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

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1.         package com.macernow.djstava;
   
2. 
   
3.         import android.support.v7.app.ActionBarActivity;
   
4.         import android.os.Bundle;
   
5.         import android.util.Log;
   
6.         import android.view.Menu;
   
7.         import android.view.MenuItem;
   
8.         import android.webkit.JavascriptInterface;
   
9.         import android.webkit.WebView;
   
10.     
    
11.     
    
12.         public class MainActivity extends ActionBarActivity {
    
13. 
    
14.      private static final String TAG = "MainActivity";
    
15.      private WebView webView;
    
16. 
    
17.      @Override
    
18.      protected void onCreate(Bundle savedInstanceState) {
    
19.      super.onCreate(savedInstanceState);
    
20.      setContentView(R.layout.activity_main);
    
21. 
    
22.      webView = (WebView)findViewById(R.id.webView);
    
23.      webView.getSettings().setJavaScriptEnabled(true);
    
24.      webView.addJavascriptInterface(this,"djstava");
    
25.      webView.loadUrl("http://192.168.31.109/demo.html");
    
26. 
    
27.         }
    
28. 
    
29.      @JavascriptInterface
    
30.      public void jsextent() {
    
31.      Log.e(TAG,"========== js extension success.");
    
32.      }
    
33. 
    
34.      @Override
    
35.      public boolean onCreateOptionsMenu(Menu menu) {
    
36.      // Inflate the menu; this adds items to the action bar if it is present.
    
37.      getMenuInflater().inflate(R.menu.menu_main, menu);
    
38.      return true;
    
39.      }
    
40. 
    
41.      @Override
    
42.      public boolean onOptionsItemSelected(MenuItem item) {
    
43.      // Handle action bar item clicks here. The action bar will
    
44.      // automatically handle clicks on the Home/Up button, so long
    
45.      // as you specify a parent activity in AndroidManifest.xml.
    
46.      int id = item.getItemId();
    
47. 
    
48.      //noinspection SimplifiableIfStatement
    
49.      if (id == R.id.action_settings) {
    
50.      return true;
    
51.      }
    
52. 
    
53.      return super.onOptionsItemSelected(item);
    
54.          }
    
55.      }

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

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1. <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   
2.      xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
   
3.      android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
   
4.      android:paddingRight="@dimen/activity_horizontal_margin"
   
5.      android:paddingTop="@dimen/activity_vertical_margin"
   
6.      android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
   
7.     
   
8.      <WebView
   
9.      android:id="@+id/webView"
   
10.      android:layout_width="fill_parent"
    
11.      android:layout_height="fill_parent">
    
12.      </WebView>
    
13. </RelativeLayout>

测试调用

在javascript脚本中调用java方法

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1. window.djstava.jsextent()

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