深海游弋的鱼 – 第 49 页 – 智障儿童欢乐多

Android获取设备DNS服务器列表

import android.annotation.TargetApi;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.LinkProperties;
import android.net.Network;
import android.net.NetworkInfo;
import android.net.RouteInfo;
import android.os.Build;
import android.util.Log;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.LineNumberReader;
import java.lang.reflect.Method;
import java.net.InetAddress;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * DNS servers detector
 * 
 * IMPORTANT: don't cache the result.
 * 
 * Or if you want to cache the result make sure you invalidate the cache
 * on any network change.
 * 
 * It is always better to use a new instance of the detector when you need
 * current DNS servers otherwise you may get into troubles because of invalid/changed
 * DNS servers.
 * 
 * This class combines various methods and solutions from:
 * Dnsjava http://www.xbill.org/dnsjava/
 * Minidns https://github.com/MiniDNS/minidns
 * 
 * Unfortunately both libraries are not aware of Orero changes so new method was added to fix this.
 * 
 * Created by Madalin Grigore-Enescu on 2/24/18.
 */

public class DnsServersDetector {

private static final String TAG = "DnsServersDetector";

/**
     * Holds some default DNS servers used in case all DNS servers detection methods fail.
     * Can be set to null if you want caller to fail in this situation.
     */
    private static final String[] FACTORY_DNS_SERVERS = {
            "8.8.8.8",
            "8.8.4.4"
    };

/**
     * Properties delimiter used in exec method of DNS servers detection
     */
    private static final String METHOD_EXEC_PROP_DELIM = "]: [";

/**
     * Holds context this was created under
     */
    private Context context;

//region - public //////////////////////////////////////////////////////////////////////////////
    ////////////////////////////////////////////////////////////////////////////////////////////////

/**
     * Constructor
     */
    public DnsServersDetector(Context context) {
        this.context = context;
    }

/**
     * Returns android DNS servers used for current connected network
     *
     * @return Dns servers array
     */
    public String[] getServers() {
        // METHOD 1: old deprecated system properties
        String[] result = getServersMethodSystemProperties();
        if (result != null && result.length > 0) {
            return result;
        }
        // METHOD 2 - use connectivity manager
        result = getServersMethodConnectivityManager();
        if (result != null && result.length > 0) {
            return result;
        }
        // LAST METHOD: detect android DNS servers by executing getprop string command in a separate process
        // This method fortunately works in Oreo too but many people may want to avoid exec
        // so it's used only as a failsafe scenario
        result = getServersMethodExec();
        if (result != null && result.length > 0) {
            return result;
        }
        // Fall back on factory DNS servers
        return FACTORY_DNS_SERVERS;
    }

//endregion

//region - private /////////////////////////////////////////////////////////////////////////////
    ////////////////////////////////////////////////////////////////////////////////////////////////

/**
 * Detect android DNS servers by using connectivity manager
 * 
 * This method is working in android LOLLIPOP or later
 *
 * @return Dns servers array
 */
 private String[] getServersMethodConnectivityManager() {

// This code only works on LOLLIPOP and higher
 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
 try {
 final ArrayList<String> priorityServersArrayList = new ArrayList<>();
 final ArrayList<String> serversArrayList = new ArrayList<>();
 final ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(android.content.Context.CONNECTIVITY_SERVICE);
 if (connectivityManager != null) {
 // Iterate all networks
 // Notice that android LOLLIPOP or higher allow iterating multiple connected networks of SAME type
 for (Network network : connectivityManager.getAllNetworks()) {
 final NetworkInfo networkInfo = connectivityManager.getNetworkInfo(network);
 if (networkInfo.isConnected()) {
 final LinkProperties linkProperties = connectivityManager.getLinkProperties(network);
 final List<InetAddress> dnsServersList = linkProperties.getDnsServers();
 // Prioritize the DNS servers for link which have a default route
 if (linkPropertiesHasDefaultRoute(linkProperties)) {
 for (InetAddress element : dnsServersList) {
 final String dnsHost = element.getHostAddress();
 priorityServersArrayList.add(dnsHost);
 }
 } else {
 for (InetAddress element : dnsServersList) {
 final String dnsHost = element.getHostAddress();
 serversArrayList.add(dnsHost);
 }
 }
 }
 }
 }

// Append secondary arrays only if priority is empty
                if (priorityServersArrayList.isEmpty()) {
                    priorityServersArrayList.addAll(serversArrayList);
                }

// Stop here if we have at least one DNS server
                if (priorityServersArrayList.size() > 0) {
                    return priorityServersArrayList.toArray(new String[0]);
                }
            } catch (Exception ex) {
                Log.d(TAG, "Exception detecting DNS servers using ConnectivityManager method", ex);
            }
        }
        // Failure
        return null;
    }

/**
 * Detect android DNS servers by using old deprecated system properties
 * 
 * This method is NOT working anymore in Android 8.0
 * Official Android documentation state this in the article Android 8.0 Behavior Changes.
 * The system properties net.dns1, net.dns2, net.dns3, and net.dns4 are no longer available,
 * a change that improves privacy on the platform.
 * 
 * https://developer.android.com/about/versions/oreo/android-8.0-changes.html#o-pri
 *
 * @return Dns servers array
 */
 private String[] getServersMethodSystemProperties() {
 if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
 // This originally looked for all lines containing .dns; but
 // http://code.google.com/p/android/issues/detail?id=2207#c73
 // indicates that net.dns* should always be the active nameservers, so
 // we use those.
 final String re1 = "^\\d+(\\.\\d+){3}$";
 final String re2 = "^[0-9a-f]+(:[0-9a-f]*)+:[0-9a-f]+$";
 ArrayList<String> serversArrayList = new ArrayList<>();
 try {
 Class<?> SystemProperties = Class.forName("android.os.SystemProperties");
 Method method = SystemProperties.getMethod("get", new Class[]{String.class});
 final String[] netdns = new String[]{"net.dns1", "net.dns2", "net.dns3", "net.dns4"};
 for (String netdn : netdns) {
 Object[] args = new Object[]{netdn};
 String v = (String) method.invoke(null, args);
 if (v != null && (v.matches(re1) || v.matches(re2)) && !serversArrayList.contains(v)) {
 serversArrayList.add(v);
 }
 }

// Stop here if we have at least one DNS server
                if (serversArrayList.size() > 0) {
                    return serversArrayList.toArray(new String[0]);
                }
            } catch (Exception e) {
                Log.d(TAG, "Exception detecting DNS servers using SystemProperties method", e);
            }
        }
        // Failed
        return null;
    }

/**
 * Detect android DNS servers by executing getprop string command in a separate process
 * 
 * Notice there is an android bug when Runtime.exec() hangs without providing a Process object.
 * This problem is fixed in Jelly Bean (Android 4.1) but not in ICS (4.0.4) and probably it will never be fixed in ICS.
 * https://stackoverflow.com/questions/8688382/runtime-exec-bug-hangs-without-providing-a-process-object/11362081
 *
 * @return Dns servers array
 */
 private String[] getServersMethodExec() {
 // We are on the safe side and avoid any bug
 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
 try {
 Process process = Runtime.getRuntime().exec("getprop");
 InputStream inputStream = process.getInputStream();
 LineNumberReader lineNumberReader = new LineNumberReader(new InputStreamReader(inputStream));
 Set<String> serversSet = methodExecParseProps(lineNumberReader);
 if (serversSet != null && serversSet.size() > 0) {
 return serversSet.toArray(new String[0]);
 }
 } catch (Exception e) {
 Log.d(TAG, "Exception in getServersMethodExec", e);
 }
 }
 // Failed
 return null;
 }

/**
 * Parse properties produced by executing getprop command
 *
 * @param lineNumberReader lineNumberReader
 * @return Set of parsed properties
 * @throws Exception Exception
 */
 private Set<String> methodExecParseProps(BufferedReader lineNumberReader) throws Exception {
 String line;
 Set<String> serversSet = new HashSet<String>(10);
 while ((line = lineNumberReader.readLine()) != null) {
 int split = line.indexOf(METHOD_EXEC_PROP_DELIM);
 if (split == -1) {
 continue;
 }
 String property = line.substring(1, split);

int valueStart = split + METHOD_EXEC_PROP_DELIM.length();
 int valueEnd = line.length() - 1;
 if (valueEnd < valueStart) {
 // This can happen if a newline sneaks in as the first character of the property value. For example
 // "[propName]: [\n…]".
 Log.d(TAG, "Malformed property detected: \"" + line + '"');
 continue;
 }

String value = line.substring(valueStart, valueEnd);

if (value.isEmpty()) {
                continue;
            }

if (property.endsWith(".dns") || property.endsWith(".dns1") ||
                property.endsWith(".dns2") || property.endsWith(".dns3") ||
                property.endsWith(".dns4")) {

// normalize the address
                InetAddress ip = InetAddress.getByName(value);
                if (ip == null) continue;
                value = ip.getHostAddress();

if (value == null) continue;
                if (value.length() == 0) continue;

serversSet.add(value);
            }
        }
        return serversSet;
    }

/**
     * Returns true if the specified link properties have any default route
     *
     * @param linkProperties linkProperties
     * @return true if the specified link properties have default route or false otherwise
     */
    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    private boolean linkPropertiesHasDefaultRoute(LinkProperties linkProperties) {
        for (RouteInfo route : linkProperties.getRoutes()) {
            if (route.isDefaultRoute()) {
                return true;
            }
        }
        return false;
    }
    //endregion
}

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import android.annotation.TargetApi;

import android.content.Context;

import android.net.ConnectivityManager;

import android.net.LinkProperties;

import android.net.Network;

import android.net.NetworkInfo;

import android.net.RouteInfo;

import android.os.Build;

import android.util.Log;

import java.io.BufferedReader;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.LineNumberReader;

import java.lang.reflect.Method;

import java.net.InetAddress;

import java.util.ArrayList;

import java.util.HashSet;

import java.util.List;

import java.util.Set;

/**

* DNS servers detector

*

* IMPORTANT: don't cache the result.

*

* Or if you want to cache the result make sure you invalidate the cache

* on any network change.

*

* It is always better to use a new instance of the detector when you need

* current DNS servers otherwise you may get into troubles because of invalid/changed

* DNS servers.

*

* This class combines various methods and solutions from:

* Dnsjava http://www.xbill.org/dnsjava/

* Minidns https://github.com/MiniDNS/minidns

*

* Unfortunately both libraries are not aware of Orero changes so new method was added to fix this.

*

* Created by Madalin Grigore-Enescu on 2/24/18.

public class DnsServersDetector {

private static final String TAG = "DnsServersDetector";

/**

* Holds some default DNS servers used in case all DNS servers detection methods fail.

* Can be set to null if you want caller to fail in this situation.

private static final String[] FACTORY_DNS_SERVERS = {

"8.8.8.8",

"8.8.4.4"

};

/**

* Properties delimiter used in exec method of DNS servers detection

private static final String METHOD_EXEC_PROP_DELIM = "]: [";

/**

* Holds context this was created under

private Context context;

//region - public //////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////////////////////

/**

* Constructor

public DnsServersDetector(Context context) {

this.context = context;

}

/**

* Returns android DNS servers used for current connected network

* @return Dns servers array

public String[] getServers() {

// METHOD 1: old deprecated system properties

String[] result = getServersMethodSystemProperties();

if (result != null && result.length > 0) {

return result;

}

// METHOD 2 - use connectivity manager

result = getServersMethodConnectivityManager();

if (result != null && result.length > 0) {

return result;

}

// LAST METHOD: detect android DNS servers by executing getprop string command in a separate process

// This method fortunately works in Oreo too but many people may want to avoid exec

// so it's used only as a failsafe scenario

result = getServersMethodExec();

if (result != null && result.length > 0) {

return result;

}

// Fall back on factory DNS servers

return FACTORY_DNS_SERVERS;

}

//endregion

//region - private /////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////////////////////

/**

* Detect android DNS servers by using connectivity manager

*

* This method is working in android LOLLIPOP or later

* @return Dns servers array

private String[] getServersMethodConnectivityManager() {

// This code only works on LOLLIPOP and higher

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {

try {

final ArrayList<String> priorityServersArrayList = new ArrayList<>();

final ArrayList<String> serversArrayList = new ArrayList<>();

final ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(android.content.Context.CONNECTIVITY_SERVICE);

if (connectivityManager != null) {

// Iterate all networks

// Notice that android LOLLIPOP or higher allow iterating multiple connected networks of SAME type

for (Network network : connectivityManager.getAllNetworks()) {

final NetworkInfo networkInfo = connectivityManager.getNetworkInfo(network);

if (networkInfo.isConnected()) {

final LinkProperties linkProperties = connectivityManager.getLinkProperties(network);

final List<InetAddress> dnsServersList = linkProperties.getDnsServers();

// Prioritize the DNS servers for link which have a default route

if (linkPropertiesHasDefaultRoute(linkProperties)) {

for (InetAddress element : dnsServersList) {

final String dnsHost = element.getHostAddress();

priorityServersArrayList.add(dnsHost);

}

} else {

for (InetAddress element : dnsServersList) {

final String dnsHost = element.getHostAddress();

serversArrayList.add(dnsHost);

}

// Append secondary arrays only if priority is empty

if (priorityServersArrayList.isEmpty()) {

priorityServersArrayList.addAll(serversArrayList);

}

// Stop here if we have at least one DNS server

if (priorityServersArrayList.size() > 0) {

return priorityServersArrayList.toArray(new String[0]);

}

} catch (Exception ex) {

Log.d(TAG, "Exception detecting DNS servers using ConnectivityManager method", ex);

}

// Failure

return null;

}

/**

* Detect android DNS servers by using old deprecated system properties

*

* This method is NOT working anymore in Android 8.0

* Official Android documentation state this in the article Android 8.0 Behavior Changes.

* The system properties net.dns1, net.dns2, net.dns3, and net.dns4 are no longer available,

* a change that improves privacy on the platform.

*

* https://developer.android.com/about/versions/oreo/android-8.0-changes.html#o-pri

* @return Dns servers array

private String[] getServersMethodSystemProperties() {

if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {

// This originally looked for all lines containing .dns; but

// http://code.google.com/p/android/issues/detail?id=2207#c73

// indicates that net.dns* should always be the active nameservers, so

// we use those.

final String re1 = "^\\d+(\\.\\d+){3}$";

final String re2 = "^[0-9a-f]+(:[0-9a-f]*)+:[0-9a-f]+$";

ArrayList<String> serversArrayList = new ArrayList<>();

try {

Class<?> SystemProperties = Class.forName("android.os.SystemProperties");

Method method = SystemProperties.getMethod("get", new Class[]{String.class});

final String[] netdns = new String[]{"net.dns1", "net.dns2", "net.dns3", "net.dns4"};

for (String netdn : netdns) {

Object[] args = new Object[]{netdn};

String v = (String) method.invoke(null, args);

if (v != null && (v.matches(re1) || v.matches(re2)) && !serversArrayList.contains(v)) {

serversArrayList.add(v);

}

// Stop here if we have at least one DNS server

if (serversArrayList.size() > 0) {

return serversArrayList.toArray(new String[0]);

}

} catch (Exception e) {

Log.d(TAG, "Exception detecting DNS servers using SystemProperties method", e);

}

// Failed

return null;

}

/**

* Detect android DNS servers by executing getprop string command in a separate process

*

* Notice there is an android bug when Runtime.exec() hangs without providing a Process object.

* This problem is fixed in Jelly Bean (Android 4.1) but not in ICS (4.0.4) and probably it will never be fixed in ICS.

* https://stackoverflow.com/questions/8688382/runtime-exec-bug-hangs-without-providing-a-process-object/11362081

* @return Dns servers array

private String[] getServersMethodExec() {

// We are on the safe side and avoid any bug

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {

try {

Process process = Runtime.getRuntime().exec("getprop");

InputStream inputStream = process.getInputStream();

LineNumberReader lineNumberReader = new LineNumberReader(new InputStreamReader(inputStream));

Set<String> serversSet = methodExecParseProps(lineNumberReader);

if (serversSet != null && serversSet.size() > 0) {

return serversSet.toArray(new String[0]);

}

} catch (Exception e) {

Log.d(TAG, "Exception in getServersMethodExec", e);

}

// Failed

return null;

}

/**

* Parse properties produced by executing getprop command

* @param lineNumberReader lineNumberReader

* @return Set of parsed properties

* @throws Exception Exception

private Set<String> methodExecParseProps(BufferedReader lineNumberReader) throws Exception {

String line;

Set<String> serversSet = new HashSet<String>(10);

while ((line = lineNumberReader.readLine()) != null) {

int split = line.indexOf(METHOD_EXEC_PROP_DELIM);

if (split == -1) {

continue;

}

String property = line.substring(1, split);

int valueStart = split + METHOD_EXEC_PROP_DELIM.length();

int valueEnd = line.length() - 1;

if (valueEnd < valueStart) {

// This can happen if a newline sneaks in as the first character of the property value. For example

// "[propName]: [\n…]".

Log.d(TAG, "Malformed property detected: \"" + line + '"');

continue;

}

String value = line.substring(valueStart, valueEnd);

if (value.isEmpty()) {

continue;

}

if (property.endsWith(".dns") || property.endsWith(".dns1") ||

property.endsWith(".dns2") || property.endsWith(".dns3") ||

property.endsWith(".dns4")) {

// normalize the address

InetAddress ip = InetAddress.getByName(value);

if (ip == null) continue;

value = ip.getHostAddress();

if (value == null) continue;

if (value.length() == 0) continue;

serversSet.add(value);

}

return serversSet;

}

/**

* Returns true if the specified link properties have any default route

* @param linkProperties linkProperties

* @return true if the specified link properties have default route or false otherwise

@TargetApi(Build.VERSION_CODES.LOLLIPOP)

private boolean linkPropertiesHasDefaultRoute(LinkProperties linkProperties) {

for (RouteInfo route : linkProperties.getRoutes()) {

if (route.isDefaultRoute()) {

return true;

}

return false;

}

//endregion

}

参考链接

Android DNS更新与DNS-Prefetch

一、什么是DNS

DNS（Domain Name System，域名系统），dns用于将域名解析解析为ip地址。

例如：给你www.baidu.com的主机名，你给
我查出对应的ip地址：163.177.151.109。一些主机名还会有别名，如www.baidu.com就
有别名www.a.shifen.com，甚至不止一个别名，或一个别名有2个ip地址。在linux机子
上，运行nslookup（name service lookup）就是进行域名解析。如下面：

~$ nslookup www.baidu.com

Server: 127.0.0.1

Address: 127.0.0.1#53

Non-authoritative answer:

www.baidu.com canonical name = www.a.shifen.com.

Name: www.a.shifen.com

Address: 163.177.151.109

Name: www.a.shifen.com

Address: 163.177.151.110

DNS工作方式分为递归查询和迭代查询，具体可参考下图

继续阅读Android DNS更新与DNS-Prefetch

ubuntu 18.04 Apache2启用HTTP/2

HTTP/2 可以让我们的应用更快、更简单、更稳定 – 这几词凑到一块是很罕见的！HTTP/2 将很多以前我们在应用中针对 HTTP/1.1 想出来的“歪招儿”一笔勾销，把解决那些问题的方案内置在了传输层中。不仅如此，它还为我们进一步优化应用和提升性能提供了全新的机会！

——《Web 性能权威指南》

Ubuntu18.04 官方源已经包含带有HTTP2模块的 Apache/2.4.29 ，所以我们可以很简单的启用 HTTP2。

1	$ sudo a2enmod http2

首先启用 http2 模块，然后在虚拟主机的配置文件中或者在Apache2的全局配置文件中加入：

1	Protocols h2 http/1.1

当客户端支持时优先使用 HTTP2 ，其次是 http/1.1，表明了一种优先顺序。目前为止就已经启用完成了，但如果你是使用的 Apache2+PHP 架构的应用程序，由于 mpm_prefork 模块不支持 mod_http2，所以我们需要切换 mpm_prefork、mod_php 到 mpm_event 和 php-fpm 来解决这个问题。

# Install php-fpm and enable

$ sudo apt install php-fpm

$ sudo systemctl enable php7.2-fpm

# To enable PHP 7.2 FPM in Apache2

$ sudo a2enmod proxy_fcgi setenvif

$ sudo a2enconf php7.2-fpm

# First to disable PHP 7.2/ mpm_prefork to avoid conflicts,then enable.

$ sudo a2dismod php7.2 mpm_prefork

$ sudo a2enmod mpm_event

继续阅读ubuntu 18.04 Apache2启用HTTP/2

解决GitHub的raw.githubusercontent.com无法连接问题

https://site.ip138.com/raw.Githubusercontent.com/

输入raw.githubusercontent.com

查询IP地址

修改hosts Ubuntu，CentOS及macOS直接在终端输入

1	$ sudo vi /etc/hosts

添加以下内容保存即可（IP地址查询后相应修改，可以ping不同IP的延时选择最佳IP地址）

# GitHub Start
52.74.223.119 github.com
192.30.253.119 gist.github.com
54.169.195.247 api.github.com
185.199.111.153 assets-cdn.github.com
199.232.96.133 raw.githubusercontent.com
#151.101.76.133 raw.githubusercontent.com
151.101.108.133 user-images.githubusercontent.com
151.101.76.133 gist.githubusercontent.com
151.101.76.133 cloud.githubusercontent.com
151.101.76.133 camo.githubusercontent.com
151.101.76.133 avatars0.githubusercontent.com
151.101.76.133 avatars1.githubusercontent.com
151.101.76.133 avatars2.githubusercontent.com
151.101.76.133 avatars3.githubusercontent.com
151.101.76.133 avatars4.githubusercontent.com
151.101.76.133 avatars5.githubusercontent.com
151.101.76.133 avatars6.githubusercontent.com
151.101.76.133 avatars7.githubusercontent.com
151.101.76.133 avatars8.githubusercontent.com
# GitHub End

参考链接

ubuntu 20.04 & ubuntu18.04快速开启TCP BBR实现高效单边加速

Linux Kernel 内核升级到 4.9 及以上版本可以实现 BBR 加速，由于Ubuntu 18.04 默认的内核就是 4.15版本的内核，由于Ubuntu 20.04 默认的内核就是 5.4 版本的内核，并已经默认编译了 TCP BBR 模块，所以可以直接通过参数开启。

新的 TCP 拥塞控制算法 BBR (Bottleneck Bandwidth and RTT) 可以让服务器的带宽尽量跑慢，并且尽量不要有排队的情况，让网络服务更佳稳定和高效。

修改系统变量：

$ echo 'net.core.default_qdisc=fq' | sudo tee -a /etc/sysctl.conf

$ echo 'net.ipv4.tcp_congestion_control=bbr' | sudo tee -a /etc/sysctl.conf

保存生效

1	$ sudo sysctl -p

执行

1	$ sysctl net.ipv4.tcp_available_congestion_control

如果结果是这样

1 2	$ sysctl net.ipv4.tcp_available_congestion_control net.ipv4.tcp_available_congestion_control = bbr cubic reno

就开启了。执行 lsmod | grep bbr ，以检测 BBR 是否开启。

一般建议重启系统，重启后执行

1 2	$ sysctl net.ipv4.tcp_congestion_control net.ipv4.tcp_congestion_control = bbr

参考链接

【解决】Unable to locate adb

环境：Android Studio 4.0 打开虚拟设备时，弹出“Unable to locate adb”，如下图：

继续阅读【解决】Unable to locate adb

Flutter Flare(Rive)动画

Flare(Rive)是一家可以快速制Flutter SVG动画的网站，提供专门的Flutter Weight承载网站导出的动画文件，相当于Android的Lottie，Flare的首次出现非常惊艳，是在Flutter发布大会上，一下就火了。

继续阅读Flutter Flare(Rive)动画

flutter动态申请权限

https://pub.flutter-io.cn/packages/permission_handler

https://www.jianshu.com/p/fa68876fbdfd

例

Future requestPermission() async {

// 申请权限

Map<PermissionGroup, PermissionStatus> permissions =

await PermissionHandler().requestPermissions([PermissionGroup.storage]);

// 申请结果

PermissionStatus permission = await PermissionHandler()

.checkPermissionStatus(PermissionGroup.storage);

if (permission == PermissionStatus.granted) {

print("权限申请通过");

} else {

print("权限申请通过");

}

参考链接

flutter 动态申请权限

Flutter 1.22最新的多国语支持配置和使用

Flutter 1.22现已发布

最新版本中，随之发布了很多新的特性以及修复了一些BUG，现在我们说说其中的新的多国语插件。个人感觉新多国语操作，多了一些模板性的东西，但是也方便了很多东西。

话不多说，现在我们进入正题，如何使用新插件呢？

配置项目的yaml文件

dependencies:

flutter:

sdk: flutter

flutter_localizations: #配置多国语支持

sdk: flutter

intl: ^0.16.1 #多国语插件,要求高于0.16.1版本

flutter:

# The following line ensures that the Material Icons font is

# included with your application, so that you can use the icons in

# the material Icons class.

uses-material-design: true

generate: true #新增配置，自动多国语代码生成

继续阅读Flutter 1.22最新的多国语支持配置和使用

AAPT: error: resource android:attr/fontVariationSettings not found

最近在编译Flutter项目的时候，报错如下：

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:processDebugResources'.
> Android resource linking failed
  Output:  /Users/xxxx/Source/developer_quest/build/app/intermediates/incremental/mergeDebugResources/merged.dir/values/values.xml:86: error: resource android:attr/fontVariationSettings not found.
  /Users/xxxx/Source/developer_quest/build/app/intermediates/incremental/mergeDebugResources/merged.dir/values/values.xml:87: error: resource android:attr/ttcIndex not found.
  error: failed linking references.

Command: /Users/xxxx/.gradle/caches/transforms-1/files-1.1/aapt2-3.2.1-4818971-osx.jar/ace5a2b7765511437e6add51febae423/aapt2-3.2.1-4818971-osx/aapt2 link -I\
          /Users/xxxx/Library/Android/sdk/platforms/android-27/android.jar\
          --manifest\
          /Users/xxxx/Source/developer_quest/build/app/intermediates/merged_manifests/debug/processDebugManifest/merged/AndroidManifest.xml\
          -o\
          /Users/xxxx/Source/developer_quest/build/app/intermediates/processed_res/debug/processDebugResources/out/resources-debug.ap_\
          -R\
          @/Users/xxxx/Source/developer_quest/build/app/intermediates/incremental/processDebugResources/resources-list-for-resources-debug.ap_.txt\
          --auto-add-overlay\
          --java\
          /Users/xxxx/Source/developer_quest/build/app/generated/not_namespaced_r_class_sources/debug/processDebugResources/r\
          --custom-package\
          dev.flutter.devrpg\
          -0\
          apk\
          --output-text-symbols\
          /Users/xxxx/Source/developer_quest/build/app/intermediates/symbols/debug/R.txt\
          --no-version-vectors
  Daemon:  AAPT2 aapt2-3.2.1-4818971-osx Daemon #0
  Output:  /Users/xxxx/.gradle/caches/transforms-1/files-1.1/core-1.1.0.aar/becc1f5b1538f3fe61f1f959fb2bd672/res/values/values.xml:174:5-210:25: AAPT: error: resource android:attr/fontVariationSettings not found.

/Users/xxxx/.gradle/caches/transforms-1/files-1.1/core-1.1.0.aar/becc1f5b1538f3fe61f1f959fb2bd672/res/values/values.xml:174:5-210:25: AAPT: error: resource android:attr/ttcIndex not found.

error: failed linking references.
  Command: /Users/xxxx/.gradle/caches/transforms-1/files-1.1/aapt2-3.2.1-4818971-osx.jar/ace5a2b7765511437e6add51febae423/aapt2-3.2.1-4818971-osx/aapt2 link -I\
          /Users/xxxx/Library/Android/sdk/platforms/android-27/android.jar\
          --manifest\
          /Users/xxxx/Source/developer_quest/build/app/intermediates/merged_manifests/debug/processDebugManifest/merged/AndroidManifest.xml\
          -o\
          /Users/xxxx/Source/developer_quest/build/app/intermediates/processed_res/debug/processDebugResources/out/resources-debug.ap_\
          -R\
          @/Users/xxxx/Source/developer_quest/build/app/intermediates/incremental/processDebugResources/resources-list-for-resources-debug.ap_.txt\
          --auto-add-overlay\
          --java\
          /Users/xxxx/Source/developer_quest/build/app/generated/not_namespaced_r_class_sources/debug/processDebugResources/r\
          --custom-package\
          dev.flutter.devrpg\
          -0\
          apk\
          --output-text-symbols\
          /Users/xxxx/Source/developer_quest/build/app/intermediates/symbols/debug/R.txt\
          --no-version-vectors
  Daemon:  AAPT2 aapt2-3.2.1-4818971-osx Daemon #0

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 13s
Exception: Gradle task assembleDebug failed with exit code 1

FAILURE: Build failed with an exception.

* What went wrong:

Execution failed for task ':app:processDebugResources'.

> Android resource linking failed

Output: /Users/xxxx/Source/developer_quest/build/app/intermediates/incremental/mergeDebugResources/merged.dir/values/values.xml:86: error: resource android:attr/fontVariationSettings not found.

/Users/xxxx/Source/developer_quest/build/app/intermediates/incremental/mergeDebugResources/merged.dir/values/values.xml:87: error: resource android:attr/ttcIndex not found.

error: failed linking references.

Command: /Users/xxxx/.gradle/caches/transforms-1/files-1.1/aapt2-3.2.1-4818971-osx.jar/ace5a2b7765511437e6add51febae423/aapt2-3.2.1-4818971-osx/aapt2 link -I\

/Users/xxxx/Library/Android/sdk/platforms/android-27/android.jar\

--manifest\

/Users/xxxx/Source/developer_quest/build/app/intermediates/merged_manifests/debug/processDebugManifest/merged/AndroidManifest.xml\

-o\

/Users/xxxx/Source/developer_quest/build/app/intermediates/processed_res/debug/processDebugResources/out/resources-debug.ap_\

-R\

@/Users/xxxx/Source/developer_quest/build/app/intermediates/incremental/processDebugResources/resources-list-for-resources-debug.ap_.txt\

--auto-add-overlay\

--java\

/Users/xxxx/Source/developer_quest/build/app/generated/not_namespaced_r_class_sources/debug/processDebugResources/r\

--custom-package\

dev.flutter.devrpg\

-0\

apk\

--output-text-symbols\

/Users/xxxx/Source/developer_quest/build/app/intermediates/symbols/debug/R.txt\

--no-version-vectors

Daemon: AAPT2 aapt2-3.2.1-4818971-osx Daemon #0

Output: /Users/xxxx/.gradle/caches/transforms-1/files-1.1/core-1.1.0.aar/becc1f5b1538f3fe61f1f959fb2bd672/res/values/values.xml:174:5-210:25: AAPT: error: resource android:attr/fontVariationSettings not found.

/Users/xxxx/.gradle/caches/transforms-1/files-1.1/core-1.1.0.aar/becc1f5b1538f3fe61f1f959fb2bd672/res/values/values.xml:174:5-210:25: AAPT: error: resource android:attr/ttcIndex not found.

error: failed linking references.

Command: /Users/xxxx/.gradle/caches/transforms-1/files-1.1/aapt2-3.2.1-4818971-osx.jar/ace5a2b7765511437e6add51febae423/aapt2-3.2.1-4818971-osx/aapt2 link -I\

/Users/xxxx/Library/Android/sdk/platforms/android-27/android.jar\

--manifest\

/Users/xxxx/Source/developer_quest/build/app/intermediates/merged_manifests/debug/processDebugManifest/merged/AndroidManifest.xml\

-o\

/Users/xxxx/Source/developer_quest/build/app/intermediates/processed_res/debug/processDebugResources/out/resources-debug.ap_\

-R\

@/Users/xxxx/Source/developer_quest/build/app/intermediates/incremental/processDebugResources/resources-list-for-resources-debug.ap_.txt\

--auto-add-overlay\

--java\

/Users/xxxx/Source/developer_quest/build/app/generated/not_namespaced_r_class_sources/debug/processDebugResources/r\

--custom-package\

dev.flutter.devrpg\

-0\

apk\

--output-text-symbols\

/Users/xxxx/Source/developer_quest/build/app/intermediates/symbols/debug/R.txt\

--no-version-vectors

Daemon: AAPT2 aapt2-3.2.1-4818971-osx Daemon #0

* Try:

Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 13s

Exception: Gradle task assembleDebug failed with exit code 1

解决方案：

try to change the compileSdkVersion above 27:

compileSdkVersion 28

参考链接

resource android:attr/fontVariationSettings not found

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