Springboot集成mapstruct

朱雀 2021-10-15 06:27 673阅读 0赞

### 一、什么是mapstruct ###

MapStruct是一个代码生成器的工具类，简化了不同的Java Bean之间映射的处理，所以映射指的就是从一个实体变化成一个实体。在实际项目中，我们经常会将PO转DTO、DTO转PO等一些实体间的转换。在转换时大部分属性都是相同的，只有少部分的不同，这时我们可以通过mapStruct的一些注解来匹配不同属性，可以让不同实体之间的转换变的简单。  
MapStruct官网地址： http://mapstruct.org/

### 二、添加依赖 ###

<dependency>
        <groupId>org.mapstruct</groupId>
        <artifactId>mapstruct-jdk8</artifactId>
        <version>1.0.0.Final</version>
    </dependency>
    
    <dependency>
        <groupId>org.mapstruct</groupId>
        <artifactId>mapstruct-processor</artifactId>
        <version>1.0.0.Final</version>
    </dependency>

### 三、mapstruct实体间的转换 ###

//Info.java
    public class Info{ 
        private Integer userId;
        private String email;
        private Integer score;
        private String remark;
        //constructor, getters, setters etc.
    }

//InfoDto.java
    public class InfoDto{ 
        private Integer id;
        private Integer value;
        private String remark;
        private User user;
        //constructor, getters, setters etc.
    }

//User.java
    public class User{ 
        private Integer userId;
        private String email;
        //constructor, getters, setters etc.
    }

### 四、mapper接口 ###

要生成一个PeopleDTO与PeopleEntity对象相互转换的映射器，我们需要定义一个mapper接口。像这两个实体类有些属性不一样时，我们可以通过@Mapping注解来进行转换.

*  @Mapper注解标记这个接口作为一个映射接口，并且是编译时MapStruct处理器的入口。
 *  @Mapping解决源对象和目标对象中，属性名字不同的情况。
 *  Mappers.getMapper自动生成的接口的实现可以通过Mapper的class对象获取,从而让客户端可以访问Mapper接口的实现。

@Mapper
    public interface InfoMapper { 
        PeopleMapper INSTANCE = Mappers.getMapper(InfoMapper.class);
    
        /** * PO转DTO * * @param info PO * @return DTO */
        @Mapping(target = "value", source = "score")
        @Mapping(target = "user.userId", source = "userId")
        @Mapping(target = "user.email", source = "email")
        InfoDTO entityToDTO(Info info);
    
        /** * DTO转PO * * @param infoDTO DTO * @param entity PO */
        @Mapping(target = "score", source = "value")
        @Mapping(target = "userId", source = "user.userId")
        @Mapping(target = "email", source = "user.email")
        void updateInfoFromDto(InfoDTO InfoDTO, @MappingTarget Info info);
    }

当运行是将会自动编译我们的InfoMapper.java

下面是我在学习时写的Mapper文件以及编译后的一个文件

@Mapper(componentModel = "spring")
    public interface TeamMapper { 
    
        TeamVo poToTeamVo(TeamPo teamPo);
    
        Team poToTeamDo(TeamPo teamPo);
    
        List<TeamVo> poListToVoList(List<TeamPo> teamPoList);
    }

@Generated(
        value = "org.mapstruct.ap.MappingProcessor",
        date = "2019-08-08T13:30:54+0800",
        comments = "version: 1.0.0.Final, compiler: javac, environment: Java 1.8.0_211 (Oracle Corporation)"
    )
    @Component
    public class TeamMapperImpl implements TeamMapper { 
    
        @Override
        public TeamVo poToTeamVo(TeamPo teamPo) { 
            if ( teamPo == null ) { 
                return null;
            }
    
            TeamVo teamVo = new TeamVo();
    
            teamVo.setId( teamPo.getId() );
            teamVo.setName( teamPo.getName() );
            teamVo.setDepartmentId( teamPo.getDepartmentId() );
            teamVo.setDepartmentName( teamPo.getDepartmentName() );
    
            return teamVo;
        }
    
        @Override
        public Team poToTeamDo(TeamPo teamPo) { 
            if ( teamPo == null ) { 
                return null;
            }
    
            Team team = new Team();
    
            team.setId( teamPo.getId() );
            team.setName( teamPo.getName() );
            team.setDepartmentId( teamPo.getDepartmentId() );
    
            return team;
        }
    
        @Override
        public List<TeamVo> poListToVoList(List<TeamPo> teamPoList) { 
            if ( teamPoList == null ) { 
                return null;
            }
    
            List<TeamVo> list = new ArrayList<TeamVo>();
            for ( TeamPo teamPo : teamPoList ) { 
                list.add( poToTeamVo( teamPo ) );
            }
    
            return list;
        }
    }

### 五、注意 ###

1、 由于编译可能不及时的原因，所以一开始遇到了修改了po或者dto的一个类，但是mapper没有及时的重新编译，所以dto，po，vo有更改的话，建议先clean一下之后重新编译然后运行

2、 在使用mapstruct + lombok时要注意maven-comiler-plugin插件版本一定要在3.6.0以上，若版本低，则会报找不到属性的错误  
下面是一个依赖模板

<?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 http://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>2.1.1.RELEASE</version>
            <relativePath/> 
        </parent>
        <groupId>xyz.suiwo</groupId>
        <artifactId>gradingdog</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>gradingdog</name>
        <description>Demo project for Spring Boot</description>
    
        <properties>
            <java.version>1.8</java.version>
            <org.mapstruct.version>1.2.0.Beta2</org.mapstruct.version>
            <org.projectlombok.version>1.16.14</org.projectlombok.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>2.0.1</version>
            </dependency>
    
            
            <dependency>
                <groupId>org.mapstruct</groupId>
                <artifactId>mapstruct</artifactId> 
                <version>${org.mapstruct.version}</version>
            </dependency>
    
            <dependency>
                <groupId>org.mapstruct</groupId>
                <artifactId>mapstruct-jdk8</artifactId>
                <version>${org.mapstruct.version}</version>
            </dependency>
            
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>${org.projectlombok.version}</version>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.6.0</version>
                    <configuration>
                        <source>${java.version}</source> 
                        <target>${java.version}</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>
                        <compilerArgs>
                            <arg>-Amapstruct.suppressGeneratorTimestamp=true</arg>
                            <arg>-Amapstruct.defaultComponentModel=spring</arg>
                        </compilerArgs>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </project>