Java语言学习二十五（线程池）

落日映苍穹つ 2023-07-20 13:59 32阅读 0赞

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package com.gf.erp.thread;
    
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import java.util.concurrent.Future;
    
    public class ThreadPoolTest { 
        public static void main(String[] args) throws Exception
        { 
        	//创建固定数量线程池
            ExecutorService executor = Executors.newFixedThreadPool(5);
            //模拟提交10个任务
            for (int i = 0; i < 10; i++) { 
                executor.submit(() -> { 
                    System.out.println("线程ID: " + Thread.currentThread().getId());
                    try { 
                    	//线程池中的线程等待1 
                        Thread.sleep(1000L);
                    } catch (InterruptedException e) { 
                        e.printStackTrace();
                    }
                });
            }
            executor.shutdown();
            System.out.println("最后执行打印...");
        }
    }

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package com.gf.erp.thread;
    
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import java.util.concurrent.Future;
    
    public class ThreadPoolTest { 
        public static void main(String[] args) throws Exception
        { 
        	//创建固定数量线程池
            ExecutorService executor = Executors.newFixedThreadPool(5);
            //模拟提交10个任务
            for (int i = 0; i < 10; i++) { 
                Future f = executor.submit(() -> { 
                    System.out.println("线程ID: " + Thread.currentThread().getId());
                    try { 
                    	//线程池中的线程等待1 
                        Thread.sleep(1000L);
                    } catch (InterruptedException e) { 
                        e.printStackTrace();
                    }
                });
                f.get();
            }
            executor.shutdown();
            System.out.println("最后执行打印...");
        }
    }

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使用Excutors线程池工厂提供的线程池实现

```csharp
    package com.gf.erp.thread;
    
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import java.util.concurrent.Future;
    
    public class MyThreadPool2 { 
    	public static void bubbleSort(int[] dim)
    	{ 
    		for(int i=0;i<dim.length;i++)
    		{ 
    			for(int j=0;j<dim.length-1-i;j++)
    			{ 
    				if(dim[j]>dim[j+1])
    				{ 
    					int temp = dim[j];
    					dim[j] = dim[j+1];
    					dim[j+1] = temp;
    				}
    			}
    		}
    	}
    	
    	public static void main(String[] args) throws Exception
    	{ 
    		int[][] tasks = { 
    				{ 123,23,22,34,56,3,2,6,7,1,2,4,7,8,5,12,323},
    				{ 5,6,45,34,34,23,22,224,12,567,678,999,66,99},
    				{ 12,30,43,63,68,6,9,67,7,689,99,4,3,5,8,9,0},
    				{ 1,4,6,7,8,5,5,6,8,0,33,22,34,11,21,45,550,4},
    				{ 12,13,5,6,7,8,9,0,45,66,77,4,9,7,8,7,6,99,8},
    				{ 3,5,7,9,0,10,13,7,8,0,55,44,3,68,22,44,67,8}
    		};
    		for(int i=0;i<tasks.length;i++)
    		{ 
    			System.out.print("排序前数组:"+i+"=");
    			for(int j=0;j<tasks[i].length;j++)
    				System.out.print(tasks[i][j]+",");
    			System.out.println();
    		}
    		
            ExecutorService executor = Executors.newFixedThreadPool(5);
            for (int i = 0; i < tasks.length; i++) { 
            	int[] tempDim = tasks[i];
                Future f = executor.submit(() -> { 
                    System.out.println("thread id is: " + Thread.currentThread().getId());
                    try { 
                        Thread.sleep(1000L);
                        bubbleSort(tempDim);
                    } catch (InterruptedException e) { 
                        e.printStackTrace();
                    }
                });
                System.out.println(f.get());
            }
            executor.shutdown();
            System.out.println("--------------here");
            
    		for(int i=0;i<tasks.length;i++)
    		{ 
    			System.out.print("排序后数组:"+i+"=");
    			for(int j=0;j<tasks[i].length;j++)
    				System.out.print(tasks[i][j]+",");
    			System.out.println();
    		}
    	}
    }

使用自定义线程池实现
    
    ```csharp
    package com.gf.erp.thread;
    
    import java.util.concurrent.ArrayBlockingQueue;
    import java.util.concurrent.BlockingQueue;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Future;
    import java.util.concurrent.RejectedExecutionHandler;
    import java.util.concurrent.ThreadFactory;
    import java.util.concurrent.ThreadPoolExecutor;
    import java.util.concurrent.TimeUnit;
    
    
    public class MyThreadPool {
    	private int corePoolSize;
    	private int maximumPoolSize;
    	private long keepAliveTime;
    	private TimeUnit unit;
    	BlockingQueue<Runnable> workQueue;
    	ThreadFactory threadFactory;
    	RejectedExecutionHandler handler;
    
    	public static void bobbleSort(int[] dim)
    	{
    		for(int i=0;i<dim.length;i++)
    		{
    			for(int j=0;j<dim.length-1-i;j++)
    			{
    				if(dim[j]>dim[j+1])
    				{
    					int temp = dim[j+1];
    					dim[j+1] = dim[j];
    					dim[j] = temp;
    				}
    			}
    		}
    	}	
    
    	public MyThreadPool(int corePoolSize,int maximumPoolSize,long keepAliveTime,TimeUnit unit,
    			BlockingQueue<Runnable> workQueue,ThreadFactory threadFactory,
    			RejectedExecutionHandler handler,int[][] task)
    	{
    		ExecutorService es = new ThreadPoolExecutor(corePoolSize,maximumPoolSize,keepAliveTime,
    	            unit,workQueue,threadFactory,handler);
    		try
    		{
    			for(int i=0;i<task.length;i++)
    			{
    				int[] tempDim = task[i];
    				Future f = es.submit(()->{
    					bobbleSort(tempDim);
    				});
    				System.out.println("f="+f.get());
    			}
    			es.shutdown();
    			for(int i=0;i<task.length;i++)
    			{
    				System.out.print("Dim:"+i+"=");
    				for(int j=0;j<task[i].length;j++)
    					System.out.print(task[i][j]+",");
    				System.out.println();
    			}
    		}
    		catch(Exception e)
    		{
    			e.printStackTrace();
    		}
    	}
    	
    	public static void main(String[] args)
    	{
    		int corePoolSize = 4;
    		int maximumPoolSize = 10;
    		long keepAliveTime = 10;
    		TimeUnit unit = TimeUnit.MINUTES;
    		BlockingQueue<Runnable> workQueue = new ArrayBlockingQueue<Runnable>(20);
    		ThreadFactory threadFactory = new MyThreadFactory();
    		RejectedExecutionHandler handler = new ThreadPoolExecutor.AbortPolicy();
    		
    		int[][] tasks = {
    				{123,23,22,34,56,3,2,6,7,1,2,4,7,8,5,12,323},
    				{5,6,45,34,34,23,22,224,12,567,678,999,66,99},
    				{12,30,43,63,68,6,9,67,7,689,99,4,3,5,8,9,0},
    				{1,4,6,7,8,5,5,6,8,0,33,22,34,11,21,45,550,4},
    				{12,13,5,6,7,8,9,0,45,66,77,4,9,7,8,7,6,99,8},
    				{3,5,7,9,0,10,13,7,8,0,55,44,3,68,22,44,67,8}
    		};
    		
    		MyThreadPool mypool = new MyThreadPool(corePoolSize,maximumPoolSize,keepAliveTime,unit,workQueue,
    				threadFactory,handler,tasks);
    
    		for(int i=0;i<tasks.length;i++)
    		{
    			for(int j=0;j<tasks[i].length;j++)
    				System.out.println(tasks[i][j]);
    			System.out.println("------------");
    		}
    	}
    }
    
    class MyThreadFactory implements ThreadFactory
    {
    	@Override
    	public Thread newThread(Runnable r) {
    		return new Thread(r);
    	}
    }

思考题  
定义一个大数组，使用线程池最高效排序。

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