如何在springboot中禁用某些jar的自动配置功能

我们知道在springboot中有这么一个自动配置的功能：假如你在工程中加入某个jar，比如mysql的jar,或者mongodb的jar，或者redis的jar,那么就算不写配置文件，springbboot也会启动相关的功能来简化构建这些客户端的复杂度。

但是有那么一种场景，比如我只想在工程中使用某个jar的某个类的功能，所以我必须要引入某个jar，但是又不想让springboot自动配置，那该怎么办？

其实很简单，只需要在启动类上进行配置，如下用mongodb来举例：

@SpringBootApplication(exclude={MongoAutoConfiguration.class})
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

}

这个时候来问题了，我假如想不包含 redis 的自动配置，那该如何写这个 XXXConfiguration.class 呢，这个到哪里找？
在回答这个问题之前，我们先来看一个错误提示，以redis的自动配置来举例，当设置不正确的时候，springboot启动的时候会进行报错，报错的内容大致如下：

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled

with ‘debug’ enabled，这个是什么鬼？这个debug在哪里设置啊，难道在 logback 中？不是吧。带着这个问题，我查了资料，找到这篇文章：http://www.it1352.com/908199.html，这篇文章里讲了该如何在springboot中进行设置，哦，原来就是在 application.properties 中假如 debug=true 即可。顺便吐槽一下这篇文章的网站，里面广告太多了，感觉是一个。。。

好了，我们继续上面的那个redis那个例子，我们把 debug=true 设置好，好了，真相出来了：

    RedisAutoConfiguration matched:
      - @ConditionalOnClass found required classes 'org.springframework.data.redis.connection.jedis.JedisConnection', 'org.springframework.data.redis.core.RedisOperations', 'redis.clients.jedis.Jedis'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)

   RedisAutoConfiguration.RedisConfiguration#redisTemplate matched:
      - @ConditionalOnMissingBean (names: redisTemplate; SearchStrategy: all) did not find any beans (OnBeanCondition)

   RedisAutoConfiguration.RedisConfiguration#stringRedisTemplate matched:
      - @ConditionalOnMissingBean (types: org.springframework.data.redis.core.StringRedisTemplate; SearchStrategy: all) did not find any beans (OnBeanCondition)

   RedisAutoConfiguration.RedisConnectionConfiguration matched:
      - @ConditionalOnClass found required class 'org.apache.commons.pool2.impl.GenericObjectPool'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)

   RedisAutoConfiguration.RedisConnectionConfiguration#redisConnectionFactory matched:
      - @ConditionalOnMissingBean (types: org.springframework.data.redis.connection.RedisConnectionFactory; SearchStrategy: all) did not find any beans (OnBeanCondition)

   RedisCacheConfiguration matched:
      - Cache org.springframework.boot.autoconfigure.cache.RedisCacheConfiguration automatic cache type (CacheCondition)

   RedisRepositoriesAutoConfiguration matched:
      - @ConditionalOnClass found required classes 'redis.clients.jedis.Jedis', 'org.springframework.data.redis.repository.configuration.EnableRedisRepositories'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)
      - @ConditionalOnProperty (spring.data.redis.repositories.enabled=true) matched (OnPropertyCondition)
      - @ConditionalOnMissingBean (types: org.springframework.data.redis.repository.support.RedisRepositoryFactoryBean; SearchStrategy: all) did not find any beans (OnBeanCondition)

于是，我们就可以这么设置我们的启动类：

@SpringBootApplication(exclude={RedisRepositoriesAutoConfiguration.class,RedisAutoConfiguration.class})
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

}

上面的RedisCacheConfiguration是个私有类，不能用，不用也达到了效果。

全文结束。