并发下，使用redis防止数据重复插入(数据库未对表字段设置唯一情况下)

@Controller
@RequestMapping("/myTest")
public class TestController {

    @Autowired(required = false)
    private TestService testService;
    
    @Autowired
    private RedisUtil redisUtil;

    @RequestMapping("add")
    public void add(HttpServletRequest request) throws Exception {
        List<Course> cList = testService.queryByName("aaaaa");//查询
        System.out.println(Thread.currentThread().getName()+"clist.size:"+cList.size());
        if(cList.size() == 0){
            if(redisUtil.setnx("name_"+"aaaaa", "aaaaa") == 1){//如果数据存在则返回0，不存在返回1
                Course course = new Course();
                course.setCname("aaaaa");
                try{
                    testService.add1(course);//插入
                }catch (Exception e) {
                    redisUtil.del("name_"+"aaaaa");//插入出异常则删除
                    throw e;
                }
                System.out.println(Thread.currentThread().getName()+"success");
                redisUtil.expire("name_"+"aaaaa", 3);//设失效时间3秒
            }else{
                System.out.println(Thread.currentThread().getName()+"exists");
            }
        }else{
            System.out.println(Thread.currentThread().getName()+"false");
        }
    }

}

RedisUtil 工具类可以网上搜

以下测试代码：

public class Test {

    /**
     * @param args
     * @throws IOException 
     * @throws HttpException 
     */
    public static void main(String[] args) throws Exception {
        for(int i=0;i<10;i++){
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            new Thread(new Runnable() {
                @Override
                public void run() {
                    // TODO Auto-generated method stub
                    post();
                }
            }).start();
        }
    }
    
    public static void post(){
        HttpClient client = new HttpClient();
        client.getParams().setContentCharset("UTF-8");
        PostMethod method = new PostMethod("http://localhost:8080/practice/myTest/add.do?time="+new Date().getTime());
        method.setRequestHeader("ContentType","application/x-www-form-urlencoded;charset=UTF-8");
        try {
            client.executeMethod(method);
        } catch (HttpException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}