安卓中webview与javascript的交互

来源:互联网 时间:1970-01-01

WebView和js的交互包含两方面,一是在html中通过js调用安卓的java代码;二是在安卓java代码中调用js。

html中通过js调用java代码

js中调用java代码其实就记住一点,webview设置一个和js交互的接口(注意这里只是一般的意思,并不是java中接口的含义),这个接口其实是一个一般的类,同时为这个接口取一个别名。这个过程如下:

mWebView.addJavascriptInterface(new DemoJavaScriptInterface(), "demo");new DemoJavaScriptInterface就是这个接口,demo就是这个接口的别名。

上面的代码执行之后在html的js中就能通过别名(这里是“demo”)来调用newDemoJavaScriptInterface类中的任何方法。

但是因为安全问题,在Android4.2中(如果应用的android:targetSdkVersion数值为17+)JS只能访问带有 @JavascriptInterface注解的Java函数。因此如果你的开发版本比较高,需要在被调用的函数前加上@JavascriptInterface注解。

下面是谷歌给出的代码示例:

WebViewDemo.java

package com.google.android.webviewdemo;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.util.Log;import android.webkit.JsResult;import android.webkit.WebChromeClient;import android.webkit.WebSettings;import android.webkit.WebView;/** * Demonstrates how to embed a WebView in your activity. Also demonstrates how * to have javascript in the WebView call into the activity, and how the activity * can invoke javascript. * <p> * In this example, clicking on the android in the WebView will result in a call into * the activities code in {@link DemoJavaScriptInterface#clickOnAndroid()}. This code * will turn around and invoke javascript using the {@link WebView#loadUrl(String)} * method. * <p> * Obviously all of this could have been accomplished without calling into the activity * and then back into javascript, but this code is intended to show how to set up the * code paths for this sort of communication. * */public class WebViewDemo extends Activity { private static final String LOG_TAG = "WebViewDemo"; private WebView mWebView; private Handler mHandler = new Handler(); @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); setContentView(R.layout.main); mWebView = (WebView) findViewById(R.id.webview); WebSettings webSettings = mWebView.getSettings(); webSettings.setSavePassword(false); webSettings.setSaveFormData(false); webSettings.setJavaScriptEnabled(true); webSettings.setSupportZoom(false); mWebView.setWebChromeClient(new MyWebChromeClient()); mWebView.addJavascriptInterface(new DemoJavaScriptInterface(), "demo"); mWebView.loadUrl("file:///android_asset/demo.html"); } final class DemoJavaScriptInterface { DemoJavaScriptInterface() { } /** * 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()"); } }); } } /** * 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) { Log.d(LOG_TAG, message); result.confirm(); return true; } }}

demo.html

<html> <script language="javascript"> /* This function is invoked by the activity */ function wave() { alert("1"); document.getElementById("droid").src="android_waving.png"; alert("2"); } </script> <body> <!-- Calls into the javascript interface for the activity --> <a onClick="window.demo.clickOnAndroid()"><div style="width:80px; margin:0px auto; padding:10px; text-align:center; border:2px solid #202020;" > <img id="droid" src="android_normal.png"/><br> Click me! </div></a> </body></html>

main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/intro" android:padding="4dip" android:textSize="16sp" /> <WebView android:id="@+id/webview" android:layout_width="fill_parent" android:layout_height="0dip" android:layout_weight="1" /></LinearLayout>

android调用js

上面的代码在演示如何在js中调用java代码的同时也演示了如何在java中调用js

调用形式:
mWebView.loadUrl("javascript:wave()");

其中wave()是js中的一个方法,当然你可以把这个方法改成其他的方法,也就是android调用其他的方法。



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