lock4j--分布式锁中间件--自定义获取锁失败的逻辑

冷不防 2023-09-28 10:44 31阅读 0赞

原文网址：[lock4j--分布式锁中间件--自定义获取锁失败的逻辑\_IT利刃出鞘的博客-CSDN博客][lock4j--_--_IT_-CSDN]

## 简介 ##

**说明**

本文介绍lock4j如何自定义获取锁失败的逻辑。

**概述**

在注解模式下，对某个方法加锁，如果方法已上锁，默认抛出异常。默认的锁获取失败策略为 com.baomidou.lock.DefaultLockFailureStrategy 。

可以自定义处理方法，比如：如果方法上锁，其他线程执行时放弃执行，而不是抛异常。

**相关网址**

gitee：[https://gitee.com/baomidou/lock4j][https_gitee.com_baomidou_lock4j]

自定义获取锁失败逻辑：[gitee官方测试用例][gitee]

**注意**

本处使用lock4j过程中遇到了问题，不推荐使用lock4j，推荐直接使用redisson的分布式锁。

遇到的问题：

1.  获取锁超时时并没有抛异常，而是一直等待获取到锁。（无论是默认策略还是自定义策略都是如此）。

## 方法概述 ##

自定义实现类，实现LockFailureStrategy接口。

import com.baomidou.lock.LockFailureStrategy;
    import lombok.extern.slf4j.Slf4j;
    import org.springframework.stereotype.Component;
    
    import java.lang.reflect.Method;
    
    /**
     * 自定义获取锁异常处理
     */
    @Slf4j
    @Component
    public class CustomLockFailureStrategy implements LockFailureStrategy {
    
        @Override
        public void onLockFailure(String key, Method method, Object[] arguments) {
            log.error("获取锁失败了,key={},method={},arguments={}", key, method, arguments);
            // 此处可以抛出指定异常，配合全局异常拦截包装统一格式返回给调用端
            throw new BusinessException("请求太快啦~");
        }
    }

默认的策略：DefaultLockFailureStrategy

package com.baomidou.lock;
    
    import com.baomidou.lock.exception.LockFailureException;
    import lombok.extern.slf4j.Slf4j;
    
    import java.lang.reflect.Method;
    
    /**
     * @author zengzhihong
     */
    @Slf4j
    public class DefaultLockFailureStrategy implements LockFailureStrategy {
    
        protected static String DEFAULT_MESSAGE = "request failed,please retry it.";
    
        @Override
        public void onLockFailure(String key, Method method, Object[] arguments) {
            throw new LockFailureException(DEFAULT_MESSAGE);
        }
    }

## 公共代码 ##

### **配置** ###

spring:
      redis:
        host: 192.168.5.193
        port: 6379
        password: 222333
    
    #lock4j:
    #  acquire-timeout: 3000 #默认值3s，可不设置。排队时长，超过就退出排队，抛出获取锁超时异常。
    #  expire: 30000 #默认值30s，可不设置
    #  primary-executor: com.baomidou.lock.executor.RedissonLockExecutor #默认redisson > redisTemplate > zookeeper，可不设置
    #  lock-key-prefix: lock4j #锁key前缀, 默认值lock4j，可不设置

### **依赖** ###

<dependency>
    	<groupId>com.baomidou</groupId>
    	<artifactId>lock4j-redisson-spring-boot-starter</artifactId>
    	<version>2.2.2</version>
    </dependency>

整个pom.xml

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.4.13</version>
            <relativePath/> 
        </parent>
        <groupId>com.knife.demo</groupId>
        <artifactId>demo_lock4j_SpringBoot</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>demo_lock4j_SpringBoot</name>
        <description>demo_lock4j_SpringBoot</description>
        <properties>
            <java.version>1.8</java.version>
        </properties>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>com.baomidou</groupId>
                <artifactId>lock4j-redisson-spring-boot-starter</artifactId>
                <version>2.2.2</version>
            </dependency>
    
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <optional>true</optional>
            </dependency>
    
            <dependency>
                <groupId>com.github.xiaoymin</groupId>
                <artifactId>knife4j-spring-boot-starter</artifactId>
                <version>3.0.3</version>
            </dependency>
    
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <configuration>
                        <excludes>
                            <exclude>
                                <groupId>org.projectlombok</groupId>
                                <artifactId>lombok</artifactId>
                            </exclude>
                        </excludes>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    
    </project>

### 代码 ###

**Controller**

package com.knife.demo.controller;
    
    import com.baomidou.lock.annotation.Lock4j;
    import com.knife.demo.entity.User;
    import io.swagger.annotations.Api;
    import lombok.extern.slf4j.Slf4j;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.ArrayList;
    import java.util.List;
    
    @Api(tags = "用户")
    @Slf4j
    @RestController
    @RequestMapping("user")
    public class UserController {
        @GetMapping("listAll")
        @Lock4j
        public List<User> listAllUser() {
            try {
                log.info("获取到锁，开始睡眠");
                Thread.sleep(15000);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
            return new ArrayList<>();
        }
    
        @GetMapping("find")
        @Lock4j(keys = {"#user.id", "#user.name"}, expire = 60000, acquireTimeout = 1000)
        public List<User> find(User user) {
            return new ArrayList<>();
        }
    }

**Entity**

package com.knife.demo.entity;
    
    import lombok.Data;
    
    @Data
    public class User {
        private Long id;
    
        private String name;
    }

## 实例1：默认的获取锁失败策略 ##

短时间内访问两次这个接口：[http://localhost:8080/user/listAll][http_localhost_8080_user_listAll]

![200c7e0e32964f21a80ea3f5945e1144.gif][]

可以看到：获取锁超时时并没有抛异常，而是一直等待获取到锁。

后端结果

![b3c40d11ea7146889aa3096bf09fcaa5.png][]

## 实例2：自定义锁获取失败策略 ##

自定义策略

package com.knife.demo.config;
    
    import com.baomidou.lock.LockFailureStrategy;
    import lombok.extern.slf4j.Slf4j;
    import org.springframework.stereotype.Component;
    
    import java.lang.reflect.Method;
    
    @Slf4j
    @Component
    public class CustomLockFailureStrategy implements LockFailureStrategy {
    
        @Override
        public void onLockFailure(String key, Method method, Object[] arguments) {
            log.error("获取锁失败了。key={},method={},arguments={}", key, method, arguments);
    
            // 此处可以抛出指定异常，配合全局异常拦截包装统一格式返回给调用端
            throw new RuntimeException("请求太快啦~");
        }
    }

短时间内访问两次这个接口：[http://localhost:8080/user/listAll][http_localhost_8080_user_listAll]

结果：获取锁超时时并没有抛异常，而是一直等待获取到锁。

![4f895fcbcc0741218c7f95d5c2e81930.gif][]

后端结果：

![b103f9f196ac4e9d88c65739f9675da0.png][]

[lock4j--_--_IT_-CSDN]: https://knife.blog.csdn.net/article/details/125321139
[https_gitee.com_baomidou_lock4j]: https://gitee.com/baomidou/lock4j
[gitee]: https://gitee.com/baomidou/lock4j/blob/master/lock4j-test/src/main/java/com/baomidou/lock/test/custom/CustomLockFailureStrategy.java
[http_localhost_8080_user_listAll]: http://localhost:8080/user/listAll
[200c7e0e32964f21a80ea3f5945e1144.gif]: https://img-blog.csdnimg.cn/200c7e0e32964f21a80ea3f5945e1144.gif
[b3c40d11ea7146889aa3096bf09fcaa5.png]: https://img-blog.csdnimg.cn/b3c40d11ea7146889aa3096bf09fcaa5.png
[4f895fcbcc0741218c7f95d5c2e81930.gif]: https://img-blog.csdnimg.cn/4f895fcbcc0741218c7f95d5c2e81930.gif
[b103f9f196ac4e9d88c65739f9675da0.png]: https://img-blog.csdnimg.cn/b103f9f196ac4e9d88c65739f9675da0.png