线程池懒加载实现初探

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单例类：

package com.ldy.utils;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.Future;import java.util.concurrent.LinkedBlockingQueue;import java.util.concurrent.ThreadFactory;import java.util.concurrent.ThreadPoolExecutor;import java.util.concurrent.TimeUnit;import org.apache.log4j.Logger;public class LazyThreadPool extends ThreadPoolExecutor{private static final Logger logger = Logger.getLogger(LazyThreadPool.class);/** * 仿Executors.newFixedThreadPool(corePoolSize, threadFactory); * return new ThreadPoolExecutor(nThreads, nThreads,                                      0L, TimeUnit.MILLISECONDS,                                      new LinkedBlockingQueue<Runnable>(),                                      threadFactory); * 创建指定大小线程池 * @param corePoolSize */private LazyThreadPool(int corePoolSize) {super(corePoolSize, corePoolSize, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>(), new ThreadFactory() {@Overridepublic Thread newThread(Runnable r) {Thread t = Executors.defaultThreadFactory().newThread(r);//t.setDaemon(true);//此线程创建后，设置为后台线程logger.info("创建线程："+t);return t;}});logger.info("懒实例执行器服务被创建：LazyThreadPool");}private static class ExecutorServiceHolder {private static ExecutorService executorService = new LazyThreadPool(1);//作为单线程池处理任务}public static ExecutorService getExecutorService() {return ExecutorServiceHolder.executorService;}@Overrideprotected void beforeExecute(Thread t, Runnable r) {System.out.println(t);if(r instanceof AbstractTask){logger.info("任务准备执行："+((AbstractTask)r).taskName);}}@Overrideprotected void afterExecute(Runnable r, Throwable t) {if(r instanceof AbstractTask){logger.info("任务执行完成："+((AbstractTask)r).taskName);}}@Overrideprotected void terminated() {logger.info("线程池退出");}@Overridepublic void execute(Runnable command) {// TODO Auto-generated method stubsuper.execute(this.wrapRunnable(command,clientTrace()));}@Overridepublic Future<?> submit(Runnable task) {// TODO Auto-generated method stubreturn super.submit(this.wrapRunnable(task,clientTrace()));}private Exception clientTrace(){return new Exception("任务提交所在处。");}/** * 1、知道异常在哪里抛出的 * 2、这个任务到底是在哪里提交的 * @param command * @return */private Runnable wrapRunnable(final Runnable command,final Exception clientTrace){return new Runnable() {@Overridepublic void run() {try{command.run();}catch(Exception e){clientTrace.printStackTrace();//追踪调用所在地e.printStackTrace();//防止部分任务运行时异常丢失throw e;}}};}}

任务抽象：

package com.ldy.utils;/** * 多线程应用基类 * 任务抽象，作用于：运行时提供任务名称 * @author ldy * */public abstract class AbstractTask implements Runnable{protected String taskName;}

调用示例：

package main;import com.ldy.utils.AbstractTask;public class TestTask extends AbstractTask{public TestTask() {this.taskName = "测试线程池框架";}@Overridepublic void run() {try {Thread.currentThread().sleep(600);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}System.out.println("执行方法主体");System.out.println(2/0);}}

package main;import java.util.concurrent.ExecutionException;import java.util.concurrent.Future;import com.ldy.utils.LazyThreadPool;public class TestExecutorService {public static void main(String[] args) throws InterruptedException, ExecutionException {Future<?> re = LazyThreadPool.getExecutorService().submit(new TestTask());//System.out.println("任务执行完后的结果："+re.get());//Executors.newFixedThreadPool(1).submit(new TestTask());}}

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