Spring-Data-Redis存储对象(redisTemplate)

先看实例：

...
    @Autowired
    RedisTemplate redisTemplate;

    public void testGetUserByName(){
        User user = new User();
        user.setUserName("用户1");
        redisTemplate.opsForValue().set("user1", user);
        Assert.assertEquals(user.getUserName(), ((User) jedisClient.get("user1")).getUserName());
    }
//User已经实现了Serializable接口
//配置的是org.springframework.data.redis.serializer.StringRedisSerializer
...

使用StringRedisSerializer直接缓存Object会出现转换错误：

java.lang.ClassCastException: dev.entity.User cannot be cast to java.lang.String

    at org.springframework.data.redis.serializer.StringRedisSerializer.serialize(StringRedisSerializer.java:32)
    at org.springframework.data.redis.core.AbstractOperations.rawValue(AbstractOperations.java:112)
    at org.springframework.data.redis.core.DefaultValueOperations.set(DefaultValueOperations.java:168)
    at dev.dao.RedisTest.testGetUserByName(RedisTest.java:22)
...

解决方法

StringRedisTemplate相当于RedisTemplate<String, String>的实现。
缓存时需要把Object类转为byte[]再存到redis中，反之要从redis中获取byte[]再转成Object。

看了很多人的实现方法，感觉这个实现最优雅便捷。最主要的转换代码如下：

    /**
     * 描述 : <byte[]转Object>. <br>
     * <p>
     * <使用方法说明>
     * </p>
     *
     * @param bytes
     * @return
     */
    private Object toObject(byte[] bytes) {
        Object obj = null;
        try {
            ByteArrayInputStream bis = new ByteArrayInputStream(bytes);
            ObjectInputStream ois = new ObjectInputStream(bis);
            obj = ois.readObject();
            ois.close();
            bis.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        } catch (ClassNotFoundException ex) {
            ex.printStackTrace();
        }
        return obj;
    }
 
    private byte[] toByteArray(Object obj) {
        byte[] bytes = null;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            ObjectOutputStream oos = new ObjectOutputStream(bos);
            oos.writeObject(obj);
            oos.flush();
            bytes = bos.toByteArray();
            oos.close();
            bos.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        return bytes;
    }
}

相当于封装了一个处理Object缓存的类，之后用这个类与redis做交流。

package dev.dao;

import dev.cache.JedisClient;
import dev.entity.User;
import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:/spring/spring-redis.xml")
public class RedisTest {
    @Autowired
    JedisClient jedisClient;

    @Test
    public void testGetUserByName(){
        User user = new User();
        user.setUserName("用户1");
        jedisClient.put("user1", user);

        Assert.assertEquals(user.getUserName(), ((User) jedisClient.get("user1")).getUserName());
    }
}

//测试成功