使用XStream轉換BEAN到XML得時候，由於bean裡面有個Collection tasks屬性，結果解析出來的節點裡面有class="list"屬性：<tasks class="list">，很不好看，後來看到一封mail後知道，原來屬性Collection tasks初始化成了ArrayList，XStream發現定義的型別和初始化型別不一樣就會增加class="list"，屬性；只要把tasks改成ArrayList tasks就可以了，class="list"不再出現。以下是原文：

          > XStream writes a class attribute if the member type does not match the
          > type of the object instance stored in this field. Otherwise it is not
          > necessary to deserialize the objects again. In your case the member seems
          > of type collection, but you use actually an ArrayList? You may set the

          > default implementation for Collection to be an ArrayList.

另一種方式：

public class XMLUtil {  
    private static final XStream xStream = new XStream();  
  
    // 將物件轉為XML字串  
    public static <T> String toXML(T obj) {  
        Class<?> cls = obj.getClass();  
        xStream.alias(cls.getSimpleName().toLowerCase(), cls);  
        [color=red]xStream.aliasSystemAttribute(null, "class"); // 去掉 class 屬性[/color]  
        return xStream.toXML(obj);  
    }  
  
    // 將XML字串轉為物件  
    @SuppressWarnings({"unchecked"})  
    public static <T> T fromXML(String xml) {  
        return (T) xStream.fromXML(xml);  
    }  
}