JAXB工具实现java实体类和xml之间的转换

末蓝、 2022-07-11 07:39 676阅读 0赞

## 1、应用场景 ##

1、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、可以使用jersey框架实现WebService接口（resetful方式）

## 2、Demo ##

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

![复制代码][copycode.gif]

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 + "]";
    }
     
    }

![复制代码][copycode.gif]

### 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 ###

![复制代码][copycode.gif]

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 + "]";
    }
    
    }

![复制代码][copycode.gif]

### 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

![复制代码][copycode.gif]

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;
        }
    }

![复制代码][copycode.gif]

### 2.4 Entry.java 类  用来封装map元素 ###

![复制代码][copycode.gif]

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;
      }
      
    }

![复制代码][copycode.gif]

### 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

![复制代码][copycode.gif]

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;
        }
    
    }

![复制代码][copycode.gif]

###  2.6 测试类 JaxbDemo.java ###

![复制代码][copycode.gif]

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();
        }
       }
    }

![复制代码][copycode.gif]

3.测试结果

![复制代码][copycode.gif]

<?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}]

[copycode.gif]: /images/20220711/ddb50fd39d314945a39af83c06ea5275.png