xml文档如下：

<?xml version="1.0" ?>
<customers>
  <customer >
    <id ref="pjl"/>
    <name dd="dd"/>
    <address ee="ds"/>
  </customer>
  <customer>
    <id ref="jjj">#002</id>
    <name dd="dd">Car</name>
    <address ee="dd">Suzhou</address>
  </customer>
  <customer>
    <id ref="ww">#003</id>
    <name dd="ee">Jimmy</name>
    <address ee="rr">ChengDu</address>
  </customer>
  <customer>
    <id ref="ww">#004</id>
    <name dd="r">Henry</name>
    <address ee="hh">Xi'an</address>
  </customer>
</customers>

程序如下，错误出处已标在程序中：

import org.w3c.dom.Document;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.NodeList;
import org.w3c.dom.Node;
import org.w3c.dom.Element;

public class Saveadds extends Object{
  public static void main(String args[]) {
    String addsFile="adds.xml";
    Document addsDoc = null;
    try {
      DocumentBuilderFactory docbuilderfactory = DocumentBuilderFactory.newInstance();
      DocumentBuilder docbuilder = docbuilderfactory.newDocumentBuilder();
      addsDoc = docbuilder.parse(addsFile);
      Element addsRoot=addsDoc.getDocumentElement();
      NodeList Address=addsRoot.getElementsByTagName("customer");
      for (int i=0;i<Address.getLength();i++){
             Element cntAddress = (Element)Address.item(i);
             String id= cntAddress.getElementsByTagName("id").item(0).getFirstChild().getNodeValue();
             System.out.println(id);
             String refattri=cntAddress.getAttribute("ref");
             System.out.println(refattri);
           /**就是上面两行，其实就是抽取并输出元素中的属性。下面还有几行相似的代码。如果不写它们，程序执行没问题，但只要有它

们，就出现“Cannot read the addsfile:null”的错误**/
             String name=cntAddress.getElementsByTagName("name").item(0).getFirstChild().getNodeValue();
             System.out.println(name);
             String ddattri=cntAddress.getAttribute("dd");
             System.out.println(ddattri);
             String address = cntAddress.getElementsByTagName("address").item(0).getFirstChild().getNodeValue();
             System.out.println(address);
             String eeattri=cntAddress.getAttribute("ee");
             System.out.println(eeattri);
           }
        }
    catch (Exception e) {
      System.out.println("Cannot read the addsfile:" + e.getMessage());
    }
  }
}

接着我又重新编写了另外的一个程序，如下：

import org.w3c.dom.Document;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.NodeList;
import org.w3c.dom.Node;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;

public class Saveadds extends Object{
  public static void main(String args[]) {
    String addsFile="adds.xml";
    Document addsDoc = null;
    try {
      DocumentBuilderFactory docbuilderfactory = DocumentBuilderFactory.newInstance();
      DocumentBuilder docbuilder = docbuilderfactory.newDocumentBuilder();
      addsDoc = docbuilder.parse(addsFile);
      addsDoc.normalize();
      NodeList Address=addsDoc.getElementsByTagName("customer");
      for (int i=0;i<Address.getLength();i++)
          {
             Node cntAddress = Address.item(i);
             NamedNodeMap nnm = cntAddress.getAttributes();
             if(nnm!=null)
             {
               Node[] matchNodes = new Node[nnm.getLength()];
               for (int j=0; j<nnm.getLength();j++)
               {
                  matchNodes[j] = nnm.item(j);
               }
               for (int ii=0;ii<nnm.getLength();ii++)
                {
                  Node node = matchNodes[i];
                  System.out.print(node.getNodeName() + "=" +node.getNodeValue() );
                }
             }
           }
        }
    catch (Exception e) {
      System.out.println("Cannot read the addsfile:" + e.getMessage());
    }
  }
}

编译没问题，但是为什么执行该程序时没有任何结果，只会再次显示java文件编辑通过的结果，难道它又一次编辑了该java文件？。

这些问题看起来复杂，其实对于高手来说应该比较简单吧，急盼各位相助，小弟感激不尽！

ref的值必须是实际存在的。看了你的文档，发现好几个ref的值并没有在文档中出现。是不是因为这个问题？

pjl
#002
jjj
#003