android:webview实现简单的浏览器

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" >

        <EditText
            android:id="@+id/et_url"
            android:layout_width="320dp"
            android:layout_height="wrap_content" />
        
        <Button 
            android:id="@+id/btn_login"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="登录"
            />
    </LinearLayout>

    <WebView
        android:layout_weight="2"
        android:id="@+id/webView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" />
    <LinearLayout 
        android:layout_weight="7.5"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="horizontal"
        android:background="#000000"
        >
        <Button 
            android:id="@+id/btn_back"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="←"
            />
        <Button 
            android:id="@+id/btn_menu"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="主页"
            />
        <Button 
            android:id="@+id/btn_forward"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="→"
            />
        <Button 
            android:id="@+id/btn_exit"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="exit"
            />
    </LinearLayout>

</LinearLayout>

package com.example.webview;

import android.os.Bundle;
import android.app.Activity;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity implements OnClickListener {

	private String url = null;
	private WebView webView;
	private EditText et_url;
	private Button btn_login;
	private Button btn_back;
	private Button btn_exit;
	private Button btn_forward;
	private Button btn_menu;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		// 窗口进度条
		requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
		setContentView(R.layout.activity_main);

		setProgressBarIndeterminate(true);

		webView = (WebView) findViewById(R.id.webView);
		et_url = (EditText) findViewById(R.id.et_url);
		btn_login = (Button) findViewById(R.id.btn_login);
		btn_back = (Button) findViewById(R.id.btn_back);
		btn_exit = (Button) findViewById(R.id.btn_exit);
		btn_forward = (Button) findViewById(R.id.btn_forward);
		btn_menu = (Button) findViewById(R.id.btn_menu);
		// 对五个按钮添加点击监听事件
		btn_login.setOnClickListener(this);
		btn_back.setOnClickListener(this);
		btn_exit.setOnClickListener(this);
		btn_forward.setOnClickListener(this);
		btn_menu.setOnClickListener(this);
	}

	// btn_login的触发事件 点击后 webView开始读取url
	protected void startReadUrl(String url) {
		// TODO Auto-generated method stub
		// webView加载web资源
		webView.loadUrl(url);
		// 覆盖webView默认通过系统或者第三方浏览器打开网页的行为
		// 如果为false调用系统或者第三方浏览器打开网页的行为
		webView.setWebViewClient(new WebViewClient() {
			@Override
			public boolean shouldOverrideUrlLoading(WebView view, String url) {
				// TODO Auto-generated method stub
				// webView加载web资源
				view.loadUrl(url);
				return true;
			}
		});
		// 启用支持javascript
		WebSettings settings = webView.getSettings();
		settings.setJavaScriptEnabled(true);
		// web加载页面优先使用缓存加载
		settings.setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
		// 当打开页面时 显示进度条 页面打开完全时 隐藏进度条
		webView.setWebChromeClient(new WebChromeClient() {
			@Override
			public void onProgressChanged(WebView view, int newProgress) {
				// TODO Auto-generated method stub
				setTitle("本页面已加载" + newProgress + "%");
				if (newProgress == 100) {
					closeProgressBar();
				} else {
					openProgressBar(newProgress);
				}
				super.onProgressChanged(view, newProgress);
			}
		});
	}

	// 打开进度条
	protected void openProgressBar(int x) {
		// TODO Auto-generated method stub
		setProgressBarIndeterminateVisibility(true);
		setProgress(x);
	}

	// 关闭进度条
	protected void closeProgressBar() {
		// TODO Auto-generated method stub
		setProgressBarIndeterminateVisibility(false);
	}

	// 改写物理按键 返回键的逻辑
	@Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		// TODO Auto-generated method stub
		if (keyCode == KeyEvent.KEYCODE_BACK) {
			if (webView.canGoBack()) {
				// 返回上一页面
				webView.goBack();
				return true;
			} else {
				// 退出程序
				finish();
			}
		}
		return super.onKeyDown(keyCode, event);
	}

	// 对按钮事件的处理
	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		switch (v.getId()) {
		case R.id.btn_login:
			url = "http://" + et_url.getText().toString();
			url = url.replace(" ", "");
			startReadUrl(url);
			break;
		case R.id.btn_back:
			if (webView.canGoBack()) {
				webView.goBack();
			} else {
				finish();
			}
			break;
		case R.id.btn_forward:
			if (webView.canGoForward()) {
				webView.goForward();
			}
			break;
		case R.id.btn_exit:
			finish();
			break;
		case R.id.btn_menu:
			startReadUrl("http://www.baidu.com");
			break;
		}
	}
}

<uses-permission android:name="android.permission.INTERNET"/>