android AsyncTask

1.http://android.tgbus.com/Android/tutorial/201109/369193.shtml
2.Android中AsyncTask的用法实例
(比较深入潜出了....膜拜一下.)
http://www.pin5i.com/showtopic-android-asynctask-sample.html


3.Android AsyncTask 详解
http://dev.10086.cn/cmdn/wiki/index.php?edition-view-5195-1.html


4.Android Threads, Handlers and AsyncTask - Tutorial
http://www.vogella.de/articles/AndroidPerformance/article.html


5.华清远见 AsyncTask视频讲解
http://v.youku.com/v_show/id_XMzExNjU0MDgw.html


6.Android如何异步获取图片
http://www.cnblogs.com/budoudou/archive/2011/07/13/2105007.html

7.异步下载图片
http://www.cnblogs.com/zhangdongzi/archive/2011/04/13/2015215.html#2311099


自己学习了AsyncTask后的例子:

package com.asynctaskdemo;

import java.io.InputStream;

import org.apache.http.HttpEntity;
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.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;

public class UpdateImgActivity extends Activity implements OnClickListener {

	private TextView tv_desc,tv_percent;
	private EditText et_imgurl;
	private Button btn_start;
	private ImageView iv_result;
	private ProgressBar pb;
	@Override
	protected void onCreate(Bundle bd)	{
		super.onCreate(bd);
		setContentView(R.layout.updateimg);
		tv_desc = (TextView)findViewById(R.id.tv_desc);
		tv_percent = (TextView)findViewById(R.id.tv_percent);
		et_imgurl = (EditText)findViewById(R.id.et_imgurl);
		btn_start = (Button)findViewById(R.id.btn_start);
		iv_result = (ImageView)findViewById(R.id.iv_fromNet);
		pb = (ProgressBar)findViewById(R.id.pb);
		
		btn_start.setOnClickListener(this);
	}
	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		switch(v.getId()){
		case R.id.btn_start:{
			if(!et_imgurl.getText().toString().equals("")){
				new UpdateImgTask().execute(et_imgurl.getText().toString());
			}
			else
				et_imgurl.setError("不能为空");
		}
		}
	}
	
	class UpdateImgTask extends AsyncTask<String, Integer, Bitmap>{


		//首先会被调用
		@Override
		protected void onPreExecute() {
			// TODO Auto-generated method stub
			super.onPreExecute();
			tv_desc.setText("从网络更新图片:开始");
		}



		@Override
		protected Bitmap doInBackground(String... params) {
			// TODO Auto-generated method stub
			try {
				HttpClient client = new DefaultHttpClient();
				// params[0] 代表连接的url
				HttpGet get = new HttpGet(params[0]);
				HttpResponse response = client.execute(get);
				HttpEntity entity = response.getEntity();
				long length = entity.getContentLength();
				InputStream is = entity.getContent();
/*				if (is != null) {
					ByteArrayOutputStream baos = new ByteArrayOutputStream();
					byte[] buf = new byte[128];
					int ch = -1;
					int count = 0;
					while ((ch = is.read(buf)) != -1) {
						baos.write(buf, 0, ch);
						count += ch;
						if (length > 0) {
							// 如果知道响应的长度，调用publishProgress（）更新进度
							publishProgress((int) ((count / (float) length) * 100));
						}
						// 为了在模拟器中清楚地看到进度，让线程休眠100ms
						Thread.sleep(100);
					}
				}*/
				for(int i=0;i<=100;i++){
					pb.setProgress(i);
					publishProgress(i);
					try {
						Thread.sleep(i);
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
				}
				// 返回结果
				return BitmapFactory.decodeStream(is);
			} catch (Exception e) {
				e.printStackTrace();
			}
			return null;
		}
		
		@Override
		protected void onProgressUpdate(Integer... values) {
			// TODO Auto-generated method stub
			//super.onProgressUpdate(values);
			tv_percent.setText(values[0]+"%");
			pb.setProgress(values[0]);
		}
		
		
		@Override
		protected void onPostExecute(Bitmap result) {
			// TODO Auto-generated method stub
			super.onPostExecute(result);
			if(result!=null)
				iv_result.setImageBitmap(result);
			else
				tv_desc.setText("从网络更新图片:失败");
				
		}
		
	}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/tv_desc"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="从网络更新图片" />
	<EditText 
	    android:id="@+id/et_imgurl"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="http://tp4.sinaimg.cn/2137426403/180/5605866249/1"
	    />
    <Button
        android:id="@+id/btn_start"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="start" />
     <TextView
        android:id="@+id/tv_percent"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
/>
    <ProgressBar
       android:id="@+id/pb"
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       style="?android:attr/progressBarStyleHorizontal"/>
    <ImageView
        android:id="@+id/iv_fromNet"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

</LinearLayout>