redis-對象的存儲-JSON

前提：

環境:SpringBoot2.0以上版本，1.0版本重寫緩存管理器的方式不同

1.存儲的對象實現序列化

public class Employee implements Serializable {
}

2.導入redis包

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
            <version>1.5.10.RELEASE</version>
        </dependency>

使用注解時：

修改默認配置

@Configuration
public class MyRedisConfig { 

     /* 緩存管理器
     */
    @Bean
    public CacheManager cacheManager(RedisConnectionFactory redisConnectionFactory) {
        //初始化一個RedisCacheWriter
        RedisCacheWriter redisCacheWriter = RedisCacheWriter.nonLockingRedisCacheWriter(redisConnectionFactory);
        //設置CacheManager的值序列化方式為json序列化
        RedisSerializer<Object> jsonSerializer = new GenericJackson2JsonRedisSerializer();
        RedisSerializationContext.SerializationPair<Object> pair = RedisSerializationContext.SerializationPair
                .fromSerializer(jsonSerializer);
        RedisCacheConfiguration defaultCacheConfig=RedisCacheConfiguration.defaultCacheConfig()
                .serializeValuesWith(pair);
        //設置默認超過期時間是30秒
        defaultCacheConfig.entryTtl(Duration.ofSeconds(30));
        //初始化RedisCacheManager
        return new RedisCacheManager(redisCacheWriter, defaultCacheConfig);
    }
}

實現

Controller層

  @GetMapping("/emp/{id}")
    public Employee getEmployee(@PathVariable("id") Integer id){
        Employee employee = employeeService.getEmp(id);
        return employee;
    }

Srevice層

    @Cacheable(cacheNames = "emp",condition = "#id>0",unless="#result == null")
    public Employee getEmp(Integer id){ 
        Employee emp = employeeMapper.getEmpById(id);  
        return emp;
    }

 修改配置前

 

 修改配后--為JSON串

 

 

不使用注解時：

方式一：按照默認的序列化存儲

@SpringBootTest
class Springboot01CacheApplicationTests {

    @Autowired
    EmployeeMapper employeeMapper;
 
    @Autowired
    RedisTemplate redisTemplate; //操作k-v都是對象

    @Test
    public void test(){
        Employee empById = employeeMapper.getEmpById(1);
        //默認如果保存對象，使用jdk序列化機制，序列化后的數據保存到redis中，
        //默認用的是jdk的序列化容器
        redisTemplate.opsForValue().set("emp-01", empById);
    }

}

方式二：將對象轉換為JSON

一：將默認的JDK序列化機制修改為JSON

配置：

@Configuration
public class MyRedisConfig {

    @Bean
    public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {
        RedisTemplate<Object, Object> template = new RedisTemplate();
        template.setConnectionFactory(redisConnectionFactory);
        Jackson2JsonRedisSerializer<Object> ser = new Jackson2JsonRedisSerializer<Object>(Object.class);
        template.setDefaultSerializer(ser);
        return template;
    }
}

實現：

@SpringBootTest
class Springboot01CacheApplicationTests {

    @Autowired
    EmployeeMapper employeeMapper;

    @Autowired
    StringRedisTemplate stringRedisTemplate;//操作k-v都是字符串的

    @Autowired
    RedisTemplate redisTemplate; //操作k-v都是對象

    @Test
    public void test02(){
        Employee empById = employeeMapper.getEmpById(1);
  
        redisTemplate.opsForValue().set("emp-04", empById);

    }

}

二：手動將對象修改為JSON字符串

方式一：

JSONObject json = JSONObject.fromObject(stu);//將對象轉換為JSON對象

String strJson=json.toString();//將JSON轉換為字符串

方式二：

ObjectMapper mapper = new ObjectMapper();/*ObjectMapper是Jackson提供的一個類，作用是將java對象與json格式相互轉化*/

jsonString = mapper.writeValueAsString(areaList);