android 通过WebView与javascript实现数据交互

在看懂这篇文章之前首先要有javascript基础。

(1) js调用android的方法:

WebView wView;

wView. addJavascriptInterface (Object obj, String interfaceName);

是实例化一个对象,在html的js中调用,第二个参数是实例化对象的别名,如果要使用这个obj,则在js中使用的名字

就是interfaceName。

public class jsWebDemo extends Activity {   
    WebView wView;

    /** Called when the activity is first created. */  
    @Override  
    public void onCreate(Bundle savedInstanceState) {   
        super.onCreate(savedInstanceState);   
        setContentView(R.layout.main);    
        wView = (WebView)findViewById(R.id.wv1);   
           
       WebSettings wSet = wView.getSettings();   
        wSet.setJavaScriptEnabled(true);  

        ProxyBridge pBridge = new ProxyBridge();   
        wView.addJavascriptInterface(pBridge, "AliansBridge");   
         
        wView.loadUrl("file:///android_asset/index.html");   
           
    }   
  
 private class ProxyBridge {   
  public int one () {   
   return 1;   
  }   
 }   
  
} 

来看一下index.html的内容:

 
<html>
  <mce:script language="javascript"><!--
  
        /* This function is invoked by the activity */   
        function wave() {   
            alert("1");   
            document.getElementById("droid").src="android_waving.png";   
            alert("2");   
        }   
    
// --></mce:script>
<body>      
<div id="output">Test page.</div>      

<a onClick="window.demo.clickOnAndroid()">
 <div style="width:100px;   
            margin:0px auto;   
            padding:10px;   
            text-align:center;   
            border:2px solid #202020;" >  
                <img id="droid" src="android_normal.png" mce_src="android_normal.png"/><br>  
                Click me!   
        </div>
 </a> 
<input type="submit" value="change to 1" onclick="document.getElementById('output').innerHTML 

=AliansBridge.one()" />      
</body>
</html> 

这里的AliansBridge即是调用的JAVA对象。

要注意的是,如果你只有一个方法需要被js调用只new一个对象就行:

ProxyBridge pBridge = new ProxyBridge();

wView.addJavascriptInterface(pBridge, "AliansBridge");

如果你需要调用好多个方法,就要把整个android程序所在的类本身实例化传递进去:

wView.addJavascriptInterface(this, "AliansBridge");

(2) android调用js的方法:wView.setWebChromeClient (WebChromeClient client)

要用到Handler更新UI,Handler mHandler = new Handler();

mWebView.setWebChromeClient(new MyWebChromeClient());                
    mWebView.addJavascriptInterface(new Object(){
    /**      
     * This is not called on the UI thread. Post a runnable to invoke      
     * loadUrl on the UI thread.      
     */        
    public void clickOnAndroid() {        
        mHandler.post(new Runnable() {         
            public void run() {         
                mWebView.loadUrl("javascript:wave()");         
            }         
        });                 
    } 
 }, "demo");

同理,在html中必须有一个名为demo的对象调用clickOnAndroid()方法。

/**      
 * Provides a hook for calling "alert" from javascript. Useful for      
 * debugging your javascript.      
 */        
final class MyWebChromeClient extends WebChromeClient {         
    @Override     
    public boolean onJsAlert(WebView view, String url, String message,      
            JsResult result) {                      
        result.confirm();       
    return super.onJsAlert(view, url, message, result);                        
    } 
}

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