一、实现Runnable接口

public classRunnableDemo implements Runnable {public voidrun() {try{

Thread.sleep(100);

}catch(InterruptedException e) {

e.printStackTrace();

}

System.out.println("in runnable demo");

}

}

非阻塞调用

public static void main(String[] args) throwsException {

Thread runnableThread= new Thread(newRunnableDemo());runnableThread.start();

System.out.println("in main");

}

输出结果

in main

in runnable demo

可以看到线程的运行没有阻塞当前线程

阻塞调用

public static void main(String[] args) throwsException {

Thread runnableThread= new Thread(newRunnableDemo());

runnableThread.start();

runnableThread.join();

System.out.println("in main");

}

输出结果

in runnable demo

in main

Join会阻塞当前线程，一直等待自定义线程才返回。

二、实现Callable接口

在Runnable的例子中，Runnable接口有一个很大的缺陷就是run方法没有返回值定义，主线程无法获取到线程执行的结果。这个时候就需要Callable接口。

public class CallableDemo implements Callable{public CallableDtocall() throwsException {try{

Thread.sleep(100);

}catch(InterruptedException e) {

e.printStackTrace();

}

System.out.println("in callable demo");return new CallableDto(1);

}

}classCallableDto {private intid;public CallableDto(intid) {this.id =id;

}public intgetId() {returnid;

}public void setId(intid) {this.id =id;

}

}

非阻塞调用

public static void main(String[] args) throwsException {

ThreadPoolExecutor executor= (ThreadPoolExecutor) Executors.newFixedThreadPool(10);

Future future = executor.submit(newCallableDemo());

System.out.println("in main");

}

输出结果，如下所示，新启动的线程没有阻塞当前线程

in main

in callable demo

阻塞调用，且拿到结果

public static void main(String[] args) throwsException {

ThreadPoolExecutor executor= (ThreadPoolExecutor) Executors.newFixedThreadPool(10);

Future future = executor.submit(newCallableDemo());

CallableDto callableDto=future.get();

System.out.println("in main");

System.out.println("id from callable is " +callableDto.getId());

}

get方法首先会阻塞主线程，等待当前线程执行结束才返回，且返回线程的执行结果。

三、CompletableFuture方式

CompletableFuture是jdk1.8引入的api，做了进一步的封装，用户线程无需实现Callable接口也能启动，且能够返回用户线程的执行结果

public static CompletableFuture supplyAsync(Supplier supplier, Executor executor)

一个没有实现Callable的普通方法

public classCompletableFutureDemo {publicCompletableFutureDemoDto action() {try{

Thread.sleep(100);

}catch(InterruptedException e) {

e.printStackTrace();

}

System.out.println("in CompletableFutureDemo ");return new CompletableFutureDemoDto(1);

}

}classCompletableFutureDemoDto {private intid;public CompletableFutureDemoDto(intid) {this.id =id;

}public intgetId() {returnid;

}public void setId(intid) {this.id =id;

}

}

非阻塞调用

public static void main(String[] args) throwsException {

ThreadPoolExecutor executor= (ThreadPoolExecutor) Executors.newFixedThreadPool(10);

CompletableFuture future = CompletableFuture.supplyAsync(() ->{return newCompletableFutureDemo().action();

}, executor);

System.out.println("in main");

}

执行结果，可以看到，主线程没有被阻塞

in main

in CompletableFutureDemo

阻塞调用且获取结果

public static void main(String[] args) throwsException {

ThreadPoolExecutor executor= (ThreadPoolExecutor) Executors.newFixedThreadPool(10);

CompletableFuture future = CompletableFuture.supplyAsync(() ->{return newCompletableFutureDemo().action();

}, executor);

CompletableFutureDemoDto demoDto=future.join();

System.out.println("in main");

System.out.println("id from demoDto is " +demoDto.getId());

}

执行结果，主线程一直被阻塞，一直等到用户线程返回

in CompletableFutureDemo

in main

id from demoDto is1