android线程之 Handler与AsyncTask的应用

<span style="color:#660000;"> package com.hqyj.asyctask;
import android.os.AsyncTask;
import android.widget.TextView;

//Params    启动任务时的输入参数类型。注意：该参数只能填写引用数据类型，如果没有参数输入，填写Void
//Progress  后台任务执行的进度的类型。
//Result    后台计算结果的类型。
public class MyAsyncTask extends AsyncTask<Integer, Integer, String> {

 <span style="white-space: pre;">	</span>TextView tv;
 <span style="white-space: pre;">	</span>int count;
 
 <span style="white-space: pre;">	</span>public MyAsyncTask(TextView tv) {
<span style="white-space: pre;">	</span>  // TODO Auto-generated constructor stub
 <span style="white-space: pre;">	</span> this.tv = tv;
 <span style="white-space: pre;">	</span>}
 
<span style="white-space: pre;">	</span> //该方法被子线程调用
 <span style="white-space: pre;">	</span>//将耗时的操作放在该方法中
 <span style="white-space: pre;">	</span>@Override
 <span style="white-space: pre;">	</span>protected String doInBackground(Integer... params) {
 <span style="white-space: pre;">	</span> // TODO Auto-generated method stub
 
 <span style="white-space: pre;">	</span> while(count < params[0]){
 <span style="white-space: pre;">	</span>  //要求系统调用onProgressUpdate方法。
 <span style="white-space: pre;">	</span>  try {
 <span style="white-space: pre;">	</span>   Thread.sleep(1000);
 <span style="white-space: pre;">	</span>  } catch (InterruptedException e) {
 <span style="white-space: pre;">	</span>   // TODO Auto-generated catch block
  <span style="white-space: pre;">	</span>  e.printStackTrace();
  <span style="white-space: pre;">	</span> }
 <span style="white-space: pre;">	</span>  count++;
 <span style="white-space: pre;">	</span>  this.publishProgress(count);
 <span style="white-space: pre;">	</span> }
 
 
 <span style="white-space: pre;">	</span> return "任务结束";
 <span style="white-space: pre;">	</span>}

<span style="white-space: pre;">	</span> //该方法被UI主线程调用
<span style="white-space: pre;">	</span> //
 <span style="white-space: pre;">	</span>@Override
 <span style="white-space: pre;">	</span>protected void onProgressUpdate(Integer... values) {
 <span style="white-space: pre;">	</span> // TODO Auto-generated method stub
 <span style="white-space: pre;">	</span> super.onProgressUpdate(values);
 <span style="white-space: pre;">	</span> tv.setText(String.valueOf(values[0]));
 <span style="white-space: pre;">	</span>}
 
<span style="white-space: pre;">	</span> //异步任务启动时调用
 <span style="white-space: pre;">	</span>@Override
 <span style="white-space: pre;">	</span>protected void onPreExecute() {
 <span style="white-space: pre;">	</span> // TODO Auto-generated method stub
 <span style="white-space: pre;">	</span> super.onPreExecute();
 <span style="white-space: pre;">	</span> tv.setText("任务开始");
 <span style="white-space: pre;">	</span>}
 
 <span style="white-space: pre;">	</span>//异步任务结束时调用
 <span style="white-space: pre;">	</span>@Override
<span style="white-space: pre;">	</span> protected void onPostExecute(String result) {
 <span style="white-space: pre;">	</span> // TODO Auto-generated method stub
 <span style="white-space: pre;">	</span> super.onPostExecute(result);
  <span style="white-space: pre;">	</span>tv.setText(result);
}</span>