执行mvn liquibase:diff时遇NullPointerException问题求助

问题背景 #

执行mvn liquibase:diff命令对比Hibernate实体与MySQL数据库结构时，构建失败，抛出异常：

java.lang.NullPointerException: Cannot invoke "java.sql.ResultSet.next()" because "schemas" is null

相关配置 #

liquibase.properties #

driver:com.mysql.cj.jdbc.Driver
changeLogFile:src/main/resources/db/changelog/dbchangelog.xml
url:jdbc:mysql://localhost:3306/liquibase
defaultSchemaName:liquibase
username:liquibase
password:liquibase
hibernate.dialect:org.hibernate.dialect.MySQL8Dialect
referenceUrl:hibernate:org.heller.liqibase.entity?dialect=org.hibernate.dialect.MySQL8Dialect
referenceDefaultSchema:hibernate

pom.xml #

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.5</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>org.heller.liquibase</groupId>
    <artifactId>liquibase</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>liquibase</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>17</java.version>
        <liquibase.version>4.27.0</liquibase.version>
        <liquibase-hibernate6.version>4.27.0</liquibase.version>
        <hibernate6.version>6.1.5.Final</hibernate6.version>
        <javassist.version>3.24.0-GA</javassist.version>
        <validation-api.version>3.0.2</validation-api.version>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <maven.build.timestamp.format>yyyyMMddHHmmss</maven.build.timestamp.format>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>6.3.1.Final</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.liquibase</groupId>
                <artifactId>liquibase-maven-plugin</artifactId>
                <version>4.27.0</version>
                <configuration>
                    <propertyFile>liquibase.properties</propertyFile>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>8.0.33</version>
                    </dependency>
                       <dependency>
                        <groupId>org.liquibase</groupId>
                        <artifactId>liquibase-core</artifactId>
                        <version>${liquibase.version}</version>
                    </dependency>
                    <dependency>
                        <groupId>org.liquibase.ext</groupId>
                        <artifactId>liquibase-hibernate6</artifactId>
                        <version>${liquibase-hibernate6.version}</version>
                    </dependency>
                    <dependency>
                        <groupId>org.springframework.boot</groupId>
                        <artifactId>spring-boot-starter-data-jpa</artifactId>
                        <version>3.2.5</version>
                    </dependency>
                    <dependency>
                        <groupId>jakarta.validation</groupId>
                        <artifactId>jakarta.validation-api</artifactId>
                        <version>${validation-api.version}</version>
                    </dependency>
                    <dependency>
                        <groupId>org.javassist</groupId>
                        <artifactId>javassist</artifactId>
                        <version>${javassist.version}</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>

    </build>

</project>

解决思路 #

• 修正实体包路径拼写错误：referenceUrl中的org.heller.liqibase.entity存在拼写错误，应改为org.heller.liquibase.entity（缺少字母u），确保Liquibase能找到实体类并生成元数据。
• 调整参考schema配置：referenceDefaultSchema设置为hibernate不合理，改为目标数据库的schema名称liquibase，或直接移除该配置。
• 确认实体类扫描有效性：检查实体类是否位于指定包下、带有@Entity注解，且编译后的class文件存在于target/classes目录中。
• 验证数据库权限：确保数据库用户liquibase拥有information_schema库的SELECT权限，Liquibase需要读取该库获取数据库元数据。
• 统一版本兼容性：当前Hibernate 6.3.1.Final与Liquibase 4.27.0可能存在版本不兼容问题，建议升级Liquibase到4.29.0+，或降低Hibernate版本到6.1.x系列，与pom中hibernate6.version配置保持一致。

内容的提问来源于stack exchange，提问作者Petr Kostroun