java 关于xml的注解，自动生成xml文件 - @XML***

用的是jdk自带的javax.xml.bind.JAXBContext将对象和xml字符串进行相互转换。
如果对要生成的 xml 格式有点些许的限制，就会对生成xml的对象就需要进行些许控制，控制对象的一个最可行的办法就是用注解。
（jdk 1.6 api：http://www.cs.uic.edu/~mcpc/Java_Docs/api/index.html?javax/xml/bind/JAXBContext.html）

比较常用的几个：
@XmlRootElement：根节点
@XmlAttribute：该属性作为xml的attribute
@XmlElement：该属性作为xml的element，且可以增加属性(name="NewElementName")，那么生成的xml串的elment的标签是NewElementName

示例：

[java]
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package test;

import java.io.StringWriter;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

import test.bean.EleClassA;
import test.bean.EleClassB;
import test.bean.RootClass;

public class Test1 {

public static void main(String[] args) {
RootClass rc = new RootClass();
EleClassA a = new EleClassA();
EleClassB b = new EleClassB();

a.setAttrC("attrc");
a.setEleA("eleA");
a.setEleB("eleB");

b.setAttrPassword("attrPassword");
b.setAttrUserName("attrUsrName");
b.setEleCode("eleCode");

rc.setA(a);
rc.setB(b);
rc.setRoot("root");
rc.setRootA("rootA");

JAXBContext context;
try {
context = JAXBContext.newInstance(RootClass.class);
Marshaller mar = context.createMarshaller();
mar.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
mar.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");

StringWriter writer = new StringWriter();

mar.marshal(rc, writer);

System.out.println(writer.toString());
} catch (JAXBException e) {
e.printStackTrace();
}

}
}

package test.bean;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="rootclass")
public class RootClass {

private EleClassA a;
private EleClassB b;
private String root;
private String rootA;

@XmlElement(name="eleClassA")
public EleClassA getA() {
return a;
}
public void setA(EleClassA a) {
this.a = a;
}
@XmlElement(name="EleclassA")
public EleClassB getB() {
return b;
}
public void setB(EleClassB b) {
this.b = b;
}
public String getRoot() {
return root;
}
public void setRoot(String root) {
this.root = root;
}
public String getRootA() {
return rootA;
}
public void setRootA(String rootA) {
this.rootA = rootA;
}

}

package test.bean;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;

public class EleClassA {

private String eleA;
private String eleB;

private String attrC;

@XmlElement
public String getEleA() {
return eleA;
}

public void setEleA(String eleA) {
this.eleA = eleA;
}

@XmlElement(name="elebnewname")
public String getEleB() {
return eleB;
}

public void setEleB(String eleB) {
this.eleB = eleB;
}

@XmlAttribute()
public String getAttrC() {
return attrC;
}

public void setAttrC(String attrC) {
this.attrC = attrC;
}

}

package test.bean;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;

public class EleClassB {

private String attrUserName;
private String attrPassword;

private String eleCode;

@XmlAttribute
public String getAttrUserName() {
return attrUserName;
}
public void setAttrUserName(String attrUserName) {
this.attrUserName = attrUserName;
}
@XmlAttribute(name="password")
public String getAttrPassword() {
return attrPassword;
}
public void setAttrPassword(String attrPassword) {
this.attrPassword = attrPassword;
}
@XmlElement
public String getEleCode() {
return eleCode;
}
public void setEleCode(String eleCode) {
this.eleCode = eleCode;
}

}

运行Test1类中main方法，执行结果：

[html]
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<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<rootclass>
<eleClassA attrC="attrc">
<eleA>eleA</eleA>
<elebnewname>eleB</elebnewname>
</eleClassA>
<EleclassA attrUserName="attrUsrName" password="attrPassword">
<eleCode>eleCode</eleCode>
</EleclassA>
<root>root</root>
<rootA>rootA</rootA>
</rootclass>