首先定義兩個(gè)示例類ClassA,ClassB，用于后續(xù)的示例演示
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");// //編碼格式
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頭聲明信息
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
調(diào)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
輸出結(jié)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>
這里要注意以下幾點(diǎn)
1要序列化的類加上 @XmlRootElement注解，否則會(huì)報(bào)錯(cuò)(錯(cuò)誤提示很清晰，這里就不貼出來了)
2JAXB序列化XML時(shí) 默認(rèn)序列化getter和setter，且getter和setter必須成對(duì)出現(xiàn)才會(huì)被序列化
3屬性名稱，默認(rèn)序列化出來的類和屬性名稱默認(rèn)是首字母轉(zhuǎn)換為小寫，若需要控制屬性名稱需要在getter或setter上使用 @XmlElement(name="ClassAId") 指定名稱，這里要注意的是@XmlElement放置在getter或setter上都行，但只能放一個(gè)，也就是說不能同時(shí)在getter和setter上使用@XmlElement注解
4如何控制根節(jié)點(diǎn)名稱？
使用@XmlRootElement指定name屬性即可，如@XmlRootElement(name="ClassA")
5怎么添加命名空間
使用@XmlRootElement(namespace="cn.lzrabbit") 指定namespace屬性
6怎么精確控制每個(gè)屬性名稱
JAXB自動(dòng)轉(zhuǎn)化為首字母小寫會(huì)導(dǎo)致不可預(yù)料的屬性名稱出現(xiàn)， 不嫌麻煩的話為每個(gè)屬性設(shè)置@XmlElement(name="")，想省事的話使用Field
7怎么樣實(shí)現(xiàn)序列化時(shí)使用Field字段而不是使用setter和getter
在要使用的類上面加上@XmlAccessorType(XmlAccessType.FIELD)注解，并指定為XmlAccessType.FIELD，這里強(qiáng)烈推薦使用@XmlAccessorType(XmlAccessType.FIELD)注解，因?yàn)檫@樣你可以精確的控制每個(gè)元素的名稱，而不需要為每個(gè)屬性去設(shè)置@XmlElement(name="")注解，當(dāng)然也可以在Field上使用@XmlElement注解
下面給出使用了使用如上注解后的代碼示例
@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;
}
}
輸出xml為
<?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>
