一、實現(xiàn)Runnable接口

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

Thread.sleep(100);

}catch(InterruptedException e) {

e.printStackTrace();

}

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

}

}

非阻塞調(diào)用

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

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

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

}

輸出結(jié)果

in main

in runnable demo

可以看到線程的運行沒有阻塞當(dāng)前線程

阻塞調(diào)用

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

Thread runnableThread= new Thread(newRunnableDemo());

runnableThread.start();

runnableThread.join();

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

}

輸出結(jié)果

in runnable demo

in main

Join會阻塞當(dāng)前線程，一直等待自定義線程才返回。

二、實現(xiàn)Callable接口

在Runnable的例子中，Runnable接口有一個很大的缺陷就是run方法沒有返回值定義，主線程無法獲取到線程執(zhí)行的結(jié)果。這個時候就需要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;

}

}

非阻塞調(diào)用

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

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

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

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

}

輸出結(jié)果，如下所示，新啟動的線程沒有阻塞當(dāng)前線程

in main

in callable demo

阻塞調(diào)用，且拿到結(jié)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方法首先會阻塞主線程，等待當(dāng)前線程執(zhí)行結(jié)束才返回，且返回線程的執(zhí)行結(jié)果。

三、CompletableFuture方式

CompletableFuture是jdk1.8引入的api，做了進一步的封裝，用戶線程無需實現(xiàn)Callable接口也能啟動，且能夠返回用戶線程的執(zhí)行結(jié)果

public static CompletableFuture supplyAsync(Supplier supplier, Executor executor)

一個沒有實現(xiàn)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;

}

}

非阻塞調(diào)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");

}

執(zhí)行結(jié)果，可以看到，主線程沒有被阻塞

in main

in CompletableFutureDemo

阻塞調(diào)用且獲取結(jié)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());

}

執(zhí)行結(jié)果，主線程一直被阻塞，一直等到用戶線程返回

in CompletableFutureDemo

in main

id from demoDto is1

總結(jié)

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