ExecutorService使用概述

背景：

java 并发中concurrent包下有很多关于并发的操作，使用最常见的为ExecutorService

支持类型：

Callable

Runnable

此两种类型中的Callable是有返回值的，那么如果很好的获取执行结果？

 

依赖：

<dependency>
	<groupId>org.apache.commons</groupId>
	<artifactId>commons-lang3</artifactId>
	<version>3.0</version>
</dependency>
<dependency>
	<groupId>commons-lang</groupId>
	<artifactId>commons-lang</artifactId>
	<version>2.6</version>
</dependency>

 

实现：

public static void getResult() throws Exception {
	long begin = System.currentTimeMillis();
	ExecutorService service = Executors.newFixedThreadPool(10000);
	List<StringCallable> all = new ArrayList<StringCallable>();
	for (int i = 0; i < 1000; i++) {
		all.add(new StringCallable(i));
	}
	List<Future<String>> result = service.invokeAll(all);

	for (Future<String> future : result) {
		String list = future.get();
		System.out.println(list);
	}
	service.shutdown();
	long end = System.currentTimeMillis();
	System.out.println("--" + (end - begin));
}

 

直接获取：

public static void get() throws Exception {
	long begin = System.currentTimeMillis();
	ExecutorService service = Executors.newFixedThreadPool(10000);
	for (int i = 0; i < 1000; i++) {
		Future<String> resul = service.submit(new StringCallable(1000));
		System.out.println(resul.get());
	}
	service.shutdown();
	long end = System.currentTimeMillis();
	System.out.println("cost:" + (end - begin));
}

后者会有等待而不是并发，因此在使用的时候需要注意

基类：

class StringCallable implements Callable<String> {
	private int index = 0;

	public StringCallable(int index) {
		super();
		this.index = index;
	}

	public String call() throws Exception {
		System.out.println("index:" + index);
		return RandomStringUtils.random(12, "abcdefghijklmnopqrstuvwxyz");
	}
}