线程池：第四章：ThreadPoolTaskExecutor和ThreadPoolExecutor有何区别?

• ThreadPoolTaskExecutor是spring core包中的，而ThreadPoolExecutor是JDK中的JUC。
• ThreadPoolTaskExecutor是对ThreadPoolExecutor进行了封装处理。

看看ThreadPoolTaskExecutor源码

看看ThreadPoolExecutor源码

public ThreadPoolExecutor(int corePoolSize,
                              int maximumPoolSize,
                              long keepAliveTime,
                              TimeUnit unit,
                              BlockingQueue<Runnable> workQueue,
                              ThreadFactory threadFactory,
                              RejectedExecutionHandler handler) {
        if (corePoolSize < 0 ||
            maximumPoolSize <= 0 ||
            maximumPoolSize < corePoolSize ||
            keepAliveTime < 0)
            throw new IllegalArgumentException();
        if (workQueue == null || threadFactory == null || handler == null)
            throw new NullPointerException();
        this.corePoolSize = corePoolSize;
        this.maximumPoolSize = maximumPoolSize;
        this.workQueue = workQueue;
        this.keepAliveTime = unit.toNanos(keepAliveTime);
        this.threadFactory = threadFactory;
        this.handler = handler;
    }

int corePoolSize:线程池维护线程的最小数量.  　　

int maximumPoolSize:线程池维护线程的最大数量.  　　

long keepAliveTime:空闲线程的存活时间.  　　

TimeUnit unit: 时间单位,现有纳秒,微秒,毫秒,秒枚举值.  　　

BlockingQueue<Runnable> workQueue:持有等待执行的任务队列.

ThreadFactory:线程工厂

RejectedExecutionHandler handler:用来拒绝一个任务的执行

而拒绝策略有四种：

(1)ThreadPoolExecutor.AbortPolicy策略，是默认的策略,处理程序遭到拒绝将抛出运行时 RejectedExecutionException。 

(2)ThreadPoolExecutor.CallerRunsPolicy策略 ,调用者的线程会执行该任务,如果执行器已关闭,则丢弃. 

(3)ThreadPoolExecutor.DiscardPolicy策略，不能执行的任务将被丢弃. 

(4)ThreadPoolExecutor.DiscardOldestPolicy策略，如果执行程序尚未关闭，则位于工作队列头部的任务将被删除，然后重试执行程序（如果再次失败，则重复此过程）.

上一章有详细讲解

那我们现在来用一用ThreadPoolTaskExecutor

弄一个工具类

package utils;

import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import org.springframework.ui.ModelMap;

import java.lang.reflect.Method;
import java.util.concurrent.CountDownLatch;

public class ThreadTool {

    static ThreadPoolTaskExecutor threadPoolTaskExecutor;

    static {
        threadPoolTaskExecutor = new ThreadPoolTaskExecutor();
        threadPoolTaskExecutor.setCorePoolSize(5);
        threadPoolTaskExecutor.setMaxPoolSize(10);
        threadPoolTaskExecutor.setQueueCapacity(100);
        threadPoolTaskExecutor.initialize();
    }

    /**
     * 使用线程池执行业务方法并加入视图
     * @param tasks 计数器
     * @param modelMap 视图
     * @param modelName 视图名
     * @param service 要调用的service
     * @param method 被调用的方法
     * @param param 方法参数
     */
    public static void runMethod(CountDownLatch tasks, ModelMap modelMap, String modelName, Object service, Method method, Object... param){
        threadPoolTaskExecutor.submit(new RunInThreadPool(
                tasks,modelMap,modelName,service,method,param));
    }
    

}

RunInThreaddPool

package utils;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Map;
import java.util.concurrent.CountDownLatch;

public class RunInThreadPool implements Runnable {

    CountDownLatch countDownLatch;
    Map modelMap;
    String keyName;
    Object service;
    Method method;
    Object[] param;

    /**
     * @param countDownLatch 计数器
     * @param modelMap       视图
     * @param keyName        参数名
     * @param service        要调用的service
     * @param method         被调用的方法
     * @param param          方法参数
     */
    public RunInThreadPool(CountDownLatch countDownLatch, Map modelMap, String keyName, Object service, Method method, Object... param) {
        this.countDownLatch = countDownLatch;
        this.modelMap = modelMap;
        this.keyName = keyName;
        this.service = service;
        this.method = method;
        this.param = param;
    }

    @Override
    public void run() {
        Object result = null;
        try {
            Long start = System.currentTimeMillis();
            result = method.invoke(service, param);
            Long end = System.currentTimeMillis();
            System.out.println(String.format("%s *** 执行 ((( %s ))) 方法,耗时 <<< %s 秒 >>> 参数",
                    service.getClass(),
                    method.getName(),
                    (end - start),
                    JsonUtils.toJson(param)));
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
        modelMap.put(keyName, result);
        countDownLatch.countDown();
    }
}

实战案例：

        @RequestMapping("/goodsDetail")
        public String goodsDetail(GoodsBean goodsBean, PageBean pageBean, ModelMap modelMap) throws Exception {
            final CountDownLatch latch = new CountDownLatch(7);
            Method getRelatedGoods = goodsService.getClass().getMethod("getRelatedGoods", GoodsBean.class, String.class);
            getRelatedGoods.setAccessible(Boolean.TRUE);
            ThreadTool.runMethod(latch , modelMap, "relatedGoods0", goodsService, getRelatedGoods, goodsBean, "0");
            //剩下六个类似的业务。。。。
            ...............................
            latch.await();
            return "production/index";
        }

对比：

    @RequestMapping("/getRelatedGoods")
    @AppController
    public String getRelatedGoods(GoodsBean goodsBean, String show_type,ModelMap modelMap) {
        modelMap.addAttribute("getRelatedGoods",goodsService.getRelatedGoods(goodsBean, show_type));
        return "production/index";
    }