Fork/Join小例子

  1、使用Fork/Join并行查询业务，如例子中根据多个id查询XX业务，可以分割成多个子任务并行查询

public class ForkJoinDemoService extends RecursiveTask<List<MSGroupVO>>
{

    /**
     * 序列
     */
    private static final long serialVersionUID = -8887828259415562910L;
    
    /**
     * 子任务查询参数阈值
     */
    private static final int LIST_SIZE_THRESHOLD = 5;
    
    // 参数，id列表
    private List<String> idList;
    
    /**
     * 构造函数
     */
    public ForkJoinDemoService(List<String> idList)
    {
        this.idList = idList;
    }

    /**
     * 并行执行
     * @return
     */
    @Override
    protected List<MSGroupVO> compute()
    {
        // 获得业务Service实例
        IGroupRoleService groupRoleService = new GroupRoleService();
        
        // 查询结果
        List<MSGroupVO> list = new ArrayList<MSGroupVO>();
        // id个数少于阈值时，可以直接执行任务
        boolean canCompute = idList.size() <= LIST_SIZE_THRESHOLD;
        if(canCompute)
        {
            String ids = StringUtils.join(idList, ",");
            list = groupRoleService.findGroups(ids);
        }
        else
        {
            // 参数id个数超过设置的阈值，则分割成两个子任务
            int mid = idList.size() / 2; 
            List<String> leftList = idList.subList(0, mid);
            List<String> rightList = idList.subList(mid, idList.size());
            ForkJoinDemoService leftTask = new ForkJoinDemoService(leftList);
            ForkJoinDemoService rightTask = new ForkJoinDemoService(rightList);
            
            //执行子任务
            leftTask.fork();
            rightTask.fork();
            
            //等待子任务执行完，并得到结果
            List<MSGroupVO> leftResult = leftTask.join();
            List<MSGroupVO> rightResult = rightTask.join();
            
            // 汇总结果并返回
            list.addAll(leftResult);
            list.addAll(rightResult);
        }
        
        
        return list;
    }
    
    /*public static void main(String[] args)
    {
        ForkJoinPool forkJoinPool = new ForkJoinPool();
        
        List<String> ids = new ArrayList<String>();
        ids.add("1800");
        ids.add("1803");
        ids.add("1804");
        ids.add("2200");
        ids.add("2201");
        ids.add("2202");
        ids.add("2203");
        ids.add("2204");
        ids.add("2205");
        ids.add("2206");
        ids.add("2207");
        ForkJoinDemoService task = new ForkJoinDemoService(ids);
        Future<List<MSGroupVO>> result = forkJoinPool.submit(task);
        try
        {
           List<MSGroupVO> list = result.get();
           System.out.println(list);
        }
        catch (Exception e)
        {
        }
    }*/
}