jsp基于XML实现用户登录与注册的实例解析（附源码）

public class DocumentFactory { 
 private static Document dom=null;//需要共享一个dom，所以需要设置为static 
 private static String name="user.xml"; 
 private static String filename; 


//写一个静态块实现对dom树的读取 
static{//dom4j技术 
 SAXReader read=new SAXReader(); 
 filename=DocumentFactory.class.getClassLoader().getResource(name).getPath();//采用类加载器进行读取文件 
  try { 
  dom=read.read(filename); 
  } catch (DocumentException e) {span style="font-family: Arial, Helvetica, sans-serif;">  e.printStackTrace();}}/span> 

//主要获得和存储的两个函数（采用单例模式）（必须共享一个dom数） 

public static Document getDocument(){ //获得xml中的dom树 
 return dom; 
} 

//注册之后需要保存 
 public static void Save() { 
 XMLWriter wr; 
 try { 
  wr = new XMLWriter(new FileOutputStream(filename)); 
 }catch (Exception e1) { 
  throw new RuntimeException("存储文件时读文件失败"); 
 } 
 try { 
  wr.write(dom); 
 } catch (IOException e) { 
  throw new RuntimeException("写文件失败"+e.getMessage()); 
 }finally{ 
  try { 
  if(wr!=null){ 
  wr.close(); 
  } 
  } catch (IOException e) { 
  throw new RuntimeException("关流失败"+e.getMessage());}}} 
} 

body> 
  form action='login' method="post"> 
  用户名：input type="text" name="name" />br/> 
  密 码 ：input type="text" name="pwd" />br/> 
  验证码：input type="text" name="checkCode">img src="/LOGIN/immg" id='imgid'>a href="javascript:flush()">看不清/a>//需要重写一个js进行刷新 
  br/> 
  input type="submit"value="登录" /> 
  input type="reset"value="重置" /> 
  a href='jsps/Reg.jsp'>注册/a> 
  
 /form> 

public class Login extends HttpServlet { 
 
 public void doGet(HttpServletRequest request, HttpServletResponse response) 
  throws ServletException, IOException { 
 doPost(request, response); 
 } 
 
 
 public void doPost(HttpServletRequest request, HttpServletResponse response) 
  throws ServletException, IOException { 
  
 request.setCharacterEncoding("utf-8");//设置utf-8的编码格式去接收 
 response.setContentType("text/html;charset=UTF-8");//span style="color:#ff0000;">设置页面显示方式，这个设置必须要在获得输出流之前设置，不然设置都没有用，照样会出现乱码/span> 
 PrintWriter out = response.getWriter(); 
  
 out.println("!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">"); 
 out.println("HTML>"); 
 out.println(" HEAD>TITLE>A Servlet/TITLE>"); 
 out.println(" meta http-equiv='content-type' content='text/html; charset=UTF-8'> /HEAD>"); 
 out.println(" BODY>"); 
 String name=request.getParameter("name"); 
 String pwd=request.getParameter("pwd"); 
 String check=request.getParameter("checkCode");//从界面获得验证码输入的值 
 ImgDemo id =new ImgDemo(); 
 String str=id.getStr(); 
 if(!check.equals(str)){ 
  out.println("登录失败，验证码不正确！！");//要是验证码不符合，直接返回登录界面 
  out.print("a href='index.jsp'>返回登录/a>"); 
  return; 
 } 
// System.out.println("11"+check); 
// System.out.println("22"+str); 
  
 //登录前获得所有的对象 
 Document dom=DocumentFactory.getDocument(); 
 boolean flag=false; 
 Element root=dom.getRootElement(); 
 IteratorElement> it=root.elementIterator(); 
  
 while(it.hasNext()){ 
  Element ele =it.next(); 
  String nameC=ele.attributeValue("name"); 
  String pwdC=ele.attributeValue("pwd"); 
  if(name.trim().equals(nameC)pwdC.equals(pwdC)){ 
  flag=true; 
  break; 
  } 
 } 
 if(flag){ 
  out.print("font color='red' size='8px'>恭喜您，登陆成功！/font>"); 
  out.println("a href='index.jsp'>返回登录/a>"); 
 }else{ 
  out.print("用户名和密码不匹配。登录失败。。。"); 
  out.println("a href='index.jsp'>返回登录/a>"); 
 } 
 out.println(" /BODY>"); 
 out.println("/HTML>"); 
 out.flush(); 
 out.close(); 
 } 
 
} 

body> 
 form action='reg' method="post"> 
  用户 名：input type="text" name="name" onblur="check()" id="name"/>span id="spanid">/span>br/> 
  密 码 ： input type="text" name="pwd" id="pwd" onblur="check1()"/>span id="spanid1">/span>br/> 
  确认密码 ：input type="text" name="pwd2" id="pwd2" onblur="check2()"/>span id="spanid2">/span>br/> 
  input type="submit"value="注册" /> 
  input type="reset"value="重置" /> 
  
 /form> 
 /body> 

public void doPost(HttpServletRequest request, HttpServletResponse response) 
  throws ServletException, IOException { 
 
 response.setContentType("text/html;charset=utf-8");//span style="color:#ff0000;">必须要设置在获得Printwrite之前，都则设置无效/span> 
 PrintWriter out = response.getWriter(); 
 out.println("!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">"); 
 out.println("HTML>"); 
 out.println(" HEAD>TITLE>A Servlet/TITLE>/HEAD>"); 
 out.println(" BODY>"); 
 boolean flag=false; 
  
 request.setCharacterEncoding("utf-8"); 
 String name=request.getParameter("name"); 
 String pwd=request.getParameter("pwd"); 
  
  
 Document dom =DocumentFactory.getDocument(); 
 Element root=dom.getRootElement(); 
 IteratorElement> it=root.elementIterator(); 
 while(it.hasNext()){ 
  Element ele=it.next(); 
  String nameR=ele.attributeValue("name");//这里传过来的值可能是null.所以我们必须在前台要预防一下，当然在这里也要考虑一下 
  String pwdR=ele.attributeValue("pwd"); 
  if(name.equals(nameR)pwd.equals(pwdR)){ 
  flag=true; 
  break; 
  } 
 } 
 if(flag){ 
  out.print("此用户已注册！！"); 
  out.print("a href='jsps/Reg.jsp'>返回注册/a>"); 
 }else{ 
  Element ele=root.addElement("user"); 
  ele.addAttribute("name", name); 
  ele.addAttribute("pwd", pwd); 
  DocumentFactory.Save(); 
  out.print("注册成功！！"); 
  out.print("a href='index.jsp'>返回登录/a>"); 
 } 
 out.println(" /BODY>"); 
 out.println("/HTML>"); 
}