用JSTL实现类似Struts1的表单验证

最新推荐文章于 2022-01-05 15:54:44 发布

xuxiaolei

最新推荐文章于 2022-01-05 15:54:44 发布

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分类专栏：我的程序文章标签： Servlet Java JSP Cache SUN

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java 代码

<%@ page language="java" import="java.util.*" pageEncoding=""%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Login</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
</head>
<body>
<form method="post" action="<c:url value='/servlet/LoginServlet'/>">
your name : <input type="text" name="userName" value="${requestScope.userName}"/>
${requestScope.errors["userName"]}<br>
your password : <input type="password" name="password" value="${requestScope.password}"/>
${requestScope.errors["password"]} <br>
<input type="submit" name="submit" value="submit"/>
<input type="reset" name="reset" value="reset"/>
</form>
</body>
</html>

java 代码

<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Login</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
</head>
<body>
your name is ${requestScope.userName} <br>
your password is ${requestScope.password}
</body>
</html>

java 代码

<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Login</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
</head>
<body>
Errors message: <br>
${requestScope.errorMsg}
</body>
</html>

java 代码

package app;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class LoginServlet extends HttpServlet {
/**
* Constructor of the object.
*/
public LoginServlet() {
super();
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
if(!invalidate(request, response)) {
RequestDispatcher dispatcher = request.getRequestDispatcher("/Login.jsp");
dispatcher.forward(request, response);
return;
}
if(userName.equals("xuxiaolei") && password.equals("123")) {
request.setAttribute("userName", userName);
request.setAttribute("password", password);
RequestDispatcher dispatcher = request.getRequestDispatcher("/ShowLogin.jsp");
dispatcher.forward(request, response);
} else {
request.setAttribute("errorMsg", "userName or password error");
RequestDispatcher dispatcher = request.getRequestDispatcher("/ErrorMsg.jsp");
dispatcher.forward(request, response);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
public boolean invalidate(HttpServletRequest request, HttpServletResponse response) {
boolean result = true;
HashMap errors = new HashMap();
setUserName(request);
setPassword(request);
if(userName == null || userName.length() < 1) {
userName = "";
errors.put("userName", "User is required");
}
if(password == null || password.length() < 1) {
password = "";
errors.put("password", "Password required");
}
if(errors.size() > 0) {
request.setAttribute("userName", userName);
request.setAttribute("password", password);
request.setAttribute("errors", errors);
result = false;
}
return result;
}
public void setUserName(HttpServletRequest request) {
userName = (String) request.getParameter("userName");
}
public void setPassword(HttpServletRequest request) {
password = (String) request.getParameter("password");
}
private String userName;
private String password;
}