别再用BeanUtils了，这款PO VO DTO转换神器不香么？

最新推荐文章于 2025-03-02 19:36:27 发布

转载最新推荐文章于 2025-03-02 19:36:27 发布 · 151 阅读

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原文链接：https://mp.weixin.qq.com/s?__biz=MzAwMTE3MDY4MQ==&mid=2652470579&idx=1&sn=d892b92eed911777e5db4808626d1bd0&chksm=813010a5b64799b385ebc62371b1c9fd16b9e39a0e932062690fac3ffd4ecb366979c511fe94&scene=126&sessionid=0

老铁们是不是经常为写一些实体转换的原始代码感到头疼，尤其是实体字段特别多的时候。介绍一个开源项目 mapstruct ，可以轻松优雅的进行转换，简化你的代码。

<properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <org.mapstruct.version>1.4.1.Final</org.mapstruct.version>
        <org.projectlombok.version>1.18.12</org.projectlombok.version>
</properties>

<dependencies>
        <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct</artifactId>
            <version>${org.mapstruct.version}</version>
        </dependency>

        <!-- lombok dependencies should not end up on classpath -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${org.projectlombok.version}</version>
            <scope>provided</scope>
        </dependency>

        <!-- idea 2018.1.1 之前的版本需要添加下面的配置，后期的版本就不需要了，可以注释掉，
我自己用的2019.3 -->
     <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct-processor</artifactId>
            <version>${org.mapstruct.version}</version>
            <scope>provided</scope>
        </dependency>

</dependencies>

<build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <annotationProcessorPaths>
                        <path>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                            <version>${org.projectlombok.version}</version>
                        </path>
                        <path>
                            <groupId>org.mapstruct</groupId>
                            <artifactId>mapstruct-processor</artifactId>
                            <version>${org.mapstruct.version}</version>
                        </path>
                    </annotationProcessorPaths>
                </configuration>
            </plugin>
        </plugins>
    </build>

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class Student {

    private String name;
    private int age;
    private GenderEnum gender;
    private Double height;
    private Date birthday;

}
public enum GenderEnum {
    Male("1", "男"),
    Female("0", "女");

    private String code;
    private String name;

    public String getCode() {
        return this.code;
    }

    public String getName() {
        return this.name;
    }

    GenderEnum(String code, String name) {
        this.code = code;
        this.name = name;
    }
}
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class StudentVO {
    private String name;
    private int age;
    private String gender;
    private Double height;
    private String birthday;
}
@Mapper
public interface StudentMapper {

    StudentMapper INSTANCE = Mappers.getMapper(StudentMapper.class);

    @Mapping(source = "gender.name", target = "gender")
    @Mapping(source = "birthday", target = "birthday", dateFormat = "yyyy-MM-dd HH:mm:ss")
    StudentVO student2StudentVO(Student student);

}

public class Test {

    public static void main(String[] args) {

        Student student = Student.builder().name("小明").age(6).gender(GenderEnum.Male).height(121.1).birthday(new Date()).build();
        System.out.println(student);
        //这行代码便是实际要用的代码
        StudentVO studentVO = StudentMapper.INSTANCE.student2StudentVO(student);
        System.out.println(studentVO);

    }

}

@Mapper
public interface StudentMapper {

    StudentMapper INSTANCE = Mappers.getMapper(StudentMapper.class);

    @Mapping(source = "gender", target = "gender")
    @Mapping(source = "birthday", target = "birthday", dateFormat = "yyyy-MM-dd HH:mm:ss")
    StudentVO student2StudentVO(Student student);

    default String getGenderName(GenderEnum gender) {
        return gender.getName();
    }

}

上面只是最简单的实体映射处理，下面介绍一些高级用法面试宝典：https://www.yoodb.com

1.List 转换

属性映射基于上面的mapping配置

@Mapper
public interface StudentMapper {

    StudentMapper INSTANCE = Mappers.getMapper(StudentMapper.class);

    @Mapping(source = "gender.name", target = "gender")
    @Mapping(source = "birthday", target = "birthday", dateFormat = "yyyy-MM-dd HH:mm:ss")
    StudentVO student2StudentVO(Student student);


    List<StudentVO> students2StudentVOs(List<Student> studentList);

}
public static void main(String[] args) {

    Student student = Student.builder().name("小明").age(6).gender(GenderEnum.Male).height(121.1).birthday(new Date()).build();

    List<Student> list = new ArrayList<>();
    list.add(student);
    List<StudentVO> result = StudentMapper.INSTANCE.students2StudentVOs(list);
    System.out.println(result);
}

2.多对象转换到一个对象

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class Student {

    private String name;
    private int age;
    private GenderEnum gender;
    private Double height;
    private Date birthday;

}
@Data
@AllArgsConstructor
@Builder
@NoArgsConstructor
public class Course {

    private String courseName;
    private int sortNo;
    private long id;

}
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class StudentVO {
    private String name;
    private int age;
    private String gender;
    private Double height;
    private String birthday;
    private String course;
}
@Mapper
public interface StudentMapper {

    StudentMapper INSTANCE = Mappers.getMapper(StudentMapper.class);

    @Mapping(source = "student.gender.name", target = "gender")
    @Mapping(source = "student.birthday", target = "birthday", dateFormat = "yyyy-MM-dd HH:mm:ss")
    @Mapping(source = "course.courseName", target = "course")
    StudentVO studentAndCourse2StudentVO(Student student, Course course);

}
public class Test {

    public static void main(String[] args) {

        Student student = Student.builder().name("小明").age(6).gender(GenderEnum.Male).height(121.1).birthday(new Date()).build();
        Course course = Course.builder().id(1L).courseName("语文").build();

        StudentVO studentVO = StudentMapper.INSTANCE.studentAndCourse2StudentVO(student, course);
        System.out.println(studentVO);
    }

}

3.默认值

@Mapper
public interface StudentMapper {

    StudentMapper INSTANCE = Mappers.getMapper(StudentMapper.class);

    @Mapping(source = "student.gender.name", target = "gender")
    @Mapping(source = "student.birthday", target = "birthday", dateFormat = "yyyy-MM-dd HH:mm:ss")
    @Mapping(source = "course.courseName", target = "course")
    @Mapping(target = "name", source = "student.name", defaultValue = "张三")
    StudentVO studentAndCourse2StudentVO(Student student, Course course);

}

作者：bettermann
https://www.toutiao.com/article/6891531055631696395/

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