乐观锁实现

mapper:

<select id="queryLock" resultType="java.util.Map">
    select upg,version from happy_lock
</select>

<update id="editHappyLock" parameterType="java.util.Map">
    update happy_lock
    set upg=#{upg},version=version+1
    where id=#{id} and version=#{version};
</update>
测试:

@Test
public void happyLock() {
    ExecutorService fixedThreadPool = Executors.newFixedThreadPool(20);
    for(int i=0;i<10;i++){
        fixedThreadPool.execute(new Runnable() {
            @Override
            public void run() {
                try{
                    Map<String, Object> map = new HashMap<>();
                    map.put("id", 1);
                    Random rand = new Random();
                    Map<String,Object> mapTemp=nyHappyLockService.queryLock();
                    int randomCount=rand.nextInt(100);
                    int upg = Integer.valueOf(mapTemp.get("upg").toString());
                    int version = Integer.valueOf(mapTemp.get("version").toString());
                    map.put("version", version);
                    map.put("upg", (randomCount+version));
                    int count=nyHappyLockService.editHappyLock(map);
                    System.out.println(Thread.currentThread()+" "+Thread.currentThread().getName()+" 执行的结果数"+count);
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
        });
    }
}
执行结果:

提交的数据 版本号大于数据库表当前版本号，更新。可以看到后面的线程版本号都低于第一个版本 只有第一个执行成功后面的 都废弃了

乐观锁实现

原文：https://www.cnblogs.com/austinspark-jessylu/p/11428129.html