java启动100线程_Java启动新线程的几种方式（Runnable、Callable、CompletableFuture）
一、實現Runnable接口
public classRunnableDemo implements Runnable {public voidrun() {try{
Thread.sleep(100);
}catch(InterruptedException e) {
e.printStackTrace();
}
System.out.println("in runnable demo");
}
}
非阻塞調用
public static void main(String[] args) throwsException {
Thread runnableThread= new Thread(newRunnableDemo());runnableThread.start();
System.out.println("in main");
}
輸出結果
in main
in runnable demo
可以看到線程的運行沒有阻塞當前線程
阻塞調用
public static void main(String[] args) throwsException {
Thread runnableThread= new Thread(newRunnableDemo());
runnableThread.start();
runnableThread.join();
System.out.println("in main");
}
輸出結果
in runnable demo
in main
Join會阻塞當前線程，一直等待自定義線程才返回。
二、實現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行的結果。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");
}
輸出結果，如下所示，新啟動的線程沒有阻塞當前線程
in main
in callable demo
阻塞調用，且拿到結果
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，等待當前線程執行結束才返回，且返回線程的執行結果。
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Callable接口也能啟動，且能夠返回用戶線程的執行結果
public static CompletableFuture supplyAsync(Supplier supplier, Executor executor)
一個沒有實現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");
}
執行結果，可以看到，主線程沒有被阻塞
in main
in CompletableFutureDemo
阻塞調用且獲取結果
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());
}
執行結果，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
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