用HTTP操作和文件操作把网页下载到sd卡

这里先把代码贴到这里做一个存档，写到SD卡的是一个txt文件，改成HTML格式之后会出现百度主页，但是中文是乱码，这一点先暂时不去研究了。

代码：

package com.larry.gotcha;

import java.io.BufferedReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {

    private Button requestButton = null ; 
    private HttpResponse httpResponse = null ; 
    private HttpEntity httpEntity = null ; 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        requestButton =(Button)findViewById(R.id.requestButton);
        requestButton.setOnClickListener(new OnClickListener()
        {
            @Override
            public void onClick(View v) {
                //生成一个请求对象
                HttpGet httpGet = new HttpGet("http://www.baidu.com/");
                //生成客户端对象
                HttpClient httpClient = new DefaultHttpClient();
                //使用客户端发送请求对象
                InputStream inputStream = null ; 

                try {
                        //execute返回一个HttpResponse类型的参数，代表服务器返回的响应
                        httpResponse = httpClient.execute(httpGet);
                        //HttpResponse代表返回的响应，那么HttpEntity就代表响应的内容Obtains the message entity of this response, if any. 
                        httpEntity = httpResponse.getEntity();
                        inputStream = httpEntity.getContent();//注意getContent()方法很常用
                        BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
                        
                        String sd = Environment.getExternalStorageDirectory().getPath();
                        @SuppressWarnings("resource")
                        FileWriter fw = new FileWriter( sd + "/gotcha.txt");
                        
                        String line = "" ;
                        String result = "" ; 
                        while((line = br.readLine()) != null)
                        {
                            result = line + result ;                         
                        }
                        System.out.println(result);
                        fw.write(result , 0 , result.length());
                    
                    } 
                catch (ClientProtocolException e) 
                    {
                        e.printStackTrace();
                    } 
                catch (IOException e) 
                    {
                        e.printStackTrace();
                    }
                finally
                    {
                        try
                        {
                            inputStream.close();
                        }
                        catch(Exception e)
                        {
                            e.printStackTrace();
                        }
                    }
            }            
        });    
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

HTTP操作顺序是：HttpGet--HttpClient--HttpResponse--HttpEntity。

这里I/O流里用的是InputStream、BufferedReader和FileWriter。

注意要在Mainifest里添加两个权限（这次忘了添加写入SD卡的权限，下午在英语课上想到了。。）

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