JAXB的XmlAttribute注解

• JAXB的XmlAttribute注解，将一个JavaBean属性映射到一个XML属性。

例如，下面的Java代码，将属性currency映射到了XML的属性currency：

package com.thb;

import jakarta.xml.bind.annotation.XmlAttribute;
import jakarta.xml.bind.annotation.XmlRootElement;
import jakarta.xml.bind.annotation.XmlType;
import jakarta.xml.bind.annotation.XmlValue;

@XmlRootElement
@XmlType(name = "", propOrder = {"value"})
public class Price {

    @XmlValue
    public String value;

    @XmlAttribute(name = "currency")
    public String currency;
}

生成的XML Schema：

• XmlAttribute的required属性指定被注解的属性是否必选。
  例如下面代码，Java属性currency用@XmlAttribute(name = "currency", required = true)注解，指明xml属性currency是必选的：

package com.thb;

import jakarta.xml.bind.annotation.XmlAttribute;
import jakarta.xml.bind.annotation.XmlRootElement;
import jakarta.xml.bind.annotation.XmlType;
import jakarta.xml.bind.annotation.XmlValue;

@XmlRootElement
@XmlType(name = "", propOrder = {"value"})
public class Price {

    @XmlValue
    public String value;

    @XmlAttribute(name = "currency", required = true)
    public String currency;
}

生成的XML Schema，属性currency中出现了use="required"：