attr.java

使用方法： 实例程序的运行： 每个实例下都有本实例的.xml文件或.html文件或.xsl文件

package org.w3c.dom;

/**
 * The <code>Attr</code> interface represents an attribute in an 
 * <code>Element</code> object.Typically the allowable values for the 
 * attribute are defined in a documenttype definition.
 * <p><code>Attr</code> objects inherit the <code>Node</code>  interface, but 
 * since they are not actually child nodes of the element  they describe, the 
 * DOM does not consider them part of the document  tree.  Thus, the 
 * <code>Node</code> attributes <code>parentNode</code>,  
 * <code>previousSibling</code>, and <code>nextSibling</code> have a  null 
 * value for <code>Attr</code> objects. The DOM takes the  view that 
 * attributes are properties of elements rather than having a  separate 
 * identity from the elements they are associated with;  this should make it 
 * more efficient to implement such features as default attributes associated 
 * with all elements of a  given type.  Furthermore, <code>Attr</code> nodes 
 * may not be immediate children of a <code>DocumentFragment</code>. However, 
 * they can be associated with <code>Element</code> nodes contained within a 
 * <code>DocumentFragment</code>. In short, users and implementors of the DOM 
 * need to be aware that  <code>Attr</code> nodes have some things in  common 
 * with other objects inheriting the <code>Node</code> interface,  but they 
 * also are quite distinct.
 * <p> The attribute's effective value is determined as follows: if this  
 * attribute has been explicitly assigned any value, that value is the  
 * attribute's effective value; otherwise, if there is a declaration for  
 * this attribute, and that declaration includes a default value, then  that 
 * default value is the attribute's effective value; otherwise, the  
 * attribute does not exist on this element in the structure model until  it 
 * has been explicitly added.  Note that the <code>nodeValue</code>  
 * attribute on the <code>Attr</code> instance can also be used to retrieve 
 * the string version of the attribute's value(s). 
 * <p>In XML, where the value of an attribute can contain entity references, 
 * the child nodes of the <code>Attr</code> node provide a representation in 
 * which entity references are not expanded. These child nodes may be either 
 * <code>Text</code> or <code>EntityReference</code> nodes. Because the 
 * attribute type may be unknown, there are no tokenized attribute values. 
 */
public interface Attr extends Node {
  /**
   * Returns the name of this attribute. 
   */
  public String             getName();
  /**
   * If this attribute was explicitly given a value in the original document, 
   * this is <code>true</code>; otherwise, it is <code>false</code>. Note 
   * that the implementation is in charge of this attribute, not the user. If 
   * the user changes the value of the attribute (even if it ends up having 
   * the same value as the default value) then the <code>specified</code> 
   * flag is automatically flipped to <code>true</code>.  To re-specify the 
   * attribute as the default value from the DTD, the user must delete the 
   * attribute. The implementation will then make a new attribute available 
   * with <code>specified</code> set to <code>false</code> and the default 
   * value (if one exists).
   * <br>In summary: If the attribute has an assigned value in the document 
   * then  <code>specified</code> is <code>true</code>, and the value is the  
   * assigned value. If the attribute has no assigned value in the document 
   * and has  a default value in the DTD, then <code>specified</code> is 
   * <code>false</code>,  and the value is the default value in the DTD. If 
   * the attribute has no assigned value in the document and has  a value of 
   * #IMPLIED in the DTD, then the  attribute does not appear  in the 
   * structure model of the document.
   */
  public boolean            getSpecified();
  /**
   * On retrieval, the value of the attribute is returned as a string. 
   * Character and general entity references are replaced with their values.
   * <br>On setting, this creates a <code>Text</code> node with the unparsed 
   * contents of the string.
   */
  public String             getValue();
  public void               setValue(String value);
}