Java XML操作之JAXB基本使用(一)

2014-11-23 23:22:33 · 作者: · 浏览: 0
JAXB主要用来实现对象和XML之间的序列化和反序列化,关于JAXB的介绍就不多说了,网上一搜一大把,这里主要总结下基本使用方法和一些注意事项
首先定义两个示例类ClassA,ClassB,用于后续的示例演示
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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;
}
}
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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;
}
}
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用于序列化的XmlUtil
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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 fromXML(String xml, Class 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());
}
}
}
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调用如下:
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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));
}
}
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输出结果如下:
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< xml version="1.0" encoding="UTF-8" standalone="yes" >
11
A1
22
B2
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这里要注意以下几点
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)
JAXB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
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