Spring-boot整合Redis，遇到的问题

1.通过set进redis中的数据，get不到

        String cityKey ="city_"+id;
        ValueOperations<String,City> operations = this.redisTemplate.opsForValue();
        // 判断缓存中是否存在
        if (this.redisTemplate.hasKey(cityKey)){

            City city = operations.get(cityKey);
            return city;
        }
        // 从 DB 中获取
        City city = this.cityRepository.findById(id).get();

        // 添加的缓存中，时间10
        operations.set(cityKey,city,, TimeUnit.SECONDS);

在redis-cli 中查看

192.168.6.3:> keys *
 \xac\xed\x00\x05t\x00\x06city_2

发现key值出现 \xac\xed\x00\x05t\x00\x06city_2 key是乱码

原因：序列化是默认用的JdkSerializationRedisSerializer

在redis配置中添加

//设置key序列-String序列化
template.setKeySerializer(new StringRedisSerializer());

2.如果希望java对象以json的方式存储到redis中

通常会在redis配置中添加

Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);

// 设置value的序列化规则
//json序列化
template.setValueSerializer(jackson2JsonRedisSerializer);

但是进行redis缓存get时会报错：java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.redis.springbootredis.pojo.City

 java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.redis.springbootredis.pojo.City
     at com.redis.springbootredis.service.impl.CityServiceImpl.findCityById(CityServiceImpl.java:59)
     at com.redis.springbootredis.SpringBootRedisApplicationTests.testFindCityById(SpringBootRedisApplicationTests.java:25)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
     at java.lang.reflect.Method.invoke(Method.java:498)
     at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
     at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
     at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
     at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
     at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
     at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
     at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
     at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
     at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
     at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
     at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
     at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
     at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
     at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
     at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
     at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
     at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
     at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
     at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
     at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
     at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
     at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
     at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
     at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
     at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
     at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

原因：redis中取出的对象数据为json，java.util.LinkedHashMap无法转换成city对象，

解决方式：在redis配置中添加

        //解决查询缓存转换异常的问题
        ObjectMapper om = new ObjectMapper();
        om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        jackson2JsonRedisSerializer.setObjectMapper(om);

还有一种方式：就是每次获取到对象数据进行json转换（每一都要转换太麻烦不太建议）

            String str = JSONObject.toJSONString(operations.get(cityKey));
            City cityy = JSON.parseObject(str,City.class);

笔者的redis配置类

 import com.fasterxml.jackson.annotation.JsonAutoDetect;
 import com.fasterxml.jackson.annotation.PropertyAccessor;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.data.redis.connection.RedisConnectionFactory;
 import org.springframework.data.redis.core.RedisTemplate;
 import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
 import org.springframework.data.redis.serializer.StringRedisSerializer;

 /**
  * @Author: GWL
  * @Description: redis配置
  * redisTemplate 序列化使用的jdkSerializeable, 存储二进制字节码, 所以自定义序列化类
  * 一般redis的序列化方式主要有：字符串序列化、json序列化、xml序列化、jdk序列化
  * 默认为 JdkSerializationRedisSerializer
  * @Date: Create in 14:43 2019/5/14
  */
 @Configuration
 public class RedisConfig {

     @Bean
     public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory redisCollectionFactory) {
         RedisTemplate template = new RedisTemplate();
         template.setConnectionFactory(redisCollectionFactory);

         Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);

         //解决查询缓存转换异常的问题
         ObjectMapper om = new ObjectMapper();
         om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
         om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
         jackson2JsonRedisSerializer.setObjectMapper(om);

         // 设置value的序列化规则
         //json序列化
         template.setValueSerializer(jackson2JsonRedisSerializer);
         //String序列化
 //        template.setValueSerializer(new StringRedisSerializer());
         //jdk序列化
 //        template.setValueSerializer(new JdkSerializationRedisSerializer());

         //设置key序列-String序列化
         template.setKeySerializer(new StringRedisSerializer());

         template.setHashKeySerializer(new StringRedisSerializer());
         template.setHashValueSerializer(new StringRedisSerializer());
         template.afterPropertiesSet();

         return template;
     }

 }

RedisConfig

再次redis中查看缓存对象：redis中中文乱码，但是存取没影响

192.168.6.3:6379> keys *
1) "city_2"
192.168.6.3:6379> get city_2
"[\"com.redis.springbootredis.pojo.City\",{\"id\":2,\"name\":\"\xe5\xa4\xa9\xe6\xb4\xa5\",\"description\":\"\xe6\xac\xa2\xe8\xbf\x8e\xe4\xbd\xa0\xe6\x9d\xa5\xe6\x8c\xa4\xe5\x9c\xb0\xe9\x93\x81\",\"createDate\":[\"java.sql.Timestamp\",1557737066000]}]"

换个姿势再来一次

如何在get时取到它的中文呢？只需要在redis-cli 后面加上 –raw

192.168.6.3:6379> QUIT
[root@localhost src]# ./redis-cli -h 192.168.6.3 -p 6379 --raw
192.168.6.3:6379> keys *
city_2
192.168.6.3:6379> get city_2
["com.redis.springbootredis.pojo.City",{"id":2,"name":"天津","description":"欢迎你来挤地铁","createDate":["java.sql.Timestamp",1557737066000]}]

有兴趣的朋友可以查看本人的spring-boot-redis：GitHub项目