一款PO VO DTO 轉(zhuǎn)換神器，求求你別在到處找工具類了！

老鐵們是不是經(jīng)常為寫一些實(shí)體轉(zhuǎn)換的原始代碼感到頭疼，尤其是實(shí)體字段特別多的時(shí)候。介紹一個(gè)開(kāi)源項(xiàng)目 mapstruct ，可以輕松優(yōu)雅的進(jìn)行轉(zhuǎn)換，簡(jiǎn)化你的代碼。當(dāng)然有的人喜歡寫get set，或者用BeanUtils 進(jìn)行復(fù)制，代碼只是工具，本文只是提供一種思路。

先貼下官網(wǎng)地址吧：https://mapstruct.org/

廢話不多說(shuō)，上代碼：

pom 配置：

????????UTF-8
????????1.8
????????1.8
????????1.4.1.Final
????????1.18.12



????????
????????????org.mapstruct
????????????mapstruct
????????????${org.mapstruct.version}
????????

????????
????????
????????????org.projectlombok
????????????lombok
????????????${org.projectlombok.version}
????????????provided
????????

????????
?????
????????????org.mapstruct
????????????mapstruct-processor
????????????${org.mapstruct.version}
????????????provided
????????




????????
????????????
????????????????org.apache.maven.plugins
????????????????maven-compiler-plugin
????????????????3.8.1
????????????????
????????????????????<source>1.8source>
????????????????????1.8
????????????????????
????????????????????????
????????????????????????????org.projectlombok
????????????????????????????lombok
????????????????????????????${org.projectlombok.version}
????????????????????????
????????????????????????
????????????????????????????org.mapstruct
????????????????????????????mapstruct-processor
????????????????????????????${org.mapstruct.version}
????????????????????????
????????????????????
????????????????
????????????
????????
????

關(guān)于lombok和mapstruct的版本兼容問(wèn)題多說(shuō)幾句，maven插件要使用3.6.0版本以上、lombok使用1.16.16版本以上，另外編譯的lombok mapstruct的插件不要忘了加上。否則會(huì)出現(xiàn)下面的錯(cuò)誤：No property named "aaa" exists in source parameter(s). Did you mean "null"?

這種異常就是lombok編譯異常導(dǎo)致缺少get setter方法造成的。還有就是缺少構(gòu)造函數(shù)也會(huì)拋異常。

@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);

}

實(shí)體類是開(kāi)發(fā)過(guò)程少不了的，就算是用工具生成肯定也是要有的，需要手寫的部分就是這個(gè)Mapper的接口，編譯完成后會(huì)自動(dòng)生成相應(yīng)的實(shí)現(xiàn)類

然后就可以直接用mapper進(jìn)行實(shí)體的轉(zhuǎn)換了

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);
????????//這行代碼便是實(shí)際要用的代碼
????????StudentVO?studentVO?=?StudentMapper.INSTANCE.student2StudentVO(student);
????????System.out.println(studentVO);

????}

}

mapper可以進(jìn)行字段映射，改變字段類型，指定格式化的方式，包括一些日期的默認(rèn)處理。

可以手動(dòng)指定格式化的方法：

@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();
????}

}

上面只是最簡(jiǎn)單的實(shí)體映射處理，下面介紹一些高級(jí)用法

1.List 轉(zhuǎn)換

屬性映射基于上面的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?students2StudentVOs(List?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?list?=?new?ArrayList<>();
????list.add(student);
????List?result?=?StudentMapper.INSTANCE.students2StudentVOs(list);
????System.out.println(result);
}

2.多對(duì)象轉(zhuǎn)換到一個(gè)對(duì)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("語(yǔ)文").build();

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

}

3.默認(rèn)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?=?"張三")
????StudentVO?studentAndCourse2StudentVO(Student?student,?Course?course);

}