在将Jedis与Spring Data一起使用时，为什么在Redis中使用奇怪的密钥存储数据？

时间：2012-11-04 00:49:11

标签： redis spring-data jedis

我正在使用Spring Data Redis和Jedis。我正在尝试使用密钥vc:${list_id}存储哈希。我能够成功插入redis。但是，当我使用redis-cli检查密钥时，我看不到密钥vc:501381。相反，我看到\xac\xed\x00\x05t\x00\tvc:501381。

为什么会发生这种情况？如何更改？

5 个答案:

答案 0 :(得分：68)

好的，谷歌搜索了一会儿，并在http://java.dzone.com/articles/spring-data-redis找到了帮助。

这是因为Java序列化。

redisTemplate的密钥序列化程序需要配置为StringRedisSerializer，如下所示：

<bean 
    id="jedisConnectionFactory" 
    class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory" 
    p:host-name="${redis.server}" 
    p:port="${redis.port}" 
    p:use-pool="true"/>

<bean 
    id="stringRedisSerializer" 
    class="org.springframework.data.redis.serializer.StringRedisSerializer"/>

<bean 
    id="redisTemplate" 
    class="org.springframework.data.redis.core.RedisTemplate"
    p:connection-factory-ref="jedisConnectionFactory" 
    p:keySerializer-ref="stringRedisSerializer"
    p:hashKeySerializer-ref="stringRedisSerializer" 
/>

现在，redis中的密钥为vc:501381。

或者像@niconic说的那样，我们也可以将默认的序列化程序本身设置为字符串序列化程序，如下所示：

<bean 
    id="redisTemplate" 
    class="org.springframework.data.redis.core.RedisTemplate"
    p:connection-factory-ref="jedisConnectionFactory" 
    p:defaultSerializer-ref="stringRedisSerializer"
/>

表示我们所有的键和值都是字符串。但请注意，这可能不是更好，因为您可能希望您的值不仅仅是字符串。

如果您的值是域对象，那么您可以使用Jackson序列化程序并按照here配置序列化程序，例如：

<bean id="userJsonRedisSerializer" class="org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer">
    <constructor-arg type="java.lang.Class" value="com.mycompany.redis.domain.User"/>
</bean>

并将模板配置为：

<bean 
    id="redisTemplate" 
    class="org.springframework.data.redis.core.RedisTemplate"
    p:connection-factory-ref="jedisConnectionFactory" 
    p:keySerializer-ref="stringRedisSerializer"
    p:hashKeySerializer-ref="stringRedisSerializer" 
    p:valueSerialier-ref="userJsonRedisSerializer"
/>

答案 1 :(得分：6)

使用StringRedisTemplate替换RedisTemplate。

默认情况下，RedisTemplate使用Java序列化，StringRedisTemplate使用StringRedisSerializer。

<bean id="stringRedisTemplate" class="org.springframework.data.redis.core.StringRedisTemplate">
    <property name="connectionFactory" ref="jedisConnectionFactory" />
</bean>

答案 2 :(得分：6)

我知道这个问题已经有一段时间了，但我最近又对这个话题进行了一些研究，所以我想分享一下这个“半散列”密钥是如何通过这里的部分Spring源代码生成的。

首先，Spring利用AOP来解析注释，例如@Cacheable, @CacheEvict or @CachePut等。来自Spring-context依赖的advice类是CacheInterceptor，它是CacheAspectSupport的子类（也来自Spring） -context）。为了便于解释，我将以@Cacheable为例通过此处的部分源代码。

当调用注释为@Cacheable的方法时，AOP会将其从protected Collection<? extends Cache> getCaches(CacheOperationInvocationContext<CacheOperation> context, CacheResolver cacheResolver)类路由到此方法CacheAspectSupport，在该类中，它会尝试解析此@Cacheable注释。反过来，它导致在实现CacheManager中调用此方法public Cache getCache(String name)。对于此解释，实现CacheManage将为RedisCacheManager（来自Spring-data-redis依赖）。

如果没有点击缓存，它将继续创建缓存。以下是RedisCacheManager的主要方法：

protected Cache getMissingCache(String name) {
    return this.dynamic ? createCache(name) : null;
}

@SuppressWarnings("unchecked")
protected RedisCache createCache(String cacheName) {
    long expiration = computeExpiration(cacheName);
    return new RedisCache(cacheName, (usePrefix ? cachePrefix.prefix(cacheName) : null), redisOperations, expiration,
            cacheNullValues);
}

基本上，它将实例化一个RedisCache对象。要做到这一点，它需要4个参数，即cacheName，前缀（这是回答此问题的关键参数），redisOperation（又名，配置的redisTemplate），到期（默认为0）和cacheNullValues（默认为false）。下面的构造函数显示了有关RedisCache的更多详细信息。

/**
 * Constructs a new {@link RedisCache} instance.
 *
 * @param name cache name
 * @param prefix must not be {@literal null} or empty.
 * @param redisOperations
 * @param expiration
 * @param allowNullValues
 * @since 1.8
 */
public RedisCache(String name, byte[] prefix, RedisOperations<? extends Object, ? extends Object> redisOperations,
        long expiration, boolean allowNullValues) {

    super(allowNullValues);

    Assert.hasText(name, "CacheName must not be null or empty!");

    RedisSerializer<?> serializer = redisOperations.getValueSerializer() != null ? redisOperations.getValueSerializer()
            : (RedisSerializer<?>) new JdkSerializationRedisSerializer();

    this.cacheMetadata = new RedisCacheMetadata(name, prefix);
    this.cacheMetadata.setDefaultExpiration(expiration);
    this.redisOperations = redisOperations;
    this.cacheValueAccessor = new CacheValueAccessor(serializer);

    if (allowNullValues) {

        if (redisOperations.getValueSerializer() instanceof StringRedisSerializer
                || redisOperations.getValueSerializer() instanceof GenericToStringSerializer
                || redisOperations.getValueSerializer() instanceof JacksonJsonRedisSerializer
                || redisOperations.getValueSerializer() instanceof Jackson2JsonRedisSerializer) {
            throw new IllegalArgumentException(String.format(
                    "Redis does not allow keys with null value ¯\\_(ツ)_/¯. "
                            + "The chosen %s does not support generic type handling and therefore cannot be used with allowNullValues enabled. "
                            + "Please use a different RedisSerializer or disable null value support.",
                    ClassUtils.getShortName(redisOperations.getValueSerializer().getClass())));
        }
    }
}

那么在这个RedisCache中使用prefix是什么意思？ - ＆GT;如构造函数about所示，它在此语句this.cacheMetadata = new RedisCacheMetadata(name, prefix);中使用，下面RedisCacheMetadata的构造函数显示更多详细信息：

/**
     * @param cacheName must not be {@literal null} or empty.
     * @param keyPrefix can be {@literal null}.
     */
    public RedisCacheMetadata(String cacheName, byte[] keyPrefix) {

        Assert.hasText(cacheName, "CacheName must not be null or empty!");
        this.cacheName = cacheName;
        this.keyPrefix = keyPrefix;

        StringRedisSerializer stringSerializer = new StringRedisSerializer();

        // name of the set holding the keys
        this.setOfKnownKeys = usesKeyPrefix() ? new byte[] {} : stringSerializer.serialize(cacheName + "~keys");
        this.cacheLockName = stringSerializer.serialize(cacheName + "~lock");
    }

此时，我们知道某些前缀参数已设置为RedisCacheMetadata，但这个前缀在Redis中用于形成密钥的确切程度如何（例如，\ xac \ xed \ x00 \ x05t \ x00 \ tvc：你提到的501381）？

基本上，CacheInterceptor随后将继续从上述private RedisCacheKey getRedisCacheKey(Object key)对象调用方法RedisCache，该对象通过利用<返回RedisCacheKey的实例来自RedisCacheMetadata的strong>前缀和来自RedisOperation的keySerializer。

private RedisCacheKey getRedisCacheKey(Object key) {
    return new RedisCacheKey(key).usePrefix(this.cacheMetadata.getKeyPrefix())
            .withKeySerializer(redisOperations.getKeySerializer());
}

到达这一点时，CacheInterceptor的“预先”建议已完成，它将继续执行由@Cacheable注释的实际方法。在完成实际方法的执行后，它将执行CacheInterceptor的“post”建议，它基本上将结果放到RedisCache中。下面是将结果放入redis缓存的方法：

public void put(final Object key, final Object value) {

    put(new RedisCacheElement(getRedisCacheKey(key), toStoreValue(value))
            .expireAfter(cacheMetadata.getDefaultExpiration()));
}

/**
 * Add the element by adding {@link RedisCacheElement#get()} at {@link RedisCacheElement#getKeyBytes()}. If the cache
 * previously contained a mapping for this {@link RedisCacheElement#getKeyBytes()}, the old value is replaced by
 * {@link RedisCacheElement#get()}.
 *
 * @param element must not be {@literal null}.
 * @since 1.5
 */
public void put(RedisCacheElement element) {

    Assert.notNull(element, "Element must not be null!");

    redisOperations
            .execute(new RedisCachePutCallback(new BinaryRedisCacheElement(element, cacheValueAccessor), cacheMetadata));
}

在RedisCachePutCallback对象中，其回调方法doInRedis()实际上调用了一个方法，用于在redis中形成实际键，方法名称为getKeyBytes()实例中的RedisCacheKey。下面显示了此方法的详细信息：

/**
 * Get the {@link Byte} representation of the given key element using prefix if available.
 */
public byte[] getKeyBytes() {

    byte[] rawKey = serializeKeyElement();
    if (!hasPrefix()) {
        return rawKey;
    }

    byte[] prefixedKey = Arrays.copyOf(prefix, prefix.length + rawKey.length);
    System.arraycopy(rawKey, 0, prefixedKey, prefix.length, rawKey.length);

    return prefixedKey;
}

正如我们在getKeyBytes方法中所看到的，它同时使用原始密钥（在您的情况下为vc：501381）和前缀密钥（在您的情况下为\ xac \ xed \ x00 \ x05t \ x00 \ t）

答案 3 :(得分：0)

您必须序列化要将其发送到redis的对象。下面是它的完整运行示例。它使用接口DomainObject作为Serializable

以下是步骤

1）使用以下jar制作你的maven pom.xml 

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>${spring.version}</version>
    </dependency>

    <dependency>
        <groupId>cglib</groupId>
        <artifactId>cglib</artifactId>
        <version>2.2.2</version>
    </dependency>

    <dependency>
           <groupId>org.springframework.data</groupId>
           <artifactId>spring-data-redis</artifactId>
           <version>1.3.0.RELEASE</version>
        </dependency>

            <dependency>
               <groupId>redis.clients</groupId>
               <artifactId>jedis</artifactId>
               <version>2.4.1</version>
            </dependency>

    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-pool2</artifactId>
        <version>2.0</version>
    </dependency>

2）按照以下方式进行配置xml 

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
        xmlns:c="http://www.springframework.org/schema/c"
        xmlns:cache="http://www.springframework.org/schema/cache"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans     
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context-3.0.xsd

        http://www.springframework.org/schema/cache 
        http://www.springframework.org/schema/cache/spring-cache.xsd">



    <bean id="jeidsConnectionFactory"
      class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"
      p:host-name="localhost" p:port="6379" p:password="" />

     <bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate"
      p:connection-factory-ref="jeidsConnectionFactory" />

     <bean id="imageRepository" class="com.self.common.api.poc.ImageRepository">
      <property name="redisTemplate" ref="redisTemplate"/>
     </bean>

</beans>

3）按如下方式制作课程

package com.self.common.api.poc;

import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class RedisMainApp {

 public static void main(String[] args) throws IOException {
  ApplicationContext applicationContext = new ClassPathXmlApplicationContext("mvc-dispatcher-servlet.xml");
  ImageRepository imageRepository = (ImageRepository) applicationContext.getBean("imageRepository");

  BufferedImage img = ImageIO.read(new File("files/img/TestImage.png"));
  BufferedImage newImg;
  String imagestr;
  imagestr = encodeToString(img, "png");
  Image image1 = new Image("1", imagestr);

  img = ImageIO.read(new File("files/img/TestImage2.png"));
  imagestr = encodeToString(img, "png");
  Image image2 = new Image("2", imagestr);

  imageRepository.put(image1);
  System.out.println(" Step 1 output : " + imageRepository.getObjects());
  imageRepository.put(image2);
  System.out.println(" Step 2 output : " + imageRepository.getObjects());
  imageRepository.delete(image1);
  System.out.println(" Step 3 output : " + imageRepository.getObjects());

 }

 /**
  * Decode string to image
  * @param imageString The string to decode
  * @return decoded image
  */
 public static BufferedImage decodeToImage(String imageString) {

     BufferedImage image = null;
     byte[] imageByte;
     try {
         BASE64Decoder decoder = new BASE64Decoder();
         imageByte = decoder.decodeBuffer(imageString);
         ByteArrayInputStream bis = new ByteArrayInputStream(imageByte);
         image = ImageIO.read(bis);
         bis.close();
     } catch (Exception e) {
         e.printStackTrace();
     }
     return image;
 }

 /**
  * Encode image to string
  * @param image The image to encode
  * @param type jpeg, bmp, ...
  * @return encoded string
  */
 public static String encodeToString(BufferedImage image, String type) {
     String imageString = null;
     ByteArrayOutputStream bos = new ByteArrayOutputStream();

     try {
         ImageIO.write(image, type, bos);
         byte[] imageBytes = bos.toByteArray();

         BASE64Encoder encoder = new BASE64Encoder();
         imageString = encoder.encode(imageBytes);

         bos.close();
     } catch (IOException e) {
         e.printStackTrace();
     }
     return imageString;
 }
}

package com.self.common.api.poc;

public class Image implements DomainObject {

 public static final String OBJECT_KEY = "IMAGE";

 public Image() {
 }

 public Image(String imageId, String imageAsStringBase64){
  this.imageId = imageId;
  this.imageAsStringBase64 = imageAsStringBase64;
 }
 private String imageId;
 private String imageAsStringBase64;

 public String getImageId() {
  return imageId;
 }

 public void setImageId(String imageId) {
  this.imageId = imageId;
 }

 public String getImageName() {
  return imageAsStringBase64;
 }

 public void setImageName(String imageAsStringBase64) {
  this.imageAsStringBase64 = imageAsStringBase64;
 }

 @Override
 public String toString() {
  return "User [id=" + imageAsStringBase64 + ", imageAsBase64String=" + imageAsStringBase64 + "]";
 }

 @Override
 public String getKey() {
  return getImageId();
 }

 @Override
 public String getObjectKey() {
  return OBJECT_KEY;
 }
}

package com.self.common.api.poc;

import java.io.Serializable;

public interface DomainObject extends Serializable {

 String getKey();

 String getObjectKey();
}

package com.self.common.api.poc;

import java.util.List;

import com.self.common.api.poc.DomainObject;

public interface Repository<V extends DomainObject> {

 void put(V obj);

 V get(V key);

 void delete(V key);

 List<V> getObjects();
}

package com.self.common.api.poc;

import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;

import com.self.common.api.poc.DomainObject;

public class ImageRepository implements Repository<Image>{

 @Autowired
 private RedisTemplate<String,Image> redisTemplate;

 public RedisTemplate<String,Image> getRedisTemplate() {
  return redisTemplate;
 }

 public void setRedisTemplate(RedisTemplate<String,Image> redisTemplate) {
  this.redisTemplate = redisTemplate;
 }

 @Override
 public void put(Image image) {
  redisTemplate.opsForHash()
    .put(image.getObjectKey(), image.getKey(), image);
 }

 @Override
 public void delete(Image key) {
  redisTemplate.opsForHash().delete(key.getObjectKey(), key.getKey());
 }

 @Override
 public Image get(Image key) {
  return (Image) redisTemplate.opsForHash().get(key.getObjectKey(),
    key.getKey());
 }

 @Override
 public List<Image> getObjects() {
  List<Image> users = new ArrayList<Image>();
  for (Object user : redisTemplate.opsForHash().values(Image.OBJECT_KEY) ){
   users.add((Image) user);
  }
  return users;
 }

}

有关sprinf jedis的更多参考，您可以看到http://www.javacodegeeks.com/2012/06/using-redis-with-spring.html

示例代码取自http://javakart.blogspot.in/2012/12/spring-data-redis-hello-world-example.html

答案 4 :(得分：0)

这是一个非常古老的问题，但我的回答可能对于在使用Redis using Spring Boot时遇到同样问题的人有所帮助。在redis中存储哈希类型数据时，我遇到了同样的问题。我已经为RedisTemplate编写了所需的配置文件更改。

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan(basePackages = "com.redis")
public class AppCofiguration {

    @Bean
    JedisConnectionFactory jedisConnectionFactory() {
        JedisConnectionFactory jedisConFactory = new JedisConnectionFactory();
        jedisConFactory.setHostName("127.0.0.1");
        jedisConFactory.setPort(6379);
        return jedisConFactory;
    }

    @Bean
    public RedisTemplate<String, Object> redisTemplate() {
        final RedisTemplate<String, Object> template = new RedisTemplate<String, Object>();
        template.setConnectionFactory(jedisConnectionFactory());
        template.setKeySerializer(new StringRedisSerializer());
        template.setValueSerializer(new StringRedisSerializer());

        // the following is not required      
        template.setHashValueSerializer(new StringRedisSerializer());
        template.setHashKeySerializer(new StringRedisSerializer());

        return template;
    }

}

如果数据类型为String，则不需要template.setHashValueSerializer(new StringRedisSerializer());和template.setHashKeySerializer(new StringRedisSerializer());。

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