登录验证添加验证码验证，Cookie保存功能

1，登录表单,login.jsp

<%@ page contentType="text/html" pageEncoding="GBK"%>
<%
    request.setCharacterEncoding("GBK");
%>
<center>
    <form action="check.jsp" method="post">
        <h1>用户登录</h1>
        <%=request.getAttribute("errMsg")!=null? request.getAttribute("errMsg"):""%><br>
        用户名:<input type="text" name="username"><br/>
        密&nbsp;码:<input type="password" name="password"><br/>
    验证码:&nbsp;<input name="code" type="text" size="4" maxlength="4"><img src="image.jsp"/><br/>
        保存密码:<select name="saveTime">
            <option value="<%=0%>">不保存</option>
            <option value="<%=3600*24%>">保存一天</option>
            <option value="<%=3600*24*7%>">保存一星期</option>
            <option value="<%=3600*24*30%>">保存一月</option>
            <option value="<%=3600*24*30*12%>">保存一年</option>
        </select><br/><br/>
        <input type="submit" value="登录">        
    </form>
</center>

2,JDBC校验,check.jsp

<%@ page contentType="text/html" pageEncoding="GBK"%>
<%@ page import="java.sql.*"%>
<%
    request.setCharacterEncoding("GBK");
String rand=(String)session.getAttribute("rand");
String userName=request.getParameter("username");
String userPass=request.getParameter("password");
String code=request.getParameter("code");    
String DBDRIVER="oracle.jdbc.driver.OracleDriver";                                     
String DBURL="jdbc:oracle:thin:@localhost:1521:study";                                
String DBUSER="scott";
String DBPASSWORD="tiger";    
long cookieTime=0;
    try
    {
        cookieTime=Long.parseLong(request.getParameter("saveTime"));
    }
    catch(Exception ex)
    {
        
    }
    
        
    Connection conn=null;
    PreparedStatement psmt=null;
    ResultSet rst=null;
    
boolean flag=false;
%>
<% //判断用户名密码是否为空
if(("".equals(userName)||null==userName)||("".equals(userPass)||null==userPass))
    {
        request.setAttribute("errMsg","用户名或密码不能为空!");
%>
    <jsp:forward page="login.jsp"/>
<%        
    }    
%>
<% //判断验证码是否正确
if(!code.equalsIgnoreCase(rand))
    {
        request.setAttribute("errMsg","输入的验证码不正确");
%>
    <jsp:forward page="login.jsp"/>
<%        
    }    
%>
<%
String sql="select id,username,password from userinfo where username=? and password=?";
    Class.forName(DBDRIVER);    
    try
    {
        conn=DriverManager.getConnection(DBURL,DBUSER,DBPASSWORD);
        psmt=conn.prepareStatement(sql);
        psmt.setString(1,userName);
        psmt.setString(2,userPass);
        rst=psmt.executeQuery();
if(rst.next())
        {
String name=rst.getString(2);
String password=rst.getString(3);
            session.setAttribute("userid",rst.getInt(1));
            session.setAttribute("username",rst.getString(2));
            Cookie c1=new Cookie("username",name);
            Cookie c2=new Cookie("password",password);
            c1.setMaxAge((int)cookieTime);
            c2.setMaxAge((int)cookieTime);
            response.addCookie(c1);
            response.addCookie(c1);
            flag=true;
        }
else
        {
            request.setAttribute("errMsg","用户名或密码不正确!");
        }
    }
    catch(Exception ex)
    {
        ex.printStackTrace();
    }
    finally
    {
        try
        {
            conn.close();
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
        }
    }
%>
<%
if(flag)
    {
%>
    <jsp:forward page="welcome.jsp"/>
<%        
    }
else
    {
%>
    <jsp:forward page="login.jsp"/>
<%        
    }
%>

3,Cookie的验证,cookie.jsp

<%@ page contentType="text/html" pageEncoding="GBK"%>
<%@ page import="java.sql.*"%>
<%
if(session.getAttribute("username")==null)
    {
String userName=null;
String userPass=null;
        Cookie[] ck=request.getCookies();
for(int i=0;i<ck.length;i++)
        {
if("username".equals(ck[i].getName()))
            {
                userName=ck[i].getValue();
            }
if("password".equals(ck[i].getName()))
            {
                userPass=ck[i].getValue();
            }
        }
%>
<%
String DBDRIVER="oracle.jdbc.driver.OracleDriver";                                     
String DBURL="jdbc:oracle:thin:@localhost:1521:study";                                
String DBUSER="scott";
String DBPASSWORD="tiger";    
        Connection conn=null;
        PreparedStatement psmt=null;
        ResultSet rst=null;
String sql="select id,username,password from userinfo where username=? and password=?";
        Class.forName(DBDRIVER);    
        try
        {
            conn=DriverManager.getConnection(DBURL,DBUSER,DBPASSWORD);
            psmt=conn.prepareStatement(sql);
            psmt.setString(1,userName);
            psmt.setString(2,userPass);
            rst=psmt.executeQuery();
if(rst.next())
            {
String name=rst.getString(2);
String password=rst.getString(3);
                session.setAttribute("userid",rst.getInt(1));
                session.setAttribute("username",rst.getString(2));        
            }
else
            {
                request.setAttribute("errMsg","用户名或密码不正确!");
            }
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
        }
        finally
        {
            try
            {
                conn.close();
            }
            catch(Exception ex)
            {
                ex.printStackTrace();
            }
        }
%>
<%
    }
%>

　　这里需要注意的是，在登录成功的欢迎页面中包含了此页面，通过判断session中是否存在登录成功后保存的用户名信息，进行处理。(如果没有就进行cookie信息的验证)
4,欢迎页,welcom.jsp

<%@ page contentType="text/html" pageEncoding="GBK"%>
<% request.setCharacterEncoding("GBK"); %>
<jsp:include page="cookie.jsp"/>
<%    
if(session.getAttribute("username")!=null)
    {
%>
    <h1>欢迎,<%=session.getAttribute("username")%>光临,此用户id为:<%=session.getAttribute("userid")%></h1>
    <a href="invalidate.jsp">注销登录</a>
    
<%
     }
%>

5,注销session,invalidate.jsp

<%@ page contentType="text/html" pageEncoding="GBK"%>
<%
    request.setCharacterEncoding("GBK");
    session.invalidate();
%>