SpringBoot集成Redisson實現(xiàn)分布式鎖的示例代碼

更新時間：2026年04月08日 08:33:44 作者：Zzxy

本文介紹了使用Redisson實現(xiàn)分布式鎖以解決并發(fā)預約號源超賣問題,首先添加Redisson依賴并配置RedissonClient,接著在預約服務中引入分布式鎖,并自定義扣減號源方法,最后總結了分布式鎖的實現(xiàn)原理,包括鎖粒度、鎖超時、可重入性和WatchDog機制,需要的朋友可以參考下

1、集成 Redisson

Redisson 是 Redis 官方推薦的 Java 客戶端，實現(xiàn)了 可靠的分布式鎖、可重入鎖、讀寫鎖 等，封裝了底層復雜性。

1.1 添加 Redisson 依賴

<!-- Redisson（Redis分布式鎖客戶端） -->
<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson-spring-boot-starter</artifactId>
    <version>3.23.4</version>
</dependency>

1.2 配置 RedissonClient

在application.yml中添加：

spring:
  redis:
    host: localhost
    port: 6379
    # Redisson自動配置，無需額外配置

2、分布式鎖解決并發(fā)預約號源超賣問題

2.1 預約服務中，增加分布式鎖

修改AppointmentServiceImpl.bookAppointment方法：

package com.example.service.impl;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.conditions.update.LambdaUpdateWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.springBoot.hospital.entity.Appointment;
import com.springBoot.hospital.entity.Department;
import com.springBoot.hospital.mapper.AppointmentMapper;
import com.springBoot.hospital.mapper.DepartmentMapper;
import com.springBoot.hospital.service.AppointmentService;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import java.text.SimpleDateFormat;
import java.util.concurrent.TimeUnit;
@Service
public class AppointmentServiceImpl implements AppointmentService {
    @Autowired
    private DepartmentMapper departmentMapper;
    @Autowired
    private AppointmentMapper appointmentMapper;
    @Autowired
    private RedissonClient redissonClient;
/*
    //預約操作后清除該用戶的預約緩存
    @CacheEvict(value = "appointments", key = "'user:' + #userId + '_page:*'",allEntries = true)
    //Spring Cache 原生不支持通配符 * 在 key 中的模糊匹配。
    //allEntries = true會清空整個緩存名下的所有條目
    @Override
    @Transactional(rollbackFor = Exception.class) //任何異常都回滾
    public boolean bookAppointment(String appointmentNo,Long userId, Long departmentId, String appointmentDate) {
        //1\插入預約記錄
        Appointment appointment = new Appointment();
        appointment.setAppointmentNo(appointmentNo);
        appointment.setUserId(userId);
        appointment.setDepartmentId(departmentId);
        //將字符串轉為Date(格式：yyyy-mm-dd)
        try {
            //使用SimpleDateFormat 定義日期格式
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");
            Date date = sdf.parse(appointmentDate); //字符串轉為Date
            appointment.setAppointmentDate(date);
        } catch (Exception e) {
            throw new RuntimeException("日期格式錯誤",e);
        }
        appointment.setStatus("PENDING"); //狀態(tài)：待就診
        int rows = appointmentMapper.insert(appointment);
        if(rows == 0){
            throw new RuntimeException("插入預約失敗");
        }
        //2\扣減號源，department中
        //使用條件更新，避免并發(fā)
        LambdaUpdateWrapper<Department> updateWrapper = new LambdaUpdateWrapper<>();
        updateWrapper.eq(Department::getId,departmentId)
                .gt(Department::getRemaining,0)
                .setSql("order_num = order_num - 1");
        int updateRows = departmentMapper.update(null,updateWrapper);
        if(updateRows == 0){
            throw new RuntimeException("號源不足或科室不存在");
        }
        return true;
    }
 */
    @Override
    @Transactional(rollbackFor = Exception.class) //事務管理，任何異常都回滾
    public boolean bookAppointment(String appointmentNo, Long userId, Long departmentId, String appointmentDate) {
        //構建分布式鎖的key(科室Id + 預約日期)
        String lockKey = "lock:dept:" + departmentId + ":date:" + appointmentDate;
        //創(chuàng)建對象,Redisson 根據 key 獲取一個可重入鎖對象。
        RLock lock = redissonClient.getLock(lockKey);
        boolean locked = false;
        try {
            // 嘗試加鎖，最多等待3秒，上鎖后10秒自動釋放(防止死鎖)
            locked = lock.tryLock(3, 10, TimeUnit.SECONDS);
            if(!locked){
                throw new RuntimeException("系統(tǒng)繁忙，請稍后重試");
            }
            //1 檢查號源
            Department dept = departmentMapper.selectById(departmentId);
            if(dept == null || dept.getRemaining() == null || dept.getRemaining() <= 0){
                throw new RuntimeException("號源不足");
            }
            //2 插入預約記錄
            Appointment appointment = new Appointment();
            appointment.setAppointmentNo(appointmentNo);
            appointment.setUserId(userId);
            appointment.setDepartmentId(departmentId);
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            appointment.setAppointmentDate(sdf.parse(appointmentDate));
            appointment.setStatus("PENDING");
            int insertRows = appointmentMapper.insert(appointment);
            if(insertRows == 0){
                throw new RuntimeException("插入預約失敗");
            }
            //3 扣減號源
            //使用自定義扣減號源方法,SQL條件更新號源數(shù)量
            int updateRows = departmentMapper.decreaseRemaining(departmentId);
            if(updateRows == 0){
                throw new RuntimeException("扣減號源失敗，可能已被搶走");
            }
            return true;
        } catch (Exception e) {
            throw new RuntimeException(e.getMessage(),e);
        } finally {
            //釋放鎖，只釋放當前線程持有的鎖
            if(locked && lock.isHeldByCurrentThread()){
                lock.unlock();
            }
        }
    }
    //分頁查詢緩存，分頁參數(shù)影響key
    @Cacheable(value = "appointments", key = "'user:' + #userId + '_page:' + #pageNum + '_size:' + #pageSize")
    @Override
    public IPage<Appointment> findAppointmentsByUserId(Long userId, Integer pageNum, Integer pageSize) {
        Page<Appointment> page = new Page<>(pageNum,pageSize);
        LambdaQueryWrapper<Appointment> queryWrapper = new LambdaQueryWrapper<>();
        queryWrapper.eq(Appointment::getUserId,userId)
                .orderByDesc(Appointment::getAppointmentDate);
        return appointmentMapper.selectPage(page,queryWrapper);
    }
}

2.2 自定義扣減號源方法

在DepartmentMapper中添加自定義扣減方法：

// DepartmentMapper.java
@Mapper
public interface DepartmentMapper extends BaseMapper<Department> {
    
    // 自定義扣減號源（使用樂觀鎖防止超賣）
    @Update("UPDATE department SET order_num = order_num - 1 where id = #{departmentId}")
    int decreaseRemaining(@Param("departmentId") Long departmentId);
}