异步下载并显示的三种方法

package com.cn.asyc; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.net.URLConnection; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import android.app.Activity; import android.app.ProgressDialog; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.AsyncTask; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.ImageView; import android.widget.ProgressBar; /** * 异步下载示例 * @author hawon1 * */ public class DownloadActivity extends Activity implements OnClickListener{ protected static final String TAG = DownloadActivity.class.getSimpleName(); private ProgressDialog progressDialog; private ProgressBar bar; private String params="http://blogfile.ifeng.com/uploadfiles/albumpic/8/8f1/pic_bfe1d14bca30b46338e6c98e18d448f1.jpg"; public static String httpurl = "http://blogfile.ifeng.com/uploadfiles/albumpic/f/fd1/pic_72af15b3c4c226306545d664e0926fd1.jpg"; public static String thirdUrl = "http://res.news.ifeng.com/attachments/2010/07/08/c40983e2e6c9ccb6d7a384ba7e671470.jpg"; private Bitmap bitmap; private ImageView imageView; private Button btn; private Button btn01,btn02; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); imageView = (ImageView)findViewById(R.id.picture); bar = (ProgressBar)findViewById(R.id.progressBar); btn = (Button)findViewById(R.id.btn); btn01 = (Button)findViewById(R.id.btn01); btn02 = (Button)findViewById(R.id.btn02); btn.setOnClickListener(this); btn01.setOnClickListener(this); btn02.setOnClickListener(this); } private Handler handler = new Handler(){ @Override public void handleMessage(Message msg) { switch(msg.what){ case 1: imageView.setImageBitmap(bitmap); progressDialog.dismiss(); break; } super.handleMessage(msg); } }; @Override public void onClick(View view) { switch(view.getId()){ /** * 第一种异步，比较常用的handler，thread机制 * @author hawon1 * */ case R.id.btn: progressDialog = ProgressDialog.show(DownloadActivity.this, "", "下载数据，请稍等...", true,true); handler.post(new Runnable() { @Override public void run() { try{ URL url = new URL(params); try { HttpURLConnection conn = (HttpURLConnection)url.openConnection(); ((URLConnection) conn).setDoInput(true); ((URLConnection)conn).connect(); InputStream inputStream=((URLConnection) conn).getInputStream(); bitmap = BitmapFactory.decodeStream(inputStream); inputStream.close(); Message msg = new Message(); msg.what=1; handler.sendMessage(msg); } catch (IOException e) { e.printStackTrace(); } }catch(MalformedURLException e){} } }); break; case R.id.btn01://第二种异步方法,继承AsyncTask类 bar.setVisibility(View.VISIBLE); MyAsycTask mysyc = new MyAsycTask(); mysyc.execute(httpurl); break; /** * //第三种异步方法，java.util.concurrent * @author hawon1 * */ case R.id.btn02: bar.setVisibility(View.VISIBLE); ExecutorService executorService = Executors.newCachedThreadPool(); executorService.submit(new Runnable(){ @Override public void run() { try{ URL newUrl = new URL(thirdUrl); HttpURLConnection conn = (HttpURLConnection)newUrl.openConnection(); conn.setDoInput(true); conn.connect(); InputStream inputStream = conn.getInputStream(); bitmap = BitmapFactory.decodeStream(inputStream); handler.post(new Runnable() { @Override public void run() { imageView.setImageBitmap(bitmap); bar.setVisibility(View.GONE); } }); }catch(MalformedURLException e){ } catch (IOException e) { e.printStackTrace(); } } }); break; } }; /** * 第二种异步方法,继承AsyncTask类 * @author hawon1 * */ public class MyAsycTask extends AsyncTask<String, Integer, Bitmap>{ @Override protected Bitmap doInBackground(String... params) { Bitmap bitmap = null; try{ URL url = new URL(httpurl); HttpURLConnection conn = (HttpURLConnection)url.openConnection(); conn.setDoInput(true); conn.connect(); InputStream inputStream = conn.getInputStream(); bitmap = BitmapFactory.decodeStream(inputStream); inputStream.close(); }catch(MalformedURLException e){ } catch (IOException e) { e.printStackTrace(); } return bitmap; } @Override protected void onPostExecute(Bitmap result) { imageView.setImageBitmap(result); bar.setVisibility(View.GONE); super.onPostExecute(result); } @Override protected void onProgressUpdate(Integer... values) { // TODO Auto-generated method stub super.onProgressUpdate(values); } } }