Spring Boot 使用Redis_spring boot引入redis

@Configuration
@EnableCaching
public class RedisConfig{
 
  private Logger logger = LoggerFactory.getLogger(this.getClass());
 
  @Value("${spring.redis.host}")
  private String host;
 
  @Value("${spring.redis.port}")
  private int port;
 
  @Value("${spring.redis.timeout}")
  private int timeout;
 
  @Value("${spring.redis.password}")
  private String password;
 
  @Value("${spring.redis.database}")
  private int database;
 
  @Value("${spring.redis.pool.max-idle}")
  private int maxIdle;
 
  @Value("${spring.redis.pool.min-idle}") 
  private int minIdle;
 
  /**
   *  注解@Cache key生成规则
   */
  @Bean
  public KeyGenerator keyGenerator() {
      return new KeyGenerator() {
        @Override
        public Object generate(Object target, Method method, Object... params) {
             StringBuilder sb = new StringBuilder();
             sb.append(target.getClass().getName());
             sb.append(method.getName());
             for (Object obj : params) {
                 sb.append(obj.toString());
             }
             return sb.toString();
        }
      };
  }
 
  /**
   *  注解@Cache的管理器，设置过期时间的单位是秒
   * @Description:
   * @param redisTemplate
   * @return
   */
  @Bean
  public CacheManager cacheManager(RedisTemplate redisTemplate) {
      RedisCacheManager cacheManager = new RedisCacheManager(redisTemplate);
      Map<String, Long> expires=new HashMap<String, Long>();
      expires.put("user", 6000L);
      expires.put("city", 600L);
      cacheManager.setExpires(expires);
      // Number of seconds before expiration. Defaults to unlimited (0)
      cacheManager.setDefaultExpiration(600); //设置key-value超时时间
     return cacheManager;
  }
 
  /**
   * redis模板，存储关键字是字符串，值是Jdk序列化
   * @Description:
   * @param factory
   * @return
   */
  @Bean
  public RedisTemplate<?,?> redisTemplate(RedisConnectionFactory factory) {
      RedisTemplate<?,?> redisTemplate = new RedisTemplate<>();
      redisTemplate.setConnectionFactory(factory);
      //key序列化方式;但是如果方法上有Long等非String类型的话，会报类型转换错误；
      RedisSerializer<String> redisSerializer = new StringRedisSerializer();//Long类型不可以会出现异常信息;
      redisTemplate.setKeySerializer(redisSerializer);
      redisTemplate.setHashKeySerializer(redisSerializer);
 
      //JdkSerializationRedisSerializer序列化方式;
      JdkSerializationRedisSerializer jdkRedisSerializer=new JdkSerializationRedisSerializer();
      redisTemplate.setValueSerializer(jdkRedisSerializer);
      redisTemplate.setHashValueSerializer(jdkRedisSerializer);
      redisTemplate.afterPropertiesSet();
      return redisTemplate; 
  }
 
 
  /**
   * redis连接的基础设置
   * @Description:
   * @return
   */
  @Bean
  public JedisConnectionFactory redisConnectionFactory() {
    JedisConnectionFactory factory = new JedisConnectionFactory();
    factory.setHostName(host);
    factory.setPort(port);
    factory.setPassword(password);
    //存储的库
    factory.setDatabase(database);
    //设置连接超时时间
    factory.setTimeout(timeout); 
    factory.setUsePool(true);
    factory.setPoolConfig(jedisPoolConfig());
    return factory;
  }
 
  /**
   * 连接池配置
   * @Description:
   * @return
   */
  @Bean
  public JedisPoolConfig jedisPoolConfig() {
    JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();
    jedisPoolConfig.setMaxIdle(maxIdle);
    jedisPoolConfig.setMinIdle(minIdle);
//    jedisPoolConfig.set ...
    return jedisPoolConfig;
  }
}
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在一个请求方法上加上@Cacheable注解，测试效果：

 @Cacheable(value = "testCache")
    @GetMapping("/{id}")
    public User getUserById(@PathVariable Integer id) {
        return userService.findUser(id);
    }
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访问这个接口后报错：

java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
at org.springframework.data.redis.serializer.StringRedisSerializer.serialize(StringRedisSerializer.java:33)
at org.springframework.data.redis.cache.RedisCacheKey.serializeKeyElement(RedisCacheKey.java:74)
at org.springframework.data.redis.cache.RedisCacheKey.getKeyBytes(RedisCacheKey.java:49)
at org.springframework.data.redis.cache.RedisCache$1.doInRedis(RedisCache.java:176)
at org.springframework.data.redis.cache.RedisCache$1.doInRedis(RedisCache.java:172)
at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:207)
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原因如下： 
Redis缓存的key生成策略：

If no params are given,return SimpleKey.EMPTY.
If only one params is given,return that instance.
If more the one param is given,return a SimpleKey containing all parameters.
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从上面的策略可以看出，上面缓存testCache中使用的key是整形的id参数，但是在设置RedisTemplate的时候设置了template.setKeySerializer(new StringRedisSerializer());所以导致类型转换错误，所以需要重写keyGenerator定制key的生成策略

修改RedisConfig类，添加keyGenerator的方法：

@Bean
public KeyGenerator keyGenerator() {
    return new KeyGenerator() {
        @Override
        public Object generate(Object target, Method method, Object... params) {
            StringBuilder sb = new StringBuilder();
            sb.append(target.getClass().getName())
                    .append(":")
                    .append(method.getName());
            for (Object obj : params) {
                sb.append(":")
                        .append(obj.toString());
            }
            return sb.toString();
        }
    };
}
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这里的策略很简单，使用类名 + 方法名 + 参数作为缓存key。

再次访问两次这个接口：

http://localhost:8080/demo/users/3
http://localhost:8080/demo/users/4
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• 查看Redis内容：

127.0.0.1:6379> keys *
1) "testCache~keys"
2) "com.example.demo.controller.UserController:getUserById:3"
3) "com.example.demo.controller.UserController:getUserById:4"
127.0.0.1:6379> get com.example.demo.controller.UserController:getUserById:3
"[\"com.example.demo.model.User\",{\"id\":3,\"name\":\"\xe7\x8e\x8b\xe5\x89\x91\xe9\x94\x8b\",\"age\":12}]"
127.0.0.1:6379> zrange testCache~keys 0 10
1) "com.example.demo.controller.UserController:getUserById:3"
2) "com.example.demo.controller.UserController:getUserById:4"
127.0.0.1:6379>
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可以看到Redis里面保存了一下内容：

• 两条String类型的键值对，key就是生成的key，value就是user对象序列化之后的结果。
• 一个有序集合。其中key为 @Cacheable中的value + ~keys.内容为String类型的键值对的key.

缓存更新与删除

更新和删除缓存使用到@CachePut和@CacheEvict。这时候发现用原来的key生成策略无法保证增删查改的key一致（因为参数不同，方法名也不同)，所以需要修改一下KeyGenerator,改为缓存key按照 缓存名称 + id的方式

@Bean
public KeyGenerator keyGenerator() {
    return new KeyGenerator() {
        @Override
        public Object generate(Object target, Method method, Object... params) {
            StringBuilder sb = new StringBuilder();
            String[] value = new String[1];
            Cacheable cacheable = method.getAnnotation(Cacheable.class);
            if (cacheable != null) {
                value = cacheable.value();
            }
            CachePut cachePut = method.getAnnotation(CachePut.class);
            if (cachePut != null) {
                value = cachePut.value();
            }
            CacheEvict cacheEvict = method.getAnnotation(CacheEvict.class);
            if (cacheEvict != null) {
                value = cacheEvict.value();
            }
            sb.append(value[0]);
            for (Object obj : params) {
                sb.append(":")
                        .append(obj.toString());
            }
            return sb.toString();
        }
    };
}
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然后修改Controller：

@Cacheable(value = "user")
@GetMapping("/{id}")
public User getUserById(@PathVariable Integer id) {
    return userService.findUser(id);
}
 
@CachePut(value = "user", key = "#root.caches[0].name + ':' + #user.id")
@PostMapping("/")
public User addUser(User user) {
    userService.add(user);
    //返回增加后的id
    return user;
}
 
@CachePut(value = "user", key = "#root.caches[0].name + ':' + #user.id")
@PutMapping("/{id}")
public User updateUser(@PathVariable Integer id, User user) {
    user.setId(id);
    userService.update(user);
    return user;
}
 
@CacheEvict(value = "user")
@DeleteMapping("/{id}")
public String deleteUser(@PathVariable Integer id) {
    int result = userService.delete(id);
    return result == 1 ? "删除成功" : "删除失败";
}
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如果@CachePut指定了key属性之后，则不会再调用keygenerator的方法。此时可以看到，增删查改的方法缓存的key都是user:id这样的格式。

然后进行测试，测试过程为测试某个方法然后到redis中查看缓存是否正确。

下面贴出所有相关的代码：

RedisConfig.java

@Configuration
@EnableCaching
public class RedisConfig extends CachingConfigurerSupport {
 
    Logger logger = LoggerFactory.getLogger(RedisConfig.class);
 
    @Bean
    public CacheManager cacheManager(RedisTemplate redisTemplate) {
        RedisCacheManager rcm = new RedisCacheManager(redisTemplate);
        // 设置缓存过期时间，秒
        rcm.setDefaultExpiration(60 * 10);
        return rcm;
    }
 
    @Bean
    public KeyGenerator keyGenerator() {
        return new KeyGenerator() {
            @Override
            public Object generate(Object target, Method method, Object... params) {
                StringBuilder sb = new StringBuilder();
                String[] value = new String[1];
                Cacheable cacheable = method.getAnnotation(Cacheable.class);
                if (cacheable != null) {
                    value = cacheable.value();
                }
                CachePut cachePut = method.getAnnotation(CachePut.class);
                if (cachePut != null) {
                    value = cachePut.value();
                }
                CacheEvict cacheEvict = method.getAnnotation(CacheEvict.class);
                if (cacheEvict != null) {
                    value = cacheEvict.value();
                }
                sb.append(value[0]);
                for (Object obj : params) {
                    sb.append(":")
                            .append(obj.toString());
                }
                return sb.toString();
            }
        };
    }
 
 
    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(factory);
        template.setKeySerializer(new StringRedisSerializer());
        Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer<>(Object.class);
        ObjectMapper om = new ObjectMapper();
        om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        jackson2JsonRedisSerializer.setObjectMapper(om);
        template.setValueSerializer(jackson2JsonRedisSerializer);
        template.afterPropertiesSet();
        return template;
    }
 
}
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UserController.java

@RestController
@RequestMapping("/users")
public class UserController {
 
    @Autowired
    UserService userService;
 
    @GetMapping(value = "/")
    public List<User> getUsers() {
        return userService.findUsers();
    }
 
    @Cacheable(value = "user")
    @GetMapping("/{id}")
    public User getUserById(@PathVariable Integer id) {
        return userService.findUser(id);
    }
 
    @CachePut(value = "user", key = "#root.caches[0].name + ':' + #user.id")
    @PostMapping("/")
    public User addUser(User user) {
        userService.add(user);
        //返回增加后的id
        return user;
    }
 
    @CachePut(value = "user", key = "#root.caches[0].name + ':' + #user.id")
    @PutMapping("/{id}")
    public User updateUser(@PathVariable Integer id, User user) {
        user.setId(id);
        userService.update(user);
        return user;
    }
 
    @CacheEvict(value = "user")
    @DeleteMapping("/{id}")
    public String deleteUser(@PathVariable Integer id) {
        int result = userService.delete(id);
        return result == 1 ? "删除成功" : "删除失败";
    }
}
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