背景介绍
Android下面WebView开发，有时候需要调用底层的一部分接口，而这部分接口只有Android的SDK才提供相关的功能，这个时候就需要进行Java与JavaScript通信。
例子
- 生成JavaScript调用Java函数的接口类
public class AndroidJavaScript { @JavascriptInterface public String getJavaString() { return new String("JavaString"); } } - 开启 JavaScript支持，并向WebView注册接口
mWebView.getSettings().setJavaScriptEnabled(true); mWebView.addJavascriptInterface(new AndroidJavaScript(), "Android");
- Html中调用接口例子
<html> <head> <script type="text/javascript"> var JavaString = window.Android.getJavaString() document.write(JavaString); </script> </head> </html>
- 销毁的时候，反注册接口，避免内存泄漏
mWebView.removeJavascriptInterface("Android"); - 销毁的时候，WebView从父容器中移除，避免内存泄漏
ViewParent viewParent = mWebView.getParent(); if(viewParent instanceof ViewGroup) { ViewGroup viewGroup = (ViewGroup)viewParent; viewGroup.removeView(mWebView); } mWebView.destroy();
完整的例子代码如下（包含WebView的XML布局文件，请自行生成）：
import android.app.Activity;
import android.os.Bundle;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.webkit.JavascriptInterface;
import android.webkit.WebSettings;
import android.webkit.WebView;
public class MainActivity extends Activity {
WebView mWebView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mWebView = (WebView)findViewById(R.id.jsBridgeWebView);
WebSettings webSettings = mWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
mWebView.addJavascriptInterface(new AndroidJavaScript(), mJsInterfaceName);
mWebView.loadDataWithBaseURL("blarg://ignored", mJsHtml, "text/html", "UTF-8", "");
}
@Override
protected void onDestroy() {
mWebView.removeJavascriptInterface(mJsInterfaceName);
ViewParent viewParent = mWebView.getParent();
if(viewParent instanceof ViewGroup) {
ViewGroup viewGroup = (ViewGroup)viewParent;
viewGroup.removeView(mWebView);
}
mWebView.destroy();
super.onDestroy();
}
private static class AndroidJavaScript {
@JavascriptInterface
public String getString() {
return new String("JavaString");
}
}
private final String mJsInterfaceName = "Android";
private final String mJsHtml = "<html>\n" +
"\t<head>\n" +
"\t\t<script type=\"text/javascript\">\n" +
"\t\t\tvar str = window.Android.getString()\r\n" +
"\t\t\tdocument.write(str)\n" +
"\t\t</script>\n" +
"\t</head>\n" +
"</html>";
}