在字段之前和getter声明之前使用@XmlElement有什么区别？ [英] What is the difference between using @XmlElement before field and before getter declaration?

问题描述

我可以用两种方式声明JAXB元素：

I can declare JAXB element in two ways:

@XmlElement
public int x;

或

private int x;

@XmlElement
public int getX(){...}

第一个变体AFAIK无论如何都会创建映射到XML的getter。这两种方式有什么区别？

The first variant, AFAIK, creates getter, mapped to XML, anyway. What is the difference between these two ways?

推荐答案

它与 @XmlAccessorType 注释有关。

• XmlAccessType.PROPERTY ：字段仅在明确注释时才绑定到XML一些JAXB注释。

• XmlAccessType.PROPERTY : Fields are bound to XML only when they are explicitly annotated by some of the JAXB annotations.

XmlAccessType.FIELD ：Getter / setter对仅绑定到XML当它们被一些JAXB注释明确注释时

XmlAccessType.FIELD: Getter/setter pairs are bound to XML only when they are explicitly annotated by some of the JAXB annotations

根据评论更新解释：

让我们考虑一个看起来像这样的简单xml：

Let's consider a simple xml that looks like this:

<root>
    <value>someValue</value>
</root>

我们有一个班级：

@XmlRootElement(name = "root")
//@XmlAccessorType(XmlAccessType.PROPERTY)
@XmlAccessorType(XmlAccessType.FIELD)
public class DemoRoot {

    @XmlElement
    private String value;

    public String getValue() {
        return value;
    }

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

如果您尝试使用 XmlAccessType.FIELD 和字段上方的 @XmlElement 注释，然后你将解组好。

If you try to unmarshal using XmlAccessType.FIELD and the @XmlElement annotation above the field, then you will unmarshal fine.

如果您使用 XmlAccessType.PROPERTY ，您将收到以下错误：

If you use XmlAccessType.PROPERTY you will receive the following error:

IllegalAnnotationsException：IllegalAnnotationExceptions的1个计数类有两个同名的属性value

IllegalAnnotationsException: 1 counts of IllegalAnnotationExceptions Class has two properties of the same name "value"

这是因为它同时考虑了明确注释的两个 @XmlElement 字段'value'和getters / setters。

This is because it takes into consideration both the explicitly annotated with @XmlElement field 'value' and the getters/setters.

反之亦然，如果移动<$ c getc / setter上的$ c> @XmlElement 注释。

And vice versa if you move the @XmlElement annotation on the getter/setter.

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