java实体映射工具mapstruct

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1、引入依赖jar包

<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>

2、官方网站提供了一种插件的方式：

<properties>
    <org.mapstruct.version>1.3.0.Final</org.mapstruct.version>
</properties>
...
<dependencies>
    <dependency>
        <groupId>org.mapstruct</groupId>
        <artifactId>mapstruct</artifactId>
        <version>${org.mapstruct.version}</version>
    </dependency>
</dependencies>
...
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.5.1</version> <!-- or newer version -->
            <configuration>
                <source>1.8</source> <!-- depending on your project -->
                <target>1.8</target> <!-- depending on your project -->
                <annotationProcessorPaths>
                    <path>
                        <groupId>org.mapstruct</groupId>
                        <artifactId>mapstruct-processor</artifactId>
                        <version>${org.mapstruct.version}</version>
                    </path>
                    <!-- other annotation processors -->
                </annotationProcessorPaths>
            </configuration>
        </plugin>
    </plugins>
</build>

我们选择第一种方式即可。以下是使用方式

@Mapper(componentModel = "spring")
public interface AppointmentOrderConverter {
	@Mappings({
	        @Mapping(source = "request.arrivalTime", target = "arrivalTime", dateFormat = "yyyy-MM-dd HH:mm"),
	        @Mapping(source = "userId", target = "userId"),
	        @Mapping(target = "applicationTime", expression = "java(com.ftcs.core.utils.DateUtil.currentDate())"),
	        @Mapping(target = "createTime", expression = "java(com.ftcs.core.utils.DateUtil.currentDate())"),
	        @Mapping(target = "updateTime", expression = "java(com.ftcs.core.utils.DateUtil.currentDate())"),
	        @Mapping(target = "status", expression = "java(com.ftcs.core.common.context.AppointmentStatusEnum.TO_BE_PROCESSED.getCode())"),
	        @Mapping(target = "isDelete", constant = "0"),
	        @Mapping(target = "loanStatus", constant = "0")
	})
	AppointmentOrder request2domain(AppointmentRequest request, Long userId);
}

注解@Mapper和@Mapping

@Mapper 只有在接口加上这个注解， MapStruct 才会去实现该接口。@Mapper 里有个 componentModel 属性，主要是指定实现类的类型，一般用到两个属性

default：默认，可以通过 Mappers.getMapper(Class) 方式获取实例对象
spring：在接口的实现类上自动添加注解 @Component，可通过 @Autowired 方式注入

@Mapping：属性映射，若源对象属性与目标对象名字一致，会自动映射对应属性

source：源属性
target：目标属性
dateFormat：String 到 Date 日期之间相互转换，通过 SimpleDateFormat，该值为 SimpleDateFormat的日期格式
ignore: 忽略这个字段

@Mappings：配置多个@Mapping
@MappingTarget 用于更新已有对象
@InheritConfiguration 用于继承配置