如何将两个XML元素合并为一个由XSD生成的JAXB类？

Got it, let's figure out how to adjust your XSD setup so that instead of generating a class with separate firstName and lastName fields, you get a single completeName field that combines both values. Here are two practical approaches depending on your workflow:

Approach 1: Use JAXB Binding Files (Recommended for XML Compatibility) #

If you need to keep compatibility with the original XML structure (that has separate firstName and lastName elements), using a JAXB binding file alongside your existing XSD is the way to go. This lets you map the two elements to a single merged field using a custom adapter.

Step 1: Keep Your Original XSD #

Your existing XSD stays unchanged since it defines the XML structure you need to parse/generate:

<xs:element name="person">
    <xs:complexType>
        <xs:sequence>
            <xs:element name="firstName" type="xs:string"/>
            <xs:element name="lastName" type="xs:string"/>
        </xs:sequence>
    </xs:complexType>
</xs:element>

Step 2: Create a JAXB Binding File (binding.xml) #

This file tells the XSD-to-Java generator (like xjc) to map the two name fields to a single completeName property, using an adapter to handle the merging/splitting:

<jaxb:bindings xmlns:jaxb="http://java.sun.com/xml/ns/jaxb"
               xmlns:xsd="http://www.w3.org/2001/XMLSchema"
               version="2.1">
    <jaxb:bindings schemaLocation="your-schema-filename.xsd">
        <jaxb:bindings node="//xsd:element[@name='person']/xsd:complexType">
            <!-- Define the generated class name -->
            <jaxb:class name="Person"/>
            
            <!-- Map individual name elements to helper properties -->
            <jaxb:bindings node=".//xsd:element[@name='firstName']">
                <jaxb:property name="firstName" />
            </jaxb:bindings>
            <jaxb:bindings node=".//xsd:element[@name='lastName']">
                <jaxb:property name="lastName" />
            </jaxb:bindings>
            
            <!-- Add the merged completeName property with an adapter -->
            <jaxb:bindings node=".">
                <jaxb:property name="completeName">
                    <jaxb:baseType name="java.lang.String"/>
                    <jaxb:adapter adapter="com.yourpackage.NameAdapter"/>
                </jaxb:property>
            </jaxb:bindings>
        </jaxb:bindings>
    </jaxb:bindings>
</jaxb:bindings>

Step 3: Create the Custom Adapter Class #

This adapter handles merging firstName and lastName into completeName when unmarshalling XML to Java, and splitting completeName back into the two fields when marshalling Java to XML:

package com.yourpackage;

import javax.xml.bind.annotation.adapters.XmlAdapter;

public class NameAdapter extends XmlAdapter<NameAdapter.NameParts, String> {

    // Helper class to hold the individual name parts
    public static class NameParts {
        public String firstName;
        public String lastName;
    }

    @Override
    public String unmarshal(NameParts parts) throws Exception {
        // Merge first and last name (adjust the separator as needed)
        return parts.firstName + " " + parts.lastName;
    }

    @Override
    public NameParts marshal(String completeName) throws Exception {
        NameParts parts = new NameParts();
        // Split the complete name back into parts (handle edge cases like single names)
        String[] nameSplit = completeName.split(" ", 2);
        parts.firstName = nameSplit[0];
        parts.lastName = nameSplit.length > 1 ? nameSplit[1] : "";
        return parts;
    }
}

Step 4: Generate the Class #

Run the xjc tool with your binding file to generate the Person class with the completeName field:

xjc -b binding.xml your-schema-filename.xsd

Approach 2: Modify the XSD Directly #

If you don't need to maintain compatibility with the original XML structure, you can rewrite the XSD to define a single completeName element. Note that this will change the XML format your class works with:

<xs:element name="person">
    <xs:complexType>
        <xs:sequence>
            <xs:element name="completeName" type="xs:string"/>
        </xs:sequence>
    </xs:complexType>
</xs:element>

Generating a class from this XSD will give you a Person class with just the completeName string field.

内容的提问来源于stack exchange，提问作者Saurabh Prajapati