Android AsyncTask用法介绍

最新推荐文章于 2025-05-21 12:53:47 发布

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最新推荐文章于 2025-05-21 12:53:47 发布

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分类专栏： Android

本文链接：https://blog.youkuaiyun.com/cxc19890214/article/details/46228533

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本文详细介绍了Android中AsyncTask的使用方法，从界面设计到代码实现，再到运行效果和Log日志分析，全面展示了AsyncTask在后台任务处理中的应用。

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1>界面设计

1.1>效果

1.2>布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.demo.asynctastdemo.MainActivity" >
    <Button 
        android:id="@+id/start_bt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/start_bt_txt"/>

    <TextView
        android:id="@+id/progress_tv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/progess_tv_txt" />
    <TextView 
        android:id="@+id/result_tv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/result_tv_txt"/>

</LinearLayout>

其中strings.xml文件内容为：

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">AsyncTastDemo</string>
    <string name="action_settings">Settings</string>
    <string name="progess_tv_txt">Progess Text</string>
    <string name="result_tv_txt">Result Text</string>
    <string name="start_bt_txt">Start</string>

</resources>

2>AsyncTask代码如下：

package com.cxc.asynctaskdemo2;

import android.R.string;
import android.os.AsyncTask;
import android.util.Log;
import android.widget.TextView;

public class MyAsyncTask extends AsyncTask<String, Integer, String> {
	private static final String TAG="MyAsyncTask";
	
	//声明控件
	private TextView progess_tv;
	private TextView result_tv;
	
	public MyAsyncTask(TextView progess_tv, TextView result_tv) {
		super();
		this.progess_tv = progess_tv;
		this.result_tv = result_tv;
	}
	

	/**  
	 * 生成该类的对象，并调用execute方法之后  
	 * 首先执行的是onProExecute方法  
	 * 其次执行doInBackgroup方法  
	 */ 
	@Override
	protected String doInBackground(String... params) {// 此方法将会在后台线程中执行
		// TODO Auto-generated method stub
		Log.d(TAG,"----doInBackground()---thread id:"+Thread.currentThread().getId());
		String resultString = "";
		int myProgress = 0;

	
		int inputLength = params[0].length();

		for (int i = 0; i < inputLength; i++) {
			myProgress = i;
			resultString += params[0].charAt(i);

			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

			Log.d(TAG,"Thread :"+Thread.currentThread().getId()+"----send:"+myProgress);
			publishProgress(myProgress);
			
		}
		return resultString;// 返回一个值，它将传递给onPostExecute()
	}

    /**  
     * 这里的String参数对应AsyncTask中的第三个参数（也就是接收doInBackground的返回值）  
     * 在doInBackground方法执行结束之后在运行，并且运行在UI线程当中 可以对UI控件进行操作  
     */  
	@Override
	protected void onPostExecute(String result) {
		// TODO Auto-generated method stub
		super.onPostExecute(result);
		Log.d(TAG,"----onPostExecute()---thread id:"+Thread.currentThread().getId()+"---reciver:"+result);

		// 和UI线程同步
		this.result_tv.setText(result);
	}

	/**  
     * 这里的Integer参数对应AsyncTask中的第二个参数  
     * 在doInBackground方法当中，，每次调用publishProgress方法都会触发onProgressUpdate执行  
     * onProgressUpdate是在UI线程中执行，所有可以对UI空间进行操作  
     */  
	@Override
	protected void onProgressUpdate(Integer... values) {
		// TODO Auto-generated method stub
		super.onProgressUpdate(values);
		
		Log.d(TAG,"----onProgressUpdate()---thread id:"+Thread.currentThread().getId());
		Log.d(TAG,"Thread :"+Thread.currentThread().getId()+"----reciver:"+values[0]);
		// 和UI线程同步
		this.progess_tv.setText(values[0].toString());
	}

}

运行后效果如下：

3>运行的Log日志如下：

06-02 09:44:34.690: D/MyAsyncTask(29285): ----main thread --id:1
06-02 09:44:49.160: D/MyAsyncTask(29285): ----doInBackground()---thread id:5293
06-02 09:44:50.165: D/MyAsyncTask(29285): Thread :5293----send:0
06-02 09:44:50.165: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:44:50.165: D/MyAsyncTask(29285): Thread :1----reciver:0
06-02 09:44:51.165: D/MyAsyncTask(29285): Thread :5293----send:1
06-02 09:44:51.165: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:44:51.165: D/MyAsyncTask(29285): Thread :1----reciver:1
06-02 09:44:52.165: D/MyAsyncTask(29285): Thread :5293----send:2
06-02 09:44:52.165: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:44:52.165: D/MyAsyncTask(29285): Thread :1----reciver:2
06-02 09:44:53.170: D/MyAsyncTask(29285): Thread :5293----send:3
06-02 09:44:53.170: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:44:53.170: D/MyAsyncTask(29285): Thread :1----reciver:3
06-02 09:44:54.165: D/MyAsyncTask(29285): Thread :5293----send:4
06-02 09:44:54.170: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:44:54.170: D/MyAsyncTask(29285): Thread :1----reciver:4
06-02 09:44:55.170: D/MyAsyncTask(29285): Thread :5293----send:5
06-02 09:44:55.170: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:44:55.170: D/MyAsyncTask(29285): Thread :1----reciver:5
06-02 09:44:56.175: D/MyAsyncTask(29285): Thread :5293----send:6
06-02 09:44:56.175: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:44:56.175: D/MyAsyncTask(29285): Thread :1----reciver:6
06-02 09:44:57.175: D/MyAsyncTask(29285): Thread :5293----send:7
06-02 09:44:57.175: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:44:57.175: D/MyAsyncTask(29285): Thread :1----reciver:7
06-02 09:44:58.175: D/MyAsyncTask(29285): Thread :5293----send:8
06-02 09:44:58.175: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:44:58.175: D/MyAsyncTask(29285): Thread :1----reciver:8
06-02 09:44:59.175: D/MyAsyncTask(29285): Thread :5293----send:9
06-02 09:44:59.180: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:44:59.180: D/MyAsyncTask(29285): Thread :1----reciver:9
06-02 09:45:00.185: D/MyAsyncTask(29285): Thread :5293----send:10
06-02 09:45:00.185: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:00.185: D/MyAsyncTask(29285): Thread :1----reciver:10
06-02 09:45:01.185: D/MyAsyncTask(29285): Thread :5293----send:11
06-02 09:45:01.185: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:01.185: D/MyAsyncTask(29285): Thread :1----reciver:11
06-02 09:45:02.190: D/MyAsyncTask(29285): Thread :5293----send:12
06-02 09:45:02.190: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:02.190: D/MyAsyncTask(29285): Thread :1----reciver:12
06-02 09:45:03.190: D/MyAsyncTask(29285): Thread :5293----send:13
06-02 09:45:03.190: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:03.190: D/MyAsyncTask(29285): Thread :1----reciver:13
06-02 09:45:04.190: D/MyAsyncTask(29285): Thread :5293----send:14
06-02 09:45:04.195: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:04.195: D/MyAsyncTask(29285): Thread :1----reciver:14
06-02 09:45:05.200: D/MyAsyncTask(29285): Thread :5293----send:15
06-02 09:45:05.200: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:05.200: D/MyAsyncTask(29285): Thread :1----reciver:15
06-02 09:45:06.200: D/MyAsyncTask(29285): Thread :5293----send:16
06-02 09:45:06.200: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:06.200: D/MyAsyncTask(29285): Thread :1----reciver:16
06-02 09:45:07.205: D/MyAsyncTask(29285): Thread :5293----send:17
06-02 09:45:07.205: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:07.205: D/MyAsyncTask(29285): Thread :1----reciver:17
06-02 09:45:08.200: D/MyAsyncTask(29285): Thread :5293----send:18
06-02 09:45:08.200: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:08.205: D/MyAsyncTask(29285): Thread :1----reciver:18
06-02 09:45:09.205: D/MyAsyncTask(29285): Thread :5293----send:19
06-02 09:45:09.205: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:09.205: D/MyAsyncTask(29285): Thread :1----reciver:19
06-02 09:45:10.215: D/MyAsyncTask(29285): Thread :5293----send:20
06-02 09:45:10.215: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:10.215: D/MyAsyncTask(29285): Thread :1----reciver:20
06-02 09:45:11.210: D/MyAsyncTask(29285): Thread :5293----send:21
06-02 09:45:11.210: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:11.210: D/MyAsyncTask(29285): Thread :1----reciver:21
06-02 09:45:12.215: D/MyAsyncTask(29285): Thread :5293----send:22
06-02 09:45:12.215: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:12.215: D/MyAsyncTask(29285): Thread :1----reciver:22
06-02 09:45:13.215: D/MyAsyncTask(29285): Thread :5293----send:23
06-02 09:45:13.215: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:13.215: D/MyAsyncTask(29285): Thread :1----reciver:23
06-02 09:45:14.215: D/MyAsyncTask(29285): Thread :5293----send:24
06-02 09:45:14.215: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:14.215: D/MyAsyncTask(29285): Thread :1----reciver:24
06-02 09:45:15.215: D/MyAsyncTask(29285): Thread :5293----send:25
06-02 09:45:15.215: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:15.215: D/MyAsyncTask(29285): Thread :1----reciver:25
06-02 09:45:16.215: D/MyAsyncTask(29285): Thread :5293----send:26
06-02 09:45:16.215: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:16.215: D/MyAsyncTask(29285): Thread :1----reciver:26
06-02 09:45:17.215: D/MyAsyncTask(29285): Thread :5293----send:27
06-02 09:45:17.215: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:17.215: D/MyAsyncTask(29285): Thread :1----reciver:27
06-02 09:45:18.220: D/MyAsyncTask(29285): Thread :5293----send:28
06-02 09:45:18.220: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:18.220: D/MyAsyncTask(29285): Thread :1----reciver:28
06-02 09:45:19.220: D/MyAsyncTask(29285): Thread :5293----send:29
06-02 09:45:19.220: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:19.220: D/MyAsyncTask(29285): Thread :1----reciver:29
06-02 09:45:20.225: D/MyAsyncTask(29285): Thread :5293----send:30
06-02 09:45:20.225: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:20.225: D/MyAsyncTask(29285): Thread :1----reciver:30
06-02 09:45:21.225: D/MyAsyncTask(29285): Thread :5293----send:31
06-02 09:45:21.225: D/MyAsyncTask(29285): ----onProgressUpdate()---thread id:1
06-02 09:45:21.225: D/MyAsyncTask(29285): Thread :1----reciver:31
06-02 09:45:21.225: D/MyAsyncTask(29285): ----onPostExecute()---thread id:1---reciver:ABCDEFGHIJKLMNOPQRSTUVWXYZ...ABC

分析：从以上Log日志可以知道，MyAsyncTask中的方法doInBackground方法运行在后台线程中，而onProgressUpdate方法和onPostExecute方法是运行在GUI线程中的。