JAXB 使用记录 bean转xml xml转bean 数组继承 CDATA（转义问题）

JAXB 使用记录

部分内容引自
https://blog.csdn.net/gengzhy/article/details/127564536

基础介绍

JAXBContext类：是应用的入口，用于管理XML/Java绑定信息
Marshaller接口：将Java对象序列化为XML数据
Unmarshaller接口：将XML数据反序列化为Java对象
@XmlRootElement：将Java类或枚举类型映射到XML元素，用在Java类上，用于标注该类是xml的一个根节点
@XmlElement：将Java类的一个属性映射到与属性同名的一个XML元素。通常与@XmlTransient搭配使用。
@XmlTransient：通常与 @XmlElement 须搭配使用的。@XmlElement用在属性上，用于指定生成xml的节点名，@XmlTransient用在对应的getter方法上，起到关联的作用
@XmlElementWrapper ：对于数组或集合（即包含多个元素的成员变量），生成一个包装该数组或集合的XML元素（称为包装器）。通常配合XmlElement一起使用，XmlElementWrapper指定数组名，XmlElement指定生成xml的节点名
@XmlElementRef：用在类属性的getter方法上（即该属性是一个JavaBean），并且该属性是某些子类的父类，起到引用的作用。同时标注得有@XmlElementRef的类属性，其子类上需要使用@XmlRootElement标注，否则转换异常，提示找不到具体的引用实现。另外，转换时，需要将其子类的class一起传递到JAXBContext上下文中，否则也无法转换
@XmlAccessorOrder：控制JAXB 绑定类中属性和字段的排序
@XmlType：将Java类或枚举类型映射到XML模式类型
@XmlAccessorType(XmlAccessType.FIELD) ：控制字段或属性的序列化。FIELD表示JAXB将自动绑定Java类中的每个非静态的（static）、非瞬态的（由@XmlTransient标注）字段到XML。还有XmlAccessType.PROPERTY和XmlAccessType.NONE
@XmlJavaTypeAdapter：使用定制的适配器（即扩展抽象类XmlAdapter并覆盖marshal()和unmarshal()方法），以序列化Java类为XML
@XmlAttribute：将Java类的一个属性映射到与属性同名的一个XML属性

工具类

package xmlAndBean;import lombok.extern.slf4j.Slf4j;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.Source;
import javax.xml.transform.sax.SAXSource;
import java.io.StringReader;
import java.io.StringWriter;/*** @version : 1.0* @Description : xml工具类* @Date: 2023/10/9 9:03**/public class XmlBeanUtils {/*** 构造方法私有**/private XmlBeanUtils() {}public static final String ENCODING_UTF = "UTF-8";public static final String ENCODING_GB = "GB18030";/*** @return java.lang.String* @Description : bean转xml不含报文头（GB18030编码格式）* @Param [obj]* @Param encoding 编码格式**/public static String beanToXml(Object obj,String encoding) {String result = null;try {JAXBContext context = JAXBContext.newInstance(obj.getClass());Marshaller marshaller = context.createMarshaller();// Marshaller.JAXB_FORMATTED_OUTPUT 决定是否在转换成xml时同时进行格式化（即按标签自动换行，否则即是一行的xml）marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);// Marshaller.JAXB_ encoding  xml的编码方式marshaller.setProperty(Marshaller.JAXB_ENCODING, encoding);// 去掉生成xml的默认报文头marshaller.setProperty(Marshaller.JAXB_FRAGMENT, Boolean.TRUE);StringWriter writer = new StringWriter();marshaller.marshal(obj, writer);result = writer.toString();} catch (Exception e) {
//            log.error("bean转xml报文失败", e);}return result;}/*** @return java.lang.String* 报文格式：* <?xml version="1.0" encoding="GB18030"?>* <ROOT>* <HEAD>* …* </HEAD>* <DATA>* <title1 >…</title1>* <title2 >…</title2>* …* </DATA>* </ROOT>* @Description : 组装报文* @Param [xmlHead, xmlData]**/public static String indentFormat(String xmlHead, String xmlData) {try {String xmlHeader = "<?xml version=\"1.0\" encoding=\"GB18030\"?>\n";StringBuilder xml = new StringBuilder();xml.append(xmlHeader).append("<ROOT>\n").append(xmlHead).append(xmlData).append("\n</ROOT>");return xml.toString();} catch (Exception e) {
//            log.error("组装xml报文失败", e);return null;}}/*** xml转对象** @param xml* @param msgVo* @param <T>* @return*/public static <T> T xmlToBean(String xml, Class<T> msgVo) {if (msgVo == null) {return null;}try {JAXBContext context = JAXBContext.newInstance(msgVo);Unmarshaller unmarshaller = context.createUnmarshaller();Source source = trunSource(xml);return (T) unmarshaller.unmarshal(source);} catch (Exception e) {
//            log.error("xml转对象异常:", e);}return null;}/*** 忽略xml命名空间** @param xmlStr* @return* @throws SAXException* @throws ParserConfigurationException*/private static Source trunSource(String xmlStr) throws SAXException, ParserConfigurationException {StringReader reader = new StringReader(xmlStr);SAXParserFactory sax = SAXParserFactory.newInstance();sax.setNamespaceAware(false);XMLReader xmlReader = sax.newSAXParser().getXMLReader();return new SAXSource(xmlReader, new InputSource(reader));}/*** Java Bean 转 Xml** @param bean         - Java Bean* @param inheritClazz - Java Bean中嵌套的类，且有继承关系的Java Class* @return - xml*/public static String beanToXml(Object bean, String encoding,Class<?>... inheritClazz) {try {JAXBContext context = initContext(bean.getClass(), inheritClazz);Marshaller marshaller = context.createMarshaller();// 格式化xmlmarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);// Marshaller.JAXB_ encoding  xml的编码方式marshaller.setProperty(Marshaller.JAXB_ENCODING, encoding);// 去掉生成xml的默认报文头marshaller.setProperty(Marshaller.JAXB_FRAGMENT, Boolean.TRUE);StringWriter writer = new StringWriter();marshaller.marshal(bean, writer);return writer.toString();} catch (JAXBException e) {e.printStackTrace();}return null;}/*** Xml 转 Java Bean** @param xml          - xml* @param beanClazz    - Java Bean Class* @param inheritClazz - Java Bean中嵌套的类，且有继承关系的Java Class* @return - bean*/public static Object xmlToBean(String xml, Class<?> beanClazz, Class<?>... inheritClazz) {try {JAXBContext context = initContext(beanClazz, inheritClazz);Unmarshaller um = context.createUnmarshaller();StringReader sr = new StringReader(xml);return um.unmarshal(sr);} catch (JAXBException e) {e.printStackTrace();}return null;}/*** 初始化JAXBContext** @param mainClazz    - 序列化或反序列化Class* @param inheritClazz - Java Bean中嵌套的类，且有继承关系的Java Class* @return - JAXBContext*/private static JAXBContext initContext(Class<?> mainClazz, Class<?>... inheritClazz) throws JAXBException {JAXBContext context;if (inheritClazz != null) {Class<?>[] clazzArr = new Class[inheritClazz.length + 1];clazzArr[0] = mainClazz;System.arraycopy(inheritClazz, 0, clazzArr, 1, clazzArr.length - 1);context = JAXBContext.newInstance(clazzArr);} else {context = JAXBContext.newInstance(mainClazz);}return context;}}

xml结构

结构如下：

<ROOT>
<HEAD>…
</HEAD>
<DATA><title1 >…</title1><title2 >…</title2>…<RECORD><LIST1 p_type="G"><title1 >…</title1></LIST1><LIST1 p_type="G"><title1 >…</title1></LIST1></RECORD>
</DATA>
</ROOT>

①存在继承关系的bean转xml

基类：用于统一，方便向下转型

/*** @version : 1.0* @Description : 基类* @Date: 2023/10/9 19:55**/
public class BaseDTO {
}

DATA标签实体类同时继承基类

import lombok.Getter;
import lombok.Setter;
import lombok.ToString;import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
import java.util.List;/*** @version : 1.0* @Description :* @Date: 2023/10/9 19:55**/
@Setter
@Getter
@ToString
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "DATA")
public class BookDTO extends BaseDTO{@XmlElement(name = "name")@XmlJavaTypeAdapter(CdataXmlAdapter.class)private String bookName;@XmlElement(name = "id")private String bookId;//@XmlElementWrapper(name = "RECORD")
//    @XmlElement(name = "LIST1")
//    private List<DescDTO> descDTOList;
}

HEAD标签实体类

import lombok.Getter;
import lombok.Setter;
import lombok.ToString;import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;/*** @version : 1.0* @Description :* @Date: 2023/10/9 19:58**/
@Getter
@Setter
@ToString
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "HEAD")
public class HeadDTO {@XmlElement(name = "SEND_NODE")private String send;@XmlElement(name = "RECV_NODE")private String receive;
}

根标签实体类
其中针对DATA标签，每个接口的DATA标签可能都不相同，这里使用了@XmlElementRef标签结合基类（BaseDTO ），在使用中将接口的实体类继承BaseDTO基类，并标注@XmlRootElement(name = “DATA”)，即可实现每个接口拥有独立的对象实现bean转xml

import lombok.*;import javax.xml.bind.annotation.*;/*** @version : 1.0* @Description :* @Date: 2023/10/9 19:55**/
@Setter
@Getter
@ToString
@NoArgsConstructor
@AllArgsConstructor
@XmlAccessorType(XmlAccessType.FIELD)
//@XmlType(propOrder = { "head", "data" }) 这句加不加无所谓
@XmlRootElement(name = "ROOT")
public class RootDTO {@XmlElement(name = "HEAD")private HeadDTO head;//@XmlElement(name = "DATA")//@XmlElementRef 注解要加载对象上不能加在get方法上，不然报错如下//com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException: 5 counts of IllegalAnnotationExceptions类的两个属性具有相同名称 "head"@XmlElementRef(name = "DATA")private BaseDTO data;}

测试类

public class XmlTest {public static void main(String[] args) {//继承基类BookDTO bookDTO = new BookDTO();bookDTO.setBookName("name");bookDTO.setBookId("id");//HEAD标签实体类，一般内容固定HeadDTO headDTO = new HeadDTO();headDTO.setSend("send");headDTO.setReceive("rece");RootDTO rootDTO = new RootDTO();rootDTO.setHead(headDTO);//因为BookDTO 继承基类所以此处能设置成功rootDTO.setData(bookDTO);//bean转xml，需要将BookDTO.class（子类）传入以告知System.out.println(XmlBeanUtils.beanToXml(rootDTO,XmlBeanUtils.ENCODING_GB,BookDTO.class));//xml转beanSystem.out.println(XmlBeanUtils.xmlToBean(xml,  RootDTO.class,BookDTO.class));}
}

运行结果：
在这里插入图片描述

②存在数组的bean转xml

DATA标签实体类同时继承基类

import lombok.Getter;
import lombok.Setter;
import lombok.ToString;import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
import java.util.List;/*** @version : 1.0* @Description :* @Date: 2023/10/9 19:55**/
@Setter
@Getter
@ToString
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "DATA")
public class BookDTO extends BaseDTO{@XmlElement(name = "name")@XmlJavaTypeAdapter(CdataXmlAdapter.class)private String bookName;@XmlElement(name = "id")private String bookId;//@XmlElementWrapper(name = "RECORD")@XmlElement(name = "LIST1")private List<DescDTO> descDTOList;
}

数组实体类对象

import lombok.Getter;
import lombok.Setter;
import lombok.ToString;import javax.xml.bind.annotation.*;/*** @version : 1.0* @Description :* @Date: 2023/10/10 10:25**/
@Getter
@Setter
@ToString
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "LIST1")
public class DescDTO{@XmlAttribute(name = "p_type")private String pType;@XmlElement(name = "description")private String description;
}

假设在DATA标签实体类中存在数组属性，则使用@XmlElement(name = “LIST1”)进行标注，即可实现每个数组对象转换成xml时都被<LIST1> </LIST1>包裹
测试类

public class XmlTest {public static void main(String[] args) {BookDTO bookDTO = new BookDTO();bookDTO.setBookName("name");bookDTO.setBookId("id");HeadDTO headDTO = new HeadDTO();headDTO.setSend("send");headDTO.setReceive("rece");RootDTO rootDTO = new RootDTO();rootDTO.setHead(headDTO);rootDTO.setData(bookDTO);DescDTO descDTO = new DescDTO();//descDTO.setPType("G");descDTO.setDescription("desc11111");DescDTO descDTO1 = new DescDTO();//descDTO1.setPType("G");descDTO1.setDescription("desc22222");ArrayList<DescDTO> descDTOS = new ArrayList<>();descDTOS.add(descDTO);descDTOS.add(descDTO1);bookDTO.setDescDTOList(descDTOS);String xml = XmlBeanUtils.beanToXml(rootDTO, XmlBeanUtils.ENCODING_GB, BookDTO.class);//bean转xmlSystem.out.println(XmlBeanUtils.beanToXml(rootDTO,XmlBeanUtils.ENCODING_GB,BookDTO.class));//xml转beanSystem.out.println(XmlBeanUtils.xmlToBean(xml,  RootDTO.class,BookDTO.class));}
}

运行结果
在这里插入图片描述
如果需要再在数组外面套一层标签则：

    @XmlElementWrapper(name = "RECORD")@XmlElement(name = "LIST1")private List<DescDTO> descDTOList;

运行结果：
在这里插入图片描述

③存在数组且数组前后标签要求不一致的bean转xml

以<LIST1 p_type="G">标签开始，以</LIST1>标签结束
在数组对象中引入@XmlAttribute

    @XmlAttribute(name = "p_type")private String pType;

测试类：

//设置属性
descDTO.setPType("G");

public class XmlTest {public static void main(String[] args) {BookDTO bookDTO = new BookDTO();bookDTO.setBookName("name");bookDTO.setBookId("id");HeadDTO headDTO = new HeadDTO();headDTO.setSend("send");headDTO.setReceive("rece");RootDTO rootDTO = new RootDTO();rootDTO.setHead(headDTO);rootDTO.setData(bookDTO);DescDTO descDTO = new DescDTO();descDTO.setPType("G");descDTO.setDescription("desc11111");DescDTO descDTO1 = new DescDTO();descDTO1.setPType("G");descDTO1.setDescription("desc22222");ArrayList<DescDTO> descDTOS = new ArrayList<>();descDTOS.add(descDTO);descDTOS.add(descDTO1);bookDTO.setDescDTOList(descDTOS);String xml = XmlBeanUtils.beanToXml(rootDTO, XmlBeanUtils.ENCODING_GB, BookDTO.class);//bean转xmlSystem.out.println(XmlBeanUtils.beanToXml(rootDTO,XmlBeanUtils.ENCODING_GB,BookDTO.class));//xml转beanSystem.out.println(XmlBeanUtils.xmlToBean(xml,  RootDTO.class,BookDTO.class));}
}

运行结果：
在这里插入图片描述

④针对<![CDATA[文本内容]]>标签

import javax.xml.bind.annotation.adapters.XmlAdapter;/*** @version : 1.0* @Description : <![CDATA]>* @Date: 2023/10/8 19:03**/
public class CdataXmlAdapter extends XmlAdapter<String, String> {public CdataXmlAdapter() {}public String marshal(String arg0) throws Exception {return "<![CDATA[" + arg0 + "]]>";}public String unmarshal(String arg0) throws Exception {return arg0;}
}

使用@XmlJavaTypeAdapter注解，在需要的字段上

	@XmlElement(name = "name")@XmlJavaTypeAdapter(CdataXmlAdapter.class)private String bookName;

运行结果：
在这里插入图片描述

解决转义问题：
思路：
在将对象转换成xml时，会用到Marshaller对象，调用该对象的setProperty方法，注入第三步中实现的类，控制转换时不进行转义，实现自定义的CharacterEscapeHandler类，拦截JAXB的转义动作

在工具类原有的基础上引入下面的语句：
jar包
import com.sun.xml.internal.bind.marshaller.CharacterEscapeHandler;

			//CData处理marshaller.setProperty(CharacterEscapeHandler.class.getName(), new CharacterEscapeHandler() {public void escape(char[] ch, int start,int length, boolean isAttVal, Writer writer) throws IOException {writer.write(ch, start, length);}});

完整方法：

/*** Java Bean 转 Xml** @param bean         - Java Bean* @param inheritClazz - Java Bean中嵌套的类，且有继承关系的Java Class* @return - xml*/public static String beanToXml(Object bean, String encoding,Class<?>... inheritClazz) {try {JAXBContext context = initContext(bean.getClass(), inheritClazz);Marshaller marshaller = context.createMarshaller();// 格式化xmlmarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);// Marshaller.JAXB_ encoding  xml的编码方式marshaller.setProperty(Marshaller.JAXB_ENCODING, encoding);// 去掉生成xml的默认报文头marshaller.setProperty(Marshaller.JAXB_FRAGMENT, Boolean.TRUE);//CData处理marshaller.setProperty(CharacterEscapeHandler.class.getName(), new CharacterEscapeHandler() {public void escape(char[] ch, int start,int length, boolean isAttVal, Writer writer) throws IOException {writer.write(ch, start, length);}});StringWriter writer = new StringWriter();marshaller.marshal(bean, writer);return writer.toString();} catch (JAXBException e) {e.printStackTrace();}return null;}