Java 异步实现的几种方式小结

public class JavaFuture {
	public static void main(String[] args) throws Throwable, ExecutionException {
		ExecutorService executor = Executors.newFixedThreadPool(1);
		Future<String> f = executor.submit(new Callable<String>() {
 
			@Override
			public String call() throws Exception {
				System.out.println("task started!");
				longTimeMethod();
				System.out.println("task finished!");
				return "hello";
			}
		});
 
		//此处get()方法阻塞main线程
		System.out.println(f.get());
		System.out.println("main thread is blocked");
	}
}

package Netty_promise; 
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.function.Supplier;
 

public class JavaPromise {
	public static void main(String[] args) throws Throwable, ExecutionException {
		// 两个线程的线程池
		ExecutorService executor = Executors.newFixedThreadPool(2);
		//jdk1.8之前的实现方式
		CompletableFuture<String> future = CompletableFuture.supplyAsync(new Supplier<String>() {
			@Override
			public String get() {
				System.out.println("task started!");
				try {
					//模拟耗时操作
					longTimeMethod();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				return "task finished!";
			}
		}, executor);
 
		//采用lambada的实现方式
		future.thenAccept(e -> System.out.println(e + " ok"));
		
		System.out.println("main thread is running");
	}
}

@Service
public class AsynchronousService{
  @Async
  public Future springAsynchronousMethod(){
    Integer result = longTimeMethod();
    return new AsyncResult(result);
  }
}

@Autowired
private AsynchronousService asynchronousService;
public void useAsynchronousMethod(){
    Future future = asynchronousService.springAsynchronousMethod();
    future.get(1000, TimeUnit.MILLISECONDS);
}

public class ExecutorDemo {
    private ExecutorService executor = Executors.newFixedThreadPool(1);    
    public void asynTask() throws InterruptedException {    
        executor.submit(new Runnable() {            
            @Override
            public void run() {
                
                try {
                    Thread.sleep(10000);//方便观察结果
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }                
                
                int sum = 0;
                for(int i = 0; i < 1000; i++) {                    
                    sum += i;
		    }                
                System.out.println(sum);
            }
        });        
    }
}

public class Client {
    public static void main(String[] args) throws InterruptedException {        
        boolean r = task2();        
        if(r) {
            task3();
        }        
        System.out.println("------------main end-----------");
    }
    
    static boolean task2() throws InterruptedException {        
        ExecutorDemo e = new ExecutorDemo();        
        e.asynTask();        
        System.out.println("------------task2 end-----------");        
        return true;
    }    
    
    static void task3() throws InterruptedException {
        int j = 0;
        while(true) {
            if(j++ > 10000) {
                break;
            }
        }
        
        System.out.println("------------task3 end-----------");
    }
}