java利用JAXB实现对象和xml互相转换方法与实例详解

2023-07-31 22:06:04 201

1、JAXB应用场景

在使用WebService实现数据上传下载，数据查询时，可以利用JAXB实现java实体类和xml互相转换

2、Demo

2.1student.java实体类

包含list（set同理）、map、Teacher、Date类型的属性

packagejaxb;
importjava.util.Date;
importjava.util.List;
importjava.util.Map;
importjavax.xml.bind.annotation.XmlAccessType;
importjavax.xml.bind.annotation.XmlAccessorType;
importjavax.xml.bind.annotation.XmlElement;
importjavax.xml.bind.annotation.XmlElementWrapper;
importjavax.xml.bind.annotation.XmlRootElement;
importjavax.xml.bind.annotation.XmlType;
importjavax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
@XmlType(propOrder={"id","name","age","birthDay","list","teacher","map"})//指定序列成的xml节点顺序
@XmlAccessorType(value=XmlAccessType.FIELD)//访问类型改为字段
@XmlRootElement
publicclassStudent{
@XmlElement
privateStringid;
@XmlElement
privateStringname;
@XmlElement
privateintage;
@XmlJavaTypeAdapter(value=DateAdapter.class)
@XmlElement
privateDatebirthDay;
@XmlElement
privateListlist;
@XmlElement
privateTeacherteacher;

@XmlJavaTypeAdapter(value=MapAdapter.class)
//@XmlElementWrapper(name="role")
@XmlElement
privateMapmap;
publicStringgetId(){
returnid;
}

publicvoidsetId(Stringid){
this.id=id;
}
publicStringgetName(){
returnname;
}

publicvoidsetName(Stringname){
this.name=name;
}
publicintgetAge(){
returnage;
}

publicvoidsetAge(intage){
this.age=age;
}
publicDategetBirthDay(){
returnbirthDay;
}


publicvoidsetBirthDay(DatebirthDay){
this.birthDay=birthDay;
}

publicListgetList(){
returnlist;
}

publicvoidsetList(Listlist){
this.list=list;
}
publicTeachergetTeacher(){
returnteacher;
}
publicvoidsetTeacher(Teacherteacher){
this.teacher=teacher;
}

publicMapgetMap(){
returnmap;
}

publicvoidsetMap(Mapmap){
this.map=map;
}

@Override
publicStringtoString(){
return"Student[id="+id+",name="+name+",age="+age
+",birthDay="+birthDay+",list="+list+",teacher="
+teacher+",map="+map+"]";
}

}

2.2Teacher.java类

注意:Teacher类不包含@XmlRootElement节点，因为目的是转成一个XML文档，根节点只有一个

packagejaxb;

importjavax.xml.bind.annotation.XmlAccessType;
importjavax.xml.bind.annotation.XmlAccessorType;
importjavax.xml.bind.annotation.XmlElement;
importjavax.xml.bind.annotation.XmlType;

@XmlAccessorType(value=XmlAccessType.FIELD)
@XmlType(propOrder={"id","name","age"})
publicclassTeacher{
@XmlElement
privateintid;
@XmlElement
privateStringname;
@XmlElement
privateintage;
publicintgetId(){
returnid;
}
publicvoidsetId(intid){
this.id=id;
}
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}
publicintgetAge(){
returnage;
}
publicvoidsetAge(intage){
this.age=age;
}
publicTeacher(intid,Stringname,intage){
super();
this.id=id;
this.name=name;
this.age=age;
}
publicTeacher(){
}
@Override
publicStringtoString(){
return"Teacher[id="+id+",name="+name+",age="+age+"]";
}

}

2.3DateApdapter.java

自定义时间适配器类

在java实体类序列化xml日期时，需要对时间进行自定义转换，jaxb提供了XmlAdapter,只要实现它后就可以自定义日期适配器

packagejaxb;

importjava.text.SimpleDateFormat;
importjava.util.Date;

importjavax.xml.bind.annotation.adapters.XmlAdapter;

publicclassDateAdapterextendsXmlAdapter{
//反序列化成日期对象Date
@Override
publicDateunmarshal(Stringstr)throwsException{
SimpleDateFormatformat=getSimpleDateFormat("yyyy-MM-ddHH:mm:ss");
returnstr==null?null:format.parse(str);
}
//序列化成xmL
@Override
publicStringmarshal(Datedate)throwsException{
SimpleDateFormatformat=getSimpleDateFormat("yyyy-MM-ddHH:mm:ss");
returndate==null?"":format.format(date);
}
privateSimpleDateFormatgetSimpleDateFormat(Stringpattern){
SimpleDateFormatformat=newSimpleDateFormat(pattern);
returnformat;
}
}

2.4Entry.java类

用来封装map元素

packagejaxb;

publicclassEntry{
privateStringkey;
privateObjectvalue;
publicStringgetKey(){
returnkey;
}
publicvoidsetKey(Stringkey){
this.key=key;
}
publicObjectgetValue(){
returnvalue;
}
publicvoidsetValue(Objectvalue){
this.value=value;
}

}

2.5、MapAdpter.java

map转换器

本人在写map转换器之后，感觉跟jaxb默认序列化的方式没什么区别，目前还不知道在javb中需不需要特地写map转换器，希望有经验的朋友分享下

packagejaxb;

importjava.util.ArrayList;
importjava.util.HashMap;
importjava.util.List;
importjava.util.Map;

importjavax.xml.bind.annotation.adapters.XmlAdapter;

publicclassMapAdapterextendsXmlAdapter>{

publicstaticclassAdapterMap{
publicListentry=newArrayList();
}
/**
*功能:xml->Map
*@paramadapterMap
*@return
*@throwsException
*/
@Override
publicMapunmarshal(AdapterMapadapterMap)throwsException{
Mapmap=newHashMap();
Listentry=adapterMap.entry;
for(Entryen:adapterMap.entry){
map.put(en.getKey(),en.getValue());
}
returnmap;
}
/**
*功能:map->xml
*/
@Override
publicAdapterMapmarshal(Mapmap)throwsException{
AdapterMapadapterMap=newAdapterMap();
for(Map.Entryentry:map.entrySet()){
Entryentry2=newEntry();
entry2.setKey(entry.getKey());
entry2.setValue(entry.getValue());
adapterMap.entry.add(entry2);
}
returnadapterMap;
}

}

2.6测试类JaxbDemo.java

packagejaxb;

importjava.io.StringReader;
importjava.io.StringWriter;
importjava.util.ArrayList;
importjava.util.Date;
importjava.util.HashMap;

importjavax.xml.bind.JAXBContext;
importjavax.xml.bind.JAXBException;
importjavax.xml.bind.Marshaller;
importjavax.xml.bind.Unmarshaller;

publicclassJaxbDemo{

publicstaticvoidmain(String[]args){
Studentstu=newStudent();
stu.setId("1");
stu.setName("罗志茂");
stu.setAge(25);
stu.setBirthDay(newDate());
//list集合，set集合一样
ArrayListlist=newArrayList();
list.add(newTeacher(2,"曾利梅",22));
list.add(newTeacher(3,"黄伙林",22));
list.add(newTeacher(4,"潘志华",22));
stu.setList(list);
//在javaBean中添加javaBean
Teacherteacher=newTeacher(1,"宋瑶",22);
stu.setTeacher(teacher);
//添加map集合
HashMapmap=newHashMap<>();
map.put("1","林乐贤");
map.put("2","德甲");
stu.setMap(map);
try{
JAXBContextcontext=JAXBContext.newInstance(Student.class);
Marshallermarshaller=context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT,true);
marshaller.setProperty(Marshaller.JAXB_ENCODING,"GBK");
//marshaller.marshal(stu,System.out);
StringWriterwriter=newStringWriter();
marshaller.marshal(stu,writer);
System.out.println(writer.toString());
//反序列化
Unmarshallerunmarshaller=context.createUnmarshaller();
StringReaderreader=newStringReader(writer.toString());
Studentstu2=(Student)unmarshaller.unmarshal(reader);
System.out.println("stu2"+stu2);
}catch(JAXBExceptione){
e.getMessage();
e.printStackTrace();
}
}
}

3.测试结果



1
罗志茂
25
2016-08-1823:07:26

2
曾利梅
22


3
黄伙林
22


4
潘志华
22


1
宋瑶
22



2
德甲


1
林乐贤

stu2Student[id=1,name=罗志茂,age=25,birthDay=ThuAug1823:07:26CST2016,list=[Teacher[id=2,name=曾利梅,age=22],Teacher[id=3,name=黄伙林,age=22],Teacher[id=4,name=潘志华,age=22]],teacher=Teacher[id=1,name=宋瑶,age=22],map={2=德甲,1=林乐贤}]

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