JAXB 解组无法正常工作

Question

我正在尝试使用JAXB将XML转换为 Object ，我的 XML 如下所示：

<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，如下所示：

实体资源.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 + "]";
    }





}

权限接收者.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 + "]";
    }


}

一切正常，我得到了一个包含 Item 的 EntityResource 对象，但 EntityResource 的 Item 属性的 permissionRecipient 属性不包含他的属性（roleName 和 externallyDefined）！

我的解组代码在这里：

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

Item的toString()函数返回了这样的结果：

[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]]

正如您可以在每个项目中标记[externallyDefined=false, roleName=null] ，为什么？ 我犯了什么错误？ 感谢这里的任何人可以帮助我解决它，最好的问候。

Answer 1

您将roleName和externallyDefined映射到@XmlAttribute而不是@XmlElement 。

调试提示

当您的对象模型没有按预期解组时，填充它并将其编组为 XML，然后将输出与您的输入进行比较。

Answer 2

在我们的例子中，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。 稍后当我们尝试在 java 中使用它时，我们声明了如下变量

Tag tag; //didn't worked

和Java类如下

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

})
public class Tag{}

并且解组不起作用并且没有加载值。 我们将变量名称从“tag”更改为“Tag”和 Bingo！ 有效。

Tag Tag; //worked

另一种类似的情况我们有标签名称

<tagNew></tagNew>

Java 类为 TagNew，变量名称为 tagNew，它工作正常。

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

})
public class TagNew{}

TagNew tagNew; // worked fine

可能仍然是我们要学习的东西！ JaxB 如何使用命名约定。