充值，提现功能涉及的多线程、队列问题

使用双乾第三方实现充值，提现功能。

思路

配置一个监听器在项目启动时初始化一个队列，开一个线程（run方法中检查队列中是否有值，有的话执行业务，没有的话线程等待）。充值，提现成功后回调方法时，填充队列，唤醒等待线程执行业务方法。

实现

web.xml中配置一个监听器

<listener>
　　<listener-class>com.wjz.listener.MyWebConfigContextListener</listener-class>
</listener>

MyWebConfigContextListener监听器

package com.wjz.listener;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

import org.springframework.context.ApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

import com.wjz.queue.MyCashJobQueue;
import com.wjz.service.MyAccountService;
import com.wjz.service.MyUserService;

public class MyWebConfigContextListener implements ServletContextListener {

    public void contextInitialized(ServletContextEvent sce) {
        ServletContext servletContext = sce.getServletContext();
        ApplicationContext context = WebApplicationContextUtils.getRequiredWebApplicationContext(servletContext);
    
        MyUserService userService = (MyUserService) context.getBean("userService");
        MyAccountService accountService = (MyAccountService) context.getBean("accountService");
        
        //初始化业务处理队列
        MyCashJobQueue.init(userService, accountService);
    }
}

MyCashJobQueue功能队列

package com.wjz.queue;

import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;

import com.wjz.model.MyCashModel;
import com.wjz.service.MyAccountService;
import com.wjz.service.MyUserService;
import com.wjz.task.MyTask;
import com.wjz.task.impl.MyCashTask;

/**
 * @author wjz
 */
public class MyCashJobQueue<T> {

    @SuppressWarnings({ "rawtypes", "unchecked" })
    private Queue<T> queue = new ConcurrentLinkedQueue();
    
    private MyTask task;
    
    public MyCashJobQueue(MyTask task) {
        this.task = task;
    }
    
    public static MyCashJobQueue<MyCashModel> CASH_QUEUE = null;
    
　　 // 初始化一个任务对象注入到功能队列中，任务对象开线程
    public static void init(MyUserService userService, MyAccountService accountService) {
        CASH_QUEUE = new MyCashJobQueue<MyCashModel>(new MyCashTask(userService, accountService));
    }
    
    public int size() {
        return queue.size();
    }
    
    public synchronized T peek() {
        return (T) queue.peek();
    }
    
    public synchronized T remove(T model) {
        return queue.remove();
    }
    // 向队列中填充值，唤醒等待线程
　　 // 同步MyCashJobQueue的实例对象
    public synchronized void offer(T model) {
        if (!queue.contains(model)) {
            queue.offer(model);
　　　　　　　 // 同步内容
            synchronized (task.getLock()) {
                task.execute();
            }
        }
    }
}

MyTask任务接口

package com.wjz.task;

public interface MyTask {
    
    public static final String CASH_STATUS = "cash_status";

    public void execute();
    
    public void doRun();
    
    public void doWait();
    
    public void stop();
    
    public Object getLock();
    
}

充值，提现功能实现类

package com.wjz.task.impl;

import com.wjz.model.MyCashModel;
import com.wjz.queue.MyCashJobQueue;
import com.wjz.service.MyAccountService;
import com.wjz.service.MyUserService;
import com.wjz.task.MyAbstractTask;
import com.wjz.task.MyTask;

public class MyCashTask extends MyAbstractTask {
    
    private MyUserService userService;
    private MyAccountService accountService;

    @Override
    public void doRun() {
        while (MyCashJobQueue.CASH_QUEUE != null && MyCashJobQueue.CASH_QUEUE.size() > 0) {
            // 取出队列中的任务
            MyCashModel cashModel = MyCashJobQueue.CASH_QUEUE.peek();
            try {
                if (cashModel != null) {
                    // 业务处理
                    accountService.doRechargeTask();
                }
            } catch (Exception e) {
                
            } finally {
                // 去除队列中的任务
                MyCashJobQueue.CASH_QUEUE.remove(cashModel); 
            } 
        }
        
    }
    
    public MyCashTask(MyUserService userService, MyAccountService accountService) {
        super();
        this.userService = userService;
        this.accountService = accountService;
    }
    
    @Override
    public Object getLock() {
        return MyTask.CASH_STATUS;
    }
}