Springboot整合MapStruct 简单使用

1.pom引入依赖

<properties>
        <java.version>1.8</java.version>
        <mapstruct.version>1.3.0.Final</mapstruct.version>
</properties>
<dependency>
    <groupId>org.mapstruct</groupId>
    <artifactId>mapstruct-jdk8</artifactId>
    <version>${mapstruct.version}</version>
</dependency>
<dependency>
    <groupId>org.mapstruct</groupId>
    <artifactId>mapstruct-processor</artifactId>
    <version>${mapstruct.version}</version>
</dependency>

引入lombok 注解替代get set方法

<dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.16</version>
        </dependency>

2.创建DO DTO 以person user 为例，user为person的一个属性 PersonDto为传输层

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Person {
    private Long id;
    private String name;
    private String email;
    private Date birthday;
    private User user;
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private Integer age;
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class PersonDTO {
    private Long id;
    private String name;
    /**
     * 对应 Person.user.age
     */
    private Integer age;
    private String email;
    /**
     * 与 DO 里面的字段名称(birthDay)不一致
     */
    private Date birth;
    /**
     * 对 DO 里面的字段(birthDay)进行拓展,dateFormat 的形式
     */
    private String birthDateFormat;
    /**
     * 对 DO 里面的字段(birthDay)进行拓展,expression 的形式
     */
    private String birthExpressionFormat;
}

3.编写接口,componentModel = “Spring.class” 交给spring管理

/* 1.源对象属性 与 目标对象属性 名字一致，自动映射对应属性
 * 2.支持表达式的方式,例如可以用 format 转成自己想要的类型
 * 3.如果某个属性你不想映射，可以加个 ignore=true
 * 4.可以看到像 id、name、email这些名词一致的我并没有指定 source-target
 * 而birthday-birth指定了，转换格式的 birthDateFormat 加了dateFormat
 * 或者 birthExpressionFormat 加了 expression
 */
@Mapper(componentModel = "Spring.class")
public interface PersonConverter {
    PersonConverter INSTANCE = Mappers.getMapper(PersonConverter.class);
    @Mapping(source = "birthday",target = "birth")
    @Mapping(source = "birthday",target = "birthDateFormat",dateFormat = "yyyy-HH-dd HH:mm:ss")
    @Mapping(target = "birthExpressionFormat",dateFormat = "yyyy-HH-dd HH:mm:ss")
    @Mapping(source = "email",target = "email",ignore = true)
    
    PersonDTO toConvertPerson(Person person);
    
    List<PersonDTO> toConvertList(List<Person> person);
}

4.测试
4.1pom引入单元测试

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.13</version>
    <scope>test</scope>
</dependency>

4.2编写测试类

@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest(classes = MapStructDemoApplication.class)
public class PersonConvertTest {

    @Test
    public void test(){
        Person person = new Person(1L,"音乐土豆","*****@qq.com",new Date(),new User(1));
        PersonDTO personDTO = PersonConverter.INSTANCE.toConvertPerson(person);
        System.out.println(personDTO);
        List<Person> list = new ArrayList<>();
        list.add(person);
        List<PersonDTO> personDTOS = PersonConverter.INSTANCE.toConvertList(list);
        personDTOS.forEach(personDto-> System.out.println(personDto));
    }
}

输出：

遇到的问题：
idea启动报错，java: Internal error in the mapping processor: java.lang.NullPointerException at org.ma…
解决方法：
1.设置File→settings→Compiler的User-local build process VM options (overrides Shared options)选项设置
-Djps.track.ap.dependencies=false