Android学习--使用url访问网络资源

package com.example.xiaocool.urltest;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ImageView;

import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;


public class MainActivity extends ActionBarActivity {

    /**
     * 使用URL 访问网络资源
     * @param savedInstanceState
     */
    private ImageView show;
    //代表从网络上下载得到的图片
    private Bitmap bitmap;

    Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
           if(msg.what==0x123){
               show.setImageBitmap(bitmap);
           }
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        show=(ImageView)this.findViewById(R.id.show);
        //耗时的操作放在辅助线程里
        new Thread(){
            @Override
            public void run() {
              try{
                  //定义一个url 对象
                  URL url=new URL("http://192.168.191.1:8080/Android_Client/userhead.jpg");
                  //打开该url 对应资源的输入流
                  InputStream is= url.openStream();
                  //从InputStream 中解析图片
                  bitmap=BitmapFactory.decodeStream(is);
                  //发送消息 通知UI组件显示图片
                  handler.sendEmptyMessage(0x123);
                  is.close();
                  //再次打开url对应资源的输入流
                  is=url.openStream();
                  //打开手机文件对应的输出流
                  OutputStream os=openFileOutput("yu.png",MODE_WORLD_READABLE);
                  byte[] buff=new byte[1024];
                  int hasRead=0;
                  //将url 对应的资源下载到本地
                  while((hasRead=is.read(buff))>0){
                      os.write(buff,0,hasRead);
                  }
                  is.close();
                  os.close();

              }catch (Exception e){
                  e.printStackTrace();
              }
            }
        }.start();
    }


}