AsynckTask的简单使用（更新进度条）

package com.example.myasynctask;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.SystemClock;
import android.util.Log;
import android.widget.ProgressBar;

public class ProgressTest extends Activity{
private ProgressBar pb;
private MyAsynctask myAsyncTask;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

setContentView(R.layout.progress_test);
pb = (ProgressBar) findViewById(R.id.pb);
myAsyncTask = new MyAsynctask();//asyncTask必须在UI线程中创建
myAsyncTask.execute();//必须在UI线程中调用execute()方法，而且中能调用一次，多次调用会引发异常
}

class MyAsynctask extends AsyncTask<Void, Integer, Void>{

@Override
protected Void doInBackground(Void... params) {
for(int i = 0 ; i < 100 ; i++){
if(isCancelled()){
return null;
}
SystemClock.sleep(500);
publishProgress(i);//当调用此方法时，系统才会调用onProgressUpdate方法，参数即是onProgressUpdate的参数
}

return null;
}

@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
if(isCancelled()){
return;
}
Log.i("TAG",""+values[0]);
pb.setProgress(values[0]);

}
}

@Override
protected void onPause() {
super.onPause();
//当activity不可见时将asyncTask标记为取消状态
if(myAsyncTask != null && myAsyncTask.getStatus() == MyAsynctask.St
4000
atus.RUNNING){
myAsyncTask.cancel(true);
}

}

}