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

/*
 * Copyright 2012-2022 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 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

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