 0 | NO PAD |

| utf8mb4_turkish_ci | utf8mb4 | 233 | | Yes | 8 | PAD SPACE |

| utf8mb4_unicode_520_ci | utf8mb4 | 246 | | Yes | 8 | PAD SPACE |

| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 8 | PAD SPACE |

| utf8mb4_vietnamese_ci | utf8mb4 | 247 | | Yes | 8 | PAD SPACE |

| utf8mb4_vi_0900_ai_ci | utf8mb4 | 277 | | Yes | 0 | NO PAD |

| utf8mb4_vi_0900_as_cs | utf8mb4 | 300 | | Yes | 0 | NO PAD |

| utf8mb4_zh_0900_as_cs | utf8mb4 | 308 | | Yes | 0 | NO PAD |

+----------------------------+---------+-----+---------+----------+---------+---------------+

75 rows in set (0.01 sec)

MariaDB 10.2.30:

mysql> SHOW COLLATION LIKE 'utf8mb4%';
+------------------------------+---------+------+---------+----------+---------+
| Collation                    | Charset | Id   | Default | Compiled | Sortlen |
+------------------------------+---------+------+---------+----------+---------+
| utf8mb4_general_ci           | utf8mb4 |   45 | Yes     | Yes      |       1 |
| utf8mb4_bin                  | utf8mb4 |   46 |         | Yes      |       1 |
| utf8mb4_unicode_ci           | utf8mb4 |  224 |         | Yes      |       8 |
| utf8mb4_icelandic_ci         | utf8mb4 |  225 |         | Yes      |       8 |
| utf8mb4_latvian_ci           | utf8mb4 |  226 |         | Yes      |       8 |
| utf8mb4_romanian_ci          | utf8mb4 |  227 |         | Yes      |       8 |
| utf8mb4_slovenian_ci         | utf8mb4 |  228 |         | Yes      |       8 |
| utf8mb4_polish_ci            | utf8mb4 |  229 |         | Yes      |       8 |
| utf8mb4_estonian_ci          | utf8mb4 |  230 |         | Yes      |       8 |
| utf8mb4_spanish_ci           | utf8mb4 |  231 |         | Yes      |       8 |
| utf8mb4_swedish_ci           | utf8mb4 |  232 |         | Yes      |       8 |
| utf8mb4_turkish_ci           | utf8mb4 |  233 |         | Yes      |       8 |
| utf8mb4_czech_ci             | utf8mb4 |  234 |         | Yes      |       8 |
| utf8mb4_danish_ci            | utf8mb4 |  235 |         | Yes      |       8 |
| utf8mb4_lithuanian_ci        | utf8mb4 |  236 |         | Yes      |       8 |
| utf8mb4_slovak_ci            | utf8mb4 |  237 |         | Yes      |       8 |
| utf8mb4_spanish2_ci          | utf8mb4 |  238 |         | Yes      |       8 |
| utf8mb4_roman_ci             | utf8mb4 |  239 |         | Yes      |       8 |
| utf8mb4_persian_ci           | utf8mb4 |  240 |         | Yes      |       8 |
| utf8mb4_esperanto_ci         | utf8mb4 |  241 |         | Yes      |       8 |
| utf8mb4_hungarian_ci         | utf8mb4 |  242 |         | Yes      |       8 |
| utf8mb4_sinhala_ci           | utf8mb4 |  243 |         | Yes      |       8 |
| utf8mb4_german2_ci           | utf8mb4 |  244 |         | Yes      |       8 |
| utf8mb4_croatian_mysql561_ci | utf8mb4 |  245 |         | Yes      |       8 |
| utf8mb4_unicode_520_ci       | utf8mb4 |  246 |         | Yes      |       8 | <--
| utf8mb4_vietnamese_ci        | utf8mb4 |  247 |         | Yes      |       8 |
| utf8mb4_croatian_ci          | utf8mb4 |  608 |         | Yes      |       8 |
| utf8mb4_myanmar_ci           | utf8mb4 |  609 |         | Yes      |       8 |
| utf8mb4_thai_520_w2          | utf8mb4 |  610 |         | Yes      |       4 |
| utf8mb4_general_nopad_ci     | utf8mb4 | 1069 |         | Yes      |       1 |
| utf8mb4_nopad_bin            | utf8mb4 | 1070 |         | Yes      |       1 |
| utf8mb4_unicode_nopad_ci     | utf8mb4 | 1248 |         | Yes      |       8 |
| utf8mb4_unicode_520_nopad_ci | utf8mb4 | 1270 |         | Yes      |       8 |
+------------------------------+---------+------+---------+----------+---------+
33 rows in set (0.00 sec)

mysql> SHOW COLLATION LIKE 'utf8mb4%';

+------------------------------+---------+------+---------+----------+---------+

+------------------------------+---------+------+---------+----------+---------+

| utf8mb4_general_ci | utf8mb4 | 45 | Yes | Yes | 1 |

| utf8mb4_bin | utf8mb4 | 46 | | Yes | 1 |

| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 8 |

| utf8mb4_icelandic_ci | utf8mb4 | 225 | | Yes | 8 |

| utf8mb4_latvian_ci | utf8mb4 | 226 | | Yes | 8 |

| utf8mb4_romanian_ci | utf8mb4 | 227 | | Yes | 8 |

| utf8mb4_slovenian_ci | utf8mb4 | 228 | | Yes | 8 |

| utf8mb4_polish_ci | utf8mb4 | 229 | | Yes | 8 |

| utf8mb4_estonian_ci | utf8mb4 | 230 | | Yes | 8 |

| utf8mb4_spanish_ci | utf8mb4 | 231 | | Yes | 8 |

| utf8mb4_swedish_ci | utf8mb4 | 232 | | Yes | 8 |

| utf8mb4_turkish_ci | utf8mb4 | 233 | | Yes | 8 |

| utf8mb4_czech_ci | utf8mb4 | 234 | | Yes | 8 |

| utf8mb4_danish_ci | utf8mb4 | 235 | | Yes | 8 |

| utf8mb4_lithuanian_ci | utf8mb4 | 236 | | Yes | 8 |

| utf8mb4_slovak_ci | utf8mb4 | 237 | | Yes | 8 |

| utf8mb4_spanish2_ci | utf8mb4 | 238 | | Yes | 8 |

| utf8mb4_roman_ci | utf8mb4 | 239 | | Yes | 8 |

| utf8mb4_persian_ci | utf8mb4 | 240 | | Yes | 8 |

| utf8mb4_esperanto_ci | utf8mb4 | 241 | | Yes | 8 |

| utf8mb4_hungarian_ci | utf8mb4 | 242 | | Yes | 8 |

| utf8mb4_sinhala_ci | utf8mb4 | 243 | | Yes | 8 |

| utf8mb4_german2_ci | utf8mb4 | 244 | | Yes | 8 |

| utf8mb4_croatian_mysql561_ci | utf8mb4 | 245 | | Yes | 8 |

| utf8mb4_unicode_520_ci | utf8mb4 | 246 | | Yes | 8 | <--

| utf8mb4_vietnamese_ci | utf8mb4 | 247 | | Yes | 8 |

| utf8mb4_croatian_ci | utf8mb4 | 608 | | Yes | 8 |

| utf8mb4_myanmar_ci | utf8mb4 | 609 | | Yes | 8 |

| utf8mb4_thai_520_w2 | utf8mb4 | 610 | | Yes | 4 |

| utf8mb4_general_nopad_ci | utf8mb4 | 1069 | | Yes | 1 |

| utf8mb4_nopad_bin | utf8mb4 | 1070 | | Yes | 1 |

| utf8mb4_unicode_nopad_ci | utf8mb4 | 1248 | | Yes | 8 |

| utf8mb4_unicode_520_nopad_ci | utf8mb4 | 1270 | | Yes | 8 |

+------------------------------+---------+------+---------+----------+---------+

33 rows in set (0.00 sec)

目前暂时没打算修改主服务器上的数据库，暂时等 MariaDB 更新吧。

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