JaxB读取类层次结构 [英] JaxB to read class hierarchy

问题描述

只需使用JaxB扩展解析类层次结构问题。
想要使用JaxB阅读以下xml文件

Just extending Parsing class hierarchy using JaxB question. Want to read following xml file using JaxB

<IMPORT>
    <TABLE NAME="USER">
        <ROW>
            <USER_ID>1</USER_ID>
            <ROW_VERSION>1</ROW_VERSION>
            <USER_NAME>Navnath</USER_NAME>
            <LOGIN>Navnath</LOGIN>
            <LOGIN_PASSWORD>Navnath</LOGIN_PASSWORD>
        </ROW>
        <ROW>
            <USER_ID>2</USER_ID>
            <ROW_VERSION>1</ROW_VERSION>
            <USER_NAME>Kumbhar</USER_NAME>
            <LOGIN>Kumbhar</LOGIN>
            <LOGIN_PASSWORD>Kumbhar</LOGIN_PASSWORD>
        </ROW>
    </TABLE>

    <TABLE NAME="WORK">
        <ROW>
            <WORK_ID>1</WORK_ID>
            <WORK_NAME>Work1</WORK_NAME>
            <ROW_VERSION TYPE="N">1</ROW_VERSION>
        </ROW>
        <ROW>
            <WORK_ID>2</WORK_ID>
            <WORK_NAME>Work2</WORK_NAME>
            <ROW_VERSION TYPE="N">1</ROW_VERSION>
        </ROW>
    </TABLE>
    <TABLE> ... </TABLE>
    <TABLE> ... </TABLE>
    <TABLE> ... </TABLE>
</IMPORT>

您可以在上面的xml文件中看到每个表中的列名都不同。我想在数据库中插入这些数据。我尝试为此创建类层次结构，但我不知道如何做到这一点。我的ROW类将包含每个表的不同xml元素，这是我无法配置的区域。请建议。

You can see in above xml file is column names are different in each table. I want to insert this data in database. I try to create class hierarchy for this, But I don't know how to do this. My ROW class will contains diffrent xml element per table and this is the area which I am not able to configure. Please suggest.

推荐答案

注意：我是 EclipseLink JAXB（MOXy） 领导和 JAXB（JSR-222） 专家组。

Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JSR-222) expert group.

您可以利用MOXy的 @XmlDescriminatorNode / @XmlDescriminatorValue 扩展此用例（请参阅： http://blog.bdoughan.com/2010/11/jaxb- and-inheritance-moxy-extension.html ）。

You could leverage MOXy's @XmlDescriminatorNode/@XmlDescriminatorValue extension for this use case (see: http://blog.bdoughan.com/2010/11/jaxb-and-inheritance-moxy-extension.html).

导入

import java.util.List;
import javax.xml.bind.annotation.*;

@XmlRootElement(name="IMPORT")
@XmlAccessorType(XmlAccessType.FIELD)
public class Import {

    @XmlElement(name="TABLE")
    private List<Table> tables;

}

表

@XmlDescriminatorNode 注释用于指定将用于指示将实例化哪个子类的XML属性。 JAXB实现不能通过反射引入类的子类，我们将使用 @XmlSeeAlso 注释来引用它们。

The @XmlDescriminatorNode annotation is used to specify the XML attribute that will be used to indicate which subclass will be instantiated. A JAXB implementation can't pull in the subclasses of a class via reflection, we will use the @XmlSeeAlso annotation to reference them.

import javax.xml.bind.annotation.XmlSeeAlso;
import org.eclipse.persistence.oxm.annotations.XmlDiscriminatorNode;

@XmlDiscriminatorNode("@NAME")
@XmlSeeAlso({UserTable.class, WorkTable.class})
public abstract class Table {

}

UserTable

@XmlDescriminatorValue 注释用于指定与特定子类对应的 NAME 属性的值。

The @XmlDescriminatorValue annotation is used to specify the value of the NAME attribute that corresponds to a particular subclass.

import java.util.List;
import javax.xml.bind.annotation.*;
import org.eclipse.persistence.oxm.annotations.XmlDiscriminatorValue;

@XmlDiscriminatorValue("USER")
@XmlAccessorType(XmlAccessType.FIELD)
public class UserTable extends Table {

    @XmlElement(name="ROW")
    private List<UserRow> rows;

}

UserRow

import javax.xml.bind.annotation.XmlElement;

public class UserRow {

    @XmlElement(name="USER_ID")
    private int userID;

    @XmlElement(name="USER_NAME")
    private String userName;

}

WorkTable

import org.eclipse.persistence.oxm.annotations.XmlDiscriminatorValue;

@XmlDiscriminatorValue("WORK")
public class WorkTable extends Table {

}

jaxb.properties

要将MOXy指定为JAXB提供程序，您需要包含一个名为 jaxb.properties 的文件与您的域模型在同一个包中，并带有以下条目（请参阅： http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html ） 。

To specify MOXy as your JAXB provider you need to include a file called jaxb.properties in the same package as your domain model with the following entry (see: http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html).

javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory

演示

import java.io.File;
import javax.xml.bind.*;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Import.class);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        File xml = new File("src/forum15741264/input.xml");
        Import result = (Import) unmarshaller.unmarshal(xml);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(result, System.out);
    }

}

input.xml /输出

以下是运行演示代码的输入和输出。

Below is the input to and output from running the demo code.

<?xml version="1.0" encoding="UTF-8"?>
<IMPORT>
   <TABLE NAME="USER">
      <ROW>
         <USER_ID>1</USER_ID>
         <USER_NAME>Navnath</USER_NAME>
      </ROW>
      <ROW>
         <USER_ID>2</USER_ID>
         <USER_NAME>Kumbhar</USER_NAME>
      </ROW>
   </TABLE>
   <TABLE NAME="WORK"/>
</IMPORT>

替代解决方案

或者仅使用标准JAXB API，您可以使用 XmlAdapter

Alternatively using only the standard JAXB APIs you could try the following approach using an XmlAdapter

$ b $尝试以下方法b
• http://blog.bdoughan.com /2012/01/jaxb-and-inhertiance-using-xmladapter.html

• http://blog.bdoughan.com/2012/01/jaxb-and-inhertiance-using-xmladapter.html

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