本文共 3042 字,大约阅读时间需要 10 分钟。
public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
if (!executor.isShutdown()) {
//直接执行run方法
r.run();
}
}
}
以下是ThreadPoolExecutor具体的继承结构
public abstract class AbstractExecutorService implements ExecutorService {
}
这是一个抽象类,实现了ExecutorService接口,并实现了ExecutorService里边的方法,下面看下ExecutorService接口的具体实现
public interface ExecutorService extends Executor {
void shutdown();
List shutdownNow();
boolean isShutdown();
boolean isTerminated();
boolean awaitTermination(long timeout, TimeUnit unit)
throws InterruptedException;
Future submit(Callable task);
Future submit(Runnable task, T result);
Future> submit(Runnable task);
List> invokeAll(Collection extends Callable> tasks)throws InterruptedException;
List> invokeAll(Collection extends Callable> tasks,
long timeout, TimeUnit unit)
throws InterruptedException;
T invokeAny(Collection extends Callable> tasks)
throws InterruptedException, ExecutionException;
T invokeAny(Collection extends Callable> tasks,
long timeout, TimeUnit unit)
throws InterruptedException, ExecutionException, TimeoutException;
}
ExecutorService继承Executor接口,下面是Executor接口的具体实现
public interface Executor {
void execute(Runnable command);
}
Executor接口是顶层接口,只声明了一个execute方法,该方法是用来执行传递进来的任务的。
回过头来,咱么重新看ThreadPoolExecutor类,改类里边有以下两个重要的方法:
public void execute(Runnable command) {
if (command == null)
throw new NullPointerException();
int c = ctl.get();
if (workerCountOf(c) < corePoolSize) {
if (addWorker(command, true))
return;
c = ctl.get();
}
if (isRunning(c) && workQueue.offer(command)) {
int recheck = ctl.get();
if (! isRunning(recheck) && remove(command))
reject(command);
else if (workerCountOf(recheck) == 0)
addWorker(null, false);
}else if (!addWorker(command, false))
reject(command);
}
public Future submit(Callable task) {
if (task == null) throw new NullPointerException();
RunnableFuture ftask = newTaskFor(task);
execute(ftask);
return ftask;
}
execute()方法是Executor中声明的方法,在ThreadPoolExecutor有了具体的实现,这个方法是ThreadPoolExecutor的核心方法,
通过这个方法可以向线程池提交一个任务,交由线程池去执行
submit()方法是ExecutorService中声明的方法,在AbstractExecutorService中进行了实现,Executor中并没有对其进行重写。从实现中可以看出,submit方法最终也调用了execute
方法,也是执行一个人去,但submit方法可以返回执行结果,利用Future来获取任务执行结果。
6、Spring中的线程池
Spring中的线程池是由ThreadPoolTaskExecutor类来实现的。该类的实现原理最终也是调用了java中的ThreadPoolExecutor类中的一些方法。具体的实现读者可以自己去翻阅Spring
的源码,这里笔者就不罗列了。我们看下ThreadPoolTaskExecutor的初始化。
ThreadPoolTaskExecutor有两种常用的有两种初始化方式:xml配置,java代码初始化
xml配置:
看过上面的内容,读者应该很清楚上面的一些参数代表的意思了吧。笔者在这里不一一去解释了。
public MyThreadPoolTaskExecutor {
@Autowired
private ThreadPoolTaskExecutor taskExecutor;
private void test(){
taskExecutor.execute(new Runnable(){
@Override
public void run() {
//执行的代码
}});
}
}
Java代码初始化:
private void test2(){
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
executor.setCorePoolSize(10);
executor.setMaxPoolSize(15);
executor.setKeepAliveSeconds(1);
executor.setQueueCapacity(5);
executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
executor.initialize();
executor.execute(new Runnable(){
@Override
public void run() {
//执行的代码
}
});
}
转载地址:https://blog.csdn.net/weixin_33826897/article/details/114059837 如侵犯您的版权,请留言回复原文章的地址,我们会给您删除此文章,给您带来不便请您谅解!