Java多线程之Callable接口的实现

淩亂°似流年 2022-10-02 10:40 212阅读 0赞

### 文章目录 ###

*  线程池管理
 *  有返回值的线程Callable接口的实现
 *  测试
 *  结果

# 线程池管理 #

package com.zfinfo;
    
    import java.util.List;
    import java.util.Vector;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import java.util.concurrent.Future;
    import java.util.concurrent.ThreadPoolExecutor;
    /**
     * 线程池管理
     * @author luww
     *
     */
    public class MyExecutor {
        
    	private ExecutorService executor = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors() + 1);
    	private List<Future> futureList = new Vector<>();
    	/**
    	 * 提交任务
    	 * @param list
    	 */
    	public void submit(List<String> list) {
        
    		for (String str : list) {
        
    			futureList.add(executor.submit(new MyCallable().init(str)));
    		}
    	}
    	/**
    	 * 获取当前活跃的线程数
    	 * @return
    	 */
    	public int getActiveCount(){
        
    		return ((ThreadPoolExecutor)executor).getActiveCount();
    	}
    	/**
    	 * 执行完后关闭线程池
    	 */
    	public void shutdown() {
        
    		executor.shutdown();
    	}
    
    	/**
    	 * 返回任务执行结果
    	 *
    	 * @return
    	 */
    	public List<Future> getFutureList() {
        
    		return futureList;
    	}
    
    	/**
    	 * 返回线程池
    	 *
    	 * @return
    	 */
    	public ExecutorService getExecutor() {
        
    		return executor;
    	}
    
    	/**
    	 * @param threads
    	 *            工作线程数量
    	 * @return
    	 */
    	public MyExecutor setThreads(int threads) {
        
    		this.executor = Executors.newFixedThreadPool(threads);
    		return this;
    	}
    }

# 有返回值的线程Callable接口的实现 #

package com.zfinfo;
    
    import java.util.concurrent.Callable;
    /**
     * 有返回值的线程
     * @author luww
     *
     */
    public class MyCallable implements Callable<Object> {
        
    	private String str;
    
    	public MyCallable init(String str) {
        
    		this.str = str;
    		return this;
    	}
    
    	@Override
    	public Object call() throws Exception {
        
    		return "call:" + str;
    	}
    
    }

# 测试 #

public static void main(String[] args) throws Exception {
        
    		List<String> list = new ArrayList<>();
    		for (int i = 0; i < 5; i++) {
        
    			list.add(UUID.randomUUID().toString());
    		}
    		// 创建myExcutor实例
    		MyExecutor myExecutor = new MyExecutor();
    		// 提交
    		myExecutor.submit(list);
    		// 获取返回值
    		List<Future> futureList = myExecutor.getFutureList();
    		// 遍历返回值
    		for (int i = 0; i < futureList.size(); i++) {
        
    			// get() 方法会阻塞当前线程直到获取返回值
    			System.out.println(i + "：" + futureList.get(i).get());
    		}
    		// 关闭线程池
    		myExecutor.shutdown();
    		System.out.println("availableProcessors:"+Runtime.getRuntime().availableProcessors());
    		System.out.println("totalMemory:"+Runtime.getRuntime().totalMemory());
    		System.out.println("freeMemory:"+Runtime.getRuntime().freeMemory());
    		System.out.println("maxMemory："+Runtime.getRuntime().maxMemory());
    	}

# 结果 #

0：call:b49d2006-8a91-4217-8f17-db2349448897
    1：call:548dba0a-0ccc-4a1f-b897-bf30c3da54c3
    2：call:00b02d86-31ef-4b5b-890d-471397eef636
    3：call:3c9f683f-43a8-4451-ac61-70bac41d8d7e
    4：call:4b18a89f-4050-4019-a78f-e481637748da
    availableProcessors:4
    totalMemory:56623104
    freeMemory:52973240
    maxMemory：826277888