import java.io.IOException;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpHead;
import org.apache.http.impl.client.DefaultHttpClient;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.KeyEvent;
import android.webkit.WebView;
import android.webkit.WebViewClient;
public class WebView_404 extends Activity {
private final String HOMEPAGE = "http://10.0.0.95/index.html";//请求的网站的主页
private WebView web;
private Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
if(msg.what==404) {//主页不存在
//载入本地assets文件夹下面的错误提示页面404.html
web.loadUrl("file:///android_asset/404.html");
} else {
web.loadUrl(HOMEPAGE);
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.webview_404);
web = (WebView) findViewById(R.id.WebView01);
web.getSettings().setJavaScriptEnabled(true);
web.setWebViewClient(new WebViewClient() {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
if(url.startsWith("http://") && getRespStatus(url)==404) {
view.stopLoading();
//载入本地assets文件夹下面的错误提示页面404.html
view.loadUrl("file:///android_asset/404.html");
} else {
view.loadUrl(url);
}
return true;
}
});
new Thread(new Runnable() {
@Override
public void run() {
Message msg = new Message();
//此处判断主页是否存在，因为主页是通过loadUrl加载的，
//此时不会执行shouldOverrideUrlLoading进行页面是否存在的判断
//进入主页后，点主页里面的链接，链接到其他页面就一定会执行shouldOverrideUrlLoading方法了
if(getRespStatus(HOMEPAGE)==404) {
msg.what = 404;
}
handler.sendMessage(msg);
}
}).start();
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(keyCode==KeyEvent.KEYCODE_BACK && web.canGoBack()) {
web.goBack();
return false;
}
return super.onKeyDown(keyCode, event);
}
private int getRespStatus(String url) {
int status = -1;
try {
HttpHead head = new HttpHead(url);
HttpClient client = new DefaultHttpClient();
HttpResponse resp = client.execute(head);
status = resp.getStatusLine().getStatusCode();
} catch (IOException e) {}
return status;
}
}
