Java线程池的四种拒绝策略详解

// 核心线程数

int corePoolSize = 1 ;

// 最大线程数

int maximumPoolSize = 2 ;

// 线程存活时间

long keepAliveTime = 10 ;

// 线程存活时间单位

TimeUnit unit = TimeUnit.SECONDS;

// 有界队列 遵循 FIFO 原则

BlockingQueue<Runnable> workQueue = new ArrayBlockingQueue<>( 1 );

// 线程工厂

ThreadFactory threadFactory = Executors.defaultThreadFactory();

class TaskThread implements Runnable{

         private int i;

         public TaskThread( int i) {

             this .i = i;

         }

         @Override

         public void run() {

             try {

                 TimeUnit.SECONDS.sleep( 2 );

                 System.out.println( "执行任务:" + i);

             } catch (InterruptedException e) {

                 e.printStackTrace();

             }

         }

     }

// 拒绝策略 默认拒绝策略，拒绝任务并抛出异常：

RejectedExecutionHandler handler = new ThreadPoolExecutor.AbortPolicy();

ThreadPoolExecutor threadPool = new ThreadPoolExecutor(corePoolSize,

                 maximumPoolSize,

                 keepAliveTime,

                 unit,

                 workQueue,

                 threadFactory,

                 handler);

         for ( int i = 1 ; i <= 5 ; i++) {

             try {

                 threadPool.execute( new TaskThread(i));

             } catch (Exception e) {

                 System.out.println( "【任务" + i + "】报错:" + e.getMessage());

             }

         }

RejectedExecutionHandler handler = new ThreadPoolExecutor.CallerRunsPolicy();

RejectedExecutionHandler handler = new ThreadPoolExecutor.DiscardPolicy();

RejectedExecutionHandler handler3 = new ThreadPoolExecutor.DiscardOldestPolicy();