JAXB解调不能正常工作。

Question

我想用 JAXB 转换 XML转对象我的XML看起来是这样的，我创建了3个java类：EntityResource.java，Item.java和PermissionRecipient.java，如下图所示：

<entityResource>
   <Item xsi:type="objectPermissionImpl">
      <permissionMask>0</permissionMask>
      <permissionRecipient xsi:type="roleImpl">
        <externallyDefined>false</externallyDefined>
        <roleName>ROLE_USER</roleName>
      </permissionRecipient>
      <URI>repo:/public/adhoc/topics/JSDiagnosticTopic</URI>
   </Item>
   <Item xsi:type="objectPermissionImpl">
      <permissionMask>0</permissionMask>
      <permissionRecipient xsi:type="roleImpl">
        <externallyDefined>false</externallyDefined>
        <roleName>ROLE_ADMINISTRATOR</roleName>
      </permissionRecipient>
      <URI>repo:/public/adhoc/topics/JSDiagnosticTopic</URI>
   </Item>
</entityResource>

所以我创建了3个java类：EntityResource.java，Item.java和PermissionRecipient.java，如下图所示。

EntityResource.java

import java.util.List;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="entityResource")
public class EntityResource {

    List<Item> ls_Item;

    public EntityResource() {
    }

    public List<Item> getLs_Item() {
        return ls_Item;
    }

    @XmlElement(name="Item")
    public void setLs_Item(List<Item> ls_Item) {
        this.ls_Item = ls_Item;
    }

    @Override
    public String toString() {
        return "EntityResource [ls_Item=" + ls_Item + "]";
    }

}

项目.java

package model;

import java.util.List;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="Item")
public class Item {

    int permissionMask;
    List<PermissionRecipient> ls_permissionRecipient;
    String URI;

    public Item() {

    }

    public int getPermissionMask() {
        return permissionMask;
    }

    @XmlElement(name="permissionMask")
    public void setPermissionMask(int permissionMask) {
        this.permissionMask = permissionMask;
    }

    public List<PermissionRecipient> getLs_permissionRecipient() {
        return ls_permissionRecipient;
    }

    @XmlElement(name="permissionRecipient")
    public void setLs_permissionRecipient(
            List<PermissionRecipient> ls_permissionRecipient) {
        this.ls_permissionRecipient = ls_permissionRecipient;
    }

    public String getURI() {
        return URI;
    }

    @XmlElement(name="URI")
    public void setURI(String uRI) {
        URI = uRI;
    }

    @Override
    public String toString() {
        return "Item [permissionMask=" + permissionMask
                + ", ls_permissionRecipient=" + ls_permissionRecipient
                + ", URI=" + URI + "]";
    }





}

PermissionRecipient.java

package model;

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

@XmlRootElement(name="permissionRecipient")
public class PermissionRecipient {

    String roleName;
    boolean externallyDefined;

    public PermissionRecipient() {

    }

    public boolean isExternallyDefined() {
        return externallyDefined;
    }

    @XmlAttribute(name="externallyDefined")
    public void setExternallyDefined(boolean externallyDefined) {
        this.externallyDefined = externallyDefined;
    }

    public String getRoleName() {
        return roleName;
    }

    @XmlAttribute(name="roleName")
    public void setRoleName(String rolename) {
        this.roleName = rolename;
    }

    @Override
    public String toString() {
        return "PermissionRecipient [externallyDefined=" + externallyDefined
                + ", roleName=" + roleName + "]";
    }


}

所有的工作都完成了，我得到了一个包含项目的EntityResource对象，但是EntityResource的Item属性的permissionRecipient属性不包含他的属性（roleName和externallyDefined） !

我的unmarshalling代码在这里。

JAXBContext jaxbContext = JAXBContext
                    .newInstance(EntityResource.class);
            Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
            EntityResource resourceDescriptors = (EntityResource) jaxbUnmarshaller
                    .unmarshal(conn.getInputStream());// conn is an HttpURLConnection

我的解调代码在这里： toString() 的功能 项目 返回这个结果。

[Item 
[permissionMask=0, 
permissionRecipient=PermissionRecipient [externallyDefined=false, roleName=null], 
URI=repo:/public/adhoc/topics/JSDiagnosticTopic], 

Item 
[permissionMask=0, 
permissionRecipient=PermissionRecipient [externallyDefined=false, roleName=null], 
URI=repo:/public/adhoc/topics/JSDiagnosticTopic]]

正如你可以标记。[externallyDefined=false, roleName=null] 在每个项目中，为什么？ 我犯了什么错误？Thanks if anyone here can help me solve it, best regards.

Answer 1

你有... roleName 和 externallyDefined 映射 @XmlAttribute 而不是 @XmlElement.

调试提示

当你的对象模型没有像预期的那样解除marshal时，填充它并将其marshal为XML，然后将输出与输入进行比较。

Answer 2

在我们的案例中，我们发现了一个不同的问题，即我们有一个xml标签，如

<tag></tag> 

并定义了一个名为Tag的java类。后来当我们尝试在java中使用它时，我们声明了如下的变量。

Tag tag; //didn't worked

和Java类如下

@XmlRootElement(name = "Tag")
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "Tag", propOrder = {

})
public class Tag{}

和解集都没有用，也没有加载值。我们把变量名从'tag'改成了'Tag'，然后Bingo！成功了。

Tag Tag; //worked

另一个类似的情况是，我们把标签的名字改为

<tagNew></tagNew>

Java类为TagNew，变量名为tagNew，工作正常。

@XmlRootElement(name = "TagNew")
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "TagNew", propOrder = {

})
public class TagNew{}

TagNew tagNew; // worked fine

可能还是需要我们学习的！那就是JaxB是如何使用命名约定的。