假设我有这些类:

public class Container {
    private String name;
    private int number;
    private List<ParentClass> list;
}

public class ParentClass {
    private String value;
}

如果我使用 JAXB 从 XML 文件中读取它，我希望 XML 是这样的:

<container>
    <name>Name</name>
    <number>1</number>
    <subclass>
        <value>Val</value>
    </subclass>
    <subclass>
        <value>Val2</value>
    </subclass>
    <subclass>
        <value>Val3</value>
    </subclass>
</container>

我会像这样装饰我的类:

@XmlRootElement(name = "container")
@XmlAccessorType(XmlAccessType.FIELD)
public class Container {
    @XmlElement(name = "name")
    private String name;

    @XmlElement(name = "number")
    private int number;

    @XmlElement(name = "subclass", type = Subclass.class)
    private List<ParentClass> list;
}

@XmlRootElement(name = "container")
@XmlAccessorType(XmlAccessType.FIELD)
public class ParentClass {
    @XmlElement(name = "value")
    private String value;
}

现在，假设 ParentClass 实际上是一个抽象类或接口(interface)，并且我有两个从它派生的子类；像这样的东西:

public abstract ParentClass {
    void doSomething();
}

public IntSubclass extends ParentClass {
    private int value;
    public void doSomething() { ... }
}

public StringSubclass extends ParentClass {
    private String value;
    public void doSomething() { ... }
}

如何使用 JAXB 和 XML 将 list 属性解析为相应的 StringSubclass 或 IntSubclass 列表？

也就是说，如果我从 XML 中读取 StringSubclass 元素或 IntSubclass 元素并且能够识别它们是一种或另一种。像这样:

<container>
    <name>Name</name>
    <number>1</number>
    <stringSubclass>
        <value>Val</value>
    </stringSubclass>
    <stringSubclass>
        <value>Val2</value>
    </stringSubclass>
    <intSubclass>
        <value>3</value>
    </intSubclass>
</container>

有什么办法吗？也许使用另一个框架？

谢谢

最佳答案

可以使用注解@XmlElements

容器类

package jaxb_element_test;

import java.util.List;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlElements;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "container")
@XmlAccessorType(XmlAccessType.FIELD)
public class Container {
    @XmlElement(name = "name")
    private String name;

    @XmlElement(name = "number")
    private int number;

    @XmlElements({
            @XmlElement(name="stringSubclass", type=StringSubclass.class),
            @XmlElement(name="intSubclass", type=IntSubclass.class)})
    private List<ParentClass> list;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getNumber() {
        return number;
    }

    public void setNumber(int number) {
        this.number = number;
    }

    public List<ParentClass> getList() {
        return list;
    }

    public void setList(List<ParentClass> list) {
        this.list = list;
    }
}

IntSubclass.class

package jaxb_element_test;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;

@XmlAccessorType(XmlAccessType.FIELD)
public class IntSubclass extends ParentClass {

    @XmlElement(name = "value")
    private int value;

    public int getValue() {
        return value;
    }

    public void setValue(int value) {
        this.value = value;
    }


}

StringSubclass.class

package jaxb_element_test;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;

@XmlAccessorType(XmlAccessType.FIELD)
public class StringSubclass extends ParentClass{

    @XmlElement(name = "value")
    private String value;

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }


}

关于java - 根据标签解析XML到具体的子类，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39714851/