My iPhone 4 is a lemon, oh my! (updated)

我是要把一个JAVABEAN写入一个XML中，然后再度出，我是利用了一个vector，先把所有要读入的同一个StudentBean都添加到一个vector中我的StudentBean如下：
        
import java.io.Serializable;


public class StudentBean implements Serializable
{
String name;
String sex;
String phone;
public StudentBean(String name, String sex, String phone) {
super();
this.name = name;
this.sex = sex;
this.phone = phone;
}
public StudentBean()
{};

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
}

       写操作是如下：
import org.w3c.dom.*;
import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import java.io.*;
import java.util.Vector;


public class writexml {
private Document document;
private String filename;


public writexml(String name) throws ParserConfigurationException{
filename=name;
DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
DocumentBuilder builder=factory.newDocumentBuilder();
document=builder.newDocument();
}

public void toWrite(Vector<StudentBean> stu_vector)
{
Element root = document.createElement("seller_record");
document.appendChild(root);
for(int i = 0;i<stu_vector.size();i++)
{
StudentBean stu = (StudentBean) stu_vector.get(i);
Element student = document.createElement("student");
student.setAttribute("name",stu.name);
root.appendChild(student);

Element sex = document.createElement("sex");
student.appendChild(sex);
Text tsex = document.createTextNode(stu.sex);
sex.appendChild(tsex);

Element phone = document.createElement("phone");
student.appendChild(phone);
Text tphone = document.createTextNode(stu.phone);
phone.appendChild(tphone);
}
}


public void toSave(){
try{
TransformerFactory tf=TransformerFactory.newInstance();
Transformer transformer=tf.newTransformer();
DOMSource source=new DOMSource(document);
transformer.setOutputProperty(OutputKeys.ENCODING,"GB2312");
transformer.setOutputProperty(OutputKeys.INDENT,"yes");
PrintWriter pw=new PrintWriter(new FileOutputStream(filename));
StreamResult result=new StreamResult(pw);
transformer.transform(source,result);
}
catch(TransformerException mye){
mye.printStackTrace();
}
catch(IOException exp){
exp.printStackTrace();
}
}
public static void main(String args[]){
Vector<StudentBean> stu_vector = new Vector<StudentBean>();
StudentBean stu = new StudentBean("姚明","男","123456");
stu_vector.add(stu);
stu = new StudentBean("刘翔","女","0988556");
stu_vector.add(stu);

try{
writexml myxml=new writexml("E:\\软件\\eclipse\\workstation\\IOxml\\src\\seller.xml");
myxml.toWrite(stu_vector);
myxml.toSave();
System.out.print("Your writing is successful.");
}
catch(ParserConfigurationException exp){
exp.printStackTrace();
System.out.print("Your writing is failed.");
}
}
}
       下面是读操作：

import java.io.*;
import java.util.Vector;
import javax.xml.parsers.*;
import org.w3c.dom.*;

public class readxml {
static Document document;
private boolean validating;

public readxml() {
}

public Vector<StudentBean> toRead(String filename)
{
Vector<StudentBean> stu_vector=new Vector<StudentBean>();
StudentBean stu = new StudentBean();
try {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setIgnoringElementContentWhitespace(true);
factory.setValidating(validating);
DocumentBuilder builder = factory.newDocumentBuilder();
document = builder.parse(new File(filename));
// document.getDocumentElement().normalize();//注释（0）
Element root = document.getDocumentElement();
NamedNodeMap attr;
NodeList children = root.getElementsByTagName("student");//注释（1）
attr = root.getAttributes();

if(attr!=null)
{
for(int i = 0;i<children.getLength();i++)
{
Element element= (Element) children.item(i);
stu.setName(element.getAttribute("name"));
NodeList list = element.getChildNodes();
System.out.println(list.getLength());
Node child = list.item(i);
System.out.println(element.getAttribute("name"));
System.out.println(list.item(1).getTextContent());//注释（2）
System.out.println(list.item(3).getTextContent());//注释（3）
stu.setName(element.getAttribute("name"));
stu.setSex(list.item(1).getTextContent());
stu.setPhone(list.item(3).getTextContent());
stu_vector.add(stu);

}
}
}
catch (Exception exp)
{
exp.printStackTrace();
return null;
}
return stu_vector;

}

public static void main(String[] args) {
Vector<StudentBean> A = null;
readxml my = new readxml();
A = my.toRead("E:\\软件\\eclipse\\workstation\\IOxml\\src\\seller.xml");
System.out.println(A.size());
System.out.println("asd");
}
}
       在下面是我读入的XML格式如下：
<seller_record>
−
<student name="姚明">
<sex>男</sex>
<phone>123456</phone>
</student>
−
<student name="刘翔">
<sex>女</sex>
<phone>0988556</phone>
</student>
</seller_record>
我写入的XML文档根有两个孩子，两个孩子又有3个node；
           下面简要谈一下我对读操作的理解（主要是我标的注释的地方）：
注释（1）：以tag为student为标志建立NodeList，其长度为2，这个是符合逻辑的，但是下面的children的长度老提示是5，开始时令我很郁闷，后来查书和上网看了一下，才知道原来
<student name="姚明">
<sex>男</sex>他们两个之间是有空格的，他们之间的空格也算一个Node，所以才形成了注释（2）（3）的item标号为1，3。书上说有办法吧他们之间的空格去掉，其给的一个办法是用以下方法：
for(int i=0;i<list.getLength();i++)
{
Node child = list.item(i);
if(child instanceof Element)
{
Element childElement = (Element)child;
System.out.println(childElement.getTextContent());
}
}
但我认为是没必要，因为它实际上是把空格去掉或者再添加到一个NodeList中，我认为完全没有这个必要，还有另一个方法就是再写入的时候注明文档的文档类型，其实我不知道注释（0）的作用，一开始感觉应该跟刚才的空格问题有关，但是后来试了一下发现有没有这行代码都没有什么影响，不知道为什么。如果大家看了还有什么不明白的地方可以共同探讨一下，我也还有很多要学习的地方。