JAXB Unmarshalling - 将子元素的属性映射到java对象

Question

I am unable to map aid attribute of answername tag in the following XML to Java field aid of Answer Class.

Any help would be appreciated. Thanks in advance.

XML:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>  
<question id="1">  
    <answers>  
        <answername aid="101">java is a programming language</answername>  
        <postedby>ravi</postedby>  
    </answers>  
    <answers>  
        <answername aid="102">java is a platform</answername>  
        <postedby>john</postedby>  
    </answers>  
    <questionname>What is java?</questionname>  
</question> 

Java Classes:

Question.java

package com.deere.ruleEngine.service;

import java.util.List;

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

@XmlRootElement  
public class Question {  
private int id;  
private String questionname;  
private List<Answer> answers;  
public Question() {}  
public Question(int id, String questionname, List<Answer> answers) {  
    super();  
    this.id = id;  
    this.questionname = questionname;  
    this.answers = answers;  
}  
@XmlAttribute  
public int getId() {  
    return id;  
}  
public void setId(int id) {  
    this.id = id;  
}  
@XmlElement  
public String getQuestionname() {  
    return questionname;  
}  
public void setQuestionname(String questionname) {  
    this.questionname = questionname;  
}  
@XmlElement  
public List<Answer> getAnswers() {  
    return answers;  
}  
public void setAnswers(List<Answer> answers) {  
    this.answers = answers;  
}  
}  

Answer.java

package com.deere.ruleEngine.service;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;

@XmlAccessorType(XmlAccessType.FIELD)
public class Answer {  
    @XmlAttribute(name="aid")
private int aid;  
private String answername;  
private String postedby;  
public Answer() {}  
public Answer(int id, String answername, String postedby) {  
    super();  
    this.aid = id;  
    this.answername = answername;  
    this.postedby = postedby;  
}  

public int getId() {  
    return aid;  
}  
public void setId(int id) {  
    this.aid = id;  
}  
public String getAnswername() {  
    return answername;  
}  
public void setAnswername(String answername) {  
    this.answername = answername;  
}  
public String getPostedby() {  
    return postedby;  
}  
public void setPostedby(String postedby) {  
    this.postedby = postedby;  
}  

}  

Current Output:

1 What is java?
Answers:
0 java is a programming language  ravi
0 java is a platform  john

Desired Output:

1 What is java?
Answers:
101 java is a programming language  ravi
102 java is a platform  john

Answer 1

As @TimurA already said, your Java classes don't match the <answername> elements of your XML files. If you want to keep the structure of your XML files, then you need to adapt your Java classes.

In your Answer class remove the aid property, and change the type of the answername property:

@XmlAccessorType(XmlAccessType.FIELD)
public class Answer {
    private Answername answername;
    private String postedby;

    // + constructors, getters, setters
}

Create a separate class for Answername :

@XmlAccessorType(XmlAccessType.FIELD)
public class Answername {

    @XmlAttribute
    private int aid;

    @XmlValue
    private String text;

    // + constructors, getters, setters
}

Answer 2

In your XML, "aid" is an attribute of "answername" not the Answer object. If you don't mind changing the XML then all you have to do is move it up one level.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>  
<question id="1">  
    <answers aid="101">  
        <answername>java is a programming language</answername>  
        <postedby>ravi</postedby>  
    </answers>  
    <answers aid="102">  
        <answername>java is a platform</answername>  
        <postedby>john</postedby>  
    </answers>  
    <questionname>What is java?</questionname>  
</question>

If you do want to keep the same XML, then you just have to create another class "answername" with the "aid" attribute and the value element, and Answer will have that as an element.

Answer 3

Setters and getters of the aid property are not named right. Rename them to getAid and setAid respectively.