Spring Boot项目之synchronized处理并发

在orderProductMockDiffUser(String productId)方法体上加入synchronized关键字，可以保证每次都是单线程处理，因为加上了锁。但这种做法只适合单点操作，即单机上的做法，对于多机上来说的话是不合适的。

package com.imooc.controller;

import com.imooc.service.SecKillService;import lombok.extern.slf4j.Slf4j;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;@RestController@RequestMapping("/skill")@Slf4jpublic class SecKillController {

@Autowired    private SecKillService secKillService;

/**     * 查询秒杀活动特价商品的信息     * @param productId     * @return     */    @GetMapping("/query/{productId}")    public String query(@PathVariable String productId)throws Exception    {        return secKillService.querySecKillProductInfo(productId);    }

/**     * 秒杀，没有抢到获得"哎呦喂,xxxxx",抢到了会返回剩余的库存量     * @param productId     * @return     * @throws Exception     */    @GetMapping("/order/{productId}")    public String skill(@PathVariable String productId)throws Exception    {        log.info("@skill request, productId:" + productId);        secKillService.orderProductMockDiffUser(productId);        return secKillService.querySecKillProductInfo(productId);    }}

package com.imooc.service.impl;

import com.imooc.exception.SellException;import com.imooc.service.RedisLock;import com.imooc.service.SecKillService;import com.imooc.utils.KeyUtil;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;

import java.util.HashMap;import java.util.Map;

/** * Created by 廖师兄 * 2017-08-06 23:18 */@Servicepublic class SecKillServiceImpl implements SecKillService {

private static final int TIMEOUT = 10 * 1000; //超时时间 10s

@Autowired    private RedisLock redisLock;

/**     * 国庆活动，皮蛋粥特价，限量100000份     */    static Map<String,Integer> products;    static Map<String,Integer> stock;    static Map<String,String> orders;    static    {        /**         * 模拟多个表，商品信息表，库存表，秒杀成功订单表         */        products = new HashMap<>();        stock = new HashMap<>();        orders = new HashMap<>();        products.put("123456", 100000);        stock.put("123456", 100000);    }

private String queryMap(String productId)    {        return "国庆活动，皮蛋粥特价，限量份"                + products.get(productId)                +" 还剩：" + stock.get(productId)+" 份"                +" 该商品成功下单用户数目："                +  orders.size() +" 人" ;    }

@Override    public String querySecKillProductInfo(String productId)    {        return this.queryMap(productId);    }

@Override    public  void orderProductMockDiffUser(String productId)    {        //加锁

//1.查询该商品库存，为0则活动结束。        int stockNum = stock.get(productId);        if(stockNum == 0) {            throw new SellException(100,"活动结束");        }else {            //2.下单(模拟不同用户openid不同)            orders.put(KeyUtil.genUniqueKey(),productId);            //3.减库存            stockNum =stockNum-1;            try {                Thread.sleep(100);            } catch (InterruptedException e) {                e.printStackTrace();            }            stock.put(productId,stockNum);        }

//解锁

}}

原文地址：https://www.cnblogs.com/bozzzhdz/p/9675909.html