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Spring Boot：运用Redis统计用户在线数量

news 2025/6/29 6:07:31

在Spring Boot里运用Redis统计用户在线数量。

项目依赖与配置

1. 引入依赖

首先，在pom.xml文件中添加Spring Data Redis依赖：

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

2. 配置Redis连接

在application.properties中进行Redis连接的配置：

spring.redis.host=localhost
spring.redis.port=6379

方案1：借助Redis Set实现精确统计

1. 创建Redis操作Service

编写一个Redis操作Service，用于处理用户在线状态：

import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;import java.util.Set;@Service
public class OnlineUserService {private static final String ONLINE_USERS_KEY = "online_users";private final RedisTemplate<String, String> redisTemplate;public OnlineUserService(RedisTemplate<String, String> redisTemplate) {this.redisTemplate = redisTemplate;}// 用户登录public void login(String userId) {redisTemplate.opsForSet().add(ONLINE_USERS_KEY, userId);}// 用户退出public void logout(String userId) {redisTemplate.opsForSet().remove(ONLINE_USERS_KEY, userId);}// 获取在线用户数public Long getOnlineCount() {return redisTemplate.opsForSet().size(ONLINE_USERS_KEY);}// 获取所有在线用户IDpublic Set<String> getOnlineUsers() {return redisTemplate.opsForSet().members(ONLINE_USERS_KEY);}
}

2. 控制器示例

创建一个控制器，用于测试上述功能：

import org.springframework.web.bind.annotation.*;@RestController
@RequestMapping("/online")
public class OnlineUserController {private final OnlineUserService onlineUserService;public OnlineUserController(OnlineUserService onlineUserService) {this.onlineUserService = onlineUserService;}@PostMapping("/login/{userId}")public String login(@PathVariable String userId) {onlineUserService.login(userId);return userId + " 已登录";}@PostMapping("/logout/{userId}")public String logout(@PathVariable String userId) {onlineUserService.logout(userId);return userId + " 已退出";}@GetMapping("/count")public Long getCount() {return onlineUserService.getOnlineCount();}@GetMapping("/users")public Set<String> getUsers() {return onlineUserService.getOnlineUsers();}
}

方案2：使用Redis Bitmap实现按位存储

1. Bitmap操作Service

创建一个专门用于Bitmap操作的Service：

import org.springframework.data.redis.connection.RedisStringCommands;
import org.springframework.data.redis.core.RedisCallback;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;@Service
public class OnlineUserBitmapService {private static final String ONLINE_USERS_BITMAP_KEY = "online_users_bitmap";private final RedisTemplate<String, Object> redisTemplate;public OnlineUserBitmapService(RedisTemplate<String, Object> redisTemplate) {this.redisTemplate = redisTemplate;}// 用户登录（userId需为Long类型）public void login(Long userId) {redisTemplate.execute((RedisCallback<Boolean>) connection ->connection.setBit(ONLINE_USERS_BITMAP_KEY.getBytes(), userId, true));}// 用户退出public void logout(Long userId) {redisTemplate.execute((RedisCallback<Boolean>) connection ->connection.setBit(ONLINE_USERS_BITMAP_KEY.getBytes(), userId, false));}// 检查用户是否在线public Boolean isOnline(Long userId) {return redisTemplate.execute((RedisCallback<Boolean>) connection ->connection.getBit(ONLINE_USERS_BITMAP_KEY.getBytes(), userId));}// 获取在线用户数public Long getOnlineCount() {return redisTemplate.execute((RedisCallback<Long>) connection ->connection.bitCount(ONLINE_USERS_BITMAP_KEY.getBytes()));}// 统计指定范围内的在线用户数public Long getOnlineCount(long start, long end) {return redisTemplate.execute((RedisCallback<Long>) connection ->connection.bitCount(ONLINE_USERS_BITMAP_KEY.getBytes(), start, end));}
}

2. 控制器示例

创建对应的控制器：

import org.springframework.web.bind.annotation.*;@RestController
@RequestMapping("/online/bitmap")
public class OnlineUserBitmapController {private final OnlineUserBitmapService onlineUserBitmapService;public OnlineUserBitmapController(OnlineUserBitmapService onlineUserBitmapService) {this.onlineUserBitmapService = onlineUserBitmapService;}@PostMapping("/login/{userId}")public String login(@PathVariable Long userId) {onlineUserBitmapService.login(userId);return userId + " 已登录";}@PostMapping("/logout/{userId}")public String logout(@PathVariable Long userId) {onlineUserBitmapService.logout(userId);return userId + " 已退出";}@GetMapping("/count")public Long getCount() {return onlineUserBitmapService.getOnlineCount();}@GetMapping("/{userId}")public Boolean isOnline(@PathVariable Long userId) {return onlineUserBitmapService.isOnline(userId);}
}