jaxb 映射 空字段

Dozer是开放源代码（ Apache 2许可 ）“ Java Bean到Java Bean映射器，可将数据从一个对象递归复制到另一个对象”。 正如从其主页上的描述所描述的那样，它用于映射两个JavaBeans实例，以在实例之间进行自动数据复制。 尽管这些可以是多种JavaBeans实例中的任何一种，但我将重点介绍如何使用Dozer将JAXB生成的对象映射到“业务数据对象”（有时称为“域对象”）。

在使用Java XML绑定体系结构 （ JAXB ）的Java应用程序中，开发人员编写特定的业务或域对象供应用程序本身使用，而仅使用JAXB生成的对象进行读取（解组）和写入操作，这是很常见的 。 （编组）XML。 尽管将JAXB生成的对象本身用作业务/域对象具有一定的吸引力 （ DRY ），但是这种方法存在一些缺点。 JAXB生成的类没有toString（） ， equals（Object）或hashCode（）实现，这使得这些生成的类不适合用于许多类型的集合中，除身份比较之外不适合比较，并且不便于记录其内容。 在对生成的类进行生成后，对其进行手动编辑很麻烦，并且即使对源XSD进行了很小的更改，也不利于再次生成JAXB类。

尽管可以使用JAXB2 Basics来确保JAXB生成的类具有在集合中使用，在比较中使用以及记录其内容所需的一些常用方法，但是使用JAXB生成的类作为domain /业务对象是业务逻辑与XSD紧密结合的必然结果。 XSD中的模式更改（例如版本更新）通常会导致通过JAXB从该XSD生成的类的包结构不同。 然后，不同的包结构将强制所有导入那些JAXB生成的类的代码来更改其导入语句。 对XSD的内容更改可能会产生更大的影响，从而影响JAXB类的get / set方法，如果将JAXB类用于域/业务对象，则该方法会散布在整个应用程序中。

假设决定不使用JAXB生成的类作为业务/域类，有多种方法可以通过代码或配置中描述的“映射层”将生成的JAXB类映射到定义业务/域对象的类。 为了演示两个基于代码的映射层的实现并演示基于Dozer的映射层，我介绍了JAXB生成的类和定制构建的业务/域类的一些简单示例。

本文的示例的第一部分是XSD，将从中指示JAXB'x xjc到通用类，以将其编组到该XSD所描述的XML或从该XSD所描述的XML解组。 接下来显示的XSD定义了一个Person元素，该元素可以具有嵌套的MailingAddress和ResidentialAddress元素以及两个用于名字和姓氏的String属性。 还要注意，主要名称空间是http://marxsoftware.blogspot.com/，JAXB将使用它来确定从该XSD生成的类的Java包层次结构。

人格

<?xml version="1.0"?>
<xs:schema version="1.0"xmlns:xs="http://www.w3.org/2001/XMLSchema"xmlns:marx="http://marxsoftware.blogspot.com/"targetNamespace="http://marxsoftware.blogspot.com/"elementFormDefault="qualified"><xs:element name="Person" type="marx:PersonType" /><xs:complexType name="PersonType"><xs:sequence><xs:element name="MailingAddress" type="marx:AddressType" /><xs:element name="ResidentialAddress" type="marx:AddressType" minOccurs="0" /></xs:sequence><xs:attribute name="firstName" type="xs:string" /><xs:attribute name="lastName" type="xs:string" /></xs:complexType><xs:complexType name="AddressType"><xs:attribute name="streetAddress1" type="xs:string" use="required" /><xs:attribute name="streetAddress2" type="xs:string" use="optional" /><xs:attribute name="city" type="xs:string" use="required" /><xs:attribute name="state" type="xs:string" use="required" /><xs:attribute name="zipcode" type="xs:string" use="required" /></xs:complexType></xs:schema>

当针对上述XSD执行xjc （Oracle JDK随附的JAXB编译器）时，在com / blogspot / marxsoftware目录（从XSD的名称空间派生）中生成以下四个类： AddressType.java ， PersonType.java ， ObjectFactory.java和package-info.java 。

接下来的两个代码清单是JAXB生成的两个主要感兴趣的类（ PersonType.java和AddressType.java ）。 在此处显示它们的主要目的是提醒他们，它们缺少我们经常需要我们的业务/域类拥有的方法。

JAXB生成的PersonType.java

//
// This file was generated by the JavaTM Architecture for XML Binding(JAXB) Reference Implementation, v2.2.4-2
// See http://java.sun.com/xml/jaxb
// Any modifications to this file will be lost upon recompilation of the source schema.
// Generated on: 2013.12.03 at 11:44:32 PM MST
//package com.blogspot.marxsoftware;import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlType;/*** <p>Java class for PersonType complex type.* * <p>The following schema fragment specifies the expected content contained within this class.* * <pre>* <complexType name="PersonType">*   <complexContent>*     <restriction base="{http://www.w3.org/2001/XMLSchema}anyType">*       <sequence>*         <element name="MailingAddress" type="{http://marxsoftware.blogspot.com/}AddressType"/>*         <element name="ResidentialAddress" type="{http://marxsoftware.blogspot.com/}AddressType" minOccurs="0"/>*       </sequence>*       <attribute name="firstName" type="{http://www.w3.org/2001/XMLSchema}string" />*       <attribute name="lastName" type="{http://www.w3.org/2001/XMLSchema}string" />*     </restriction>*   </complexContent>* </complexType>* </pre>* * */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "PersonType", propOrder = {"mailingAddress","residentialAddress"
})
public class PersonType {@XmlElement(name = "MailingAddress", required = true)protected AddressType mailingAddress;@XmlElement(name = "ResidentialAddress")protected AddressType residentialAddress;@XmlAttribute(name = "firstName")protected String firstName;@XmlAttribute(name = "lastName")protected String lastName;/*** Gets the value of the mailingAddress property.* * @return*     possible object is*     {@link AddressType }*     */public AddressType getMailingAddress() {return mailingAddress;}/*** Sets the value of the mailingAddress property.* * @param value*     allowed object is*     {@link AddressType }*     */public void setMailingAddress(AddressType value) {this.mailingAddress = value;}/*** Gets the value of the residentialAddress property.* * @return*     possible object is*     {@link AddressType }*     */public AddressType getResidentialAddress() {return residentialAddress;}/*** Sets the value of the residentialAddress property.* * @param value*     allowed object is*     {@link AddressType }*     */public void setResidentialAddress(AddressType value) {this.residentialAddress = value;}/*** Gets the value of the firstName property.* * @return*     possible object is*     {@link String }*     */public String getFirstName() {return firstName;}/*** Sets the value of the firstName property.* * @param value*     allowed object is*     {@link String }*     */public void setFirstName(String value) {this.firstName = value;}/*** Gets the value of the lastName property.* * @return*     possible object is*     {@link String }*     */public String getLastName() {return lastName;}/*** Sets the value of the lastName property.* * @param value*     allowed object is*     {@link String }*     */public void setLastName(String value) {this.lastName = value;}}

JAXB生成的AddressType.java

//
// This file was generated by the JavaTM Architecture for XML Binding(JAXB) Reference Implementation, v2.2.4-2
// See http://java.sun.com/xml/jaxb
// Any modifications to this file will be lost upon recompilation of the source schema.
// Generated on: 2013.12.03 at 11:44:32 PM MST
//package com.blogspot.marxsoftware;import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlType;/*** <p>Java class for AddressType complex type.* * <p>The following schema fragment specifies the expected content contained within this class.* * <pre>* <complexType name="AddressType">*   <complexContent>*     <restriction base="{http://www.w3.org/2001/XMLSchema}anyType">*       <attribute name="streetAddress1" use="required" type="{http://www.w3.org/2001/XMLSchema}string" />*       <attribute name="streetAddress2" type="{http://www.w3.org/2001/XMLSchema}string" />*       <attribute name="city" use="required" type="{http://www.w3.org/2001/XMLSchema}string" />*       <attribute name="state" use="required" type="{http://www.w3.org/2001/XMLSchema}string" />*       <attribute name="zipcode" use="required" type="{http://www.w3.org/2001/XMLSchema}string" />*     </restriction>*   </complexContent>* </complexType>* </pre>* * */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "AddressType")
public class AddressType {@XmlAttribute(name = "streetAddress1", required = true)protected String streetAddress1;@XmlAttribute(name = "streetAddress2")protected String streetAddress2;@XmlAttribute(name = "city", required = true)protected String city;@XmlAttribute(name = "state", required = true)protected String state;@XmlAttribute(name = "zipcode", required = true)protected String zipcode;/*** Gets the value of the streetAddress1 property.* * @return*     possible object is*     {@link String }*     */public String getStreetAddress1() {return streetAddress1;}/*** Sets the value of the streetAddress1 property.* * @param value*     allowed object is*     {@link String }*     */public void setStreetAddress1(String value) {this.streetAddress1 = value;}/*** Gets the value of the streetAddress2 property.* * @return*     possible object is*     {@link String }*     */public String getStreetAddress2() {return streetAddress2;}/*** Sets the value of the streetAddress2 property.* * @param value*     allowed object is*     {@link String }*     */public void setStreetAddress2(String value) {this.streetAddress2 = value;}/*** Gets the value of the city property.* * @return*     possible object is*     {@link String }*     */public String getCity() {return city;}/*** Sets the value of the city property.* * @param value*     allowed object is*     {@link String }*     */public void setCity(String value) {this.city = value;}/*** Gets the value of the state property.* * @return*     possible object is*     {@link String }*     */public String getState() {return state;}/*** Sets the value of the state property.* * @param value*     allowed object is*     {@link String }*     */public void setState(String value) {this.state = value;}/*** Gets the value of the zipcode property.* * @return*     possible object is*     {@link String }*     */public String getZipcode() {return zipcode;}/*** Sets the value of the zipcode property.* * @param value*     allowed object is*     {@link String }*     */public void setZipcode(String value) {this.zipcode = value;}}

在JAXB生成的对象和自定义编写的业务/域对象之间复制数据的一种常见而直接的策略是使用一个对象的“ get”方法，并将其返回值传递给另一个对象的“ set”方法。 例如，在将XML解组/读取到应用程序的过程中，可以将JAXB生成的对象上调用的“ get”方法的结果传递给业务/域对象的“ set”方法。 相反，通过将域/业务对象上的“ get”方法的结果传递给JAXB生成的对象的相应“ set”方法，可以轻松完成编组/编写XML。 下一个代码清单用于PersonCoverter.java并说明了此方法的一种实现。

PersonConverter.java

package dustin.examples.dozerdemo;import com.blogspot.marxsoftware.AddressType;
import com.blogspot.marxsoftware.ObjectFactory;
import com.blogspot.marxsoftware.PersonType;
import dustin.examples.Address;
import dustin.examples.Person;/*** Static functions for converting between JAXB-generated objects and domain* objects.* * @author Dustin*/
public class PersonConverter
{/*** Extract business object {@link dustin.examples.Person} from the JAXB* generated object {@link com.blogspot.marxsoftware.PersonType}.* * @param personType JAXB-generated {@link com.blogspot.marxsoftware.PersonType}*    from which to extract {@link dustin.examples.Person} object.* @return Instance of {@link dustin.examples.Person} based on the provided*    {@link com.blogspot.marxsoftware.PersonType}.*/public static Person extractPersonFromPersonType(final PersonType personType){final String lastName = personType.getLastName();final String firstName = personType.getFirstName();final Address residentialAddress =extractAddressFromAddressType(personType.getResidentialAddress());final Address mailingAddress =extractAddressFromAddressType(personType.getMailingAddress());return new Person(lastName, firstName, residentialAddress, mailingAddress);}/*** Extract business object {@link dustin.examples.Address} from the JAXB* generated object {@link com.blogspot.marxsoftware.AddressType}.* * @param addressType JAXB-generated {@link com.blogspot.marxsoftware.AddressType}*    from which to extract {@link dustin.examples.Address} object.* @return Instance of {@link dustin.examples.Address} based on the provided*    {@link com.blogspot.marxsoftware.AddressType}.*/public static Address extractAddressFromAddressType(final AddressType addressType){return new Address(addressType.getStreetAddress1(), addressType.getStreetAddress2(),addressType.getCity(), addressType.getState(), addressType.getZipcode());}/*** Extract an instance of {@link com.blogspot.marxsoftware.PersonType} from* an instance of {@link dustin.examples.Person}.* * @param person Instance of {@link dustin.examples.Person} from which*    instance of JAXB-generated {@link com.blogspot.marxsoftware.PersonType}*    is desired.* @return Instance of {@link com.blogspot.marxsoftware.PersonType} based on*    provided instance of {@link dustin.examples.Person}.*/public static PersonType extractPersonTypeFromPerson(final Person person){final ObjectFactory objectFactory = new ObjectFactory();final AddressType residentialAddressType =extractAddressTypeFromAddress(person.getResidentialAddress());final AddressType mailingAddressType =extractAddressTypeFromAddress(person.getMailingAddress());final PersonType personType = objectFactory.createPersonType();personType.setLastName(person.getLastName());personType.setFirstName(person.getFirstName());personType.setResidentialAddress(residentialAddressType);personType.setMailingAddress(mailingAddressType);return personType;}/*** Extract an instance of {@link com.blogspot.marxsoftware.AddressType} from* an instance of {@link dustin.examples.Address}.* * @param address Instance of {@link dustin.examples.Address} from which*    instance of JAXB-generated {@link com.blogspot.marxsoftware.AddressType}*    is desired.* @return Instance of {@link com.blogspot.marxsoftware.AddressType} based on*    provided instance of {@link dustin.examples.Address}.*/public static AddressType extractAddressTypeFromAddress(final Address address){final ObjectFactory objectFactory = new ObjectFactory();final AddressType addressType = objectFactory.createAddressType();addressType.setStreetAddress1(address.getStreetAddress1());addressType.setStreetAddress2(address.getStreetAddress2());addressType.setCity(address.getMunicipality());addressType.setState(address.getState());addressType.setZipcode(address.getZipCode());return addressType;}
}

最后的代码清单演示了一种通用的第三方类方法，用于在JAXB生成的对象和域/业务对象之间双向复制数据。 另一种方法是将这种复制功能构建到域/业务对象本身中。 这在PersonPlus.java和AddressPlus.java两个代码清单中PersonPlus.java ，它们是先前介绍的Person.java和Address.java版本，并添加了对从JAXB生成的对象复制数据的支持。 为了方便起见，我在toString实现之后将新方法添加到类的底部。

PersonPlus.java

package dustin.examples;import com.blogspot.marxsoftware.ObjectFactory;
import com.blogspot.marxsoftware.PersonType;
import java.util.Objects;/*** Person class enhanced to support copying to/from JAXB-generated PersonType.* * @author Dustin*/
public class PersonPlus
{private String lastName;private String firstName;private AddressPlus mailingAddress;private AddressPlus residentialAddress;public PersonPlus(final String newLastName,final String newFirstName,final AddressPlus newResidentialAddress,final AddressPlus newMailingAddress){this.lastName = newLastName;this.firstName = newFirstName;this.residentialAddress = newResidentialAddress;this.mailingAddress = newMailingAddress;}public String getLastName(){return this.lastName;}public void setLastName(String lastName) {this.lastName = lastName;}public String getFirstName(){return this.firstName;}public void setFirstName(String firstName){this.firstName = firstName;}public AddressPlus getMailingAddress(){return this.mailingAddress;}public void setMailingAddress(AddressPlus mailingAddress){this.mailingAddress = mailingAddress;}public AddressPlus getResidentialAddress(){return this.residentialAddress;}public void setResidentialAddress(AddressPlus residentialAddress){this.residentialAddress = residentialAddress;}@Overridepublic int hashCode(){int hash = 3;hash = 19 * hash + Objects.hashCode(this.lastName);hash = 19 * hash + Objects.hashCode(this.firstName);hash = 19 * hash + Objects.hashCode(this.mailingAddress);hash = 19 * hash + Objects.hashCode(this.residentialAddress);return hash;}@Overridepublic boolean equals(Object obj){if (obj == null){return false;}if (getClass() != obj.getClass()){return false;}final PersonPlus other = (PersonPlus) obj;if (!Objects.equals(this.lastName, other.lastName)){return false;}if (!Objects.equals(this.firstName, other.firstName)){return false;}if (!Objects.equals(this.mailingAddress, other.mailingAddress)){return false;}if (!Objects.equals(this.residentialAddress, other.residentialAddress)){return false;}return true;}@Overridepublic String toString() {return  "PersonPlus{" + "lastName=" + lastName + ", firstName=" + firstName+ ", mailingAddress=" + mailingAddress + ", residentialAddress="+ residentialAddress + '}';}/*** Provide a JAXB-generated instance of {@link com.blogspot.marxsoftware.PersonType}* that corresponds to me.* * @return Instance of {@link com.blogspot.marxsoftware.PersonType} that*    corresponds to me.*/public PersonType toPersonType(){final ObjectFactory objectFactory = new ObjectFactory();final PersonType personType = objectFactory.createPersonType();personType.setFirstName(this.firstName);personType.setLastName(this.lastName);personType.setResidentialAddress(this.residentialAddress.toAddressType());personType.setMailingAddress(this.mailingAddress.toAddressType());return personType;}/*** Provide instance of {@link dustin.examples.PersonPlus} corresponding* to the provided instance of JAXB-generated object* {@link com.blogspot.marxsoftware.PersonType}.* * @param personType Instance of JAXB-generated object*    {@link com.blogspot.marxsoftware.PersonType}.* @return Instance of me corresponding to provided JAXB-generated object*    {@link com.blogspot.marxsoftware.PersonType}.*/public static PersonPlus fromPersonType(final PersonType personType){final AddressPlus residentialAddress =AddressPlus.fromAddressType(personType.getResidentialAddress());final AddressPlus mailingAddress =AddressPlus.fromAddressType(personType.getMailingAddress());return new PersonPlus(personType.getLastName(), personType.getFirstName(),residentialAddress, mailingAddress);}
}

AddressPlus.java

package dustin.examples;import com.blogspot.marxsoftware.AddressType;
import com.blogspot.marxsoftware.ObjectFactory;
import java.util.Objects;/*** Address class with support for copying to/from JAXB-generated class* {@link com.blogspot.marxsoftware.AddressType}.* * @author Dustin*/
public class AddressPlus
{private String streetAddress1;private String streetAddress2;private String municipality;private String state;private String zipCode;public AddressPlus(final String newStreetAddress1,final String newStreetAddress2,final String newMunicipality,final String newState,final String newZipCode){this.streetAddress1 = newStreetAddress1;this.streetAddress2 = newStreetAddress2;this.municipality = newMunicipality;this.state = newState;this.zipCode = newZipCode;}public String getStreetAddress1(){return this.streetAddress1;}public void setStreetAddress1(String streetAddress1){this.streetAddress1 = streetAddress1;}public String getStreetAddress2(){return this.streetAddress2;}public void setStreetAddress2(String streetAddress2){this.streetAddress2 = streetAddress2;}public String getMunicipality(){return this.municipality;}public void setMunicipality(String municipality){this.municipality = municipality;}public String getState() {return this.state;}public void setState(String state){this.state = state;}public String getZipCode() {return this.zipCode;}public void setZipCode(String zipCode){this.zipCode = zipCode;}@Overridepublic int hashCode(){return Objects.hash(this.streetAddress1, this.streetAddress2, this.municipality,this.state, this.zipCode);}@Overridepublic boolean equals(Object obj){if (obj == null) {return false;}if (getClass() != obj.getClass()) {return false;}final AddressPlus other = (AddressPlus) obj;if (!Objects.equals(this.streetAddress1, other.streetAddress1)){return false;}if (!Objects.equals(this.streetAddress2, other.streetAddress2)){return false;}if (!Objects.equals(this.municipality, other.municipality)){return false;}if (!Objects.equals(this.state, other.state)){return false;}if (!Objects.equals(this.zipCode, other.zipCode)){return false;}return true;}@Overridepublic String toString(){return "Address{" + "streetAddress1=" + streetAddress1 + ", streetAddress2="+ streetAddress2 + ", municipality=" + municipality + ", state=" + state+ ", zipCode=" + zipCode + '}';}/*** Provide a JAXB-generated instance of {@link com.blogspot.marxsoftware.AddressType}* that corresponds to an instance of me.** @return Instance of JAXB-generated {@link com.blogspot.marxsoftware.AddressType}*    that corresponds to me.*/public AddressType toAddressType(){final ObjectFactory objectFactory = new ObjectFactory();final AddressType addressType = objectFactory.createAddressType();addressType.setStreetAddress1(this.streetAddress1);addressType.setStreetAddress2(this.streetAddress2);addressType.setCity(this.municipality);addressType.setState(this.state);addressType.setZipcode(this.zipCode);return addressType;}/*** Provide instance of {@link dustin.examples.AddressPlus} corresponding* to the provided instance of JAXB-generated object* {@link com.blogspot.marxsoftware.AddressType}.* * @param addressType Instance of JAXB-generated object*    {@link com.blogspot.marxsoftware.AddressType}.* @return Instance of me corresponding to provided JAXB-generated object*    {@link com.blogspot.marxsoftware.AddressType}.*/public static AddressPlus fromAddressType(final AddressType addressType){return new AddressPlus(addressType.getStreetAddress1(),addressType.getStreetAddress2(),addressType.getCity(),addressType.getState(),addressType.getZipcode());}
}

上面演示的将JAXB生成的对象映射到业务/域对象的两种方法肯定会起作用，对于我的简单示例，可以将其视为最佳的使用方法（尤其是考虑到NetBeans使业务/域对象的生成几乎变得微不足道）。 但是，对于需要映射的更重要的对象层次结构，可以认为基于Dozer配置的映射是更可取的。

从下载页面 （在此情况下为dozer-5.3.2.jar ）下载了Dozer。 “ 入门”页面显示，当要映射的类的属性具有相同的名称时，映射确实非常容易（最小配置）。 在我的示例中，情况并非如此，我故意将一个属性设为“城市”，将另一个属性设为“市政性”，以使映射更加有趣。 由于这些名称不同，因此我需要自定义Dozer映射 ，这是通过XML映射配置完成的。 必要的映​​射文件以dozerBeanMapping.xml的“默认映射名称”命名，并在下面显示。 我只需要映射两个具有不同名称的字段（ city和municipality ），因为被映射的两个类的所有其他字段都具有相同的名称，并且无需显式配置即可自动映射在一起。

dozerBeanMapping.xml

<?xml version="1.0" encoding="UTF-8"?>
<mappings xmlns="http://dozer.sourceforge.net"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://dozer.sourceforge.nethttp://dozer.sourceforge.net/schema/beanmapping.xsd"><configuration><stop-on-errors>true</stop-on-errors><date-format>MM/dd/yyyy HH:mm:ss</date-format><wildcard>true</wildcard></configuration><mapping><class-a>dustin.examples.Address</class-a><class-b>com.blogspot.marxsoftware.AddressType</class-b><field><a>municipality</a><b>city</b></field></mapping>  </mappings>

请注意， XML并非可用于自定义Dozer映射的唯一方法 。 还支持注释和程序化API 。

“ Dozer 第三方对象工厂”页面简要介绍了如何将Dozer与JAXB以及JAXBBeanFactory一起使用。 还建议将推土器与Dozer一起使用，并提供Spring集成示例。 对于应用Dozer的简单示例，我没有使用这些方法，而是使用了非常简单的实例化方法。 这显示在下一个代码清单中。

DozerPersonConverter.java

package dustin.examples.dozerdemo;import com.blogspot.marxsoftware.PersonType;
import dustin.examples.Person;
import java.util.ArrayList;
import java.util.List;
import org.dozer.DozerBeanMapper;/*** Dozer-based converter.* * @author Dustin*/
public class DozerPersonConverter
{static final DozerBeanMapper mapper = new DozerBeanMapper();static{final List<String> mappingFilesNames = new ArrayList<>();mappingFilesNames.add("dozerBeanMapping.xml");mapper.setMappingFiles(mappingFilesNames);}/*** Provide an instance of {@link com.blogspot.marxsoftware.PersonType}* that corresponds with provided {@link dustin.examples.Person} as* mapped by Dozer Mapper.* * @param person Instance of {@link dustin.examples.Person} from which*    {@link com.blogspot.marxsoftware.PersonType} will be extracted.* @return Instance of {@link com.blogspot.marxsoftware.PersonType} that*    is based on provided {@link dustin.examples.Person} instance.*/public PersonType copyPersonTypeFromPerson(final Person person){final PersonType personType = mapper.map(person, PersonType.class);return personType;}/*** Provide an instance of {@link dustin.examples.Person} that corresponds* with the provided {@link com.blogspot.marxsoftware.PersonType} as * mapped by Dozer Mapper.* * @param personType Instance of {@link com.blogspot.marxsoftware.PersonType}*    from which {@link dustin.examples.Person} will be extracted.* @return Instance of {@link dustin.examples.Person} that is based on the*    provided {@link com.blogspot.marxsoftware.PersonType}.*/public Person copyPersonFromPersonType(final PersonType personType){final Person person = mapper.map(personType, Person.class);return person;}
}

前面的示例显示了将JAXB生成的对象映射到业务/域对象所需的代码量。 当然，需要一些XML，但仅适用于名称不同的字段。 这意味着字段名称之间的差异越大，就需要进行更多的配置。 但是，只要大多数字段是一对一映射的，并且它们之间没有任何特殊的“转换”逻辑，Dozer就会用配置映射替换许多繁琐的代码。

如果需要转换字段（例如将一个对象中的米转换为另一对象中的公里），则当必须编写自定义转换器时，此映射支持可能会不太吸引人。 推土机映射也很难更正确地应用于深层嵌套的对象，但是我的示例在Person嵌套了Address作为一个简单示例。 尽管复杂的映射在Dozer中可能不再那么吸引人，但是JAXB生成的对象到业务/域对象的许多映射都足够简单，足以被Dozer服务。

我想在这篇文章中指出的最后一件事是，Dozer对某些第三方库具有运行时依赖性。 幸运的是，这些库无论如何都经常在Java项目中使用，并且随时可用。 如下面的两个图像所示，所需的运行时依赖项是SLF4J，Apache Commons Lang，Apache Commons Logging和Apache BeanUtils。

推土机运行时相关性页面

本文的示例的NetBeans 7.4项目库 设置Dozer及其依赖项并配置映射需要花费很少的精力，但是在许多常见的JAXB到企业对象数据复制应用程序中，可以通过大大减少映射代码来很好地回报这种努力。

翻译自: https://www.javacodegeeks.com/2013/12/dozer-mapping-jaxb-objects-to-businessdomain-objects.html

jaxb 映射 空字段