线程池拒绝策略的类图：大致有七种左右

具体看下每个类的源码：

AbortPolicy（直接抛异常）

public static class AbortPolicy implements RejectedExecutionHandler {        public AbortPolicy() { }        public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {            throw new RejectedExecutionException("Task " + r.toString" rejected from " + e.toString());        }    }

AbortPolicyWithReport（记录日志）

public class AbortPolicyWithReport extends ThreadPoolExecutor.AbortPolicy {    static private final Logger logger = LoggerInit.LOGGER;     private final String threadName;    private final URL url;    public AbortPolicyWithReport(String threadName, URL url) {        this.threadName = threadName;        this.url = url;    }    @Override    public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {        String msg = String.format("Thread pool is EXHAUSTED!" +                " Thread Name: %s, Pool Size: %d (active: %d, core: %d, max: %d, largest: %d), Task: %d (completed: %d)," +                " Executor status:(isShutdown:%s, isTerminated:%s, isTerminating:%s), in %s://%s:%d!" ,                threadName, e.getPoolSize(), e.getActiveCount(), e.getCorePoolSize(), e.getMaximumPoolSize(), e.getLargestPoolSize(),                e.getTaskCount(), e.getCompletedTaskCount(), e.isShutdown(), e.isTerminated(), e.isTerminating(),                url.getProtocol(), url.getIp(), url.getPort());        logger.warn(msg);        throw new RejectedExecutionException(msg);    }}

CallerRunsPolicy（调用者执行）

public static class CallerRunsPolicy implements RejectedExecutionHandler {        public CallerRunsPolicy() { }        public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {            if (!e.isShutdown()) {                r.run();            }        }    }

DiscardOldestPolicy（抛弃线程池中最旧的未处理的任务）

public static class DiscardOldestPolicy implements RejectedExecutionHandler {        public DiscardOldestPolicy() { }        public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {            if (!e.isShutdown()) {                e.getQueue().poll();                e.execute(r);            }        }    }

DiscardPolicy（直接拒绝，不作处理）

public static class DiscardPolicy implements RejectedExecutionHandler {        public DiscardPolicy() { }        public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {        }    }

IgnoreRunsPolicy（忽略运行测试，dump jvm信息）

private static class IgnoreRunsPolicy implements RejectedExecutionHandler {        private final static Logger LOGGER = LoggerInit.LOGGER;        public volatile boolean hasDump = false;        public IgnoreRunsPolicy() {        }        public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {            dumpJVMInfo();   //方法太长不予展示，就是这个dump jvm信息的意思            // ignore it when thread full and it will be timeout response for client            throw new RejectedExecutionException();        }

NewThreadRunsPolicy（在MemoryAwareThreadPoolExecutor里面新建一个临时线程去处理）

private static final class NewThreadRunsPolicy implements RejectedExecutionHandler {        public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {            try {                final Thread t = new Thread(r, "Temporary task executor");                t.start();            } catch (Throwable e) {                throw new RejectedExecutionException(                        "Failed to start a new thread", e);            }        }    }

看完源码是不是对线程池拒绝策略有了更深的认识了？