Spring Boot如何排除自动加载数据源

目录

前言

有些老项目使用spring mvc里面有写好的数据库连接池，比如redis/mongodb/mybatis(mysql其他oracle同理)。在这些项目迁入spring boot框架时，会报错。

原因是我们业务写好了连接池，但spring boot在jar包存在的时候会主动加载spring boot的autoconfiguration创建连接池，但我们并未配置spring 金华职业技术学院boot参数，也不需要配置。

1. mongodb

mongodb自动配置错误如下：

org.mongodb.driver.cluster : exception in monitor thread while connecting to rver localhost:27017
com.mongodb.mongosocketopenexception: exception opening socket
caud by: java.net.connectexception: connection refud (connection refud)

但是我没有引入spring-boot-starter-data-mongodb的jar包，后来发现我引入了spring-data-mongodb的jar

检查spring-boot-starter-data-mongodb的jar，包括3部分，如下：

我的jar包都有，相当于这些jar拼装成了 spring-boot-starter-data-mongodb

在spring boot中自动引入了自动配置功能

需要手动排除自动配置的数据源，在springbootapplication中exclude

@springbootapplication(exclude = {mongoautoconfiguration.class, mongodataautoconfiguration.class})

启动不再报错连接localhost:27017，业务正常。原理见spring boot官方文档

2. mybatis

mybatis同理

failed to auto-configure a datasource: ‘spring.datasource.url&borrowed#8217; is not specified and no embedded data

***************************
application failed to start
***************************

description:

cannot determine embedded databa driver class for databa type none

action:

if you want an embedded databa plea put a supported one on the classpath. if you have databa ttings to be loaded from a particular profile you may need to active it (no profiles are currently active).

需要排除

@springbootapplication(exclude = {datasourceautoconfiguration.class})

3. 原理讲解

原理是enableautoconfiguration

进一步跟踪：

autoconfigurationimportlector这个类有自动加载与排除的逻辑

public string[] lectimports(annotation红斑狼疮metadata annotationmetadata) {if (!inabled(annotationmetadata)) {return no_imports;}autoconfigurationmetadata autoconfigurationmetadata = autoconfigurationmetadataloader.loadmetadata(this.beanclassloader);autoconfigurationentry autoconfigurationentry = getautoconfigurationentry(autoconfigurationmetadata,annotationmetadata);return stringutils.tostringarray(autoconfigurationentry.getconfigurations());}

注意加载代码

getautoconfigurationentry(autoconfigurationmetadata, annotationmetadata);

/** * return the {@link autoconfigurationentry} bad on the {@link annotationmetadata} * of the importing {@link configuration @configuration} class. * @param autoconfigurationmetadata the auto-configuration metadata * @param annotationmetadata the annotation metadata of the configuration class * @return the auto-configurations that should be imported */protected autoconfigurationentry getautoconfigurationentry(autoconfigurationmetadata autoconfigurationmetadata,annotationmetadata annotationmetadata) {if (!inabled(annotationmetadata)) {return empty_entry;}annotationattributes attributes = getattributes(annotationmetadata);list<string> configurations = getcandidateconfigurations(annotationmetadata, attributes);configurations = removeduplicates(configurations);t<string> exclusions = getexclusions(annotationmetada芭蕾舞女孩ta, attributes);checkexcludedclass(configurations, exclusions);configurations.removeall(exclusions);configurations = filter(configurations, autoconfigurationmetadata);fireautoconfigurationimportevents(configurations, exclusions);return new autocoplay的现在分词nfigurationentry(configurations, exclusions);}

里面

getexclusions(annotationmetadata, attributes);

/** * return any exclusions that limit the candidate configurations. * @param metadata the source metadata * @param attributes the {@link #getattributes(annotationmetadata) annotation * attributes} * @return exclusions or an empty t */protected t<string> getexclusions(annotationmetadata metadata, annotationattributes attributes) {t<string> excluded = new linkedhasht<>();excluded.addall(aslist(attributes, "exclude"));excluded.addall(arrays.aslist(attributes.getstringarray("excludename")));excluded.addall(getexcludeautoconfigurationsproperty());return excluded;}

看到了，exclude或者excludename，当然还有一种方法

private list<string> getexcludeautoconfigurationsproperty() {if (getenvironment() instanceof configurableenvironment) {binder binder = binder.get(getenvironment());return binder.bind(property_name_autoconfigure_exclude, string[].class).map(arrays::aslist).orel(collections.emptylist());}string[] excludes = getenvironment().getproperty(property_name_autoconfigure_exclude, string[].class);return (excludes != null) ? arrays.aslist(excludes) : collections.emptylist();}

通过application.properties文件配置spring.autoconfigure.exclude

private static final string property_name_autoconfigure_exclude = "spring.autoconfigure.exclude";

总结

出现这种错误多半发生在引入了spring-boot-starter-mongodb等这样的starter插件jar，没有配置数据源url；或者旧业务升级spring boot（笔者就是这种情况）

解决方法

不需要的jar不要引入即可解决问题

使用exclude排除，有三种实现方式exclude、excludename、spring.autoconfigure.exclude

以上为个人经验，希望能给大家一个参考，也希望大家多多支持www.887551.com。