Mapstruct中复用@Mapping映射定义的实现方法咨询

嘿，你这个复用映射配置的需求太贴合实际开发场景了！MapStruct专门提供了@InheritConfiguration注解来解决这种重复编写映射规则的问题，刚好你后来尝试的写法就是正确的方向，我来给你捋清楚细节~

首先看你最初的代码，remoteToNewLocalApp和remoteToLocalAppUpdate两个方法里重复写了相同的@Mapping配置，确实有点冗余：

@Mapper
interface AppMapper {

    @Mapping(target = "appId", source = "atemsPackage.appId", defaultExpression = "java(packageId)")
    @Mapping(target = "appOnRemote", constant = "true")
    fun remoteToNewLocalApp(atemsPackage: AtemsPackage, packageId: String): LocalApp

    @Mapping(target = "appId", source = "atemsPackage.appId", defaultExpression = "java(packageId)")
    @Mapping(target = "appOnRemote", constant = "true")
    fun remoteToLocalAppUpdate(atemsPackage: AtemsPackage, packageId: String): LocalAppRemoteUpdate

    companion object {
        val INSTANCE: AppMapper = Mappers.getMapper(AppMapper::class.java)
    }
}

而你更新后的写法就完美解决了这个问题：通过@InheritConfiguration(name = "remoteToNewLocalApp")指定要继承的方法，MapStruct会自动把remoteToNewLocalApp上的所有映射规则复用给remoteToLocalAppUpdate，不用再重复写一遍了：

@Mapper
interface AppMapper {

    @Mapping(target = "appId", source = "atemsPackage.appId", defaultExpression = "java(packageId)")
    @Mapping(target = "appOnRemote", constant = "true")
    fun remoteToNewLocalApp(atemsPackage: AtemsPackage, packageId: String): LocalApp

    @InheritConfiguration(name = "remoteToNewLocalApp")
    fun remoteToLocalAppUpdate(atemsPackage: AtemsPackage, packageId: String): LocalAppRemoteUpdate

    companion object {
        val INSTANCE: AppMapper = Mappers.getMapper(AppMapper::class.java)
    }
}

这里还有几个实用的细节要提醒你：

• 要确保被继承的方法和新方法的参数列表完全匹配，就像你这里两个方法都是(AtemsPackage, String)，这样继承才会生效；如果参数有差异，可能需要配合@Named或者调整参数顺序
• 如果新方法需要个别调整映射规则，完全可以在@InheritConfiguration下面再额外加@Mapping，新的@Mapping会覆盖继承来的对应配置
• 如果你的项目里有更多方法需要复用相同的映射规则，还可以用@MapperConfig定义一个全局的配置接口，然后在@Mapper的config属性里指定，这样整个Mapper都能复用这套规则，适合更复杂的场景

这样一来，不仅代码更简洁，后续如果要修改映射规则，只需要改被继承的那个方法即可，维护起来也方便多啦！

备注：内容来源于stack exchange，提问作者rkr87