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JAXB HashMap无法映射

本文介绍了JAXB HashMap无法映射的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我想将POJO类中的HashMap转换为XML。我尝试过使用XmlAdapter，但它只导致HashMap的键和值对作为XML元素的属性。我需要Key作为元素本身，而HashMap的值是元素的值。例如，我需要以下XML： 

 <？xml version =1.0encoding =UTF-8standalone ？= 是 > 
< cart> 
< supervisor_id> 555< / supervisor_id> 
<付款> 
< payment sequence =1> 
<金额> 123.45< /金额> 
< billing_method> 12345< / billing_method> 
< form>卡< / form> 
< delivery_mode> Q< / delivery_mode> 
< /付款> 
<付款顺序=2> 
<金额> 123.45< /金额> 
< person_id> 2333< / person_id> 
<表格>现金< / form> 
< delivery_mode> Q< / delivery_mode> 
< /付款> 
< / payments> 
< / cart>

我创建了以下类：MyMapType包含MyMapEntryType类的列表，其中包含Key和Value两个字段。如何将Key元素更改为@XmlElement并将值字段赋予Key字段？





这是我的源文件。



MyMapType.java 

  import java.util.ArrayList; 
 import java.util.List; 
 
 public class MyMapType {
 
 private List< MyMapEntryType> entry = new ArrayList< MyMapEntryType>（）; 
 
公共列表< MyMapEntryType> getEntry（）{
返回条目; 
} 
 
 public void setEntry（List< MyMapEntryType> entry）{
 this.entry = entry; 
} 
 
}

MyMapEntryType.java 

  import javax.xml.bind.annotation.XmlAccessType; 
 import javax.xml.bind.annotation.XmlAccessorType; 
 import javax.xml.bind.annotation.XmlAttribute; 
 import javax.xml.bind.annotation.XmlValue; 
 
 @XmlAccessorType（XmlAccessType.FIELD）
 public class MyMapEntryType {
 $ b $ @ @mlAttribute 
 private String key; 
 @XmlValue 
私有字符串值; 
 public String getKey（）{
 return key; 
} 
 public void setKey（String key）{
 this.key = key; 
} 
 public String getValue（）{
返回值; 
} 
 public void setValue（String value）{
 this.value = value;

请另外找到适配器类：



MyMapAdapter.java 

  import java.util。 HashMap的; 
 import java.util.Map; 
 import java.util.Map.Entry; 
 import javax.xml.bind.annotation.adapters.XmlAdapter; 
 
 public class MyMapAdapter extends XmlAdapter< MyMapType，Map< String，String>> {
 
 @Override 
 MyMapType marshal（Map< String，String> map）抛出异常{
 
 MyMapType myMapType = new MyMapType（）; （Entry< String，String> entry：map.entrySet（））{
 MyMapEntryType myMapEntryType = new MyMapEntryType（）; 
 
 
 myMapEntryType.setKey（entry.getKey（））; 
 myMapEntryType.setValue（entry.getValue（））; 
 myMapType.getEntry（）。add（myMapEntryType）; 
} 
返回myMapType; 
} 
 
 @Override 
 public Map< String，String> unmarshal（MyMapType映射）抛出异常{
 HashMap< String，String> hashMap = new HashMap< String，String>（）; （MyMapEntryType myEntryType：map.getEntry（））{
 hashMap.put（myEntryType.getKey（），myEntryType.getValue（））; 
} 
返回hashMap; 
 
 
 
 
 $ b $ p $这是有HashMap字段的类： / p> 
 
 
  XmlElementMap.java  
  @XmlAccessorType （XmlAccessType.FIELD）
 public class XmlElementMap {
 
 @XmlAttribute（name =sequence）
 private int sequence; 
 
 @XmlJavaTypeAdapter（MyMapAdapter.class）
私人地图< String，String> map = new HashMap< String，String>（）; 
 
 public int getSequence（）{
 return sequence; 
} 
 
 public void setSequence（int sequence）{
 this.sequence = sequence; 
} 
 
 public Map< String，String> getMap（）{
 return map; 
 
 
 public void setMap（Map< String，String> map）{
 this.map = map; 
} 
 
 
} 
  
 
 
请告知如何实现此目的。
 
 
 
问候，
 
 -Anand 
 
 
 
目前它产生以下输出：我有相同的要求我需要钥匙是元素本身并且HashMap的值为元素的值。
 
 
我没有使用自定义的适配器，而是通过动态地将HashMap条目转换为列表来实现它的JAXBElement对象，然后使用@XmlAnyElement注释列表。  
 
 
  @XmlRootElement（name =root）
 public class MyMapType {
 
 @ XmlAnyElement 
 public List< JAXBElement> entries = new ArrayList< JAXBElement>（）; 
 $ b $ public MyMapType（）{// JAXB required 
} 
 $ b $ public MyMapType（Map< String，String> map）{
 for（Map。条目< String，String>条目：map.entrySet（））{
 entries.add（new JAXBElement（new QName（entry.getKey（）），
 String.class，entry.getValue（）） ）; 
 
 
 
 public static void main（String [] args）throws Exception {
 JAXBContext context = JAXBContext.newInstance（MyMapType.class）; 
 Marshaller marshaller = context.createMarshaller（）; 
 marshaller.setProperty（Marshaller.JAXB_FORMATTED_OUTPUT，true）; 
 
地图< String，String> map = new LinkedHashMap< String，String>（）; 
 map.put（key1，value1）; 
 map.put（key2，value2）; 
 MyMapType mt = new MyMapType（map）; 
 
 marshaller.marshal（mt，System.out）; 
 
 
 
 
 $ b $ p 
 $输出是
 
 
 <？xml version =1.0encoding =UTF-8standalone =yes？> 
< root> 
< / key1> value1< / key1> 
< key2> value2< / key2> 
< / root> 
  
 
I want to convert a HashMap in a POJO class to XML. I tried using the XmlAdapter but it results in only the key and value pairs of the HashMap being the attributes of the XML Elements. I need the Key to be the Element itself and the value of the HashMap to be the value of the element. For instance, I need the following XML:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<cart>
<supervisor_id>555</supervisor_id>
<payments>
    <payment sequence="1">
        <amount>123.45</amount>
        <billing_method>12345</billing_method>
        <form>card</form>
        <delivery_mode>Q</delivery_mode>
    </payment>
<payment sequence="2">
        <amount>123.45</amount>
        <person_id>2333</person_id>
        <form>cash</form>
        <delivery_mode>Q</delivery_mode>
    </payment>
</payments>
</cart>

I created the following classes: MyMapType holds a list of MyMapEntryType class which has two fields namely Key and Value. How do I change the Key element to be @XmlElement and assign the value field to the Key field?
Here are my source files.
MyMapType.java
import java.util.ArrayList;
import java.util.List;

public class MyMapType {

    private List<MyMapEntryType> entry = new ArrayList<MyMapEntryType>();

    public List<MyMapEntryType> getEntry() {
        return entry;
    }

    public void setEntry(List<MyMapEntryType> entry) {
        this.entry = entry;
    }

}

MyMapEntryType.java
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlValue;

@XmlAccessorType(XmlAccessType.FIELD)
public class MyMapEntryType {

@XmlAttribute
private String key;
@XmlValue
private String value;
public String getKey() {
    return key;
}
public void setKey(String key) {
    this.key = key;
}
public String getValue() {
    return value;
}
public void setValue(String value) {
    this.value = value;
}
}

Please also find the adapter class:
MyMapAdapter.java
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import javax.xml.bind.annotation.adapters.XmlAdapter;

public class MyMapAdapter extends XmlAdapter<MyMapType, Map<String, String>> {

    @Override
   public MyMapType marshal(Map<String, String> map) throws Exception {

        MyMapType myMapType = new MyMapType();

      for(Entry<String, String> entry : map.entrySet()) {
         MyMapEntryType myMapEntryType = new MyMapEntryType();
         myMapEntryType.setKey(entry.getKey());
         myMapEntryType.setValue(entry.getValue());
         myMapType.getEntry().add(myMapEntryType);
      }
      return myMapType;
   }

   @Override
   public Map<String, String> unmarshal(MyMapType map) throws Exception {
      HashMap<String, String> hashMap = new HashMap<String, String>();
      for(MyMapEntryType myEntryType : map.getEntry()) {
         hashMap.put(myEntryType.getKey(), myEntryType.getValue());
      }
      return hashMap;
   }
 }

This is the class which has the HashMap field:
XmlElementMap.java
@XmlAccessorType(XmlAccessType.FIELD)
public class XmlElementMap {

@XmlAttribute(name="sequence")
private int sequence;

@XmlJavaTypeAdapter(MyMapAdapter.class)
private Map<String, String> map = new HashMap<String, String>();

public int getSequence() {
    return sequence;
}

public void setSequence(int sequence) {
    this.sequence = sequence;
}

public Map<String, String> getMap() {
    return map;
}

public void setMap(Map<String, String> map) {
    this.map = map;
}


}


Please advise on how to achieve this.
Regards,
-Anand
Currently it produces the following output:
 解决方案 
I have the same requirement "I need the Key to be the Element itself and the value of the HashMap to be the value of the element".
I didn't use customized adapter, but implemented it by converting the HashMap entries dynamically to a list of JAXBElement objects, and then annotated the list with @XmlAnyElement. 
@XmlRootElement(name="root")
public class MyMapType {

    @XmlAnyElement
    public List<JAXBElement> entries = new ArrayList<JAXBElement>();

    public MyMapType() {    // JAXB required
    }

    public MyMapType(Map<String, String> map) {
        for (Map.Entry<String, String> entry : map.entrySet()) {
            entries.add(new JAXBElement(new QName(entry.getKey()),
                    String.class, entry.getValue()));
        }
    }

    public static void main(String[] args) throws Exception {
        JAXBContext context = JAXBContext.newInstance(MyMapType.class);
        Marshaller marshaller = context.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

        Map<String, String> map = new LinkedHashMap<String, String>();
        map.put("key1", "value1");
        map.put("key2", "value2");
        MyMapType mt = new MyMapType(map);

        marshaller.marshal(mt, System.out);
    }
}

The output is,
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root>
    <key1>value1</key1>
    <key2>value2</key2>
</root>

                        
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08-19 10:42
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