ThreadPoolExecutor中的RejectedExecutionHandler浅析

当ThreadPoolExecutor中的线程都已经忙于执行，且有界队列也满了，这个时候就需要自己写reject策略；此处给一个demo，供大家去理解和参考：

1、先写一个可执行的线程

package zhengchao_001_005.ThreadPoolExecutor;public class Task implements Runnable{private int id ;private String name ;public Task(int id, String name){this.id = id;this.name = name;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}@Overridepublic void run() {//System.out.println("当前线程id和名称为:" + this.id +", " + this.name);try {Thread.sleep(5*1000);} catch (Exception e) {e.printStackTrace();}}public String toString(){return "{ id : " + this.id + ", name : " + this.name + "}";}}

2、我们写一个RejectedExecutionHandler，必须要实现RejectedExecutionHandler接口，并实现他的rejectedExecution()方法

两个参数，一个是需要拒绝的线程，另一个是我们的线程池，至于如何拒绝，按照自己的业务逻辑去进行处理，

package zhengchao_001_005.ThreadPoolExecutor;import java.util.concurrent.RejectedExecutionHandler;import java.util.concurrent.ThreadPoolExecutor;public class MyRejected implements RejectedExecutionHandler{@Overridepublic void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {System.out.println("自定义拒绝处理_"+r.toString());}}

3、测试用例

package zhengchao_001_005.ThreadPoolExecutor;import java.util.concurrent.ArrayBlockingQueue;import java.util.concurrent.ThreadPoolExecutor;import java.util.concurrent.TimeUnit;public class TestThreadPoolExecutor {public static void main(String[] args) {ThreadPoolExecutor pool = new ThreadPoolExecutor(1, //核心的线程数量1, //最大的线程数量10, //空闲数值 TimeUnit.SECONDS, //空闲时间单位new ArrayBlockingQueue<Runnable>(3),//有界队列new MyRejected()); Task t1 = new Task(1, "任务" + 1);Task t2 = new Task(2, "任务" + 2);Task t3 = new Task(3, "任务" + 3);Task t4 = new Task(4, "任务" + 4);Task t5 = new Task(5, "任务" + 5);pool.execute(t1);pool.execute(t2);pool.execute(t3);pool.execute(t4);pool.execute(t5);try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}//System.out.println(pool.getQueue().size());try {Thread.sleep(6000);} catch (InterruptedException e) {e.printStackTrace();}}}

运行结果：

自定义拒绝处理_{ id : 5, name : 任务5}当前线程id和名称为:1, 任务1当前线程id和名称为:2, 任务2当前线程id和名称为:3, 任务3当前线程id和名称为:4, 任务4

注意点：

如果使用LinkedBlockingQueue则不会有队列满的问题，LinkedBlockingQueue直到系统资源耗尽才会出问题，但这种体验可能会比较差，至于用哪种好，仁者见仁，不是，业务为前提。