WebView之2

package com.wyl.webview;

import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {
WebView webview;
ProgressDialog dialog;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
}

public void init() {
webview = (WebView) findViewById(R.id.webview01);
webview.loadUrl("http://www.baidu.com");
webview.setWebViewClient(new WebViewClient() {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return true;// 用webview打开，
}
});

WebSettings settings = webview.getSettings();
settings.setJavaScriptEnabled(true);// 允许js
settings.setCacheMode(settings.LOAD_CACHE_ELSE_NETWORK);// 使用缓存
webview.setWebChromeClient(new WebChromeClient() {
@Override
// 这个方法可以检测网页的变化
public void onProgressChanged(WebView view, int newProgress) {
// newProgress 1-100之间的整数
if (newProgress == 100) {
// 网页加载完毕后，关闭进度条progressDialog
closeDialog(newProgress);
} else {
// 网页正在加载,打开dialog
openDialog(newProgress);
}

super.onProgressChanged(view, newProgress);
}

private void closeDialog(int newProgress) {
if (dialog != null && dialog.isShowing()) {
dialog.dismiss();// 取消显示
dialog = null;
}

}

private void openDialog(int newProgress) {
//
if (dialog == null) {
dialog = new ProgressDialog(MainActivity.this);
dialog.setTitle("我正在努力正在加载。。。");
dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
dialog.setProgress(newProgress);// 显示当前的进度
dialog.show();// 展示进度

} else {
// 如果已经有了dialog，只需要刷新进度就可以
dialog.setProgress(newProgress);
}
}

});

}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
String url = webview.getUrl();
Toast.makeText(MainActivity.this, "返回上一页，wyl," + url,
Toast.LENGTH_SHORT).show();

System.out.println("===toast===");
if (webview.canGoBack()) {
webview.goBack();
return true;
} else {
System.exit(0);// 退出程序
}
}
return super.onKeyDown(keyCode, event);
}

@Override
public void onClick(View v) {
// TODO Auto-generated method stub

}

}