AsyncTask总结（经典，附带源码）

一、整体工程图

二、MainActivity.java

package com.jltxgcy.asynctaskdemo;

import android.app.Activity;

import android.os.Bundle;

public class MainActivity extends Activity {

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        for(int i= 0;i<45;i++){

        	 final BitmapWorkerTask task = new BitmapWorkerTask();

             task.execute(Images.imageThumbUrls[i]);

        }

    }

}

三、Images.java

/*

 * Copyright (C) 2012 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.jltxgcy.asynctaskdemo;

/**

 * Some simple test data to use for this sample app.

 */

public class Images {

    /**

     * This are PicasaWeb URLs and could potentially change. Ideally the PicasaWeb API should be

     * used to fetch the URLs.

     */

    public final static String[] imageUrls = new String[] {

        "https://lh6.googleusercontent.com/-jZgveEqb6pg/T3R4kXScycI/AAAAAAAAAE0/xQ7CvpfXDzc/s1024/sample_image_01.jpg",

        "https://lh4.googleusercontent.com/-K2FMuOozxU0/T3R4lRAiBTI/AAAAAAAAAE8/a3Eh9JvnnzI/s1024/sample_image_02.jpg",

        "https://lh5.googleusercontent.com/-SCS5C646rxM/T3R4l7QB6xI/AAAAAAAAAFE/xLcuVv3CUyA/s1024/sample_image_03.jpg",

        "https://lh6.googleusercontent.com/-f0NJR6-_Thg/T3R4mNex2wI/AAAAAAAAAFI/45oug4VE8MI/s1024/sample_image_04.jpg",

        "https://lh3.googleusercontent.com/-n-xcJmiI0pg/T3R4mkSchHI/AAAAAAAAAFU/EoiNNb7kk3A/s1024/sample_image_05.jpg",

        "https://lh3.googleusercontent.com/-X43vAudm7f4/T3R4nGSChJI/AAAAAAAAAFk/3bna6D-2EE8/s1024/sample_image_06.jpg",

        "https://lh5.googleusercontent.com/-MpZneqIyjXU/T3R4nuGO1aI/AAAAAAAAAFg/r09OPjLx1ZY/s1024/sample_image_07.jpg",

        "https://lh6.googleusercontent.com/-ql3YNfdClJo/T3XvW9apmFI/AAAAAAAAAL4/_6HFDzbahc4/s1024/sample_image_08.jpg",

        "https://lh5.googleusercontent.com/-Pxa7eqF4cyc/T3R4oasvPEI/AAAAAAAAAF0/-uYDH92h8LA/s1024/sample_image_09.jpg",

        "https://lh4.googleusercontent.com/-Li-rjhFEuaI/T3R4o-VUl4I/AAAAAAAAAF8/5E5XdMnP1oE/s1024/sample_image_10.jpg",

        "https://lh5.googleusercontent.com/-_HU4fImgFhA/T3R4pPVIwWI/AAAAAAAAAGA/0RfK_Vkgth4/s1024/sample_image_11.jpg",

        "https://lh6.googleusercontent.com/-0gnNrVjwa0Y/T3R4peGYJwI/AAAAAAAAAGU/uX_9wvRPM9I/s1024/sample_image_12.jpg",

        "https://lh3.googleusercontent.com/-HBxuzALS_Zs/T3R4qERykaI/AAAAAAAAAGQ/_qQ16FaZ1q0/s1024/sample_image_13.jpg",

        "https://lh4.googleusercontent.com/-cKojDrARNjQ/T3R4qfWSGPI/AAAAAAAAAGY/MR5dnbNaPyY/s1024/sample_image_14.jpg",

        "https://lh3.googleusercontent.com/-WujkdYfcyZ8/T3R4qrIMGUI/AAAAAAAAAGk/277LIdgvnjg/s1024/sample_image_15.jpg",

        "https://lh6.googleusercontent.com/-FMHR7Vy3PgI/T3R4rOXlEKI/AAAAAAAAAGs/VeXrDNDBkaw/s1024/sample_image_16.jpg",

        "https://lh4.googleusercontent.com/-mrR0AJyNTH0/T3R4rZs6CuI/AAAAAAAAAG0/UE1wQqCOqLA/s1024/sample_image_17.jpg",

        "https://lh6.googleusercontent.com/-z77w0eh3cow/T3R4rnLn05I/AAAAAAAAAG4/BaerfWoNucU/s1024/sample_image_18.jpg",

        "https://lh5.googleusercontent.com/-aWVwh1OU5Bk/T3R4sAWw0yI/AAAAAAAAAHE/4_KAvJttFwA/s1024/sample_image_19.jpg",

        "https://lh6.googleusercontent.com/-q-js52DMnWQ/T3R4tZhY2sI/AAAAAAAAAHM/A8kjp2Ivdqg/s1024/sample_image_20.jpg",

        "https://lh5.googleusercontent.com/-_jIzvvzXKn4/T3R4t7xpdVI/AAAAAAAAAHU/7QC6eZ10jgs/s1024/sample_image_21.jpg",

        "https://lh3.googleusercontent.com/-lnGi4IMLpwU/T3R4uCMa7vI/AAAAAAAAAHc/1zgzzz6qTpk/s1024/sample_image_22.jpg",

        "https://lh5.googleusercontent.com/-fFCzKjFPsPc/T3R4u0SZPFI/AAAAAAAAAHk/sbgjzrktOK0/s1024/sample_image_23.jpg",

        "https://lh4.googleusercontent.com/-8TqoW5gBE_Y/T3R4vBS3NPI/AAAAAAAAAHs/EZYvpNsaNXk/s1024/sample_image_24.jpg",

        "https://lh6.googleusercontent.com/-gc4eQ3ySdzs/T3R4vafoA7I/AAAAAAAAAH4/yKii5P6tqDE/s1024/sample_image_25.jpg",

        "https://lh5.googleusercontent.com/--NYOPCylU7Q/T3R4vjAiWkI/AAAAAAAAAH8/IPNx5q3ptRA/s1024/sample_image_26.jpg",

        "https://lh6.googleusercontent.com/-9IJM8so4vCI/T3R4vwJO2yI/AAAAAAAAAIE/ljlr-cwuqZM/s1024/sample_image_27.jpg",

        "https://lh4.googleusercontent.com/-KW6QwOHfhBs/T3R4w0RsQiI/AAAAAAAAAIM/uEFLVgHPFCk/s1024/sample_image_28.jpg",

        "https://lh4.googleusercontent.com/-z2557Ec1ctY/T3R4x3QA2hI/AAAAAAAAAIk/9-GzPL1lTWE/s1024/sample_image_29.jpg",

        "https://lh5.googleusercontent.com/-LaKXAn4Kr1c/T3R4yc5b4lI/AAAAAAAAAIY/fMgcOVQfmD0/s1024/sample_image_30.jpg",

        "https://lh4.googleusercontent.com/-F9LRToJoQdo/T3R4yrLtyQI/AAAAAAAAAIg/ri9uUCWuRmo/s1024/sample_image_31.jpg",

        "https://lh4.googleusercontent.com/-6X-xBwP-QpI/T3R4zGVboII/AAAAAAAAAIs/zYH4PjjngY0/s1024/sample_image_32.jpg",

        "https://lh5.googleusercontent.com/-VdLRjbW4LAs/T3R4zXu3gUI/AAAAAAAAAIw/9aFp9t7mCPg/s1024/sample_image_33.jpg",

        "https://lh6.googleusercontent.com/-gL6R17_fDJU/T3R4zpIXGjI/AAAAAAAAAI8/Q2Vjx-L9X20/s1024/sample_image_34.jpg",

        "https://lh3.googleusercontent.com/-1fGH4YJXEzo/T3R40Y1B7KI/AAAAAAAAAJE/MnTsa77g-nk/s1024/sample_image_35.jpg",

        "https://lh4.googleusercontent.com/-Ql0jHSrea-A/T3R403mUfFI/AAAAAAAAAJM/qzI4SkcH9tY/s1024/sample_image_36.jpg",

        "https://lh5.googleusercontent.com/-BL5FIBR_tzI/T3R41DA0AKI/AAAAAAAAAJk/GZfeeb-SLM0/s1024/sample_image_37.jpg",

        "https://lh4.googleusercontent.com/-wF2Vc9YDutw/T3R41fR2BCI/AAAAAAAAAJc/JdU1sHdMRAk/s1024/sample_image_38.jpg",

        "https://lh6.googleusercontent.com/-ZWHiPehwjTI/T3R41zuaKCI/AAAAAAAAAJg/hR3QJ1v3REg/s1024/sample_image_39.jpg",

    };

    /**

     * This are PicasaWeb thumbnail URLs and could potentially change. Ideally the PicasaWeb API

     * should be used to fetch the URLs.

     */

    public final static String[] imageThumbUrls = new String[] {

        "https://lh6.googleusercontent.com/-jZgveEqb6pg/T3R4kXScycI/AAAAAAAAAE0/xQ7CvpfXDzc/s160-c/sample_image_01.jpg",

        "https://lh4.googleusercontent.com/-K2FMuOozxU0/T3R4lRAiBTI/AAAAAAAAAE8/a3Eh9JvnnzI/s160-c/sample_image_02.jpg",

        "https://lh5.googleusercontent.com/-SCS5C646rxM/T3R4l7QB6xI/AAAAAAAAAFE/xLcuVv3CUyA/s160-c/sample_image_03.jpg",

        "https://lh6.googleusercontent.com/-f0NJR6-_Thg/T3R4mNex2wI/AAAAAAAAAFI/45oug4VE8MI/s160-c/sample_image_04.jpg",

        "https://lh3.googleusercontent.com/-n-xcJmiI0pg/T3R4mkSchHI/AAAAAAAAAFU/EoiNNb7kk3A/s160-c/sample_image_05.jpg",

        "https://lh3.googleusercontent.com/-X43vAudm7f4/T3R4nGSChJI/AAAAAAAAAFk/3bna6D-2EE8/s160-c/sample_image_06.jpg",

        "https://lh5.googleusercontent.com/-MpZneqIyjXU/T3R4nuGO1aI/AAAAAAAAAFg/r09OPjLx1ZY/s160-c/sample_image_07.jpg",

        "https://lh6.googleusercontent.com/-ql3YNfdClJo/T3XvW9apmFI/AAAAAAAAAL4/_6HFDzbahc4/s160-c/sample_image_08.jpg",

        "https://lh5.googleusercontent.com/-Pxa7eqF4cyc/T3R4oasvPEI/AAAAAAAAAF0/-uYDH92h8LA/s160-c/sample_image_09.jpg",

        "https://lh4.googleusercontent.com/-Li-rjhFEuaI/T3R4o-VUl4I/AAAAAAAAAF8/5E5XdMnP1oE/s160-c/sample_image_10.jpg",

        "https://lh5.googleusercontent.com/-_HU4fImgFhA/T3R4pPVIwWI/AAAAAAAAAGA/0RfK_Vkgth4/s160-c/sample_image_11.jpg",

        "https://lh6.googleusercontent.com/-0gnNrVjwa0Y/T3R4peGYJwI/AAAAAAAAAGU/uX_9wvRPM9I/s160-c/sample_image_12.jpg",

        "https://lh3.googleusercontent.com/-HBxuzALS_Zs/T3R4qERykaI/AAAAAAAAAGQ/_qQ16FaZ1q0/s160-c/sample_image_13.jpg",

        "https://lh4.googleusercontent.com/-cKojDrARNjQ/T3R4qfWSGPI/AAAAAAAAAGY/MR5dnbNaPyY/s160-c/sample_image_14.jpg",

        "https://lh3.googleusercontent.com/-WujkdYfcyZ8/T3R4qrIMGUI/AAAAAAAAAGk/277LIdgvnjg/s160-c/sample_image_15.jpg",

        "https://lh6.googleusercontent.com/-FMHR7Vy3PgI/T3R4rOXlEKI/AAAAAAAAAGs/VeXrDNDBkaw/s160-c/sample_image_16.jpg",

        "https://lh4.googleusercontent.com/-mrR0AJyNTH0/T3R4rZs6CuI/AAAAAAAAAG0/UE1wQqCOqLA/s160-c/sample_image_17.jpg",

        "https://lh6.googleusercontent.com/-z77w0eh3cow/T3R4rnLn05I/AAAAAAAAAG4/BaerfWoNucU/s160-c/sample_image_18.jpg",

        "https://lh5.googleusercontent.com/-aWVwh1OU5Bk/T3R4sAWw0yI/AAAAAAAAAHE/4_KAvJttFwA/s160-c/sample_image_19.jpg",

        "https://lh6.googleusercontent.com/-q-js52DMnWQ/T3R4tZhY2sI/AAAAAAAAAHM/A8kjp2Ivdqg/s160-c/sample_image_20.jpg",

        "https://lh5.googleusercontent.com/-_jIzvvzXKn4/T3R4t7xpdVI/AAAAAAAAAHU/7QC6eZ10jgs/s160-c/sample_image_21.jpg",

        "https://lh3.googleusercontent.com/-lnGi4IMLpwU/T3R4uCMa7vI/AAAAAAAAAHc/1zgzzz6qTpk/s160-c/sample_image_22.jpg",

        "https://lh5.googleusercontent.com/-fFCzKjFPsPc/T3R4u0SZPFI/AAAAAAAAAHk/sbgjzrktOK0/s160-c/sample_image_23.jpg",

        "https://lh4.googleusercontent.com/-8TqoW5gBE_Y/T3R4vBS3NPI/AAAAAAAAAHs/EZYvpNsaNXk/s160-c/sample_image_24.jpg",

        "https://lh6.googleusercontent.com/-gc4eQ3ySdzs/T3R4vafoA7I/AAAAAAAAAH4/yKii5P6tqDE/s160-c/sample_image_25.jpg",

        "https://lh5.googleusercontent.com/--NYOPCylU7Q/T3R4vjAiWkI/AAAAAAAAAH8/IPNx5q3ptRA/s160-c/sample_image_26.jpg",

        "https://lh6.googleusercontent.com/-9IJM8so4vCI/T3R4vwJO2yI/AAAAAAAAAIE/ljlr-cwuqZM/s160-c/sample_image_27.jpg",

        "https://lh4.googleusercontent.com/-KW6QwOHfhBs/T3R4w0RsQiI/AAAAAAAAAIM/uEFLVgHPFCk/s160-c/sample_image_28.jpg",

        "https://lh4.googleusercontent.com/-z2557Ec1ctY/T3R4x3QA2hI/AAAAAAAAAIk/9-GzPL1lTWE/s160-c/sample_image_29.jpg",

        "https://lh5.googleusercontent.com/-LaKXAn4Kr1c/T3R4yc5b4lI/AAAAAAAAAIY/fMgcOVQfmD0/s160-c/sample_image_30.jpg",

        "https://lh4.googleusercontent.com/-F9LRToJoQdo/T3R4yrLtyQI/AAAAAAAAAIg/ri9uUCWuRmo/s160-c/sample_image_31.jpg",

        "https://lh4.googleusercontent.com/-6X-xBwP-QpI/T3R4zGVboII/AAAAAAAAAIs/zYH4PjjngY0/s160-c/sample_image_32.jpg",

        "https://lh5.googleusercontent.com/-VdLRjbW4LAs/T3R4zXu3gUI/AAAAAAAAAIw/9aFp9t7mCPg/s160-c/sample_image_33.jpg",

        "https://lh6.googleusercontent.com/-gL6R17_fDJU/T3R4zpIXGjI/AAAAAAAAAI8/Q2Vjx-L9X20/s160-c/sample_image_34.jpg",

        "https://lh3.googleusercontent.com/-1fGH4YJXEzo/T3R40Y1B7KI/AAAAAAAAAJE/MnTsa77g-nk/s160-c/sample_image_35.jpg",

        "https://lh4.googleusercontent.com/-Ql0jHSrea-A/T3R403mUfFI/AAAAAAAAAJM/qzI4SkcH9tY/s160-c/sample_image_36.jpg",

        "https://lh5.googleusercontent.com/-BL5FIBR_tzI/T3R41DA0AKI/AAAAAAAAAJk/GZfeeb-SLM0/s160-c/sample_image_37.jpg",

        "https://lh4.googleusercontent.com/-wF2Vc9YDutw/T3R41fR2BCI/AAAAAAAAAJc/JdU1sHdMRAk/s160-c/sample_image_38.jpg",

        "https://lh6.googleusercontent.com/-ZWHiPehwjTI/T3R41zuaKCI/AAAAAAAAAJg/hR3QJ1v3REg/s160-c/sample_image_39.jpg",

        "https://lh4.googleusercontent.com/-Ql0jHSrea-A/T3R403mUfFI/AAAAAAAAAJM/qzI4SkcH9tY/s160-c/sample_image_40.jpg",

        "https://lh5.googleusercontent.com/-BL5FIBR_tzI/T3R41DA0AKI/AAAAAAAAAJk/GZfeeb-SLM0/s160-c/sample_image_41.jpg",

        "https://lh4.googleusercontent.com/-wF2Vc9YDutw/T3R41fR2BCI/AAAAAAAAAJc/JdU1sHdMRAk/s160-c/sample_image_42.jpg",

        "https://lh6.googleusercontent.com/-ZWHiPehwjTI/T3R41zuaKCI/AAAAAAAAAJg/hR3QJ1v3REg/s160-c/sample_image_43.jpg",

        "https://lh4.googleusercontent.com/-Ql0jHSrea-A/T3R403mUfFI/AAAAAAAAAJM/qzI4SkcH9tY/s160-c/sample_image_44.jpg",

        "https://lh5.googleusercontent.com/-BL5FIBR_tzI/T3R41DA0AKI/AAAAAAAAAJk/GZfeeb-SLM0/s160-c/sample_image_45.jpg",

        "https://lh4.googleusercontent.com/-wF2Vc9YDutw/T3R41fR2BCI/AAAAAAAAAJc/JdU1sHdMRAk/s160-c/sample_image_46.jpg",

        "https://lh6.googleusercontent.com/-ZWHiPehwjTI/T3R41zuaKCI/AAAAAAAAAJg/hR3QJ1v3REg/s160-c/sample_image_47.jpg",

        "https://lh4.googleusercontent.com/-Ql0jHSrea-A/T3R403mUfFI/AAAAAAAAAJM/qzI4SkcH9tY/s160-c/sample_image_48.jpg",

        "https://lh5.googleusercontent.com/-BL5FIBR_tzI/T3R41DA0AKI/AAAAAAAAAJk/GZfeeb-SLM0/s160-c/sample_image_49.jpg",

        "https://lh4.googleusercontent.com/-wF2Vc9YDutw/T3R41fR2BCI/AAAAAAAAAJc/JdU1sHdMRAk/s160-c/sample_image_50.jpg",

        "https://lh6.googleusercontent.com/-ZWHiPehwjTI/T3R41zuaKCI/AAAAAAAAAJg/hR3QJ1v3REg/s160-c/sample_image_51.jpg",

    };

}

四、ImageAsyncTask.java

package com.jltxgcy.asynctaskdemo;

import java.util.concurrent.Callable;

import java.util.concurrent.CancellationException;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.FutureTask;

import java.util.concurrent.LinkedBlockingQueue;

import java.util.concurrent.ThreadFactory;

import java.util.concurrent.ThreadPoolExecutor;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.TimeoutException;

import java.util.concurrent.atomic.AtomicInteger;

import android.os.Handler;

import android.os.Message;

import android.os.Process;

public abstract class ImageAsyncTask<Params, Progress, Result> {

	// private static final String LOG_TAG = "ImageAsyncTask";

	private static final int CORE_POOL_SIZE = 6;

	private static final int MAXIMUM_POOL_SIZE = 18;

	private static final int KEEP_ALIVE = 5;

	private static final LinkedBlockingQueue<Runnable> sWorkQueue = new LinkedBlockingQueue<Runnable>(

			12);

	private static final ThreadFactory sThreadFactory = new ThreadFactory() {

		private final AtomicInteger mCount = new AtomicInteger(1);//原子量，线程安全

		public Thread newThread(Runnable r) {

			//Log.d("jltxgcy", ""+mCount);

			return new Thread(r, "ImageAsyncTask #" + mCount.getAndIncrement());

		}

	};

	private static final ThreadPoolExecutor sExecutor = new ThreadPoolExecutor(CORE_POOL_SIZE,

			MAXIMUM_POOL_SIZE, KEEP_ALIVE, TimeUnit.SECONDS, sWorkQueue, sThreadFactory,

			new ThreadPoolExecutor.DiscardOldestPolicy());

	//private static ExecutorService pool = Executors.newFixedThreadPool(2);

	private static final int MESSAGE_POST_RESULT = 0x1;

	private static final int MESSAGE_POST_PROGRESS = 0x2;

	private static final int MESSAGE_POST_CANCEL = 0x3;

	private static final InternalHandler sHandler = new InternalHandler();

	private final WorkerRunnable<Params, Result> mWorker;

	private final FutureTask<Result> mFuture;

	private volatile Status mStatus = Status.PENDING;

	public enum Status {

		PENDING,

		RUNNING,

		FINISHED,

	}

	public static void clearQueue() {

		sWorkQueue.clear();

	}

	public ImageAsyncTask() {

		mWorker = new WorkerRunnable<Params, Result>() {

			public Result call() throws Exception {

				Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);

				return doInBackground(mParams);//调用了BitmapWorkerTask中的doInBackground方法

			}

		};

		mFuture = new FutureTask<Result>(mWorker) {

			@SuppressWarnings("unchecked")

			@Override

			protected void done() {//都是在子线程中

				Message message;

				Result result = null;

				try {

					result = get();//获取BitmapWorkerTask中doInBackground方法执行后的Result

				} catch (InterruptedException e) {

				} catch (ExecutionException e) {//注意异常先后顺序

					throw new RuntimeException("An error occured while executing doInBackground()",

							e.getCause());

				} catch (CancellationException e) {//如果取消了，那么执行这里

					message = sHandler.obtainMessage(MESSAGE_POST_CANCEL,

							new ImageAsyncTaskResult<Result>(ImageAsyncTask.this, (Result[]) null));

					message.sendToTarget();

					return;

				} catch (Throwable t) {

					throw new RuntimeException("An error occured while executing "

							+ "doInBackground()", t);

				}

				message = sHandler.obtainMessage(MESSAGE_POST_RESULT,

						new ImageAsyncTaskResult<Result>(ImageAsyncTask.this, result));

				//发送执行完消息，到主线程

				message.sendToTarget();

			}

		};

	}

	public final Status getStatus() {

		return mStatus;

	}

	protected abstract Result doInBackground(Params... params);

	protected void onPreExecute() {

	}

	protected void onPostExecute(Result result) {

	}

	protected void onProgressUpdate(Progress... values) {

	}

	protected void onCancelled() {

	}

	public final boolean isCancelled() {

		return mFuture.isCancelled();

	}

	public final boolean cancel(boolean mayInterruptIfRunning) {

		return mFuture.cancel(mayInterruptIfRunning);//如果调用此方法，会在done方法中发送取消消息到InternalHandler

	}

	public final Result get() throws InterruptedException, ExecutionException {

		return mFuture.get();

	}

	public final Result get(long timeout, TimeUnit unit) throws InterruptedException,

			ExecutionException, TimeoutException {

		return mFuture.get(timeout, unit);

	}

	public final ImageAsyncTask<Params, Progress, Result> execute(Params... params) {

		if (mStatus != Status.PENDING) {

			switch (mStatus) {

			case RUNNING:

				throw new IllegalStateException("Cannot execute task:"

						+ " the task is already running.");

			case FINISHED:

				throw new IllegalStateException("Cannot execute task:"

						+ " the task has already been executed "

						+ "(a task can be executed only once)");

			}

		}

		mStatus = Status.RUNNING;

		onPreExecute();//第一个方法

		mWorker.mParams = params;//把参数传了过去

		sExecutor.execute(mFuture);//最后调用mWorker的call方法执行

		return this;

	}

	protected final void publishProgress(Progress... values) {

		sHandler.obtainMessage(MESSAGE_POST_PROGRESS,

				new ImageAsyncTaskResult<Progress>(this, values)).sendToTarget();

	}

	private void finish(Result result) {

		onPostExecute(result);//调用了BitmapWorkerTask中的onPostExecute方法

		mStatus = Status.FINISHED;

	}

	private static class InternalHandler extends Handler {

		@SuppressWarnings({ "unchecked", "rawtypes" })

		@Override

		public void handleMessage(Message msg) {

			ImageAsyncTaskResult result = (ImageAsyncTaskResult) msg.obj;

			switch (msg.what) {

			case MESSAGE_POST_RESULT:

				// There is only one result

				result.mTask.finish(result.mData[0]);

				break;

			case MESSAGE_POST_PROGRESS:

				result.mTask.onProgressUpdate(result.mData);

				break;

			case MESSAGE_POST_CANCEL:

				result.mTask.onCancelled();

				break;

			}

		}

	}

	private static abstract class WorkerRunnable<Params, Result> implements Callable<Result> {

		Params[] mParams;

	}

	private static class ImageAsyncTaskResult<Data> {

		@SuppressWarnings({ "rawtypes" })

		final ImageAsyncTask mTask;

		final Data[] mData;

		@SuppressWarnings({ "rawtypes" })

		ImageAsyncTaskResult(ImageAsyncTask task, Data... data) {

			mTask = task;

			mData = data;

		}

	}

}

五、BitmapWorkerTask.java

package com.jltxgcy.asynctaskdemo;

import android.graphics.Bitmap;

import android.util.Log;

public class BitmapWorkerTask extends ImageAsyncTask<Object, Void, Bitmap> {

    @Override

    protected Bitmap doInBackground(Object... params) {

        String data = (String)params[0];

        Log.d("jltxgcy", data);

        //Log.d("jltxgcy", Thread.currentThread().getName());//如果测试pool线程池，用这个看的清楚

        try {

			Thread.sleep(2000);

		} catch (InterruptedException e) {

			// TODO Auto-generated catch block

			e.printStackTrace();

		}

        return null;

    }

    /**

     * Once the image is processed, associates it to the imageView

     */

    @Override

    protected void onPostExecute(Bitmap bitmap) {

    }

}

六、详解

BitmapWorkerTask继承了ImageAsyncTask，大家如果仔细观察，那么这里ImageAsyncTask，其实就是Android自带的源码，具体分析请看注释。那为什么不直接继承呢，是因为这样做可以修改sExecutor.execute(mFuture)，这里的线程池。如果采用

private static final ThreadPoolExecutor sExecutor = new ThreadPoolExecutor(CORE_POOL_SIZE,

			MAXIMUM_POOL_SIZE, KEEP_ALIVE, TimeUnit.SECONDS, sWorkQueue, sThreadFactory,

			new ThreadPoolExecutor.DiscardOldestPolicy());

那么结果如下：

CORE_POOL_SIZE = 6，所以刚开始执行前六个线程

new LinkedBlockingQueue<Runnable>(12)，把7-18共12个线程放入了队列中

MAXIMUM_POOL_SIZE = 18，最后会执行34-45，那么总共舍弃而来7-18，31-33

这部分具体可以参考http://my.oschina.net/sunjun/blog/9017。

上面sExecutor.execute(mFuture)，如果改为private static ExecutorService pool = Executors.newFixedThreadPool(2);pool.execute(mFuture),那么输出结果如下：

启动Log.d("jltxgcy", Thread.currentThread().getName())

启动了两个线程同时执行，其他线程排队执行。

最后所有的都执行了，你看观察到2个 2个的依次执行。

里面涉及到具有返回值的线程，请参考http://lavasoft.blog.51cto.com/62575/222082。

源码地址：http://download.csdn.net/detail/jltxgcy/6015765

ImageAsyncTask<Object, Void, Bitmap>，第一个表示最开始的参数，第二个是中间参数，最后一个是输出结果。

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