MapStruct生成的映射器未映射属性问题排查求助

问题现象 #

MapStruct映射器已生成实现类，但方法体内仅执行无参构造并返回实例，未包含Lombok生成的getter/setter调用。Maven命令行编译时生成的实现正常，但IntelliJ IDEA环境下生成的代码不符合预期，导致属性映射失败（测试中name属性为null）。

最小复现代码 #

实体类 Cat #

package com.example.demo.data;

import lombok.Getter;
import lombok.Setter;

@Getter
@Setter
public class Cat {
    private String name;
}

DTO类 CatDto #

package com.example.demo.data;

import lombok.Getter;
import lombok.Setter;

@Getter
@Setter
public class CatDto {
    private String name;
}

映射器接口 CatMapper #

package com.example.demo.mapper;

import com.example.demo.data.Cat;
import com.example.demo.data.CatDto;
import org.mapstruct.Mapper;

@Mapper(componentModel = "spring")
public interface CatMapper {
    Cat toCat(CatDto cat);
}

Maven配置 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>3.3.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for MapStruct</description>
    <properties>
        <java.version>17</java.version>
        <mapstruct.version>1.6.3</mapstruct.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct</artifactId>
            <version>${mapstruct.version}</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok-mapstruct-binding</artifactId>
            <version>0.2.0</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <annotationProcessorPaths>
                        <path>
                            <groupId>org.mapstruct</groupId>
                            <artifactId>mapstruct-processor</artifactId>
                            <version>${mapstruct.version}</version>
                        </path>
                        <path>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                            <version>${lombok.version}</version>
                        </path>
                    </annotationProcessorPaths>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

测试代码 #

package com.example.demo;

import com.example.demo.data.Cat;
import com.example.demo.data.CatDto;
import com.example.demo.mapper.CatMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import static org.junit.jupiter.api.Assertions.assertEquals;

@SpringBootTest
class DemoApplicationTests {
    @Autowired
    private CatMapper catMapper;
    
    @Test
    void contextLoads() {
        CatDto catDto = new CatDto();
        catDto.setName("Kitty");
        Cat cat = catMapper.toCat(catDto);
        assertEquals(catDto.getName(), cat.getName()); // 失败：预期"Kitty"，实际为null
    }
}

IntelliJ生成的异常实现类 #

package com.example.demo.mapper;

import com.example.demo.data.Cat;
import com.example.demo.data.CatDto;
import javax.annotation.processing.Generated;
import org.springframework.stereotype.Component;

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2024-11-14T19:21:15+0300",
    comments = "version: 1.6.3, compiler: javac, environment: Java 17.0.13 (Amazon.com Inc.)"
)
@Component
public class CatMapperImpl implements CatMapper {

    @Override
    public Cat toCat(CatDto cat) {
        if ( cat == null ) {
            return null;
        }

        Cat cat1 = new Cat();

        return cat1;
    }

    @Override
    public CatDto toDto(Cat cat) {
        if ( cat == null ) {
            return null;
        }

        CatDto catDto = new CatDto();

        return catDto;
    }
}

问题原因推测 #

IntelliJ IDEA默认按注解处理器的groupId首字母排序执行，Lombok（groupId首字母P）晚于MapStruct（groupId首字母M）执行，导致MapStruct处理时Lombok尚未生成getter/setter，无法识别属性映射关系。

解决方案 #

1. 调整IntelliJ注解处理器顺序

   • 打开File > Settings > Build, Execution, Deployment > Compiler > Annotation Processors
   • 勾选Enable annotation processing
   • 在Processor path列表中，将lombok处理器移到mapstruct-processor之前
   • 点击Apply后重新编译项目

2. 强制使用Maven编译流程

   • 在IntelliJ中执行Maven > Lifecycle > compile，而非IDE自带的编译按钮
   • 可配置IDE默认使用Maven编译：File > Settings > Build, Execution, Deployment > Build Tools > Maven > Runner，勾选Delegate IDE build/run actions to Maven

内容的提问来源于stack exchange，提问作者Cagepi