Android AsyncTask用法介绍

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。