Redis核心原理与Java应用实践

一、Redis Java客户端选型

1.1 主流Java客户端对比

客户端	特点	适用场景	性能基准
Jedis	同步阻塞IO，线程不安全	简单应用，连接池管理	50,000 ops/s
Lettuce	异步非阻塞IO，Netty实现	高并发，响应式编程	80,000 ops/s
Redisson	分布式服务封装，丰富功能	分布式系统集成	60,000 ops/s

1.2 Jedis基本使用

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// 创建连接池配置
JedisPoolConfig poolConfig = new JedisPoolConfig();
poolConfig.setMaxTotal(128);
poolConfig.setMaxIdle(32);
poolConfig.setMinIdle(8);

// 创建连接池
try (JedisPool jedisPool = new JedisPool(poolConfig, "localhost", 6379);
     Jedis jedis = jedisPool.getResource()) {
     
    // 字符串操作
    jedis.set("user:1001", "张三");
    String userName = jedis.get("user:1001");
    
    // 哈希操作
    jedis.hset("user:1001:info", "age", "28");
    Map<String, String> userInfo = jedis.hgetAll("user:1001:info");
}

二、Redis数据结构Java实现

2.1 字符串操作优化

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// 批量操作减少网络开销
List<String> keys = Arrays.asList("key1", "key2", "key3");
List<String> values = jedis.mget(keys.toArray(new String[0]));

// 原子计数器
jedis.incr("article:1001:views");
jedis.incrBy("user:1001:credits", 10);

2.2 哈希结构应用

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// 存储对象
public void saveUser(User user) {
    Map<String, String> hash = new HashMap<>();
    hash.put("id", user.getId());
    hash.put("name", user.getName());
    hash.put("age", String.valueOf(user.getAge()));
    jedis.hmset("user:" + user.getId(), hash);
}

// 获取对象
public User getUser(String userId) {
    Map<String, String> hash = jedis.hgetAll("user:" + userId);
    User user = new User();
    user.setId(hash.get("id"));
    user.setName(hash.get("name"));
    user.setAge(Integer.parseInt(hash.get("age")));
    return user;
}

三、Java中的Redis高级特性

3.1 管道技术实现

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// Jedis管道示例
Pipeline pipeline = jedis.pipelined();
pipeline.set("key1", "value1");
pipeline.incr("counter");
pipeline.zadd("sortedSet", 1, "member");
List<Object> results = pipeline.syncAndReturnAll();

// Lettuce异步管道
StatefulRedisConnection<String, String> connection = client.connect();
RedisAsyncCommands<String, String> async = connection.async();
async.setAutoFlushCommands(false);

async.set("key1", "value1");
async.incr("counter");
async.zadd("sortedSet", 1, "member");

async.flushCommands();

3.2 发布订阅模式

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// Jedis订阅实现
new Thread(() -> {
    jedis.subscribe(new JedisPubSub() {
        @Override
        public void onMessage(String channel, String message) {
            System.out.println("收到消息: " + message);
        }
    }, "channel1");
}).start();

// 发布消息
jedis.publish("channel1", "Hello Redis!");

四、Spring整合Redis

4.1 Spring Data Redis配置

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@Configuration
public class RedisConfig {
    
    @Bean
    public RedisConnectionFactory redisConnectionFactory() {
        LettuceConnectionFactory factory = new LettuceConnectionFactory();
        factory.setHostName("localhost");
        factory.setPort(6379);
        factory.setDatabase(0);
        return factory;
    }
    
    @Bean
    public RedisTemplate<String, Object> redisTemplate() {
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(redisConnectionFactory());
        template.setKeySerializer(new StringRedisSerializer());
        template.setValueSerializer(new GenericJackson2JsonRedisSerializer());
        return template;
    }
}

4.2 Repository模式使用

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@RedisHash("persons")
public class Person {
    @Id String id;
    String name;
    Integer age;
    // getters/setters
}

public interface PersonRepository extends CrudRepository<Person, String> {
    List<Person> findByName(String name);
}

// 使用示例
personRepository.save(new Person("1001", "张三", 28));
Person person = personRepository.findById("1001").get();

五、Redis缓存实战

5.1 Spring Cache集成

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@Configuration
@EnableCaching
public class CacheConfig {
    
    @Bean
    public CacheManager cacheManager(RedisConnectionFactory factory) {
        RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig()
            .entryTtl(Duration.ofMinutes(30))
            .disableCachingNullValues();
        
        return RedisCacheManager.builder(factory)
            .cacheDefaults(config)
            .transactionAware()
            .build();
    }
}

@Service
public class UserService {
    
    @Cacheable(value = "users", key = "#userId")
    public User getUser(String userId) {
        // 数据库查询逻辑
    }
    
    @CachePut(value = "users", key = "#user.id")
    public User updateUser(User user) {
        // 更新数据库
        return user;
    }
    
    @CacheEvict(value = "users", key = "#userId")
    public void deleteUser(String userId) {
        // 删除数据库记录
    }
}

5.2 缓存穿透解决方案

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// 布隆过滤器实现
public class BloomFilter {
    private final Jedis jedis;
    private final String filterName;
    
    public BloomFilter(Jedis jedis, String filterName) {
        this.jedis = jedis;
        this.filterName = filterName;
    }
    
    public void add(String value) {
        jedis.setbit(filterName, hash(value), true);
    }
    
    public boolean exists(String value) {
        return jedis.getbit(filterName, hash(value));
    }
    
    private long hash(String value) {
        // 简单哈希实现，实际应使用多个哈希函数
        return Math.abs(value.hashCode()) % (1 << 32);
    }
}

// 使用示例
BloomFilter filter = new BloomFilter(jedis, "user_filter");
if (!filter.exists(userId)) {
    return null; // 不存在直接返回
}

六、Redis事务与Lua脚本

6.1 Java中的Redis事务

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// Jedis事务示例
Transaction tx = jedis.multi();
try {
    tx.set("key1", "value1");
    tx.incr("counter");
    tx.exec();
} catch (Exception e) {
    tx.discard();
}

// Spring事务集成
@Transactional
public void transfer(String from, String to, int amount) {
    redisTemplate.opsForValue().decrement(from, amount);
    redisTemplate.opsForValue().increment(to, amount);
}

6.2 Lua脚本执行

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// 执行Lua脚本
String script = "local current = redis.call('GET', KEYS[1])\n" +
               "if current and tonumber(current) >= tonumber(ARGV[1]) then\n" +
               "    return redis.call('DECRBY', KEYS[1], ARGV[1])\n" +
               "else\n" +
               "    return -1\n" +
               "end";

List<String> keys = Collections.singletonList("inventory:1001");
List<String> args = Collections.singletonList("5");

Long result = (Long) jedis.eval(script, keys, args);

七、Redis集群与哨兵模式

7.1 集群模式配置

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// Jedis集群配置
Set<HostAndPort> nodes = new HashSet<>();
nodes.add(new HostAndPort("127.0.0.1", 7001));
nodes.add(new HostAndPort("127.0.0.1", 7002));
nodes.add(new HostAndPort("127.0.0.1", 7003));

JedisCluster cluster = new JedisCluster(nodes, 2000, 5);
cluster.set("clusterKey", "value");
String value = cluster.get("clusterKey");

7.2 哨兵模式配置

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// Lettuce哨兵配置
RedisURI redisUri = RedisURI.Builder.sentinel("sentinel1", 26379)
    .withSentinel("sentinel2", 26379)
    .withSentinel("sentinel3", 26379)
    .withMasterId("mymaster")
    .build();

RedisClient client = RedisClient.create(redisUri);
StatefulRedisConnection<String, String> connection = client.connect();

八、性能监控与调优

8.1 Jedis连接池监控

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// 连接池监控指标
GenericObjectPoolConfig<Jedis> config = new GenericObjectPoolConfig<>();
config.setJmxEnabled(true);
config.setJmxNamePrefix("redis-pool");
config.setJmxNameBase("type=RedisPool");

// 获取监控数据
int active = jedisPool.getNumActive();
int idle = jedisPool.getNumIdle();
int waiters = jedisPool.getNumWaiters();

8.2 慢查询分析

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// 获取慢查询日志
List<Slowlog> slowlogs = jedis.slowlogGet();
for (Slowlog log : slowlogs) {
    System.out.println("命令: " + log.getArgs() + 
                      " 执行时间: " + log.getExecutionTime() + "微秒");
}

// 重置慢查询日志
jedis.slowlogReset();

九、安全最佳实践

9.1 SSL连接配置

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// Lettuce SSL配置
RedisURI redisUri = RedisURI.create("rediss://localhost");
redisUri.setVerifyPeer(false); // 生产环境应验证证书

RedisClient client = RedisClient.create(redisUri);
StatefulRedisConnection<String, String> connection = client.connect();

9.2 访问控制

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// 认证配置
JedisPoolConfig poolConfig = new JedisPoolConfig();
JedisPool jedisPool = new JedisPool(poolConfig, "localhost", 6379, 2000, "password");

// ACL用户管理（Redis 6.0+）
jedis.aclSetUser("appuser", "on", ">apppassword", 
    "+@read", "+@write", "-@admin");

十、实战案例：秒杀系统设计

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@Service
public class SeckillService {
    
    private final RedisTemplate<String, Object> redisTemplate;
    
    public SeckillService(RedisTemplate<String, Object> redisTemplate) {
        this.redisTemplate = redisTemplate;
    }
    
    public boolean seckill(String productId, String userId) {
        // 1. 校验库存
        Integer stock = (Integer) redisTemplate.opsForValue().get("stock:" + productId);
        if (stock == null || stock <= 0) {
            return false;
        }
        
        // 2. 使用Lua脚本保证原子性
        String script = "local stock = tonumber(redis.call('GET', KEYS[1]))\n" +
                      "if stock > 0 then\n" +
                      "    redis.call('DECR', KEYS[1])\n" +
                      "    redis.call('SADD', KEYS[2], ARGV[1])\n" +
                      "    return 1\n" +
                      "else\n" +
                      "    return 0\n" +
                      "end";
        
        List<String> keys = Arrays.asList("stock:" + productId, "success:" + productId);
        Long result = (Long) redisTemplate.execute(
            new DefaultRedisScript<>(script, Long.class),
            keys, userId);
        
        return result == 1;
    }
}

结语

通过本文的Java视角Redis实践指南，我们深入探讨了Redis在Java生态系统中的各种应用场景和最佳实践。从基础数据结构操作到高级特性应用，从单机部署到集群管理，这些知识将帮助您构建高性能、可靠的Java应用系统。