无意中见同事在比较BeanCopier的效率，MapStruct的使用者很牛皮的说我的效率是你的XX倍，今天认识了一下MapStrut，毫无疑问反射的效率绝对输给setter/getter

引入

            <!-- OR use this with Java 8 and beyond: <artifactId>mapstruct-jdk8</artifactId> --><dependency><groupId>org.mapstruct</groupId><artifactId>mapstruct-jdk8</artifactId><version>${org.mapstruct.version}</version></dependency><dependency><groupId>org.mapstruct</groupId><artifactId>mapstruct-processor</artifactId><version>${org.mapstruct.version}</version><scope>provided</scope></dependency>

maven编译更新成1.8结合lombok，同时更新maven-compiler-plugin

                <plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.6.2</version><configuration><source>${java.version}</source><target>${java.version}</target><encoding>${project.encoding}</encoding><annotationProcessorPaths><path><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>${lombok.version}</version></path><path><groupId>org.mapstruct</groupId><artifactId>mapstruct-processor</artifactId><version>${org.mapstruct.version}</version></path></annotationProcessorPaths><compilerArgs><compilerArg>-Amapstruct.defaultComponentModel=spring</compilerArg></compilerArgs></configuration></plugin>

加-Amapstruct.defaultComponentModel=spring编译配置的目的是指定mapstruct编译生成实现类的时候支持spring的扫描

编译

忽略具体bean，copier如下

@Mapper
public interface OrderFundsLiteMapper {WjsOrderFundsLiteToValidBean toWjsOrderFundsLiteToValidBean(OrderFundsLiteDO orderFundsLiteDO);}

maven编译，实现类如下

@Generated(value = "org.mapstruct.ap.MappingProcessor",date = "2018-04-12T10:58:53+0800",comments = "version: 1.2.0.Final, compiler: javac, environment: Java 1.8.0_111 (Oracle Corporation)"
)
@Component
public class OrderFundsLiteMapperImpl implements OrderFundsLiteMapper {@Overridepublic WjsOrderFundsLiteToValidBean toWjsOrderFundsLiteToValidBean(OrderFundsLiteDO orderFundsLiteDO) {if ( orderFundsLiteDO == null ) {return null;}WjsOrderFundsLiteToValidBean wjsOrderFundsLiteToValidBean = new WjsOrderFundsLiteToValidBean();wjsOrderFundsLiteToValidBean.setOrderFundsId( orderFundsLiteDO.getOrderFundsId() );wjsOrderFundsLiteToValidBean.setAgencyCode( orderFundsLiteDO.getAgencyCode() );wjsOrderFundsLiteToValidBean.setOrderFundsAmt( orderFundsLiteDO.getOrderFundsAmt() );wjsOrderFundsLiteToValidBean.setGmtContractUpdate( orderFundsLiteDO.getGmtContractUpdate() );return wjsOrderFundsLiteToValidBean;}
}

可见MapStruct在编译期生成实现类，同时作为spring的@Component，可以直接注入使用。

运行

WjsOrderFundsLiteToValidBean(orderFundsId=1, agencyCode=twen, orderFundsAmt=1, gmtContractUpdate=Thu Apr 12 11:05:13 CST 2018)

总结

MapStruct在编译时，自动生成具体的setter/getter，减少了代码量，同时避免反射带来的效率牺牲。

后

具体学习文档 参见 MapStruct 1.2.0.Final参考指南 http://mapstruct.org/documentation/stable/reference/html/