AsyncTask应用示例

package com.example.testdemo;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {

    private  Button btn;
    private ImageView mg;
    private ProgressDialog pDialog;
    private String path="http://himg2.huanqiu.com/attachment2010/111207/zip1323221781/1323221781_6.jpg";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn=(Button)findViewById(R.id.button1);
        mg=(ImageView)findViewById(R.id.imageView1);
        pDialog=new ProgressDialog(this);
        pDialog.setTitle("提示");
        pDialog.setCancelable(false);
        pDialog.setMessage("正在下载，请稍后……");
        pDialog.setIcon(R.drawable.ic_launcher);
        pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        btn.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new MyTask().execute(path);
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
    
    public class MyTask extends AsyncTask<String, Integer, Bitmap>
    {

        /* (non-Javadoc)
         * @see android.os.AsyncTask#doInBackground(Params[])
         */
        @Override
        protected Bitmap doInBackground(String... params) {
            // TODO Auto-generated method stub
            Bitmap bitmap=null;
            ByteArrayOutputStream outputStream=new ByteArrayOutputStream();
            InputStream inputStream=null;
            try {
                HttpClient httpClient=new DefaultHttpClient();
                HttpGet httpGet=new HttpGet(params[0]);
                HttpResponse httpResponse=httpClient.execute(httpGet);
                if (httpResponse.getStatusLine().getStatusCode()==200) {
                    inputStream=httpResponse.getEntity().getContent();
                    long file_length=httpResponse.getEntity().getContentLength();
                    byte[] data=new byte[1024];
                    int len=0;
                    int total=0;
                    while ((len = inputStream.read(data)) != -1) {
                        total+=len;
                        int values=(int)((total/(float)file_length)*100);
                        publishProgress(values);
                        outputStream.write(data, 0, len);
                        
                    }
                    byte[] result01=outputStream.toByteArray();
                    bitmap=BitmapFactory.decodeByteArray(result01, 0, result01.length);
                }
                
            } catch (Exception e) {
                // TODO: handle exception
                e.printStackTrace();
            }finally{
                if (inputStream != null) {
                    try {
                        inputStream.close();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }
            return bitmap;
        }

        @Override
        protected void onPostExecute(Bitmap result) {
            // TODO Auto-generated method stub
            super.onPostExecute(result);
            pDialog.dismiss();
            mg.setImageBitmap(result);
            
        }

        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            super.onPreExecute();
            pDialog.show();
        }

        @Override
        protected void onProgressUpdate(Integer... values) {
            // TODO Auto-generated method stub
            super.onProgressUpdate(values);
            pDialog.setProgress(values[0]);
        }
        
        
    }

}

 apk下载点击这里TestDemo.apk