Servlet访问postgresql数据库并提取数据显示在前端jsp页面-白红宇

Servlet访问postgresql数据库并提取数据显示在前端jsp页面

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发布时间：2019-06-24

本文共 7429 字，大约阅读时间需要 24 分钟。

1 结构

2 LoginTestServlet.java

package com.test;        import java.io.IOException;  import java.sql.Connection;import java.sql.DriverManager;  import java.sql.ResultSet;        import java.sql.Statement;import javax.servlet.ServletException;  import javax.servlet.annotation.WebServlet;  import javax.servlet.http.HttpServlet;  import javax.servlet.http.HttpServletRequest;  import javax.servlet.http.HttpServletResponse;  import javax.servlet.http.HttpSession;                   /**      * Servlet implementation class LoginTestServlet      */      @WebServlet("/LoginTestServlet")      public class LoginTestServlet extends HttpServlet {          private static final long serialVersionUID = 1L;                       /**          * @see HttpServlet#HttpServlet()          */          public LoginTestServlet() {              super();                        }                /**          * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)          */          protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {              doPost(request, response);          }                /**          * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)          */          protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {              response.setContentType("text/html;charset=gb2312");              request.setCharacterEncoding("gb2312");                            String result = "";                        String username = request.getParameter("username");              String psw = request.getParameter("password");                            if(username == "" || username == null || username.length()>20){                  try {                      result = "请输入用户名（不能超过20个字符）";                      request.setAttribute("message", result);                      response.sendRedirect("login.jsp");                      return;                  } catch (Exception e) {                      e.printStackTrace();                  }              }                            if(psw == "" || psw == null || psw.length() > 20){                  try {                      result = "请输入密码（不能超过20个字符）";                      request.setAttribute("message", result);                      response.sendRedirect("login.jsp");                      return;                  } catch (Exception e) {                      e.printStackTrace();                  }              }                            //登记JDBC驱动程序              try {                  Class.forName("org.postgresql.Driver");              } catch (Exception e) {                  System.out.print("Class Not Found Exception");              }                            //链接URL              String url = "jdbc:postgresql://localhost:5432/mydb";              Connection conn = null;              Statement stmt = null;              ResultSet rs = null;                            try {                  conn = (Connection) DriverManager.getConnection(url,"postgres","postgres");                  stmt = (Statement) conn.createStatement();                                    String sql = "select * from userInfo where username='"+username+"' and userpsw= '"+psw+"'";                  rs = stmt.executeQuery(sql);              } catch (Exception e) {                  e.printStackTrace();              }                        HttpSession session = request.getSession();          session.setAttribute("username", username);                        try {              if(rs.next()){                  session.setAttribute("age",rs.getString("age")) ;                  session.setAttribute("sex",rs.getString("sex")) ;                  session.setAttribute("weight",rs.getString("weight")) ;                  response.sendRedirect("success.jsp") ;                  return;              }else{                  session.setAttribute("message", "用户名或密码不匹配。");                  response.sendRedirect("fail.jsp") ;                  return;              }                        } catch (Exception e) {              e.printStackTrace();          }          }            }

3 login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>
    
     User Login    
     
                
      
       用户登录          
       
                      
        
                                                 用户名：                                                
                                                                                         密  码：                                                
         
                                                                                                                    
          
                                                                                 
                                                                           
          
         
        
                         
       
                         function validateLogin(){                   var sUserName = document.frmLogin.username.value;                   var sPassword = document.frmLogin.psssword.value;                  if (sUserName ==""){                   alert("请输入用户名!");                   return false ;                  }                                    if (sPassword ==""){                   alert("请输入密码!");                   return false ;                  }          }

4 success.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>
    
     Insert title here<%     String userName = (String)session.getAttribute("username") ;     String age = (String)session.getAttribute("age") ;     String weight = (String)session.getAttribute("weight") ;     String sex = (String)session.getAttribute("sex") ;     System.out.println("性别：A" + sex +"A")  ;   /*   if (sex.trim().equals("M")) {      sex ="男" ;     }else{      sex = "女" ;     }   */  %>    
     
           <%=userName %>     欢迎您，登陆成功！
           
      
       登陆用户信息：     
       
                      姓名：          <%=userName %>                      年龄：          <%=age %>                      体重：          <%=weight %> kg                     性别：          <%=sex %>                  
        
         返回

5 fail.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>
    
     Insert title here<%          String userName = (String) session.getAttribute("username");          String msg = (String) session.getAttribute("message");      %>      
     
                <%=userName%>          对不起，登陆失败！
       
      
       原因：           <%=msg%>          
        
        5秒后将返回登陆界面。              <%          response.setHeader("Refresh", "5;URL=/ServletDemo01/login.jsp");      %>

6. 数据库表

CREATE TABLE userinfo(  username character varying NOT NULL,  userpsw character varying NOT NULL,  age integer,  sex character(1),  weight integer,  CONSTRAINT userinfo_pkey PRIMARY KEY (username))

7.web.xml


    
    
       
     
      ServletDemo01
       
     
          
      
       index.html
          
      
       index.htm
          
      
       index.jsp
          
      
       default.html
          
      
       default.htm
          
      
       default.jsp
        
           
     
                
      
       LoginTestServlet
                
      
       com.test.LoginTestServlet
            
                 
     
                
      
       LoginTestServlet
                
      
       /loginTestServlet