xml与java对象转换

jackson-dataformat-xml工具包xml与java对象转换说明

1、引入依赖包

<dependency><groupId>com.fasterxml.jackson.dataformat</groupId><artifactId>jackson-dataformat-xml</artifactId><version>2.10.2</version></dependency>

2、测试使用的对象

importcom.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper;importcom.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty;importjava.util.List;/**
 * 测试对象School，包含普通属性name:名称  列表属性grades:多个Grade对象集合
 */publicclassSchool{@JacksonXmlProperty(localName ="NAME")privateString name;@JacksonXmlElementWrapper(localName ="Grades")@JacksonXmlProperty(localName ="Grade")privateList<Grade> grades;publicStringgetName(){return name;}publicvoidsetName(String name){this.name = name;}publicList<Grade>getGrades(){return grades;}publicvoidsetGrades(List<Grade> grades){this.grades = grades;}}

importcom.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper;importcom.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty;importjava.util.List;/**
 * 测试对象Grade，包含普通属性name:名称  列表属性Classes:多个Classes对象集合
 */publicclassGrade{@JacksonXmlProperty(localName ="NAME")privateString name;@JacksonXmlElementWrapper(localName ="ClassList")@JacksonXmlProperty(localName ="Class")privateList<Classes> classes;publicStringgetName(){return name;}publicvoidsetName(String name){this.name = name;}publicList<Classes>getClasses(){return classes;}publicvoidsetClasses(List<Classes> classes){this.classes = classes;}}

/**
 * 测试对象Classes，包含普通属性name:名称  属性studentCount:数量
 */publicclassClasses{privateString name;privateInteger studentCount;publicStringgetName(){return name;}publicvoidsetName(String name){this.name = name;}publicIntegergetStudentCount(){return studentCount;}publicvoidsetStudentCount(Integer studentCount){this.studentCount = studentCount;}}

3、单元测试和效果

importcom.fasterxml.jackson.dataformat.xml.XmlMapper;importorg.dom4j.Document;importorg.dom4j.io.OutputFormat;importorg.dom4j.io.SAXReader;importorg.dom4j.io.XMLWriter;importorg.junit.Test;importjava.io.IOException;importjava.io.StringReader;importjava.io.StringWriter;importjava.util.ArrayList;importjava.util.List;publicclassObjectToXml{//创建XmlMapper对象，用于实体与json和xml之间的相互转换privatestaticfinalXmlMapper xmlMapper =newXmlMapper();@Testpublicvoidt1()throwsException{School school =newSchool();
        school.setName("学校名称");Grade grade1 =newGrade();
        grade1.setName("年级1");Grade grade2 =newGrade();
        grade2.setName("年级2");Grade grade3 =newGrade();
        grade3.setName("年级3");Grade grade4 =newGrade();
        grade4.setName("年级4");Classes classes1 =newClasses();
        classes1.setName("年级1-班级1");
        classes1.setStudentCount(60);Classes classes2 =newClasses();
        classes2.setName("年级1-班级2");
        classes2.setStudentCount(50);Classes classes3 =newClasses();
        classes3.setName("年级1-班级3");
        classes3.setStudentCount(52);List<Classes> classesList1 =newArrayList<>();
        classesList1.add(classes1);
        classesList1.add(classes2);
        classesList1.add(classes3);
        grade1.setClasses(classesList1);Classes classes4 =newClasses();
        classes4.setName("年级2-班级1");
        classes4.setStudentCount(45);Classes classes5 =newClasses();
        classes5.setName("年级2-班级2");
        classes5.setStudentCount(46);Classes classes6 =newClasses();
        classes6.setName("年级2-班级3");
        classes6.setStudentCount(42);List<Classes> classesList2 =newArrayList<>();
        classesList2.add(classes4);
        classesList2.add(classes5);
        classesList2.add(classes6);
        grade2.setClasses(classesList2);List<Grade> grades =newArrayList<>();
        grades.add(grade1);
        grades.add(grade2);
        grades.add(grade3);
        grades.add(grade4);
        school.setGrades(grades);String xmlStr = xmlMapper.writeValueAsString(school);
        xmlStr =formatXML(xmlStr);System.out.println(xmlStr);}/**
     * 格式化xml
     * @param inputXML
     * @return
     * @throws Exception
     */publicStringformatXML(String inputXML)throwsException{SAXReader reader =newSAXReader();Document document = reader.read(newStringReader(inputXML));String requestXML =null;XMLWriter writer =null;if(document !=null){try{StringWriter stringWriter =newStringWriter();OutputFormat format =newOutputFormat(" ",true);
                format.setTrimText(true);
                format.setExpandEmptyElements(true);
                writer =newXMLWriter(stringWriter, format);
                writer.write(document);
                writer.flush();
                requestXML = stringWriter.getBuffer().toString();}finally{if(writer !=null){try{
                        writer.close();}catch(IOException e){}}}}return requestXML;}}

输出效果：

<?xml version="1.0" encoding="UTF-8"?><School><NAME>学校名称</NAME><Grades><Grade><NAME>年级1</NAME><ClassList><Class><name>年级1-班级1</name><studentCount>60</studentCount></Class><Class><name>年级1-班级2</name><studentCount>50</studentCount></Class><Class><name>年级1-班级3</name><studentCount>52</studentCount></Class></ClassList></Grade><Grade><NAME>年级2</NAME><ClassList><Class><name>年级2-班级1</name><studentCount>45</studentCount></Class><Class><name>年级2-班级2</name><studentCount>46</studentCount></Class><Class><name>年级2-班级3</name><studentCount>42</studentCount></Class></ClassList></Grade><Grade><NAME>年级3</NAME></Grade><Grade><NAME>年级4</NAME></Grade></Grades></School>

4、注解说明

1、@JacksonXmlProperty

​ 注解是用于对象属性，源代码如下，

@Target({ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
public @interface JacksonXmlProperty {
   boolean isAttribute() default false;

   String namespace() default "";

   String localName() default "";
}

​ 包含三个可设置属性，

localName：表明在当前转换的xml串中，次属性的标签名称，如上面转换出来的 学校名称标签，

namespace：设置命名空间，假设给school对象的name属性设置命名空间：@JacksonXmlProperty(localName = “NAME”,namespace = “xxx”)

输出效果如下：

<wstxns1:NAME xmlns:wstxns1=“xxx”>学校名称</wstxns1:NAME>

isAttribute：设置该属性是否为标签内属性，默认为false

设置示例：把School对象的那么设置为标签内属性：

@JacksonXmlProperty(localName = “NAME”,isAttribute = true)

效果：NAME属性不在独立成为标签，而是成为School标签的内属性

2、@JacksonXmlElementWrapper

​ 作用于对象的集合属性上，@JacksonXmlElementWrapper(localName = “ClassList”)，能够让集合属性决定是否使用包装元素，并且也可以控制包装元素的本地名称和命名空间。

<ClassList><Class><name>年级2-班级1</name><studentCount>45</studentCount></Class><Class><name>年级2-班级2</name><studentCount>46</studentCount></Class><Class><name>年级2-班级3</name><studentCount>42</studentCount></Class></ClassList>

对象转xml字符串以上注解基本可以实现所需功能，其中转换出来的字符串是连接的，需要格式化一下方便查看结构

5、xml串转换对象

@Testpublicvoidt2()throwsJsonProcessingException{String xmlStr ="<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"+"\n"+"<School>\n"+" <NAME>学校名称</NAME>\n"+" <Grades>\n"+"  <Grade>\n"+"   <NAME>年级1</NAME>\n"+"   <ClassList>\n"+"    <Class>\n"+"     <name>年级1-班级1</name>\n"+"     <studentCount>60</studentCount>\n"+"    </Class>\n"+"    <Class>\n"+"     <name>年级1-班级2</name>\n"+"     <studentCount>50</studentCount>\n"+"    </Class>\n"+"    <Class>\n"+"     <name>年级1-班级3</name>\n"+"     <studentCount>52</studentCount>\n"+"    </Class>\n"+"   </ClassList>\n"+"  </Grade>\n"+"  <Grade>\n"+"   <NAME>年级2</NAME>\n"+"   <ClassList>\n"+"    <Class>\n"+"     <name>年级2-班级1</name>\n"+"     <studentCount>45</studentCount>\n"+"    </Class>\n"+"    <Class>\n"+"     <name>年级2-班级2</name>\n"+"     <studentCount>46</studentCount>\n"+"    </Class>\n"+"    <Class>\n"+"     <name>年级2-班级3</name>\n"+"     <studentCount>42</studentCount>\n"+"    </Class>\n"+"   </ClassList>\n"+"  </Grade>\n"+"  <Grade>\n"+"   <NAME>年级3</NAME>\n"+"  </Grade>\n"+"  <Grade>\n"+"   <NAME>年级4</NAME>\n"+"  </Grade>\n"+" </Grades>\n"+"</School>";School school = xmlMapper.readValue(xmlStr,School.class);System.out.println(school.getName());}