java使用jaxb操作xml示例

package cn.lzrabbit;  public class ClassA {      private int classAId;      private String classAName;      private ClassB classB;      public int getClassAId() {          return classAId;      }      public void setClassAId(int classAId) {          this.classAId = classAId;      }      public String getClassAName() {          return classAName;      }      public void setClassAName(String classAName) {          this.classAName = classAName;      }      public ClassB getClassB() {          return classB;      }      public void setClassB(ClassB classB) {          this.classB = classB;      }  }  ClassA

package cn.lzrabbit;  public class ClassB {      private int classBId;      private String classBName;      public int getClassBId() {          return classBId;      }      public void setClassBId(int classBId) {          this.classBId = classBId;      }      public String getClassBName() {          return classBName;      }      public void setClassBName(String classBName) {          this.classBName = classBName;      }  }  ClassB

用于序列化的XmlUtil

package cn.lzrabbit;  import java.io.StringReader;  import java.io.StringWriter;  import javax.xml.bind.*;  public class XmlUtil {      public static String toXML(Object obj) {          try {              JAXBContext context = JAXBContext.newInstance(obj.getClass());              Marshaller marshaller = context.createMarshaller();              marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");// //编码格式              marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);// 是否格式化生成的xml串              marshaller.setProperty(Marshaller.JAXB_FRAGMENT, false);// 是否省略xm头声明信息              StringWriter writer = new StringWriter();              marshaller.marshal(obj, writer);              return writer.toString();          } catch (Exception e) {              throw new RuntimeException(e);          }      }      @SuppressWarnings("unchecked")      public static <T> T fromXML(String xml, Class<T> valueType) {          try {              JAXBContext context = JAXBContext.newInstance(valueType);              Unmarshaller unmarshaller = context.createUnmarshaller();              return (T) unmarshaller.unmarshal(new StringReader(xml));          } catch (Exception e) {              throw new RuntimeException(e.getMessage());          }      }  }  XmlUtil

调用如下：

package cn.lzrabbit;    public class MainRun {      /**       * @param args       */      public static void main(String[] args) {          ClassB classB = new ClassB();          classB.setClassBId(22);          classB.setClassBName("B2");          ClassA classA = new ClassA();          classA.setClassAId(11);          classA.setClassAName("A1");          classA.setClassB(classB);          System.out.println(XmlUtil.toXML(classA));      }  }  MainRun

输出结果如下：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>  <classA>      <classAId>11</classAId>      <classAName>A1</classAName>      <classB>          <classBId>22</classBId>          <classBName>B2</classBName>      </classB>  </classA>

这里要注意以下几点

1要序列化的类加上 @XmlRootElement注解，否则会报错(错误提示很清晰，这里就不贴出来了)

2JAXB序列化XML时 默认序列化getter和setter，且getter和setter必须成对出现才会被序列化

3属性名称，默认序列化出来的类和属性名称默认是首字母转换为小写，若需要控制属性名称需要在getter或setter上使用 @XmlElement(name="ClassAId") 指定名称，这里要注意的是@XmlElement放置在getter或setter上都行，但只能放一个，也就是说不能同时在getter和setter上使用@XmlElement注解

下面给出使用了使用如上注解后的代码示例

@XmlRootElement(namespace="cn.lzrabbit")  @XmlAccessorType(XmlAccessType.FIELD)  public class ClassA {      private int classAId;            @XmlElement(name="ClassAName")      private String classAName;      private ClassB classB;      public int getClassAId() {          return classAId;      }      public void setClassAId(int classAId) {          this.classAId = classAId;      }      public String getClassAName() {          return classAName;      }      public void setClassAName(String classAName) {          this.classAName = classAName;      }      public ClassB getClassB() {          return classB;      }      public void setClassB(ClassB classB) {          this.classB = classB;      }  }  @XmlRootElement  @XmlAccessorType(XmlAccessType.FIELD)  public class ClassB {      private int ClassBId;      private String ClassBName;      public int getClassBId() {          return ClassBId;      }      public void setClassBId(int classBId) {          this.ClassBId = classBId;      }      public String getClassBName() {          return ClassBName;      }      public void setClassBName(String classBName) {          this.ClassBName = classBName;      }  }

输出xml为

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>  <ns2:classA xmlns:ns2="cn.lzrabbit">      <classAId>11</classAId>      <ClassAName>A1</ClassAName>      <classB>          <ClassBId>22</ClassBId>          <ClassBName>B2</ClassBName>      </classB>  </ns2:classA>

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