Java web页面form提交请求转发forward到web页面

Java web实现jsp页面的form表单提交forward到jsp页面

1. 创建一个用于提交的jsp页面

myLogin.jsp

<form action="ValidateServlet">
    username: <input type="text" name="username" id="username1"><br>
    password: <input type="password" name="password" id="password1"><br>
    re-password: <input type="password" name="repassword" id="repassword1"><br>
<input type="submit" value="submit">

2. 创建处理请求的servlet，使用请求转发request.getRequestDispatcher("success.jsp").forward(request,response);

ValidateServlet.java

package com.andrew.servlet;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ValidateServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException{
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        String repassword = req.getParameter("repassword");
        List<String> list = new ArrayList<String>();
        if(null == username || "".equals(username)){
            list.add("username can't be blank!");
        }
        if(password == null || password.length() < 6 || password.length() > 10) {
            list.add("length of password should be between 6 and 10");
        }
        if(repassword == null || repassword.length() < 6 || repassword.length() > 10) {
            list.add("length of repassword should be between 6 and 10");
        }
        if(password != null && repassword != null && !password.equals(repassword)) {
            list.add("password and repassword not the same");
        }
        if(list.isEmpty()){
            req.setAttribute("username", username);
            req.setAttribute("password", password);
            req.getRequestDispatcher("success.jsp").forward(req, resp);
        } else {
            req.setAttribute("error", list);
            req.getRequestDispatcher("error.jsp").forward(req, resp);
        }
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException{
        this.doGet(req, resp);
    }
}

3. 在web.xml文件中配置servlet

web.xml

<servlet>
    <servlet-name>ValidateServlet</servlet-name>
    <servlet-class>com.andrew.servlet.ValidateServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>ValidateServlet</servlet-name>
    <url-pattern>/ValidateServlet</url-pattern>
</servlet-mapping>

4. 创建成功和失败页面用于跳转

success.jsp

This is my success JSP page. <br>
username: <%= request.getAttribute("username") %><br>
password: <%= request.getAttribute("password") %>

error.jsp

This is my error JSP page. <br>
<h1> login failed</h1>
<% List<String> list = (List<String>)request.getAttribute("error"); 
for(String str : list){
out.println(str + "<br>");
}%>

5. 启动tomcat执行页面提交

This is my error JSP page. 
login failed
length of password should be between 6 and 10
length of repassword should be between 6 and 10

This is my success JSP page. 
username: ABC
password: 1234567