来源: 互联网  发布时间: 2014-02-18

newFixedThreadPool与Callable结合用法

package com.sohu.test;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;

/**
 * @author qiaowang
 * @date 2013-12-26 上午10:39:01
 */
public class TestThreadDemo {

    private ExecutorService exec;
    private int cpuNum;
    private List<Future<Long>> tasks = new ArrayList<Future<Long>>();
    
    class SumCalculator implements Callable<Long> {  
        private int[] numbers;  
        private int start;  
        private int end;  
  
        public SumCalculator(final int[] numbers, int start, int end) {  
            this.numbers = numbers;  
            this.start = start;  
            this.end = end;  
        }  
  
        public Long call() throws Exception {  
            Long sum = 0l;  
            for (int i = start; i < end; i++) {  
                sum += numbers[i];  
            }  
            return sum;  
        }  
    }   
    
    public TestThreadDemo() {
        cpuNum = Runtime.getRuntime().availableProcessors();
        exec = Executors.newFixedThreadPool(cpuNum);
    }
    
    public Long sum(final int[] numbers) {  
        // 根据CPU核心个数拆分任务，创建FutureTask并提交到Executor  
        System.out.println(cpuNum);
        for (int i = 0; i < cpuNum; i++) {  
            int increment = numbers.length / cpuNum + 1;  
            int start = increment * i;  
            int end = increment * i + increment;  
            if (end > numbers.length)  
                end = numbers.length;  
            SumCalculator subCalc = new SumCalculator(numbers, start, end);  
            FutureTask<Long> task = new FutureTask<Long>(subCalc);  
            tasks.add(task);  
            if (!exec.isShutdown()) {  
                exec.submit(task);  
            }  
        }  
        return getResult();  
    }
    
    public Long getResult() {
        Long result = 0l;
        for(Future<Long> task : tasks){
            try {
                Long subSum = task.get();
                result +=subSum;
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return result;
    }
    
    public void close(){
        exec.shutdown();
    }
    
    public static void main(String args[]){
        int[] numbers = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 10, 11 ,12};  
        TestThreadDemo calc = new TestThreadDemo();  
        Long sum = calc.sum(numbers);  
        System.out.println(sum);  
        calc.close(); 
    }
}

参见
http://www.iteye.com/topic/366591

Executors类，提供了一系列工厂方法用于创先线程池，返回的线程池都实现了ExecutorService接口。
public static ExecutorService newFixedThreadPool(int nThreads)
创建固定数目线程的线程池。
public static ExecutorService newCachedThreadPool()
创建一个可缓存的线程池，调用execute 将重用以前构造的线程（如果线程可用）。如果现有线程没有可用的，则创建一个新线程并添加到池中。终止并从缓存中移除那些已有 60 秒钟未被使用的线程。
public static ExecutorService newSingleThreadExecutor()
创建一个单线程化的Executor。
public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize)
创建一个支持定时及周期性的任务执行的线程池，多数情况下可用来替代Timer类。

    

    来源: 互联网  发布时间: 2014-02-18

dwr.util.addOptions方法的使用

    

    来源: 互联网  发布时间: 2014-02-18

Hibernate:More than one row with the given identifier was found解决办法

今天写一个Action 通过 HQL 查询一个表 出现异常 “More than one row with the given identifier was found”

问题原因： 数据库出现数据异常 存在多条主键不唯一的数据

问题解决： 找到数据库表 删除全部数据 然后重新导入 问题没了


我的情况：写请假表单的时候，form表单被提交了两次，导致我的@OneToOne 出错，因为里面有
两条数据了，导致主键不唯一！