用MVC架构简单的注册、登录例子
MVC的概念，大家都清楚吧，Model，View，Control
首先我们看看这个目录结构
--+login
----------+WEB-INF
-----------------------+classes
-beans
-tags
-----------+tlds
login 是主目录放jsp文件，在例子login.jsp，loginFailed.jsp，login_form.jsp，newAccount.jsp，welcome.jsp，accountCreated.jsp
Web-inf下面有web.XML配置文件，classes文件夹放类，tlds文件夹放自定义标签
由于我没有用到数据库，所以没有用LIB文件夹，是来放置 *.jar 文件的。
classes目录下，有beans，tags文件夹，分别放置User，LoginDB类，和自定义标签类GetRequestParameterTag，classes目录下还直接放了LoginServlet，NewAccountServlet控制器类
我们先看beans下的两个业务对象类
User.Java
package beans;
public class User implements java.io.Serializable {
private final String userName, passWord, hint;
//final强调此属性初始化后，不能修改hint是口令提示
public User(String userName, String password, String hint) {
this.userName = userName;
this.password = password;
this.hint = hint;
}
public String getUserName(){
return userName;
}
public String getPassword(){
return password;
}
public String getHint(){
return hint;
}
//判定当前对象用户名和密码是否相等
public boolean equals(String uname, String upwd) {
return getUserName().equals(uname) && getPassword().equals(upwd);
}
}
LoginDB.java
package beans;
import java.util.Iterator;
import java.util.Vector;
public class LoginDB implements java.io.Serializable {
private Vector users = new Vector();
//Vector类是同步的，所以addUser就不需要同步了
public void addUser(String name, String pwd, String hint) {
users.add(new User(name, pwd, hint));
}
//下面方法判定是否存在正确的user
public User getUser(String name,String pwd) {
Iterator it = users.iterator();
User user;
//迭代需要同步
synchronized(users) {
while(it.hasNext()){
user = (User)it.next();
if(user.equals(name,pwd))
return user;//假如返回真，就返回当前user
}
}
return null;
}
public String getHint(String name) {
Iterator it = users.iterator();
User user;
synchronized(users) {
while(it.hasNext()){
user = (User)it.next();
if(user.getUserName().equals(name))
return user.getHint();
}
}
return null;
}
}
login.jsp
<Html
<head
<meta http-equiv="Content-Type" content="text/html; charset=gb2312"
<titleLogin Page</title
</head
<body
<%@ include file="login_form.jsp" %
</body
</html
被包含的login_form.jsp
<%@ taglib uri="utilities" prefix="util" %
<!--调用自定义标签，引用为util，uri的utilities在web.xml映射了--
<p<font color="#6666CC"请登陆</font</p
<hr
<form name="form1" method="post" action="<%=response.encodeURL("login")%"<!--login是LoginSevlet通过在web.xml映射了--
<table width="68%" border="0" cellpadding="2" cellspacing="2"
<tr
<td width="33%" align="right"用户名：</td
<td width="67%"
<input type="text" name="userName" value="<util:requestParameter property='userName'/"</td<!--注重这里用了自定义标签，假如有值就显示--
</tr
<tr
<td align="right"密码：</td
<td<input type="text" name="userPwd" </td
</tr
<tr align="center"
<td colspan="2"
<input type="submit" name="Submit" value="登陆"
</td
</tr
</table
</form
LoginServlet.java
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
import beans.User;
import beans.LoginDB;
public class LoginServlet extends HttpServlet {
private LoginDB loginDB;
public void init(ServletConfig config) throws ServletException {
super.init(config);
loginDB = new LoginDB();
config.getServletContext().setAttribute("loginDB",loginDB);
}
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException,IOException{
String name = request.getParameter("userName"); //从login_form 表单得到值
String pwd = request.getParameter("userPwd");
User user = loginDB.getUser(name,pwd);
if(user != null){//说明存在用户
request.getSession().setAttribute("user",user); //放到session 里面
request.getRequestDispatcher(response.encodeURL("/welcome.jsp")).forward(request,response);//成功转发到welcome.jsp
}else{
request.getRequestDispatcher(response.encodeURL("/loginFailed.jsp")).forward(request, response);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException,IOException{
doGet(request,response);
}
}
web.xml添加
<servlet
<servlet-nameLogin</servlet-name<!--名字--
<servlet-classLoginServlet</servlet-class<!--指定类--
</servlet<servlet
<servlet-namenew_account</servlet-name
<servlet-classNewAccountServlet</servlet-class
</servlet
<servlet-mapping
<servlet-namenew_account</servlet-name
<url-pattern/new_account</url-pattern
</servlet-mapping
<servlet-mapping
<servlet-nameLogin</servlet-name<!--和上面的名字一致--
<url-pattern/login</url-pattern<!--映射路径--
</servlet-mapping
<taglib
<taglib-uriutilities</taglib-uri
<taglib-location/WEB-INF/tlds/utilities.tld</taglib-location
<!--自定义标签的实际位置--
</taglib
utilities.tld要害部分
<taglib
<tag
<namerequestParameter</name
<tagclasstags.GetRequestParameterTag</tagclass
<!--类的位置，假如有包写上--
<infoSimplest example: inserts one line of output</info
<bodycontentEmpty</bodycontent
<attribute
<nameproperty</name
<requiredtrue</required
<rteXPrvaluetrue</rtexprvalue
</attribute
</tag
</taglib
自定义标签类GetRequestParameterTag.java
package tags;
import javax.servlet.ServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
public class GetRequestParameterTag extends TagSupport {
private String property;
public void setProperty(String property){
this.property = property;
}
public int doStartTag() throws JspException {
ServletRequest reg = pageContext.getRequest();
String value = reg.getParameter(property);
try{
pageContext.getOut().print(value == null ? "":va
