当SpringBoot引用Redis依赖但没有配置Redis信息时
一、介绍
在SpringBoot当中，我们往往使用多模块的方式对相对应的功能进行拆分。
当然Redis也不例外，一般来说是在一个公共的模块中添加下面的依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>那么只要是Jar服务模块引用了这个公共模块，就自动引入了Redis的相关依赖。
好，到了这边，就出现了一点小小的问题。
虽然引用了这个公共模块，但是没有配置相对应的**Redis**信息，在项目启动后会出现异常报错
只需要一点小小的配置，就可以解决这个问题。
二、代码
大家都知道，SpringBoot的stater是如何配置运行的吧，问题出现的原因就出现在这里面
分别是RedisAutoConfiguration.java和RedisReactiveAutoConfiguration.java，平常的web项目我们关注前者就好
里面代码并不复杂，看看源代码
代码语言：javascript复制/*
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package org.springframework.boot.autoconfigure.data.redis;
import org.springframework.boot.autoconfigure.AutoConfiguration;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnSingleCandidate;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
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
*/
@AutoConfiguration
@ConditionalOnClass(RedisOperations.class)
@EnableConfigurationProperties(RedisProperties.class)
@Import({ LettuceConnectionConfiguration.class, JedisConnectionConfiguration.class })
public class RedisAutoConfiguration {
@Bean
@ConditionalOnMissingBean(name = "redisTemplate")
@ConditionalOnSingleCandidate(RedisConnectionFactory.class)
public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
RedisTemplate<Object, Object> template = new RedisTemplate<>();
template.setConnectionFactory(redisConnectionFactory);
return template;
}
@Bean
@ConditionalOnMissingBean
@ConditionalOnSingleCandidate(RedisConnectionFactory.class)
public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory redisConnectionFactory) {
return new StringRedisTemplate(redisConnectionFactory);
}
}就是这里，如果我们没有redisTemplate这个bean的话，它就会自动生成了。
当然主要的redisConnectionFactory的bean生成，也可以仔细去看看，没有配置就默认给你一个localhost:6379。
那么，我们应该如何避免他自动生成默认的redisTemplate呢，我们又改动不了它的源代码。
如果没有头绪，那说明你还没有掌握@Condition等相关的注解，可以看看我的这篇文章
SpringBoot中的@Conditional注解 | 半月无霜 (banmoon.top)
好的，那么可以这样解决
代码语言：javascript复制package com.banmoon.business.config;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
import org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration;
import org.springframework.boot.autoconfigure.data.redis.RedisReactiveAutoConfiguration;
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 banmoon
* @date 2024/03/07 12:08:25
*/
@Configuration
@SuppressWarnings("all")
@EnableAutoConfiguration(exclude = {RedisAutoConfiguration.class, RedisReactiveAutoConfiguration.class})
public class RedisConfig {
@Bean
@ConditionalOnBean(RedisConnectionFactory.class)
@ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.SERVLET)
public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
RedisTemplate<String, Object> template = new RedisTemplate<String, Object>();
template.setConnectionFactory(factory);
Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
ObjectMapper om = new ObjectMapper();
om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
jackson2JsonRedisSerializer.setObjectMapper(om);
StringRedisSerializer stringRedisSerializer = new StringRedisSerializer();
// key采用String的序列化方式
template.setKeySerializer(stringRedisSerializer);
// hash的key也采用String的序列化方式
template.setHashKeySerializer(stringRedisSerializer);
// value序列化方式采用jackson
template.setValueSerializer(jackson2JsonRedisSerializer);
// hash的value序列化方式采用jackson
template.setHashValueSerializer(jackson2JsonRedisSerializer);
template.afterPropertiesSet();
return template;
}
}- 首先，排除掉两个
Redis自动配置类，我们自己来 - 其次，我们自己创建一个
redisTemplate的bean，上面记得写上@ConditionalOnBean(RedisConnectionFactory.class)，代表当存在RedisConnectionFactory的bean时，才生成redisTemplate - 最后，其它模块引用，启动就不会再报错了
三、最后
你需要了解spring-boot-start自动配置的机制。
如果写过，那么上面的将不再是问题。
我是半月，你我一同共勉！！！
