生成实现接口的 JAXB 类 [英] Generating a JAXB class that implements an interface

问题描述

我目前正在使用 JAXB 生成 Java 类以解组 XML.现在我想创建一个与第一个非常相似的新模式，并让生成的类实现相同的接口.

I'm currently using JAXB to generate java classes in order to unmarshall XML. Now I would like to create a new schema very similar to the first and have the classes that are generated implement the same interface.

例如，我有两个模式文件，它们定义了具有相似标签的 XML:

Say for example, I have two schema files which define XML with similar tags:

成人.xsd

<?xml version="1.0" encoding="UTF-8"?>
<xs:element name="Person">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="Name" type="xs:string" />
      <xs:element name="Age" type="xs:integer" />
      <xs:element name="Job" type="xs:string" />
    </xs:sequence>
  </xs:complexType>
</xs:element>

kid.xsd

<?xml version="1.0" encoding="UTF-8"?>
<xs:element name="Person">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="Name" type="xs:string" />
      <xs:element name="Age" type="xs:integer" />
      <xs:element name="School" type="xs:string" />
    </xs:sequence>
  </xs:complexType>
</xs:element>

使用 JAXB 和 XJC 我想生成两个类文件:

Using JAXB and XJC I'd like to generate two class files:

public class Adult implements Person {
    ...
    public String getName() { ... }
    public int getAge() { ... }
    public String getJob { ... }
}

public class Kid implements Person {
    ...
    public String getName() { ... }
    public int getAge() { ... }
    public String getSchool { ... }
}

Person 接口定义了 getName() 和 getAge() 方法.

where the Person interface defines the getName() and getAge() methods.

我查看了一些关于映射接口的文档，但是这个似乎仅适用于您已经拥有要映射到 DOM 的 Java 类的情况.

I've looked at some of the documentation for mapping interfaces but this appears to only be for the situation when you already have java classes that you want to map to a DOM.

另外，我尝试使用这个外部插件但它似乎不起作用.这是我的 xjb 绑定文件:

Also, I've tried to use this external plugin but it doesn't appear to work. Here is my xjb binding file:

<jxb:bindings version="1.0" 
  xmlns:jxb="http://java.sun.com/xml/ns/jaxb" 
  xmlns:xs="http://www.w3.org/2001/XMLSchema" 
  xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc"
  xmlns:ext="http://xml.w-wins.com/xjc-plugins/interfaces"
  jxb:extensionBindingPrefixes="xjc">

    <jxb:bindings schemaLocation="xsd/adult.xsd" node="xs:schema/xs:complexType[@name='Person']">
        <ext:interface>mypackage.Hello</ext:interface> 
    </jxb:bindings>

</jxb:bindings>

但这会产生以下错误:

$ java -cp "lib/activation.jar;lib/InterfacesXJCPlugin.jar;lib/jaxb1-impl.jar;lib/jaxb-api.jar;lib/jaxb-xjc.jar;lib/jsr173_1.0_api.jar" com.sun.tools.xjc.XJCFacade -p mypackage.myxml -extension -Xinterfaces xsd/adult.xsd -b binding.xjb
parsing a schema...
[ERROR] XPath evaluation of "xs:schema/xs:complexType[@name='Person']" results in empty target node
  line 8 of file:/C:/dev/jaxb/jaxb-ri/binding.xjb

Failed to parse a schema.

是否可以使用实现接口的 JAXB 生成类?

Is it possible to generate a class with JAXB that implements an interface?

更新

我尝试过使用 接口插入 插件，但出于某种原因无法让它工作.这就是我调用 xjc 的方式，但好像插件 jar 没有从类路径中提取:

I've tried using the Interface Insertion plugin but for some reason can't get it to work. This is how I'm calling xjc yet it is as if the plugin jar is not getting picked up from the classpath:

$ java -cp "lib/xjc-if-ins.jar;lib/jaxb-xjc.jar" com.sun.tools.xjc.XJCFacade -p mypackage -extension -Xifins myschema.xsd -b binding.xjb

我收到错误:

unrecognized parameter -Xifins

有什么想法吗?

推荐答案

不幸的是，其他一些答案中提到的接口注入插件似乎不再得到很好的支持.事实上，我很难找到要下载的 JAR.

Unfortunately, it looks like the interface-injection plugin mentioned in some of the other answers is no longer well-supported. In fact, I'm having trouble finding the JAR for download.

幸运的是，JAXB2 Basics Plugins 提供了类似的机制来向生成的 JAXB 存根(请参阅 继承插件).

Thankfully, the JAXB2 Basics Plugins provides a similar mechanism for adding an interface to the generated JAXB stubs (see the Inheritance plugin).

继承插件文档有一个示例，展示了 XML 架构文件的外观.但是，由于您无法修改架构，因此可以改用外部绑定文件:

The Inheritance plugin documentation has an example showing what the XML schema file might look like. However, since you cannot modify the schema, you can use an external bindings file instead:

<?xml version="1.0"?>
<jxb:bindings version="1.0" 
  xmlns:jxb="http://java.sun.com/xml/ns/jaxb" 
  xmlns:xs="http://www.w3.org/2001/XMLSchema" 
  xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc"
  xmlns:inheritance="http://jaxb2-commons.dev.java.net/basic/inheritance"
  jxb:extensionBindingPrefixes="xjc">

    <jxb:bindings schemaLocation="xsd/adult.xsd">
      <jxb:bindings node="//xs:complexType[@name='Person']">
        <inheritance:implements>mypackage.Hello</inheritance:implements> 
      </jxb:bindings>
    </jxb:bindings>

</jxb:bindings>

JAXB2 基础插件文档包括将插件与 Ant 和 Maven 结合使用的说明.您也可以直接从命令行使用它，但是命令有点乱(由于必须添加到类路径中的 jar 数量):

The JAXB2 Basics Plugins documentation includes instructions for using the plugin with Ant and Maven. You can also use it straight from the command line, but the command is a bit messy (due to the number of jars you have to add to the classpath):

java -jar jaxb-xjc.jar 
     -classpath jaxb2-basics-0.5.3.jar,jaxb2-basics-runtime-0.5.3.jar,
                jaxb2-basics-tools-0.5.3.jar,commons-beanutils-0.5.3.jar,
                commons-lang.jar,commons-logging.jar
     -p mypackage.myxml -extension -Xinheritance xsd/adult.xsd -b binding.xjb

JAXB2 Basics Plugins 提供了许多其他实用程序，您可能也会发现它们很有用(例如自动生成 equals、hashCode 和 toString 方法).

The JAXB2 Basics Plugins provides a number of other utilities which you might also find useful (such as autogeneration of equals, hashCode, and toString methods).

这篇关于生成实现接口的 JAXB 类的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！