spring boot 自定义注解实现本地锁

「爱情、让人受尽委屈。」 2022-12-19 16:17 213阅读 0赞

# 技术点 #

1.  AOP
2.  注解声明
3.  自动配置

## 声明注解 ##

import java.lang.annotation.*;
    
    @Target(ElementType.METHOD)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Inherited
    public @interface LocalLock { 
        String key() default "";
    }

> key为锁标识

## AOP 实现注解 ##

import cn.hutool.cache.Cache;
    import cn.hutool.cache.CacheUtil;
    import cn.hutool.core.date.DateUnit;
    import cn.hutool.core.util.NumberUtil;
    import cn.hutool.core.util.ReflectUtil;
    import cn.hutool.core.util.StrUtil;
    import com.alibaba.fastjson.JSON;
    import com.guodun.aiosign.tools.lock.LocalLock;
    import lombok.extern.slf4j.Slf4j;
    import org.aspectj.lang.ProceedingJoinPoint;
    import org.aspectj.lang.annotation.Around;
    import org.aspectj.lang.annotation.Aspect;
    import org.aspectj.lang.reflect.MethodSignature;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.util.StringUtils;
    
    import java.lang.reflect.Method;
    
    @Aspect
    @Configuration
    @Slf4j
    public class LocalLockInterceptor { 
        private static Cache<String, String> lockCache = CacheUtil.newLFUCache(200, DateUnit.SECOND.getMillis() * 10);
        @Around("@annotation(com.guodun.aiosign.tools.lock.LocalLock)")
        public Object interceptor(ProceedingJoinPoint pjp) { 
            MethodSignature signature = (MethodSignature) pjp.getSignature();
            Method method = signature.getMethod();
            LocalLock localLock = method.getAnnotation(LocalLock.class);
            String key = getKey(localLock.key(), pjp.getArgs());
            if (!StringUtils.isEmpty(key)) { 
                if (lockCache.containsKey(key)) { 
                    log.debug("发生死锁 ： {} ",key);
                    checkLock(key);
                }else { 
                    lockCache.put(key, key);
                }
            }
            try { 
                return pjp.proceed();
            } catch (Throwable throwable) { 
                throw new RuntimeException("服务器异常");
            } finally { 
                // 请求结束后解除锁
               if (!StringUtils.isEmpty(key)) lockCache.remove(key);
            }
        }
        private void checkLock(String key)  { 
            try { 
                for (int i = 0; i < 20; i++) { 
                    if (!lockCache.containsKey(key)) return;
                    Thread.sleep(500);
                }
            }catch (InterruptedException e) { 
                e.printStackTrace();
            }
            if (lockCache.containsKey(key))  throw new RuntimeException("请勿重复请求");
        }
        private String getKey(String keyExpress, Object[] args) { 
            String[] keys = StrUtil.splitToArray(keyExpress,'.');
            log.debug("参数 {} ", JSON.toJSONString(keys));
            if (keys.length>0&&args.length>0){ 
                String args_str = keys[0];
                if(!NumberUtil.isInteger(args_str)) return null;
                int args_index = Integer.valueOf(args_str);
                if (args_index>args.length)return null;
                if(keys.length<2) { 
                    log.info("value : {} ",args[args_index-1].toString());
                    return args[args_index-1].toString();
                }
                Object value = ReflectUtil.getFieldValue(args[args_index-1],keys[1]);
                log.info("value : {} ",value.toString());
                return value.toString();
            }
            return null;
        }
    }

## 自动配置（spring boot） ##

![在这里插入图片描述][20201109084434932.png_pic_center]

#配置自定义Starter的自动化配置
    org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.keepgoon.tools.lock.local.LocalLockInterceptor

[20201109084434932.png_pic_center]: /images/20221120/b9f2db5aa9b04f7185b1389d5c8fde68.png