Android开发实现加载网络图片并下载至本地SdCard的方法

package com.example.myimagedemo;import java.io.BufferedOutputStream;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.URL;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Bundle;import android.os.Environment;import android.os.Handler;import android.os.Message;import android.widget.ImageView;public class MainActivity extends Activity {  private ImageView mImageView;  private String imgPath="http://pic.nipic.com/2007-11-09/200711912453162_2.jpg";  private File cache;//缓存路径  Handler handler=new Handler(new Handler.Callback() {    @Override    public boolean handleMessage(Message msg) {      //显示      Bitmap b=(Bitmap)msg.obj;      mImageView.setImageBitmap(b);      //保存至本地      File imgFile=new File(cache,"woca.jpg");      try {        BufferedOutputStream bos=new BufferedOutputStream(new FileOutputStream(imgFile));        b.compress(Bitmap.CompressFormat.JPEG,80,bos);        bos.flush();        bos.close();      } catch (Exception e) {        // TODO Auto-generated catch block        e.printStackTrace();      }      return false;    }  });  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    mImageView=(ImageView)findViewById(R.id.mImageView);    //创建缓存路径    //Environment.getExternalStorageDirectory()获取手机内存卡根路径    cache=new File(Environment.getExternalStorageDirectory(),"Test");    if(!cache.exists()){      cache.mkdirs();    }    //耗时操作都要放在子线程操作    //开启子线程获取输入流    new Thread(new Runnable() {      @Override      public void run() {        HttpURLConnection conn=null;        InputStream is=null;        try {          URL url=new URL(imgPath);          //开启连接          conn=(HttpURLConnection) url.openConnection();          //设置连接超时          conn.setConnectTimeout(5000);          //设置请求方式          conn.setRequestMethod("GET");          //conn.connect();          if(conn.getResponseCode()==200){            is=conn.getInputStream();            Bitmap b=BitmapFactory.decodeStream(is);            //把输入流转化成bitmap格式，以msg形式发送至主线程            Message msg=new Message();            msg.obj=b;            handler.sendMessage(msg);          }        } catch (Exception e) {          e.printStackTrace();        }finally{          try {          //用完记得关闭            is.close();            conn.disconnect();          } catch (IOException e) {            e.printStackTrace();          }        }      }    }).start();  }}

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