重定向验证 [英] Validation on Redirect
问题描述
validation.java
validation.java
try
{
conn = dsEvent.getConnection();
String userCheck = "select * from customer";
stmt = conn.createStatement();
rs = stmt.executeQuery(userCheck);
while(rs.next()){
if((email.equals(rs.getString("email")))&&(password.equals(rs.getString("password"))))
{
RequestDispatcher rd = req.getRequestDispatcher("/success.jsp");
rd.forward(req,res);
}
else
{
req.getSession().setAttribute("error", "The email or password you entered is incorrect. Please try again");
res.sendRedirect(this.getServletContext().getContextPath() + "/index.jsp");
}
}
} catch (SQLException ex) {
System.err.println(ex);
}
}
index.jsp
index.jsp
<body>
<h2>System</h2>
<p style ="color:red"><%=session.getAttribute("error")!=null ? "":session.getAttribute("error") %></p>
<form method ="post" action="validation">
Please Login: <br/>
Email: <input type="email" name="email" required/><br/>
Password: <input type="password" name="password" required/><br/>
<input type ="submit" value="Login"/>
</form>
</body>
我正在验证电子邮件和密码。因此，当用户输入正确的电子邮件和密码时，它将转发到success.jsp。如果用户输入错误的细节，它会将页面重定向到index.jsp以及错误。
I'm doing a validation for email and password. So when user input correct email and password it will forward to success.jsp. And if the user input wrong details, it will redirect the page to index.jsp together with the error.
但我似乎无法让它在错误上工作详细信息parts.It给了我
But I can't seem to get it work on the wrong detail parts.It gave me
警告：StandardWrapperValve [com.events.ValidationServlet]：PWC1406：
Servlet.service（） for servlet com.events.ValidationServlet抛出
异常
WARNING: StandardWrapperValve[com.events.ValidationServlet]: PWC1406: Servlet.service() for servlet com.events.ValidationServlet threw exception
推荐答案
为什么要迭代通过整个结果集并验证用户是否存在而不是尝试更改选择查询以检查特定用户是否存在在您的数据库中或不。
Why are you iterating through whole resultset and validating if user is present or not instead try changing your select query to check if particular user is present in your database or not.
为此，请尝试以下代码
String email = request.getParameter("email");
String password = request.getParameter("password");
String userCheck = "select * from tableName where username = ? AND password = ?";
PreparedStatement ps = con.prepareStatement(userCheck);
ps.setString(1, email);
ps.setString(2, password);
ResultSet rs = ps.executeQuery();
而不仅仅是检查 resultset 是否为空或者没有。
And than just check whether resultset is empty or not.
检查结果集是否为空或未放在代码下面：
To check resultset is empty or not put below code:
if(rs.isBeforeFirst()) {
request.getSession().setAttribute("email",email);
response.sendRedirect("success.jsp");
} else {
request.setAttribute("error", "Invalid Username & Password");
request.getRequestDispatcher("index.jsp").forward(request, response);
}
对于 isBeforeFirst（）方法查看此处。
同时更改 index.jsp 以显示错误消息
Also change index.jsp to show error message
<p style ="color:red"><%=request.getAttribute("error")!=null ? request.getAttribute("error"): "" %></p>
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