AsyncTask的用法

根据前面的自己写了一个测试程序:

MainActivity.java如下:

package com.example.androidasynctaskdemos;

import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.widget.TextView;

public class MainActivity extends Activity {

    private final static String TAG="MainActivity";
    
    private myTask tasker;
    private TextView mText;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        mText=(TextView)findViewById(R.id.text_view);
        mText.setText("start");
        tasker=new myTask();
        
        tasker.execute("","","");//开始执行
        
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    public class myTask extends AsyncTask {

        @Override
        protected String doInBackground(String... arg0) {
            // TODO Auto-generated method stub
            Log.i(TAG,"doInBackground");
            
            for(int i=1;i<1000;i++){
                publishProgress(i);//通知更新UI信息
                try {
                    Thread.sleep(250);//每隔250ms更新一次UI
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            return null;
        }

        @Override
        protected void onPostExecute(String result) {
            // TODO Auto-generated method stub
            super.onPostExecute(result);
            
            //这里将在doInBackground全部执行完成后开始执行
        }

        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            super.onPreExecute();
            Log.i(TAG,"onPreExecute");
            //启动任何之前首先执行的地方,可以用于初始化UI信息
        }

        @Override
        protected void onProgressUpdate(Integer... values) {
            // TODO Auto-generated method stub
            super.onProgressUpdate(values);
            Log.i(TAG,"onProgressUpdate");
            mText.setText("result : "+values[0]);//实时更新UI处
        }
        
        
        
    }

}

布局文件:

    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/text_view"
        android:textSize="48dip"
        android:layout_gravity="center"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" />