Eclipse中Spring Boot项目application.properties复制为空问题

在Spring Boot项目中遇到以下问题：更新src/main/resources/application.properties后，生成的target/classes/application.properties被复制为空文件。

项目采用双数据源/JPA配置，核心配置代码如下：

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = { PJE_BPMN_PACKAGES }, entityManagerFactoryRef = PJE_BPMN_EMF, transactionManagerRef = PJE_BPMN_TM)
public class PjeBpmnDbConfig {
    @Autowired
    private Environment env;

    @Primary
    @Bean(name = PJE_BPMN_DS)
    @ConfigurationProperties(prefix = "pjebpmn.datasource")
    public DataSource createDataSource() {
        return DataSourceBuilder.create().build();
    }


    @Bean(name = PJE_BPMN_EMF)
    @Primary
    @ConfigurationProperties(prefix = "pjebpmn.jpa")
    public LocalContainerEntityManagerFactoryBean createEntityManager(EntityManagerFactoryBuilder entityManagerFactoryBuilder,
            @Qualifier(PJE_BPMN_DS) DataSource dataSource) {

        Map<String, String> properties = new HashMap<>();
        System.out.println(
                "lendo pjebpmn.jpa.hibernate.ddl-auto do properties, e retornou: " + env.getProperty("pjebpmn.jpa.hibernate.ddl-auto", "NADA"));
        properties.put("hibernate.hbm2ddl.auto", env.getProperty("pjebpmn.jpa.hibernate.ddl-auto", "update"));
        properties.put("hibernate.dialect", env.getProperty("pjebpmn.jpa.properties.hibernate.dialect", "org.hibernate.dialect.PostgreSQLDialect"));

        return entityManagerFactoryBuilder.dataSource(dataSource).packages(PJE_BPMN_PACKAGES).persistenceUnit(PJE_BPMN_DS).properties(properties)
                .build();
    }

    @Primary
    @Bean(name = PJE_BPMN_TM)
    public PlatformTransactionManager createTransactionManager(@Qualifier(PJE_BPMN_EMF) EntityManagerFactory entityManagerFactory) {

        JpaTransactionManager transactionManager = new JpaTransactionManager(entityManagerFactory);
        return transactionManager;
    }

}

项目环境与依赖 #

• pom.xml由start.spring.io生成，包含依赖：spring-boot-starter-data-jpa、spring-boot-starter-web、lombok、spring-boot-devtools、spring-boot-configuration-processor、postgresql
• 环境：Mac Os Catalina、Eclipse 2022-09、Spring Boot 2.7.6
• 曾开启后关闭Eclipse设置：Preferences > Maven > Annotation Processing > "Experimental"选项

已尝试的无效方案 #

• 删除Eclipse项目及相关文件（.project、.settings等）后重新导入为“现有Maven项目”
• 移除pom.xml中的lombok和spring-boot-configuration-processor依赖

结合你的操作历史和环境，问题大概率出在Eclipse的Maven注解处理缓存、资源过滤配置异常或devtools缓存，以下是针对性解决步骤：

1. 检查Maven资源过滤配置
   打开pom.xml，确认<build>节点下的资源规则是否正确，错误的过滤会导致文件被清空：

   <build>
       <resources>
           <resource>
               <directory>src/main/resources</directory>
               <!-- 若不需要变量替换，将filtering改为false -->
               <filtering>true</filtering>
               <includes>
                   <include>**/*.properties</include>
                   <include>**/*.yml</include>
               </includes>
           </resource>
       </resources>
   </build>
   

   如果开启了filtering但没有配置对应的变量替换，会导致文件内容被空值覆盖。

2. 清理Eclipse注解处理缓存
   你修改过注解处理的Experimental选项，可能引发缓存异常：

   • 执行Project > Clean，选择当前项目并勾选Start a build immediately
   • 手动删除target目录，再执行Maven > Clean + Maven > Install
   • 打开Eclipse > Preferences > Maven > Annotation Processing，确认Enable annotation processing状态，若不需要则关闭，点击Apply and Close后重启Eclipse

3. 排查spring-boot-devtools缓存
   devtools的自动重启功能可能缓存资源文件：

   • 在application.properties中临时添加spring.devtools.restart.enabled=false，重新编译查看文件是否正常
   • 若正常，删除项目根目录下的.spring-boot-devtools.properties缓存文件（若存在），再恢复重启配置

4. 检查文件权限与终端编译验证
   MacOS Catalina的权限可能导致Maven无法写入target目录：

   • 右键项目目录选择Get Info，确认Sharing & Permissions有读写权限
   • 用终端执行mvn clean install，跳过Eclipse内置Maven，验证是否能生成正常的application.properties

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