在JAXB，如何使用@XmlJavaTypeAdapters注解？

问题描述

我想改变从XML解组到Java类JAXB的时候javax.xml.datatype.XMLGregorianCalendar中的到java.util.Date。

I want to change "javax.xml.datatype.XMLGregorianCalendar" to "java.util.Date" when unmarshalling from xml to Java class of JAXB.

但我不把@XmlJavaTypeAdapter任何注释Java类。

But I don't put any annotations of @XmlJavaTypeAdapter in Java classes.

所以，我将尝试使用@XmlJavaTypeAdapters的注解，但我不知道如何使用它...

So, I'm going to try to use an annotation of @XmlJavaTypeAdapters, but I don't know how to use it...

请给我的例子使用它。

推荐答案

作为一个有趣的不谈，你实际上并不需要XMLGregorianCalendar的适应时间，因为JAXB支持java.util.Date本身 - 是这样的：

As an interesting aside, you don't actually need to adapt XMLGregorianCalendar to Date, since JAXB supports java.util.Date natively -- like this:

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
public class Example {
    @XmlSchemaType(name = "date")
    public Date publishingDate;
}

如果你需要它，@XmlJavaTypeAdapter能像这样工作，假设您的自定义类：

If you need it, @XmlJavaTypeAdapter can work like this, assuming your custom class:

public class SillyDate {
    public SillyDate(int year, int month, int day) {
        super();
        this.year = year;
        this.month = month;
        this.day = day;
    }

    public String toString() {
      return "SillyDate [year=" + year + ", month=" + month + ", day=" + day + "]";
    }

    public int year;
    public int month;
    public int day;
}

您需要一类JAXB能理解，然后写类和定制类之间的适配器，例如：

You need a class which JAXB can understand, and then write an adapter between that class and the custom class, like this:

public class SillyDateAdapter extends XmlAdapter<XMLGregorianCalendar, SillyDate> {
    public SillyDate unmarshal(XMLGregorianCalendar val) throws Exception {
      return new SillyDate(val.getYear(), val.getMonth(), val.getDay());
    }

    public XMLGregorianCalendar marshal(SillyDate val) throws Exception {
      return DatatypeFactory.newInstance().newXMLGregorianCalendarDate(val.year, val.month, val.day, 0);
    }
}

现在你可以用在自己的类，如：

Now you can use that in your own classes, like this:

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
public class Example2 {
    @XmlSchemaType(name = "date")
    @XmlJavaTypeAdapter(type=XMLGregorianCalendar.class,value =SillyDateAdapter.class)
    public SillyDate publishingDate;
}

有大量的使用@XmlJavaTypeAdapter的好例子可在网上，类似的和，和其他几个人。快乐适配！

There are plenty of good examples of using the @XmlJavaTypeAdapter available on the net, like this one and this one, and several others. Happy adapting!

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