Callable 与 Future

Posted 2020-12-05 lxh520

package cn.itcast.write;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class FutureAndCall {
    /**
     * Callable与Runnable类似
     * call方法和run方法
     * 
     * Future 获取结果异常
     */
    public static void main(String[] args) {
        
        //1---------------------------------
        ExecutorService threadPool = Executors.newSingleThreadExecutor();
        Future<String> future = threadPool.submit(new Callable<String>() {
            @Override
            public String call() throws Exception {
                return "200";
            }
        });
        try {
            System.out.println(future.get());
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ExecutionException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        threadPool.shutdownNow();
        
        //2---------------------------------
        CallableTask task1 = new CallableTask(1);
        CallableTask task2 = new CallableTask(2);
        CallableTask task3 = new CallableTask(3);
        
        
        try {
            ExecutorService threadPool1= Executors.newFixedThreadPool(3);
            Future<Integer> f1 =  threadPool1.submit(task1);
            System.out.println(f1.get());
            
            Future<Integer> f2 =  threadPool1.submit(task2);
            System.out.println(f2.get());
            try {
                Thread.sleep(5000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            f2.cancel(true);
            
            
            Future<Integer> f3 =  threadPool1.submit(task3);
            System.out.println(f3.get());
            
            
            threadPool1.shutdownNow();
        } catch (InterruptedException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (ExecutionException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        
        
    }
}


class CallableTask implements Callable<Integer>{
    
    private int data;
    public CallableTask(int data){
        this.data = data;
    }
    
    @Override
    public Integer call() throws Exception {
        
        if (data == 1) {
            return 1;
        }
        
        if (data == 2) {
            while(true){
                System.out.println("2222");
                Thread.sleep(1000);
                return 2;
            }
        }
        
        if (data == 3) {
            /*try {
                throw new Throwable();
            } catch (Throwable e) {
                e.printStackTrace();
            }*/
        }
        
        
        return null;
    }

    
}