如何让javascript调用android中的函数？

本篇通过一个实例来说明如何在javascript中去调用android的函数，其实方法也比较简单，只要调用addJavascriptInterface方法即可映射一个java对象到javascript对象。

Android代码

        package com.macernow.djstava;

        import android.support.v7.app.ActionBarActivity;
        import android.os.Bundle;
        import android.util.Log;
        import android.view.Menu;
        import android.view.MenuItem;
        import android.webkit.JavascriptInterface;
        import android.webkit.WebView;


        public class MainActivity extends ActionBarActivity {

     private static final String TAG = "MainActivity";
     private WebView webView;

        @Override
     protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            webView = (WebView)findViewById(R.id.webView);
            webView.getSettings().setJavaScriptEnabled(true);
            webView.addJavascriptInterface(this,"djstava");
            webView.loadUrl("");

        }

        @JavascriptInterface
     public void jsextent() {
     Log.e(TAG,"========== js extension success.");
     }

        @Override
     public boolean onCreateOptionsMenu(Menu menu) {
     // Inflate the menu; this adds items to the action bar if it is present.
            getMenuInflater().inflate(R.menu.menu_main, menu);
     return true;
     }

        @Override
     public boolean onOptionsItemSelected(MenuItem item) {
     // Handle action bar item clicks here. The action bar will
     // automatically handle clicks on the Home/Up button, so long
     // as you specify a parent activity in AndroidManifest.xml.
     int id = item.getItemId();

     //noinspection SimplifiableIfStatement
     if (id == R.id.action_settings) {
     return true;
     }

     return super.onOptionsItemSelected(item);
            }
     }

WebView一定要使能javascript。在Android 4.2之后，抛出给javascript的java方法必须加上@JavascriptInterface。

布局文件

<RelativeLayout xmlns:android=""
        xmlns:tools="" android:layout_width="match_parent"
        android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
        android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

     <WebView
            android:id="@+id/webView"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent">
     </WebView>
</RelativeLayout>

测试调用

在javascript脚本中调用java方法

window.djstava.jsextent()

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