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参考链接:mapstruct的基本使用
介绍
是不是有时候发现明明source和target不是同一个类型,但是却转换成功了,这是因为mapstruct有一套自己的类型转换机制
类型转换的流程
首先尝试自动进行类型转换
若是无法支持的类型转换,则是尝试调用已经存在的类型转换方法
不存在可用的方法则是尝试自己创建一个类型转换方法
类型转换分类
自动转换
以下的类型之间是mapstruct自动进行类型转换的。
- 基本类型及其他们对应的包装类型。
此时mapstruct会自动进行拆装箱。不需要人为的处理 - 基本类型的包装类型和string类型之间
@Data
@NoArgsConstructor
@FieldDefaults(level = AccessLevel.PRIVATE)
@AllArgsConstructor
public class Item1 {
Long itemId;
String title;
}
@Data
@NoArgsConstructor
@FieldDefaults(level = AccessLevel.PRIVATE)
@AllArgsConstructor
public class Item2 {
Long itemId;
String title;
}
@Data
@NoArgsConstructor
@FieldDefaults(level = AccessLevel.PRIVATE)
@AllArgsConstructor
public class Sku2 {
Long skuId;
String skuCode;
String skuPrice;
List<String> nameList;
Item1 item;
}
@Data
@NoArgsConstructor
@FieldDefaults(level = AccessLevel.PRIVATE)
@AllArgsConstructor
public class SkuDTO2 {
Long skuId;
String skuCode;
Long skuPrice;
List<String> nameList;
Item2 item;
}
@Mapper
public interface ItemConvert {
ItemConvert INSTANCE = Mappers.getMapper(ItemConvert.class);
SkuDTO2 domain2Dto(Sku2 sku2);
}
// 以下为mapstruct自动生成
public class ItemConvertImpl implements ItemConvert {
@Override
public SkuDTO2 domain2Dto(Sku2 sku2) {
if ( sku2 == null ) {
return null;
}
SkuDTO2 skuDTO2 = new SkuDTO2();
skuDTO2.setSkuId( sku2.getSkuId() );
skuDTO2.setSkuCode( sku2.getSkuCode() );
if ( sku2.getSkuPrice() != null ) {
skuDTO2.setSkuPrice( Long.parseLong( sku2.getSkuPrice() ) );
}
List<String> list = sku2.getNameList();
if ( list != null ) {
skuDTO2.setNameList( new ArrayList<String>( list ) );
}
skuDTO2.setItem( item1ToItem2( sku2.getItem() ) );
return skuDTO2;
}
protected Item2 item1ToItem2(Item1 item1) {
if ( item1 == null ) {
return null;
}
Item2 item2 = new Item2();
item2.setItemId( item1.getItemId() );
item2.setTitle( item1.getTitle() );
return item2;
}
自定义转换类型
- 使用表达式进行定义类型转换,expression=“java(。。。)”
注意:使用表达式的时候,类必须是全路径的使用,或者@Mapper(imports={类名.class}
@Mapper(imports={
DemandSourceEnum.class})
public interface CarDealMapper {
CarDealMapper INSTANCE = Mappers.getMapper(CarDealMapper.class);
@Mappings({
@Mapping(target = "demandSource", expression = "java(DemandSourceEnum.getMeaning(carDealDO.getDemandSource()))"),
SaleDemandVO doToVo(CarDealDO carDealDO);
}
- 自定义方法进行类型转换
@Mapper
public interface ItemConvert {
ItemConvert INSTANCE = Mappers.getMapper(ItemConvert.class);
SkuDTO2 domain2Dto(Sku2 sku2);
default Item2 item1ToItem2(Item1 item1) {
if (item1 == null) {
return null;
}
Item2 item2 = new Item2();
item2.setItemId(11111L);
item2.setTitle(item1.getTitle());
return item2;
}
}
// mapstruct 的实现类
@Generated(
value = "org.mapstruct.ap.MappingProcessor",
date = "2019-07-30T18:38:11+0800",
comments = "version: 1.3.0.Final, compiler: javac, environment: Java 1.8.0_101 (Oracle Corporation)"
)
public class ItemConvertImpl implements ItemConvert {
@Override
public SkuDTO2 domain2Dto(Sku2 sku2) {
if ( sku2 == null ) {
return null;
}
SkuDTO2 skuDTO2 = new SkuDTO2();
skuDTO2.setSkuId( sku2.getSkuId() );
skuDTO2.setSkuCode( sku2.getSkuCode() );
if ( sku2.getSkuPrice() != null ) {
skuDTO2.setSkuPrice( Long.parseLong( sku2.getSkuPrice() ) );
}
List<String> list = sku2.getNameList();
if ( list != null ) {
skuDTO2.setNameList( new ArrayList<String>( list ) );
}
// mapstruct直接调用的是在接口中自定义的实现
skuDTO2.setItem( item1ToItem2( sku2.getItem() ) );
return skuDTO2;
}
}
- 使用策略的方式进行类型转换
若是类型在很多Mapper中都需要使用,比较使用下例
public class BooleanStrategy {
public String booleanToString(Boolean value) {
if (value == null) {
return "--";
}
return value ? "是" : "否";
}
public Integer booleanToInteger(Boolean value) {
if (value == null) {
return null;
}
return value ? 1 : 0;
}
public Boolean IntegerToBoolean(Integer value) {
if (value == null) {
return null;
}
return value == 0 ? false : true;
}
public String dateFormate(Date date) {
if (date == null) {
return "--";
}
return DateFormatUtils.format(date, "yyyy-MM-dd HH:mm:ss");
}
}
@Mapper(uses = BooleanStrategy.class)
public interface CarDealMapper {
CarDealMapper INSTANCE = Mappers.getMapper(CarDealMapper.class);
CarDealDO dtoToDo(PlateCityMessageDTO plateCityMessageDTO);
}
方法中target和source 类型满足 BooleanStrategy方法的,会自动进行调用这个方法的类型转换进行处理
- 自定义常量的方法
若是我们需要给一些属性定义一个固定的值,这个时候可以使用 constant
@Mapping(target = "whetherPass", constant = "true")
CentralizedNewCarShipDTO doToDubboDto(CarDealDO carDealDO);
- 特殊类型的转换
@Mapping(target = "createTime", dateFormat = "yyyy-MM-dd HH:mm:ss", expression = "java(new Date())")
CarDTO doToDTO(CarDO carDO);
另外还有numberFormat定义数字的格式转换
- 自定义初始值 defaultValue
当source值为空的时候则会使用defaultValue定义的值。而constant则是无论source是否为空,都会使用constant定义的值,注意区分两者
/** * 单个参数的直接使用 * * @param carDO source do * @return target dto */
@Mapping(target = "userName", constant = "yby")
@Mapping(target = "modelColor", source = "modelColor", defaultValue = "标致")
@Mapping(target = "createTime", dateFormat = "yyyy-MM-dd HH:mm:ss", expression = "java(new Date())")
CarDTO doToDTO(CarDO carDO);
额外的请参考 org.mapstruct.Mapping
Collection转换
原理是遍历source collection然后转换类型,put到target collection中 如果是可以自动转换的则自动转换,同date type conversion;若是无法自动转换的,则会查看是否有可以调用的类型
@Mapper(imports = Date.class)
public interface CarMapper {
CarMapper INSTANCE = Mappers.getMapper(CarMapper.class);
/** * 基本类型collection的转换 * * @param integers * @return */
Set<String> integerSetToStringSet(Set<Integer> integers);
/** * 调用存在已有方法的转换 * * @param cars * @return */
List<CarDTO> carsToCarDtos(List<CarDO> cars);
/** * 单个参数的直接使用 * * @param carDO source do * @return target dto */
@Mapping(target = "userName", constant = "yby")
@Mapping(target = "modelColor", source = "modelColor", defaultValue = "标致")
@Mapping(target = "createTime", dateFormat = "yyyy-MM-dd HH:mm:ss", expression = "java(new Date())")
CarDTO doToDTO(CarDO carDO);
/** * DTO转为VO * * @param warehouseValidDTOList * @return */
List<WarehouseValidPageVO> dtoToVo(List<WarehouseValidDTO> warehouseValidDTOList);
}
// mapstruct实现
@Generated(
value = "org.mapstruct.ap.MappingProcessor",
date = "2019-07-30T19:27:05+0800",
comments = "version: 1.3.0.Final, compiler: javac, environment: Java 1.8.0_101 (Oracle Corporation)"
)
public class CarMapperImpl implements CarMapper {
@Override
public Set<String> integerSetToStringSet(Set<Integer> integers) {
if ( integers == null ) {
return null;
}
Set<String> set = new HashSet<String>( Math.max( (int) ( integers.size() / .75f ) + 1, 16 ) );
for ( Integer integer : integers ) {
set.add( String.valueOf( integer ) );
}
return set;
}
@Override
public List<CarDTO> carsToCarDtos(List<CarDO> cars) {
if ( cars == null ) {
return null;
}
List<CarDTO> list = new ArrayList<CarDTO>( cars.size() );
for ( CarDO carDO : cars ) {
list.add( doToDTO( carDO ) );
}
return list;
}
@Override
public CarDTO doToDTO(CarDO carDO) {
if ( carDO == null ) {
return null;
}
CarDTO carDTO = new CarDTO();
if ( carDO.getModelColor() != null ) {
carDTO.setModelColor( carDO.getModelColor() );
}
else {
carDTO.setModelColor( "标致" );
}
if ( carDO.getNewCarGuidePrice() != null ) {
carDTO.setNewCarGuidePrice( BigDecimal.valueOf( carDO.getNewCarGuidePrice() ) );
}
carDTO.setBrandCode( carDO.getBrandCode() );
carDTO.setBrandName( carDO.getBrandName() );
carDTO.setSeriesCode( carDO.getSeriesCode() );
carDTO.setSeriesName( carDO.getSeriesName() );
carDTO.setModelCode( carDO.getModelCode() );
carDTO.setModelName( carDO.getModelName() );
carDTO.setModelColorCode( carDO.getModelColorCode() );
carDTO.setUserName( "yby" );
carDTO.setCreateTime( new Date() );
return carDTO;
}
@Override
public List<WarehouseValidPageVO> dtoToVo(List<WarehouseValidDTO> warehouseValidDTOList) {
if ( warehouseValidDTOList == null ) {
return null;
}
List<WarehouseValidPageVO> list = new ArrayList<WarehouseValidPageVO>( warehouseValidDTOList.size() );
for ( WarehouseValidDTO warehouseValidDTO : warehouseValidDTOList ) {
list.add( warehouseValidDTOToWarehouseValidPageVO( warehouseValidDTO ) );
}
return list;
}
protected WarehouseValidPageVO warehouseValidDTOToWarehouseValidPageVO(WarehouseValidDTO warehouseValidDTO) {
if ( warehouseValidDTO == null ) {
return null;
}
WarehouseValidPageVO warehouseValidPageVO = new WarehouseValidPageVO();
warehouseValidPageVO.setId( warehouseValidDTO.getId() );
warehouseValidPageVO.setWarehouseNo( warehouseValidDTO.getWarehouseNo() );
warehouseValidPageVO.setWarehouseName( warehouseValidDTO.getWarehouseName() );
warehouseValidPageVO.setPlateValid( warehouseValidDTO.getPlateValid() );
return warehouseValidPageVO;
}
}
map
public interface SourceTargetMapper {
@MapMapping(valueDateFormat = "dd.MM.yyyy")
Map<String, String> longDateMapToStringStringMap(Map<Long, Date> source);
}
// mapstruct自己实现
@Generated(
value = "org.mapstruct.ap.MappingProcessor",
date = "2019-07-30T19:35:22+0800",
comments = "version: 1.3.0.Final, compiler: javac, environment: Java 1.8.0_101 (Oracle Corporation)"
)
public class SourceTargetMapperImpl implements SourceTargetMapper {
@Override
public Map<String, String> longDateMapToStringStringMap(Map<Long, Date> source) {
if ( source == null ) {
return null;
}
Map<String, String> map = new HashMap<String, String>( Math.max( (int) ( source.size() / .75f ) + 1, 16 ) );
for ( java.util.Map.Entry<Long, Date> entry : source.entrySet() ) {
String key = new DecimalFormat( "" ).format( entry.getKey() );
String value = new SimpleDateFormat( "dd.MM.yyyy" ).format( entry.getValue() );
map.put( key, value );
}
return map;
}
}
案例
Mappings中qualifiedByName属性可以取由@Named声明的名称
import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
import org.mapstruct.Mappings;
@Mapper(componentModel = "spring")
public interface UserMapping {
/** * Student 转化为 User * @param Student * @return */
@Mappings({
@Mapping(target = "uname", source = "sname",qualifiedByName = "booleanToString")
// 多个属性不对应可以用 "," 隔开编写多个@Mapping // ,@Mapping(target = "uname", source = "sname") }) User studentToUser(Student student); @Named("booleanToString")default String booleanToString(boolean value){ if(value){
return "男"; } return "女"; }}
有的时候有一个额外的转换方法多个mapping类文件都要用到,所以肯定有写一个工具类,mapping引用外部的方法
public class Utils{
@Named("booleanToString")
default String booleanToString(boolean value){
if(value){
return "男";
}
return "女";
}
}
@Mapper(componentModel = "spring",uses=Utils.class)
public interface UserMapping {
/** * Student 转化为 User * @param Student * @return */
@Mappings({
@Mapping(target = "uname", source = "sname",qualifiedByName = "booleanToString")
})
User studentToUser(Student student); }
也可以直接使用expression
@Mappings({
@Mapping(target = "uname",expression = "java(booleanToString(student.getSname()))")
// 多个属性不对应可以用 "," 隔开编写多个@Mapping // ,@Mapping(target = "uname", source = "sname")
})
多个来源实体转换成一个参数实体
@Mappings({
@Mapping(target = "chartName", source = "chart.name"),
@Mapping(target = "title", source = "song.title"),
@Mapping(target = "artistName", source = "song.artist.name"),
@Mapping(target = "recordedAt", source = "song.artist.label.studio.name"),
@Mapping(target = "city", source = "song.artist.label.studio.city"),
@Mapping(target = "position", source = "position") })
ChartEntry map(Chart chart, Song song, Integer position);
有一些参数不是来自传入参数,而是默认是一些外部的枚举类或者常量类数据,
就可以在mapper中声明要导入的外部枚举类或者常量类,
@Mapper(componentModel = "spring",
unmappedTargetPolicy = ReportingPolicy.IGNORE,
imports = {
StringUtils.class,
UserConsts.class,
UserStatusEnum.class
})
@Mapping(target = "key",expression = "java( UserConsts.FULL_GIFT)"),
@Mapping(target = "status",expression = "java(UserStatusEnum.VALID_STATUS_NO.getCode())"),
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