以有效的方式将 XML 解析为 JAVA POJO

Posted 2023-02-26

【中文标题】以有效的方式将 XML 解析为 JAVA POJO

【英文标题】：Parse XML TO JAVA POJO in efficient way

【发布时间】：2013-01-25 04:57:28

【问题描述】：

如何有效地为下面的xml解析和创建java pojo？请推荐任何有效的解析器。

XML格式是

<?xml version="1.0" encoding="utf-8"?>
<CCMainRootTag ID="12">
  <Header TableName="TableName"    TableVersion="12" TableID="12" CreatedDate="2013-02-09T15:35:33" CreatedByUserName="ABC" CreatedBySystem="ABC" />
  <ClassPrimary ID="12" Code="Y" DescriptionDK="DK language " DescriptionUK="" DefDK="" DefUK="" IFDGUID="">
    <ObjectClass ID="12" Code="YA" DescriptionDK="DK Language" DescriptionUK="" DefDK=""     DefUK="" IFDGUID="">
      <Synonym>
        <Concept Description="Description" Language="DK" />
        <Concept Description="" Language="UK" />
        <Concept Description="Description" Language="DK" />
        <Concept Description="" Language="UK" />
        <Concept Description="Description" Language="DK" />
        <Concept Description="" Language="UK" />
        <Concept Description="Description" Language="DK" />
        <Concept Description="" Language="UK" />
      </Synonym>
    </ObjectClass>
    <ObjectClass ID="12" Code="YB" DescriptionDK="DK Language" DescriptionUK="" DefDK="" DefUK="" IFDGUID=""> </ObjectClass>
    <ObjectClass ID="12" Code="YC" DescriptionDK="DK Language" DescriptionUK="" DefDK="" DefUK="" IFDGUID=""> </ObjectClass>
    <ObjectClass ID="12" Code="YD" DescriptionDK="DK language" DescriptionUK="" DefDK="" DefUK="" IFDGUID=""> </ObjectClass>
  </ClassPrimary>
</CCMainRootTag>

我已经在使用 thisLink，但是它的性能很慢，并且有问题并没有有效的 pojo。

我想以一种有效的方式为我提供直接 java pojo 的解析器。

【参考方案1】：

您可以使用JAXB 将 XML 转换为 Java POJO。但在您最终确定解决方案之前check this site 进行性能比较。

【讨论】：

您好 CuriousMind，但在我的情况下，xml 属性将是类变量。参见这个例子。 TableName="TableName" TableVersion="12" TableID="12" CreatedDate="2013-02-09T15:35:33" CreatedByUserName="ABC" CreatedBySystem="ABC" /> 如何为这种类型定义 xml pojo结构。？

JAXB 为您提供注释以将属性绑定到类变量。查看 JAXB 文档站点了解更多详细信息。

【参考方案2】：

对于那些正在寻找将 xml 转换为 java 对象的 JAXB 代码的人：

//Convert xml to String first
Element partyLoaderRequest; // your xml data
String xmlString = new XMLOutputter().outputString(partyLoaderRequest);   
InputStream is = new ByteArrayInputStream(xmlString.getBytes());
DocumentBuilder docBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document document = docBuilder.parse(is);
org.w3c.dom.Element varElement = document.getDocumentElement();
JAXBContext context = JAXBContext.newInstance(Person.class);
Unmarshaller unmarshaller = context.createUnmarshaller();
JAXBElement<Person> loader = unmarshaller.unmarshal(varElement, Person.class);
Person inputFromXml = loader.getValue();

而 Person 有适当的 XML 注释：

@XmlRootElement(name="Person")
public class CimbWlAdminUserAmendInput 
    @XmlElement(name="companyName",required=true,nillable=false) 
    private String companyName;
    ...
    //setters getters
    @XmlTransient
    public String getCompanyName() 
        return companyName;
    

    public void setCompanyName(String companyName) 
        this.companyName = companyName;
    

【参考方案3】：

序列化和反序列化可以由 JacksonXmlModule 处理。

// Item.class - use lombok or create g/setters
@JsonPropertyOrder("name", "description", "note")
public class Item  
   private String name;
   private String description;
   private String note;



// Test.class
package hello.service;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.dataformat.xml.JacksonXmlModule;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;

import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlRootElement;
import hello.entity.Item;
import org.junit.Before;

import org.junit.Test;

import java.util.ArrayList;
import java.util.List;

import static org.junit.Assert.*;

public class NameServiceImplTest 

    ObjectMapper objectMapper;

    @Before
    public void setup() 
        JacksonXmlModule xmlModule = new JacksonXmlModule();
        xmlModule.setDefaultUseWrapper(false);
        this.objectMapper = new XmlMapper(xmlModule);
        this.objectMapper.enable(SerializationFeature.INDENT_OUTPUT);
    

    @Test
    public void serializeTest() 

        // Wrapper
        @JacksonXmlRootElement(localName = "names")
        class Names 
            public List<Item> item = new ArrayList<>();
        

        Item item = new Item();
        item.setName("Vladimir");
        item.setDescription("Desc");
        item.setNote("Note");

        Item item2 = new Item();
        item2.setName("Iva");
        item2.setDescription("Desc2");
        item2.setNote("Note2");

        Names names = new Names();
        names.item.add(item);
        names.item.add(item2);

        try 
            String xml = objectMapper.writeValueAsString(names);
            assertNotNull(xml);
            System.out.println(xml);
         catch (Exception e)  // IOException
            System.out.println(e.getMessage());
            fail();
        
    

    @Test
    public void deserializeTest() 
        String xml = "<names>" +
                "<item><name>name</name><description>desc</description><note>note</note></item>" +
                "<item><name>name</name><description>desc</description><note>note</note></item>" +
                "</names>";

        try 
            List<Item> names = objectMapper.readValue(xml, new TypeReference<List<Item>>() );
            names.forEach(item -> 

                assertEquals("name", item.getName());
                assertEquals("desc", item.getDescription());
                assertEquals("note", item.getNote());

             );
         catch (Exception e)  // IOException

        


    

【参考方案4】：

public class XmlConvertUtil 

    public static void main(String[] args) 
        ResultDataSet resultDataSet = new ResultDataSet(new DtInformation("0", "Success"), new DtData("980000001"));
        //Method which uses JAXB to convert object to XML
        System.out.println(JaxbObjToXML(resultDataSet));
    

    public static Object JaxbXmlToObj(String xmlString, Object obj) 

        JAXBContext jaxbContext;
        try 
            jaxbContext = JAXBContext.newInstance(obj.getClass());

            Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();

            Object resultDataSet = (Object) jaxbUnmarshaller.unmarshal(new StringReader(xmlString));

            //System.out.println(resultDataSet);
        
        catch (JAXBException e) 
            e.printStackTrace();
        
        return obj;
    

    public static String JaxbObjToXML(Object object) 
        String xmlContent = null;
        try 
            //Create JAXB Context
            JAXBContext jaxbContext = JAXBContext.newInstance(object.getClass());

            //Create Marshaller
            Marshaller jaxbMarshaller = jaxbContext.createMarshaller();

            //Required formatting??
            jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
            jaxbMarshaller.setProperty(Marshaller.JAXB_FRAGMENT, Boolean.TRUE);

            //Print XML String to Console
            StringWriter sw = new StringWriter();

            //Write XML to StringWriter
            jaxbMarshaller.marshal(object, sw);

            //Verify XML Content
            xmlContent = sw.toString();
            //System.out.println(xmlContent);
        
        catch (JAXBException e) 
            e.printStackTrace();
        
        return xmlContent;
    

【讨论】：

嘿，谢谢你的回答。你也能解释一下吗？