Android WebView的加载超时处理
jopen
9年前
android项目中有这样一个需求：android中webView加载网页时，加 一个链接超时处理，翻阅google官方api，非常奇怪的是Google竟然没有超时的这项设置。随后又Google到处查阅有没有现成的例子，结果还 是一无所获。最后，不得不自己来写一个。废话不多说了，直接上代码。
package com.test.js2java; import java.util.Timer; import java.util.TimerTask; import android.app.Activity; import android.graphics.Bitmap; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.util.Log; import android.view.Window; import android.webkit.WebSettings; import android.webkit.WebView; import android.webkit.WebViewClient; public class TestJsActivity extends Activity { private long timeout = 5000; private WebView mWebView; private Handler mHandler = new Handler(); private Timer timer; @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.main); mWebView = (WebView) findViewById(R.id.webview); WebSettings webSettings = mWebView.getSettings(); webSettings.setJavaScriptEnabled(true); webSettings.setAllowFileAccess(true); mWebView.setWebViewClient(new WebViewClient() { /* * 创建一个WebViewClient,重写onPageStarted和onPageFinished * * * onPageStarted中启动一个计时器,到达设置时间后利用handle发送消息给activity执行超时后的动作. * */ @Override public void onPageStarted(WebView view, String url, Bitmap favicon) { Log.d("testTimeout", "onPageStarted..........."); // TODO Auto-generated method stub super.onPageStarted(view, url, favicon); timer = new Timer(); TimerTask tt = new TimerTask() { @Override public void run() { /* * 超时后,首先判断页面加载进度,超时并且进度小于100,就执行超时后的动作 */ if (TestJsActivity.this.mWebView.getProgress() < 100) { Log.d("testTimeout", "timeout..........."); Message msg = new Message(); msg.what = 1; mHandler.sendMessage(msg); timer.cancel(); timer.purge(); } } }; timer.schedule(tt, timeout, 1); } /** * onPageFinished指页面加载完成,完成后取消计时器 */ @Override public void onPageFinished(WebView view, String url) { // TODO Auto-generated method stub super.onPageFinished(view, url); Log.d("testTimeout", "onPageFinished+++++++++++++++++++++++++"); Log.d("testTimeout", "+++++++++++++++++++++++++" + TestJsActivity.this.mWebView.getProgress()); timer.cancel(); timer.purge(); } }); mWebView.loadUrl("http://image.baidu.com/i?ct=201326592&cl=2&nc=1&lm=-1&st=-1&tn=baiduimage&istype=2&fm=index&pv=&z=0&word=%D7%C0%C3%E6&s=0"); } }其中要注意的是onPageFinished的两点，第一点，官方是这样解释的：
Notify the host application that a page has finished loading. This method is called only for main frame. When onPageFinished() is called, the rendering picture may not be updated yet. To get the notification for the new Picture, use onNewPicture(WebView, Picture).
也就是说，程序只认为DOM加载完成就完成了，正在加载的图片不在这个范围之内。
第二点是，如果在JS文件中又动态去加载另一JS，onPageFinished方法会在所有的JS全部加载完毕后才调用。
最近又在研究PhoneGap，突然发现它里面也有个超时处理。顺便贴上关键代码
public class DroidGap extends Activity implements CordovaInterface { // Flag indicates that a loadUrl timeout occurred int loadUrlTimeout = 0; // LoadUrl timeout value in msec (default of 20 sec) protected int loadUrlTimeoutValue = 20000; ........... // Load URL on UI thread final DroidGap me = this; // Create a timeout timer for loadUrl final int currentLoadUrlTimeout = me.loadUrlTimeout; Runnable runnable = new Runnable() { public void run() { try { synchronized(this) { wait(me.loadUrlTimeoutValue); } } catch (InterruptedException e) { e.printStackTrace(); } // If timeout, then stop loading and handle error if (me.loadUrlTimeout == currentLoadUrlTimeout) { me.appView.stopLoading(); LOG.e(TAG, "DroidGap: TIMEOUT ERROR! - calling webViewClient"); me.webViewClient.onReceivedError(me.appView, -6, "The connection to the server was unsuccessful.", url); } } }; Thread thread = new Thread(runnable); thread.start(); me.appView.loadUrl(url); }其实两种方法的基本思路都是在程序里开个线程，然后再一段时间（timeout）后处理超时。至于用哪种，就要看程序中具体的需求了。