如何使用JAXB将HashTable <String,String>序列化为XML？

Question

我试图使用JAXB序列化HashTable<String, String>到XML.我是Java的新手(来自C#),所以我对此任务感到困惑.

我看过以下代码:

public static <T> String ObjectToXml(T object, Class<T> classType) throws JAXBException
{
  JAXBContext jaxbContext = JAXBContext.newInstance(classType);
  StringWriter writerTo = new StringWriter();
  Marshaller marshaller = jaxbContext.createMarshaller();
  marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); 
  marshaller.marshal(object, writerTo); //create xml string from the input object
  return writerTo.toString();
}

这是如此调用:ObjectToXml(o, ClassOfO.class)但是HashTable<String, String>.class错了(我已经知道了).

那里的Java大师能告诉我如何调用这段代码吗？建议更简单的实现(当然还有调用示例)也是最受欢迎的.

谢谢.

Answer 1

您需要创建一个包装类来保存Hashtable:

package forum7534500;

import java.util.Hashtable;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Wrapper {

    private Hashtable<String, String> hashtable;

    public Hashtable<String, String> getHashtable() {
        return hashtable;
    }

    public void setHashtable(Hashtable<String, String> hashtable) {
        this.hashtable = hashtable;
    }

}

然后,您可以执行以下操作:

package forum7534500;

import java.io.StringWriter;
import java.util.Hashtable;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Wrapper.class);
        Wrapper wrapper = new Wrapper();
        Hashtable<String, String> hashtable = new Hashtable<String,String>();
        hashtable.put("foo", "A");
        hashtable.put("bar", "B");
        wrapper.setHashtable(hashtable);
        System.out.println(objectToXml(jc, wrapper));
    }

    public static String objectToXml(JAXBContext jaxbContext, Object object) throws JAXBException
    {
      StringWriter writerTo = new StringWriter();
      Marshaller marshaller = jaxbContext.createMarshaller();
      marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); 
      marshaller.marshal(object, writerTo); //create xml string from the input object
      return writerTo.toString();
    }

}

这将产生以下输出:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<wrapper>
    <hashtable>
        <entry>
            <key>bar</key>
            <value>B</value>
        </entry>
        <entry>
            <key>foo</key>
            <value>A</value>
        </entry>
    </hashtable>
</wrapper>

注意事项

• JAXBContext 是一个线程安全的对象,应该创建一次并重用.
• Hashtable是同步的,如果你不需要这个,那么使用HashMap是常见的替代品.
• 惯例是使用小写字母启动Java方法名称.

自定义映射

您可以XmlAdapter在JAXB中使用a 来自定义任何类的映射.以下是我博客上帖子的链接,我将演示如何做到这一点:

• http://blog.bdoughan.com/2010/07/xmladapter-jaxbs-secret-weapon.html