redis兩種默認的Template
之前的一篇博客Springboot項目整合Redis記錄了RedisTemplate和StringRedisTemplate的使用效果，由於分別使用了不同的序列化器，所以在Redis中存儲的形式也不相同。redisTemplate使用的是默認的序列化器jdk序列化方式，而StringRedisTemplate使用了String序列化方式。這裏不再贅述。爲了與後面使用自定義RedisTemplate進行存儲進行對比，這裏先分別使用RedisTemplate和StringRedisTemplate兩種模板進行數據存儲：
package org.magic.redis;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
@SpringBootTest
class RedisApplicationTests {
@Autowired
@Qualifier("redisTemplate")
private RedisTemplate redisTemplate;
@Autowired
private StringRedisTemplate stringRedisTemplate;
@Test
void useRedisTemplate() {
redisTemplate.opsForValue().set("User","張三");
}
@Test
void useStringTemplate(){
stringRedisTemplate.opsForValue().set("User","張三");
}
}
RedisTemplate
StringRedisTemplate
如果每次使用Redis進行存儲的時候還需要考慮怎麼選擇序列化方式未免太過麻煩，實際上在項目中我們一般會自定義一個RedisTemplate，這樣就不會產生由於序列化方式而引起的不必要的麻煩。
自定義RedisTemplate
package org.magic.redis.config;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectMapper.DefaultTyping;
import com.fasterxml.jackson.databind.jsontype.impl.LaissezFaireSubTypeValidator;
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 無關痛癢
* @create 2020/5/8
* @Description: 方法是自定義redis的配置類，自定義序列化器
*/
@Configuration
public class RedisConfig {
@Bean
@SuppressWarnings("all")
public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory connectionFactory) {
RedisTemplate<String, Object> template = new RedisTemplate<>();
template.setConnectionFactory(connectionFactory);
//自定義Jackson序列化配置
Jackson2JsonRedisSerializer jsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
objectMapper.activateDefaultTyping(LaissezFaireSubTypeValidator.instance, DefaultTyping.NON_FINAL);
jsonRedisSerializer.setObjectMapper(objectMapper);
//key使用String的序列化方式
StringRedisSerializer stringRedisSerializer = new StringRedisSerializer();
template.setKeySerializer(stringRedisSerializer);
//hash的key也是用String的序列化方式
template.setHashKeySerializer(stringRedisSerializer);
//value的key使用jackson的序列化方式
template.setValueSerializer(jsonRedisSerializer);
//hash的value也是用jackson的序列化方式
template.setHashValueSerializer(jsonRedisSerializer);
template.afterPropertiesSet();
return template;
}
}
從序列化器源碼中可以看到Redis有很多種序列化方式：（ctrl+n 搜索RedisSerializer可以查看序列化器源碼，ctrl+alt+鼠標左鍵可查看接口實現類）
然後再注入自定義的RedisTemplate進行存儲測試：
package org.magic.redis;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
@SpringBootTest
class RedisApplicationTests {
@Autowired
@Qualifier("redisTemplate")
private RedisTemplate redisTemplate;
@Test
void useRedisTemplate() {
redisTemplate.opsForValue().set("Trade","張三");
}
}
看到這裏說明我們自定義的RedisTemplate使用成功了。
看看Redis的配置源碼：
/*
* Copyright 2012-2019 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.boot.autoconfigure.data.redis;
import java.net.UnknownHostException;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisOperations;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
/**
* {@link EnableAutoConfiguration Auto-configuration} for Spring Data's Redis support.
*
* @author Dave Syer
* @author Andy Wilkinson
* @author Christian Dupuis
* @author Christoph Strobl
* @author Phillip Webb
* @author Eddú Meléndez
* @author Stephane Nicoll
* @author Marco Aust
* @author Mark Paluch
* @since 1.0.0
*/
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(RedisOperations.class)
@EnableConfigurationProperties(RedisProperties.class)
@Import({ LettuceConnectionConfiguration.class, JedisConnectionConfiguration.class })
public class RedisAutoConfiguration {
@Bean
@ConditionalOnMissingBean(name = "redisTemplate")
public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory)
throws UnknownHostException {
RedisTemplate<Object, Object> template = new RedisTemplate<>();
template.setConnectionFactory(redisConnectionFactory);
return template;
}
@Bean
@ConditionalOnMissingBean
public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory redisConnectionFactory)
throws UnknownHostException {
StringRedisTemplate template = new StringRedisTemplate();
template.setConnectionFactory(redisConnectionFactory);
return template;
}
}
源碼中有一個@ConditionalOnMissingBean註解，該註解作用在@Bean上，Spring容器啓動的時候檢查容器中是否已經有@ConditionalOnMissingBean作用的@bean了，如果有則跳過@ConditionalOnMissingBean作用的bean，如果沒有則加載該bean。說白了就是如果有自定義的redisTemplate或者stringRedisTemplate就用自定義的，沒有自定義的再用這個默認的。