详解jdk中executorservice与callable和future对线程的支持
1、代码背景：
假如有thread1、thread2、thread3、thread4四条线程分别统计c、d、e、f四个盘的大小，所有线程都统计完毕交给thread5线程去做汇总，应当如何实现？
2、代码：
统计“盘子”大小的代码，此处实现jdk中的callable接口，
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package com.wang.test.concurrent;
import java.util.concurrent.callable;
public class task1 implements callable<integer> {
private int x;
private int y;
public task1(int x, int y) {
this.x = x;
this.y = y;
}
@override
public integer call() throws exception {
return x*y;
}
}
统计汇总的代码，也是实现jdk中的callable接口，
package com.wang.test.concurrent;
import java.util.concurrent.callable;
public class task2 implements callable<integer> {
private int x;
private int y;
private int q;
private int w;
public task2(int x, int y, int q, int w) {
this.x = x;
this.y = y;
this.q = q;
this.w = w;
}
@override
public integer call() throws exception {
return x + y + q + w;
}
}
客户端：使用jdk中executors.newfixedthreadpool方法创建executorservice，executorservice的submit方法接收callable接口的实现，jdk内部将弄成线程处理，使用future接收submit方法的返回值，当future调用get方法时，如果线程还没有执行完，程序阻塞在这里，知道线程执行完。
package com.wang.test.concurrent;
import java.util.concurrent.executorservice;
import java.util.concurrent.executors;
import java.util.concurrent.future;
public class client {
public static void main(string[] args) throws exception {
executorservice pool = executors.newfixedthreadpool(4);
task1 t1 = new task1(1,2);
task1 t2 = new task1(23,34);
task1 t3 = new task1(23,456);
task1 t4 = new task1(3,33);
future<integer> f1 = pool.submit(t1);
future<integer> f2 = pool.submit(t2);
future<integer> f3 = pool.submit(t3);
future<integer> f4 = pool.submit(t4);
//future调用get方法时，如果线程还没有执行完，程序阻塞在这里
task2 t5 = new task2(f1.get(), f2.get(), f3.get(), f4.get());
future<integer> f5 = pool.submit(t5);
system.out.println(f5.get());
pool.shutdown();
}
}
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