前言

此篇重点是SpringBoot自动装配Liquibase时，如何实现把changelog文件外置到jar包外

问题

spring.liquibase.change-log 是changlog的位置，但是他默认位置是LiquibaseProperties类中属性changeLog的默认值”classpath:/db/changelog/db.changelog-master.yaml”，一般配置也只能从classpath:出发读jar包内的路径，

如果你直接配了包外的位置，不带classpath，会报错如下：

2022-10-09 11:05:10.859  WARN 22524 --- [           main] s.c.a.AnnotationConfigApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'liquibase' defined in class path resource [org/springframework/boot/autoconfigure/liquibase/LiquibaseAutoConfiguration$LiquibaseConfiguration.class]: Invocation of init method failed; nested exception is liquibase.exception.ChangeLogParseException: The file master.xml was not found in
    - jar:file:/D:/GitAll/liquibase-tool/target/liquibase-tool-/liquibase-tool.jar!/BOOT-INF/classes!/
    **省略中间**
    - jar:file:/D:/GitAll/liquibase-tool/target/liquibase-tool-/liquibase-tool.jar!/BOOT-INF/lib/spring-tx-5.3.23.jar!/
Specifying files by absolute path was removed in Liquibase 4.0. Please use a relative path or add '/' to the classpath parameter.
2022-10-09 11:05:10.871  INFO 22524 --- [           main] ConditionEvaluationReportLoggingListener :

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2022-10-09 11:05:10.885 ERROR 22524 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'liquibase' defined in class path resource [org/springframework/boot/autoconfigure/liquibase/LiquibaseAutoConfiguration$LiquibaseConfiguration.class]: Invocation of init method failed; nested exception is liquibase.exception.ChangeLogParseException: The file master.xml was not found in
    - jar:file:/D:/GitAll/liquibase-tool/target/liquibase-tool-/liquibase-tool.jar!/BOOT-INF/classes!/
    **省略中间**
    - jar:file:/D:/GitAll/liquibase-tool/target/liquibase-tool-/liquibase-tool.jar!/BOOT-INF/lib/spring-tx-5.3.23.jar!/
Specifying files by absolute path was removed in Liquibase 4.0. Please use a relative path or add '/' to the classpath parameter.
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1804) ~[spring-beans-5.3.23.jar!/:5.3.23]
        **省略中间**
        at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:65) [liquibase-tool.jar:0.0.1]
Caused by: liquibase.exception.ChangeLogParseException: The file master.xml was not found in
    - jar:file:/D:/GitAll/liquibase-tool/target/liquibase-tool-/liquibase-tool.jar!/BOOT-INF/classes!/
    **省略中间**
    - jar:file:/D:/GitAll/liquibase-tool/target/liquibase-tool-/liquibase-tool.jar!/BOOT-INF/lib/spring-tx-5.3.23.jar!/
Specifying files by absolute path was removed in Liquibase 4.0. Please use a relative path or add '/' to the classpath parameter.
        at liquibase.parser.core.xml.XMLChangeLogSAXParser.parseToNode(XMLChangeLogSAXParser.java:99) ~[liquibase-core-4.9.1.jar!/:na]
       **省略中间**
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800) ~[spring-beans-5.3.23.jar!/:5.3.23]
        ... 23 common frames omitted

关键信息就是这些，意思是现在只支持包里的相对路径，不支持绝对路径，就算把liquibase版本从4降成3也会报错，还没4报的详细

Invocation of init method failed; nested exception is liquibase.exception.ChangeLogParseException: The file master.xml was not found in ***

Specifying files by absolute path was removed in Liquibase 4.0. Please use a relative path or add '/' to the classpath parameter.

外置changelog

修改文件加载器

找到源码中这个类，把类复制到自己liquibase项目里修改，以后启动的时候加载的就是自定义的类了

liquibase.integration.spring.SpringLiquibase 找到createLiquibase方法

原方法：

protected Liquibase createLiquibase(Connection c) throws LiquibaseException {
    SpringResourceAccessor resourceAccessor = this.createResourceOpener();
    Liquibase liquibase = new Liquibase(this.getChangeLog(), resourceAccessor, this.createDatabase(c, resourceAccessor));
    **省略**

改成：

protected Liquibase createLiquibase(Connection c) throws LiquibaseException {
    ResourceAccessor resourceAccessor = new FileSystemResourceAccessor(System.getProperty("user.dir"));
    Liquibase liquibase = new Liquibase(this.getChangeLog(), resourceAccessor, this.createDatabase(c, resourceAccessor));
    **省略**

什么意思，我把文件系统定位到我jar包位置，然后我把配置文件放这就行，比如使用assembly把资源文件外置到jar同级目录再打成tar或zip包

SpringBoot配置文件设置相对路径

spring.liquibase.change-log=master.xml

change-log配置相对路径

关键是属性relativeToChangelogFile设为true，意思是我不去resource下面找了，我根据主配置文件master的位置，设置相对路径找changelog

<?xml version="1.0" encoding="UTF-8"?>
<databaseChangeLog
        xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
            http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.8.xsd">
    <include file="changelog/test.xml" author="oxye" relativeToChangelogFile="true"/>
</databaseChangeLog>