Android 手机浏览器的开发

最近看android资料，随手写了个简单手机浏览器应用，该应用很简单，主要包括AutoCompleteTextView 、WebView、Button控件，但是涉及到了很多android开发常识，例如：权限管理、布局标题栏状态栏隐藏、开辟线程监听事件、子线程不能更新主线程UI等，下面介绍一下代码示例：

1，修改AndroidManifest.xml文件，首先添加上网和应用旋转权限， 如下：

在此也可以添加如下代码使应用全屏，即隐藏状态栏和标题栏

2， xml布局代码如下：

布局设计中要注意实现适应屏幕。

3， java代码

package com.example.webbrowser;

import java.util.Timer;
import java.util.TimerTask;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import android.app.Activity;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.Button;
import android.widget.Toast;

public class WebBrowser extends Activity {

	AutoCompleteTextView url;
	WebView show;
	
	String[] booksArray = new String[]
	{
			"http://maps.google.com",
			"http://maps.baidu.com",
			"http://qq.com",
			"www.baidu.com",
			"www.163.com"
	};
	
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_web_browser);
        
        final Activity activity = this;
                
        show = (WebView)findViewById(R.id.show);
        show.getSettings().setJavaScriptEnabled(true);
        show.getSettings().setBuiltInZoomControls(true);
        //show.getSettings().setDisplayZoomControls(false);
        show.setWebViewClient(new WebViewClient()
        {
        	public boolean shouldOverrideUrlLoading(WebView view, String strUrl)
        	{
        		view.loadUrl(strUrl);
        		url.setText(strUrl);
        		return false;
        	}
        	
        	public void onPageStarted(WebView view, String strUrl, Bitmap favicon)
        	{
                super.onPageStarted(view, strUrl, favicon);
        		url.setText(strUrl);
        	}
        	
        	public void onPageFinished(WebView view, String strUrl)
        	{
        	}
        	
        	public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) 
        	{
        	     Toast.makeText(activity, "Oh no! " + description, Toast.LENGTH_SHORT).show();
        	}
        });
        
                
        url = (AutoCompleteTextView)findViewById(R.id.url);
        ArrayAdapter aa = new ArrayAdapter(this, android.R.layout.simple_dropdown_item_1line, booksArray);
        url.setAdapter(aa);
        url.setOnKeyListener(new View.OnKeyListener() 
        {			
			public boolean onKey(View v, int keyCode, KeyEvent ev) 
			{
				if (keyCode == KeyEvent.KEYCODE_ENTER)
				{
			        String strUrl = url.getText().toString();
			        
					Pattern p = Pattern.compile("http://([\\w-]+\\.)+[\\w-]+(/[\\w-\\./?%=]*)?");
					Matcher m = p.matcher(strUrl);
					if (!m.find())
					{
						strUrl = "http://" + strUrl;
					}
					
		    		show.loadUrl(strUrl);
		    		
					return true;
				}
				
				return false;
			}
		});
        
        // button 
        final Button backBtn = (Button)findViewById(R.id.back);
        final Button forwardBtn = (Button)findViewById(R.id.forward);
        Button refreshBtn = (Button)findViewById(R.id.refresh);
        Button homeBtn = (Button)findViewById(R.id.home);
        backBtn.setEnabled(false);
        forwardBtn.setEnabled(false);
        
        backBtn.setOnClickListener(new OnClickListener()
        {
        	public void onClick(View v)
        	{
        		show.goBack();
        	}
        });
        
        forwardBtn.setOnClickListener(new OnClickListener()
        {
        	public void onClick(View v)
        	{
        		// TODO
        		show.goForward();
        	}
        });
        
        refreshBtn.setOnClickListener(new OnClickListener()
        {
        	public void onClick(View v)
        	{
        		// TODO
        		String strUrl = url.getText().toString();
	    		show.loadUrl(strUrl);
        	}
        });
        
        homeBtn.setOnClickListener(new OnClickListener()
        {
        	public void onClick(View v)
        	{
        		// TODO
	    		show.loadUrl("http://maps.google.com");
        	}
        });
        
        final Handler handler = new Handler()
        {
        	@Override
        	public void handleMessage(Message msg)
        	{
        		if (msg.what == 0x1111)
        		{
        			// whether can go back  
            		if (show.canGoBack())
            		{
            			backBtn.setEnabled(true);
            		}
            		else
            		{
            			backBtn.setEnabled(false);
            		}
            		
            		// whether can go forward
            		if (show.canGoForward())
            		{
            			forwardBtn.setEnabled(true);
            		}
            		else
            		{
            			forwardBtn.setEnabled(false);
            		}
        		}
        		
        		super.handleMessage(msg);
        	}
        };
        
        // create thread to change button states 
        new Timer().schedule(new TimerTask()
        {
        	public void run()
        	{
        		Message msg = new Message();
        		msg.what = 0x1111;
        		handler.sendMessage(msg);
        	}
        }, 0, 100);
    }
    
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // Check if the key event was the Back button and if there's history
        if ((keyCode == KeyEvent.KEYCODE_BACK) && show.canGoBack())
        {
            show.goBack();
            return true;
        }
        // If it wasn't the Back key or there's no web page history, bubble up to the default
        // system behavior (probably exit the activity)
        return super.onKeyDown(keyCode, event);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_web_browser, menu);
        return true;
    }
}

除了AutoCompleteTextView输入URL和WebView显示网页内容外，应用底部有四个Button分别实现后退、前进、刷新、主页（暂未实现）等功能，到此就可以在android手机上使用自己的浏览器了。

4，应用截图：