Java并发编程系列学习_invokeAny()方法与invokeAll()方法

一、invokeAny()方法

作用&＃xff1a;取得第一个完成任务的结果值&＃xff0c;当第一个任务执行完成后&＃xff0c;会调用interrupt方法将其他的任务中断。

在这里会出现两种情况&＃xff1a;

• 无 Thread.currentThread().isInterrupted() 的判断&＃xff0c;则已经获得第一个运行的结果的值后&＃xff0c;其他线程继续运行&＃xff1b;
• 有 Thread.currentThread().isInterrupted() 的判断&＃xff0c;再结合new InterruptedException使得这些线程中断&＃xff1b;

例子如下&＃xff1a;

package invoke;import java.util.concurrent.Callable;/*** &＃64;Author: jiaqing.xu&＃64;hand-china.com* &＃64;Date: 2019-04-07 21:41* &＃64;Description*/
public class MyCallableA implements Callable {&＃64;Overridepublic String call() throws Exception {System.out.println("CallableA begin:" &＃43; System.currentTimeMillis());for (int i &＃61; 0; i <1000; i&＃43;&＃43;) {System.out.println("A:" &＃43; i);}System.out.println("CallableA end:" &＃43; System.currentTimeMillis());return "call A";}
}


package invoke;import java.util.concurrent.Callable;/*** &＃64;Author: jiaqing.xu&＃64;hand-china.com* &＃64;Date: 2019-04-07 21:43* &＃64;Description*/
public class MyCallableB implements Callable {&＃64;Overridepublic String call() throws Exception {System.out.println("CallableB begin:" &＃43; System.currentTimeMillis());for (int i &＃61; 0; i <1000; i&＃43;&＃43;) {System.out.println("B:" &＃43; i);}System.out.println("CallableB end:" &＃43; System.currentTimeMillis());return "call B";}
}


package invoke;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;/*** &＃64;Author: jiaqing.xu&＃64;hand-china.com* &＃64;Date: 2019-04-07 21:46* &＃64;Description*/
public class RunMain1 {public static void main(String[] args) {List list &＃61; new ArrayList();list.add(new MyCallableA());list.add(new MyCallableB());ExecutorService executorService &＃61; Executors.newCachedThreadPool();try {String getValueA &＃61; (String) executorService.invokeAny(list);System.out.println(getValueA);} catch (InterruptedException e) {e.printStackTrace();} catch (ExecutionException e) {e.printStackTrace();}}
}


结果不会因为A的invokeAny而导致&＃xff0c;B的终止&＃xff1a;

但是&＃xff0c;如果将MyCallableB改造成如下形式&＃xff1a;

import java.util.concurrent.Callable;/*** &＃64;Author: jiaqing.xu&＃64;hand-china.com* &＃64;Date: 2019-04-07 21:43* &＃64;Description*/
public class MyCallableB implements Callable {&＃64;Overridepublic String call() throws Exception {System.out.println("CallableB begin:" &＃43; System.currentTimeMillis());for (int i &＃61; 0; i <1000; i&＃43;&＃43;) {if (!Thread.currentThread().isInterrupted()) {System.out.println("B:" &＃43; i);} else {System.out.println("开始抛出异常...");throw new InterruptedException("异常");}}System.out.println("CallableB end:" &＃43; System.currentTimeMillis());return "call B";}
}


A线程会正常执行完毕&＃xff0c;但是B线程会因为A的invokeAny而终止执行&＃xff1a;

二、invokeAll()方法

作用&＃xff1a;返回所有任务的执行结果&＃xff0c;该方法的执行效果也是阻塞执行的&＃xff0c;要把所有的结果都取回时再继续向下执行。

MyCallableA等待3s:

package invoke;import java.util.concurrent.Callable;/*** &＃64;Author: jiaqing.xu&＃64;hand-china.com* &＃64;Date: 2019-04-07 21:41* &＃64;Description*/
public class MyCallableA implements Callable {&＃64;Overridepublic String call() throws Exception {System.out.println("CallableA begin:" &＃43; System.currentTimeMillis()); Thread.sleep(3000);System.out.println("CallableA end:" &＃43; System.currentTimeMillis());return "call A";}
}


MyCallableB等待5s:

package invoke;import java.util.concurrent.Callable;/*** &＃64;Author: jiaqing.xu&＃64;hand-china.com* &＃64;Date: 2019-04-07 21:43* &＃64;Description*/
public class MyCallableB implements Callable {&＃64;Overridepublic String call() throws Exception {System.out.println("CallableB begin:" &＃43; System.currentTimeMillis());Thread.sleep(5000);System.out.println("CallableB end:" &＃43; System.currentTimeMillis());return "call B";}
}


package invoke;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
/*** &＃64;Author: jiaqing.xu&＃64;hand-china.com* &＃64;Date: 2019-04-07 22:06* &＃64;Description*/
public class RunMain2 {public static void main(String[] args) throws InterruptedException {MyCallableA myCallableA &＃61; new MyCallableA();MyCallableB myCallableB &＃61; new MyCallableB();List> callableList &＃61; new ArrayList<>();callableList.add(myCallableA);callableList.add(myCallableB);ExecutorService executorService &＃61; Executors.newCachedThreadPool();//开始时间Long startTime &＃61; System.currentTimeMillis();System.out.println("invoke all begin: " &＃43; startTime);//invokeAll等到两个线程的返回 它是阻塞的List> futureList &＃61; executorService.invokeAll(callableList);//结束时间Long endTime &＃61; System.currentTimeMillis();System.out.println("invoke all end: " &＃43; endTime);//输出最后的耗时System.out.println("all time: " &＃43; (endTime - startTime) / 1000 &＃43; "s");}
}