利用JAXB实现java实体类和xml互相转换

2022-12-09 18:17:26

1、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

2.1 student.java 实体类，包含list（set同理）、map、Teacher、Date 类型的属性

package jaxb;

import java.util.Date;

import java.util.List;

import java.util.Map;

import javax.xml.bind.annotation.XmlAccessType;

import javax.xml.bind.annotation.XmlAccessorType;

import javax.xml.bind.annotation.XmlElement;

import javax.xml.bind.annotation.XmlElementWrapper;

import javax.xml.bind.annotation.XmlRootElement;

import javax.xml.bind.annotation.XmlType;

import javax.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

public class Student {

     @XmlElement

     private String id;

     @XmlElement

     private String name;

     @XmlElement

     private int age;

     @XmlJavaTypeAdapter(value=DateAdapter.class)

     @XmlElement

     private Date birthDay;

     @XmlElement

     private List<Teacher> list;

     @XmlElement

     private Teacher teacher;

     @XmlJavaTypeAdapter(value=MapAdapter.class)

    // @XmlElementWrapper(name="role")

     @XmlElement

     private Map map;

    public String getId() {

        return id;

    }

    public void setId(String id) {

        this.id = id;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public int getAge() {

        return age;

    }

    public void setAge(int age) {

        this.age = age;

    }

    public Date getBirthDay() {

        return birthDay;

    }

    public void setBirthDay(Date birthDay) {

        this.birthDay = birthDay;

    }

    public List getList() {

        return list;

    }

    public void setList(List list) {

        this.list = list;

    }

  public Teacher getTeacher() {

    return teacher;

  }

   public void setTeacher(Teacher teacher) {

    this.teacher = teacher;

   }

  public Map getMap() {

    return map;

  }

  public void setMap(Map map) {

    this.map = map;

 }

@Override

public String toString() {

    return "Student [id=" + id + ", name=" + name + ", age=" + age

            + ", birthDay=" + birthDay + ", list=" + list + ", teacher="

            + teacher + ", map=" + map + "]";

}

}

2.2 Teacher.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

package jaxb;

import javax.xml.bind.annotation.XmlAccessType;

import javax.xml.bind.annotation.XmlAccessorType;

import javax.xml.bind.annotation.XmlElement;

import javax.xml.bind.annotation.XmlType;

@XmlAccessorType(value=XmlAccessType.FIELD)

@XmlType(propOrder={"id","name","age"})

public class Teacher {

 @XmlElement

 private int id;

 @XmlElement

 private String name;

 @XmlElement

 private int age;

public int getId() {

    return id;

}

public void setId(int id) {

    this.id = id;

}

public String getName() {

    return name;

}

public void setName(String name) {

    this.name = name;

}

public int getAge() {

    return age;

}

public void setAge(int age) {

    this.age = age;

}

public Teacher(int id, String name, int age) {

    super();

    this.id = id;

    this.name = name;

    this.age = age;

}

public Teacher() {

}

@Override

public String toString() {

    return "Teacher [id=" + id + ", name=" + name + ", age=" + age + "]";

}

}

2.3 DateApdapter.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

package jaxb;

import java.text.SimpleDateFormat;

import java.util.Date;

import javax.xml.bind.annotation.adapters.XmlAdapter;

public class DateAdapter extends XmlAdapter<String, Date> {

    //反序列化成日期对象Date

    @Override

    public Date unmarshal(String str) throws Exception {

        SimpleDateFormat format = getSimpleDateFormat("yyyy-MM-dd HH:mm:ss");

        return str==null ? null:format.parse(str);

    }
    //序列化成xmL

    @Override

    public String marshal(Date date) throws Exception {

        SimpleDateFormat format = getSimpleDateFormat("yyyy-MM-dd HH:mm:ss");

        return date==null ? "":format.format(date);

    }

    private SimpleDateFormat getSimpleDateFormat(String pattern){

        SimpleDateFormat format = new SimpleDateFormat(pattern);

        return format;

    }

}

2.4 Entry.java 类  用来封装map元素

package jaxb;

public class Entry {

  private String key;

  private Object value;

  public String getKey() {

    return key;

  }

  public void setKey(String key) {

    this.key = key;

  }

   public Object getValue() {

    return value;

  }

  public void setValue(Object value) {

    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

package jaxb;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import javax.xml.bind.annotation.adapters.XmlAdapter;

public class MapAdapter extends XmlAdapter<MapAdapter.AdapterMap,Map<String,Object>> {

    public static class AdapterMap {

        public List<Entry> entry =new ArrayList<Entry>();

    }

    /**

     * 功能:xml->Map<String,Object>

     * @param adapterMap

     * @return

     * @throws Exception

     */

    @Override

    public Map<String, Object> unmarshal(AdapterMap adapterMap) throws Exception {

        Map<String, Object> map = new HashMap<String, Object>();

        List entry = adapterMap.entry;

        for(Entry en:adapterMap.entry){

            map.put(en.getKey(), en.getValue());

        }

        return map;

    }

    /**

     * 功能:map<String,Object> -> xml

     */

    @Override

    public AdapterMap marshal(Map<String, Object> map) throws Exception {

        AdapterMap adapterMap = new AdapterMap();

        for (Map.Entry<String, Object> entry : map.entrySet()) {

            Entry entry2 = new Entry();

            entry2.setKey(entry.getKey());

            entry2.setValue(entry.getValue());

            adapterMap.entry.add(entry2);

        }

        return adapterMap;

    }

}

2.6 测试类 JaxbDemo.java

package jaxb;

import java.io.StringReader;

import java.io.StringWriter;

import java.util.ArrayList;

import java.util.Date;

import java.util.HashMap;

import javax.xml.bind.JAXBContext;

import javax.xml.bind.JAXBException;

import javax.xml.bind.Marshaller;

import javax.xml.bind.Unmarshaller;

public class JaxbDemo {

   public static void main(String[] args) {

       Student stu = new Student();

       stu.setId("1");

       stu.setName("罗志茂");

       stu.setAge(25);

       stu.setBirthDay(new Date());

       //list集合，set集合一样

       ArrayList<Teacher> list = new ArrayList<Teacher>();

       list.add(new Teacher(2,"曾利梅",22));

       list.add(new Teacher(3,"黄伙林",22));

       list.add(new Teacher(4,"潘志华",22));

       stu.setList(list);

       //在javaBean中添加javaBean

       Teacher teacher = new Teacher(1,"宋瑶",22);

       stu.setTeacher(teacher);

       //添加map集合

       HashMap<Object, Object> map = new HashMap<>();

       map.put("1", "林乐贤");

       map.put("2", "德甲");

       stu.setMap(map);

       try {

        JAXBContext context = JAXBContext.newInstance(Student.class);

        Marshaller marshaller = context.createMarshaller();

        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

        marshaller.setProperty(Marshaller.JAXB_ENCODING, "GBK");

        //marshaller.marshal(stu, System.out);

        StringWriter writer = new StringWriter();

        marshaller.marshal(stu, writer);

        System.out.println(writer.toString());

        //反序列化

        Unmarshaller unmarshaller = context.createUnmarshaller();

        StringReader reader = new StringReader(writer.toString());

        Student stu2 = (Student) unmarshaller.unmarshal(reader);

        System.out.println("stu2"+stu2);

    } catch (JAXBException e) {

        e.getMessage();

        e.printStackTrace();

    }

   }

}

3.测试结果

<?xml version="1.0" encoding="GBK" standalone="yes"?>

<student>

    <id>1</id>

    <name>罗志茂</name>

    <age>25</age>

    <birthDay>2016-08-18 23:07:26</birthDay>

    <list>

        <id>2</id>

        <name>曾利梅</name>

        <age>22</age>

    </list>

    <list>

        <id>3</id>

        <name>黄伙林</name>

        <age>22</age>

    </list>

    <list>

        <id>4</id>

        <name>潘志华</name>

        <age>22</age>

    </list>

    <teacher>

        <id>1</id>

        <name>宋瑶</name>

        <age>22</age>

    </teacher>

    <map>

        <entry>

            <key>2</key>

            <value xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">德甲</value>

        </entry>

        <entry>

            <key>1</key>

            <value xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">林乐贤</value>

        </entry>

    </map>

</student>

stu2Student [id=1, name=罗志茂, age=25, birthDay=Thu Aug 18 23:07:26 CST 2016, 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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