简单实现用户注册,登录的留言簿

1.用户登录界面P142-1.1.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" isErrorPage="true"%>
    <%@ page import="java.net.URLEncoder" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>请登录</title>
<script type="text/javascript">

function check()
{
    var uid = document.getElementById("userid");
    
    if(uid.value == "")
        {
        alert("用户代码不能为空")
        return false;
        }
    if(login.password.value == "")
        {
        alert("密码不能为空");
        return false;
        }
    return true;
}


</script>

</head>
<body>

<form id="login" method="post" action="P142-1.3.jsp" onSubmit="return check();">
用户代码:
<input id="userid" name="userid" type="text" width="30" />
<a href="P142-3.1.jsp">注册新用户</a>
<br>
登录密码:
<input id="password" name="password" type="password" width="30" />
<br>
<input type="submit" value="登录"/>


</form>

</body>
</html>

2.服务器端返回登录信息P142-1.2.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@ page import="java.util.*" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>服务器端返回登录信息</title>

</head>
<body>
<%
String strmsgid = request.getParameter("msgid");

if(strmsgid == null || strmsgid.trim().length() == 0)
{
    out.print("请正确传递信息");
}
else
{
    int imsgid = Integer.parseInt(strmsgid);
    switch(imsgid)
    {
    case 1:
        out.print("请正确输入用户代码");
        
        break;
        
    case 2:
        out.print("请输入密码");
        
        break;
    case 3:
        out.print("密码输入错误");
        
        break;
    case 4:
        out.print("该用户不存在,请注册");
        
        break;
    case 5:
        out.print("请正确输入用户名称");
        
        break;
    case 6:
        out.print("提交成功");
        
        break;
    case 7:
        out.print("用户代码已存在");
        
        break;
    case 8:
        out.print("请登录");
        
        break;

        
        default:
            out.print("传递的msgid不认识");
            break; 
    
    }
    
}


out.print(", 秒后跳转回登录界面");
response.setHeader("refresh","3;P142-1.1.jsp");
%>







</body>
</html>

3.登录信息处理P142-1.3.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>登录信息处理</title>
</head>
<body>
<%



String ui = request.getParameter("userid");

String un = request.getParameter("username");

String pw = request.getParameter("password");

if(ui == null || ui.trim().length() == 0)
{
    response.sendRedirect("P142-1.2.jsp?msgid=1");
}
else if(pw == null || pw.trim().length() == 0)
{
    response.sendRedirect("P142-1.2.jsp?msgid=2");
}
else
{
    //查找用户信息
    Object obj = application.getAttribute(ui);
    
    if(obj != null)
    {
        String struser = obj.toString();
        
        String[] user = struser.split("#");
        
        String yonghu = user[0];
        String strusername = user[1];
        String mima = user[2];
    
        if(pw.equals(mima))
        {
            out.print("欢迎" +strusername + "登录成功,3秒后跳转到留言界面");
            //跳转到系统页面
            session.setAttribute("logining",strusername);
            
            response.setHeader("refresh","3;P142-2.1.jsp");
        }
        else
        {
            response.sendRedirect("P142-1.2.jsp?msgid=3");
        }
    }
    else
    {
        response.sendRedirect("P142-1.2.jsp?msgid=4");
    }
}

%>

</body>
</html>

4.留言簿界面P142-2.1.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>  
    <%@ page import="java.util.*" %>
    <%@ page import="java.text.*" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>留言簿</title>

<%

//检查登录状态
String Username = "";

Object o = session.getAttribute("logining");

if(o == null)
{
    response.sendRedirect("P142-1.2.jsp?msgid=8");
}
else
{
    Username = o.toString();
}

String liuy = request.getParameter("liuy");

if(liuy != null && liuy.trim().length() != 0)
{
    String strliuy = new String(liuy.getBytes("ISO-8859-1"),"UTF-8");
    
    //附加时间信息
    Date dt = new Date();
    
    //格式化时间
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    
    strliuy += "&nbsp;&nbsp;" + sdf.format(dt) + "&nbsp;&nbsp;留言人:&nbsp;" + Username;
    
    Object obj = application.getAttribute("liuy");
    ArrayList<String> al;
    if(obj == null)
    {
    al = new ArrayList<String>();
    
    al.add(strliuy);
    
    application.setAttribute("liuy", al);    
    }
    else
    {
        ArrayList<String> A = (ArrayList<String>)obj;
        
        A.add(strliuy);
        
        application.setAttribute("liuy", A);
    }
}
else
{
    
}


%>



</head>
<body>

<form method="post">    


<p>输入您的留言：    
<br>     
 <textarea rows="10" cols="36"  name="liuy">    
</textarea>    
<br>字数不多于100字
<input type="submit" name="submit" value="提交信息">    </p>    </form>     

<form action="P142-2.2.jsp" method="post">    
<input type="submit" name="look" value="查看留言板">   
</form>

<br><br>




</body>
</html>

5.留言查看界面P142-2.2.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@ page import="java.util.*" %>
    <%@ page import="java.text.*" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>留言板</title>



</head>
<body>

<form>
最新留言:


<br>

<%



int i = 1;

Object obj = application.getAttribute("liuy");

if(obj != null)
{
    ArrayList<String> A = (ArrayList<String>)obj;

for(int m = A.size() - 1; m >= 0 ; m--)
{
    out.print(i + "." + A.get(m) + "<br>");
    
    i++;
}
}
%>
<br>


</form>



</body>
</html>

6.用户注册界面以及从客户端返回信息P142-3.1.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>注册新用户</title>
<script type="text/javascript">

function check()
{    
    if(zhuce.userid.value == null || zhuce.userid.value.trim().length ==0)
        {
        alert("请输入用户代码")
        return false;
        }
    if(zhuce.username.value == null || zhuce.username.value.trim().length ==0)
        {
        alert("请输入用户名称");
        return false;
        }
    if(zhuce.password.value == null || zhuce.password.value.trim().length ==0)
        {
        alert("请输入密码");
        return false;
        }
    if(zhuce.password2.value == null || zhuce.password2.value.trim().length ==0)
        {
        alert("请再次密码");
        return false;
        }
    if(zhuce.password2.value != zhuce.password.value)
        {
        alert("两次输入的密码不一致");
        return false;
        }
    return true;
}


</script>
</head>
<body>
<form id="zhuce" action="P142-3.2.jsp" onSubmit="return check()" >

用户代码:<input id="userid" type="text" name="userid" width=30 />
<br><br>
用户名称:<input id="username" type="text" name="username" width=30 />
<br><br>
输入密码:<input id="password" type="password" name="password" width=30 />
<br><br>
确认密码:<input id="password2" type="password" name="password2" width=30 />
<br><br>
<input type="submit" value="提交" />

</form>

</body>
</html>

7.用户注册信息处理P142-3.2.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>用户注册信息保存</title>
</head>
<body>

<%
String un = request.getParameter("username");

String ui = request.getParameter("userid");

String pw = request.getParameter("password");

String pw2 = request.getParameter("password2");

if(ui == null || ui.trim().length() == 0)
{
    response.sendRedirect("P142-1.2.jsp?msgid=1");
}
else if(un == null || un.trim().length() == 0)
{
    response.sendRedirect("P142-1.2.jsp?msgid=5");
}
else if(pw == null || pw.trim().length() == 0)
{
    response.sendRedirect("P142-1.2.jsp?msgid=2");
}
else
{
    Object obj = application.getAttribute(ui);
    
    if(obj != null)
    {
        response.sendRedirect("P142-1.2.jsp?msgid=7");
    }
    else
    {
    String struser = ui + "#" + new String(un.getBytes("ISO-8859-1"),"UTF-8") + "#" + pw;
    
    application.setAttribute(ui, struser);
    
    response.sendRedirect("P142-1.2.jsp?msgid=6");
    }
}



%>

</body>
</html>
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原文地址：https://www.cnblogs.com/shadowduke/p/5005868.html