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学习篇--（jsp+servlet+mysql） 登录界面 【前后台交互学习笔记】_jsp+servlet+mysql前后端如何交互

作者：我家自动化 | 2024-04-19 20:12:51

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jsp+servlet+mysql前后端如何交互

 

经典的样例，自己手打一边，学习一下！

 

UserBean，代码如下：

  1. package com.szx.jnmc;
  2.  
  3.     public class User {
  4.  
  5.     private String username;
  6.     private String userpass;
  7.     private int role;
  8.     private int lognum;
  9.     private  String regtime;
  10.     public String getUsername() {
  11.         return username;
  12.     }
  13.     public void setUsername(String username) {
  14.         this.username = username;
  15.     }
  16.     public String getUserpass() {
  17.         return userpass;
  18.     }
  19.     public void setUserpass(String userpass) {
  20.         this.userpass = userpass;
  21.     }
  22.     public int getRole() {
  23.         return role;
  24.     }
  25.     public void setRole(int role) {
  26.         this.role = role;
  27.     }
  28.  
  29.     public int getLognum() {
  30.         return lognum;
  31.     }
  32.     public void setLognum(int lognum) {
  33.         this.lognum = lognum;
  34.     }
  35.     public String getRegtime() {
  36.         return regtime;
  37.     }
  38.     public void setRegtime(String regtime) {
  39.         this.regtime = regtime;
  40.     }
  41.  
  42. }

================================================================================================

对user进行数据的封装。

下面再写一个数据库连接类DBOper 这个类具有连接数据库以及增删改（executeUpdate）查（executeQuery）的功能，以便于AddUserServlet的调用

  1. package com.szx.jnmc;
  2.  
  3. import java.sql.Connection;
  4. import java.sql.DriverManager;
  5. import java.sql.PreparedStatement;
  6. import java.sql.ResultSet;
  7. import java.sql.SQLException;
  8.  
  9. public class DBOper {
  10.  
  11.     Connection conn = null;
  12.     PreparedStatement ps = null;
  13.     ResultSet rs = null;
  14.     //打开连接
  15.     public Connection getConn(String server,String dbname,String dbuser,String dbpwd){      
  16.         String DRIVER = "com.mysql.jdbc.Driver";
  17.         String URL = "jdbc:mysql://"+server+":3306/"+dbname+"?user="+dbuser+"&password="+dbpwd+"&useUnicode=true&characterEncoding=utf8";
  18.         try{
  19.             Class.forName(DRIVER);  
  20.             conn = DriverManager.getConnection(URL);
  21.         }catch(Exception e){
  22.             e.printStackTrace();
  23.         }
  24.         return conn;
  25.     }
  26.     //关闭连接
  27.     public void closeAll(){
  28.         try{
  29.             if(rs != null){
  30.                 rs.close();
  31.             }
  32.         }catch(SQLException e){
  33.             e.printStackTrace();
  34.         }finally{
  35.             try{
  36.                 if(ps != null){
  37.                     ps.close();
  38.                 }
  39.             }catch(SQLException e){
  40.                 e.printStackTrace();
  41.             }finally{
  42.             try{
  43.                 if(conn != null){
  44.                     conn.close();
  45.                 }
  46.             }catch (SQLException e){
  47.                 e.printStackTrace();
  48.             }
  49.             }
  50.         }
  51.  
  52.     }
  53.     //执行sql语句，可以进行查询
  54.     public ResultSet executeQuery(String preparedSql,String []param){
  55.         try{
  56.             ps = conn.prepareStatement(preparedSql);
  57.             if(param != null){
  58.                 for (int i = 0; i < param.length; i++) {
  59.                     ps.setString(i + 1, param[i]);
  60.                 }
  61.             }
  62.             rs = ps.executeQuery();
  63.         }catch(SQLException e){
  64.             e.printStackTrace();
  65.         }       
  66.         return rs;
  67.  
  68.     }
  69.     //执行sql语句，增加，修改，删除
  70.     public int executeUpdate(String preparedSql,String[]param){
  71.         int num = 0;
  72.         try{
  73.             ps = conn.prepareStatement(preparedSql);
  74.             if(ps != null){
  75.                 for (int i = 0; i < param.length; i++) {
  76.                     ps.setString(i + 1, param[i]);
  77.                 }
  78.             }
  79.             num = ps.executeUpdate();
  80.         }catch(SQLException e){
  81.             e.printStackTrace();
  82.         }
  83.         return num;
  84.     }
  85. }

==========================================================================

数据库连接类写完之后，继续写一个UserDao，这个类主要功能是对用户进行增删改查 代码如下：

  1. package com.szx.jnmc;
  2.  
  3. import java.sql.ResultSet;
  4. import java.sql.SQLException;
  5. import java.util.ArrayList;
  6. import java.util.List;
  7.  
  8. public class UserDao extends DBOper{
  9.     //获取用户列表
  10.     public List<User> getUser(){
  11.         List<User>userList = new ArrayList<User>();
  12.         User user = new User();
  13.         String sql = "SELECT * FROM tb_user";
  14.         try{
  15.             ResultSet rs = this.executeQuery(sql,null);
  16.             while(rs.next()){
  17.                 user.setUsername(rs.getString("username"));
  18.                 user.setUserpass(rs.getString("userpass"));
  19.                 user.setLognum(rs.getInt("lognum"));
  20.                 user.setRegtime(rs.getString("regtime"));
  21.                 user.setRole(rs.getInt("role"));
  22.                 userList.add(user);
  23.             }
  24.  
  25.         }catch(SQLException e){
  26.             e.printStackTrace();
  27.         }finally{
  28.             this.closeAll();
  29.         }
  30.         return userList;
  31.     }
  32.     //根据用户名获取用户
  33.     public User getUserByName(String name){
  34.         User user = null;
  35.         String sql = "SELECT * FROM tb_user WHERE　username = ?";
  36.         try{            
  37.             ResultSet rs = this.executeQuery(sql, new String[]{name});
  38.             if(rs.next()){
  39.                 user = new User();
  40.                 user.setUsername(rs.getString("username"));
  41.                 user.setUserpass(rs.getString("userpass"));
  42.                 user.setRole(rs.getInt("role"));
  43.                 user.setLognum(rs.getInt("lognum"));
  44.                 user.setRegtime(rs.getString("regtime"));
  45.             }
  46.         }catch(SQLException e){
  47.             e.printStackTrace();
  48.         }finally{
  49.             this.closeAll();
  50.         }
  51.         return user;
  52.     }
  53.     //修改用户信息
  54.     public boolean editUser(User user){
  55.         boolean r = false;
  56.         String sql = "UPDATE tb_user SET userpass = ?,role = ?,regtime = ?,lognum = ? WHERE username = ?";
  57.         try{
  58.             int num = this.executeUpdate(sql, new String[]{user.getUserpass(),""+user.getRole(),""+user.getLognum(),user.getRegtime(),user.getUsername()});
  59.             if(num > 0){
  60.                 r = true;
  61.             }
  62.         }catch(Exception e){
  63.             e.printStackTrace();
  64.         }finally{
  65.             this.closeAll();
  66.         }
  67.         return r;
  68.  
  69.     }
  70.     //添加用户
  71.     public boolean addUser(User user){
  72.         boolean r = false;
  73.         String sql = "INSERT INTO tb_user(username,userpass,role,regtime)VALUES(?,?,?,?) ";
  74.         try{
  75.             int num = this.executeUpdate(sql,new String[]{user.getUsername(),user.getUserpass(),""+user.getRole(),user.getRegtime()});
  76.             if(num > 0){
  77.                 r = true;
  78.             }
  79.         }catch(Exception e){
  80.             e.printStackTrace();
  81.         }finally{
  82.             this.closeAll();
  83.         }
  84.         return r;
  85.     }
  86.     //删除指定用户
  87.     public boolean delUser(String name){
  88.         boolean r = false;
  89.         String sql = "DELETE FROM tb_user WHERE username = ?";
  90.         try{
  91.             int num = this.executeUpdate(sql,new String[]{name});
  92.             if(num > 0){
  93.                 r = true;
  94.             }
  95.         }catch(Exception e){
  96.             e.printStackTrace();
  97.         }finally{
  98.             this.closeAll();
  99.         }
  100.         return r;
  101.     }
  102. }

===============================================================================================

注册部分的jsp，addUser.jsp用来接收用户的输入。抛开各种样式，直接用最原始的样式呈现吧，代码如下：

  1.  <%@ page language="java" contentType="text/html; charset=GBK"
  2.     pageEncoding="GBK"%>
  3.     <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"         "http://www.w3.org/TR/html4/loose.dtd">
  4.     <html>
  5.     <head>
  6.     <meta http-equiv="Content-Type" content="text/html; charset=GBK">
  7.     <title>添加用户页面</title>
  8.     </head>
  9.     <body>
  10.     <form action = "AddUserServlet" method = "POST">
  11.     用户名:<input type = "text" name = "username">
  12.     密码:<input type = "password" name = "userpass">
  13.     <input type = "submit" value = "注册">
  14.     <input type = "reset" value = "重置">
  15.     </form>
  16.     </body>
  17.     </html>

===============================================

注意页面的字符编码设置统一为GBK(以GBK为例，如果自己写的话最好用UTF-8）

下面写我们的AddUserServlet，不多说，直接贴代码：

  1.   package com.szx.jnmc;
  2.  
  3.     import java.io.IOException;
  4.     import java.io.PrintWriter;
  5.     import java.text.SimpleDateFormat;
  6.     import java.util.Date;
  7.  
  8.     import javax.servlet.ServletContext;
  9.     import javax.servlet.ServletException;
  10.     import javax.servlet.annotation.WebServlet;
  11.     import javax.servlet.http.HttpServlet;
  12.     import javax.servlet.http.HttpServletRequest;
  13.     import javax.servlet.http.HttpServletResponse;
  14.  
  15.     /**
  16.      * Servlet implementation class AddUserServlet
  17.      */
  18.     @WebServlet("/AddUserServlet")
  19.     public class AddUserServlet extends HttpServlet {
  20.         private static final long serialVersionUID = 1L;
  21.  
  22.     /**
  23.      * @see HttpServlet#HttpServlet()
  24.      */
  25.     public AddUserServlet() {
  26.         super();
  27.         // TODO Auto-generated constructor stub
  28.     }
  29.  
  30.     /**
  31.      * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
  32.      */
  33.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  34.         // TODO Auto-generated method stub
  35.         doPost(request,response);
  36.     }
  37.  
  38.     /**
  39.      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  40.      */
  41.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  42.         // TODO Auto-generated method stub
  43.         request.setCharacterEncoding("GBK");
  44.         response.setContentType("text/html;charset = GBK");
  45.         String username = request.getParameter("username");
  46.         String userpass = request.getParameter("userpass");
  47.         //String role = request.getParameter("role");
  48.         Date curTime = new Date();
  49.         SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
  50.         String regtime = sdf.format(curTime);
  51.         PrintWriter out = response.getWriter();
  52.         ServletContext ctx = this.getServletContext();
  53.         String server = ctx.getInitParameter("server");
  54.         String dbname = ctx.getInitParameter("dbname");
  55.         String dbuser = ctx.getInitParameter("dbuser");
  56.         String dbpwd = ctx.getInitParameter("dbpwd");
  57.         User user = new User();
  58.         user.setUsername(username);
  59.         user.setUserpass(userpass);
  60.         user.setRegtime(regtime);
  61.         //user.setRole(Integer.parseInt(role));
  62.         UserDao dao = new UserDao();
  63.         dao.getConn(server, dbname, dbuser, dbpwd);
  64.         if(dao.addUser(user)){
  65.             out.print("注册成功！");
  66.         }
  67.         else{
  68.             out.print("注册失败！");
  69.         }
  70.  
  71.  
  72.     }
  73.  
  74.     }

===============================================================================================

接下来我们写登陆部分，login.jsp代码如下：

  1. <%@ page language="java" contentType="text/html; charset=GBK"
  2.     pageEncoding="GBK"%>
  3. <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
  4. <html>
  5. <head>
  6. <meta http-equiv="Content-Type" content="text/html; charset=GBK">
  7. <title>登陆页面</title>
  8. </head>
  9. <body>
  10. <form method = "POST" action = "LoginServlet">
  11. 用户名：<input type = "text" name = "username">
  12. 密码：<input type = "password" name = "userpass">
  13. <input type = "submit" value = "登陆">
  14. <input type = "reset" value = "重置">
  15. </form>
  16. </body>
  17. </html>

================================================================================================

LoginServlet代码如下：

  1. package com.szx.jnmc;
  2.  
  3. import java.io.IOException;
  4. import java.io.PrintWriter;
  5. import java.sql.ResultSet;
  6. import java.sql.SQLException;
  7. import java.text.SimpleDateFormat;
  8. import java.util.Date;
  9.  
  10. import javax.servlet.RequestDispatcher;
  11. import javax.servlet.ServletContext;
  12. import javax.servlet.ServletException;
  13. import javax.servlet.annotation.WebServlet;
  14. import javax.servlet.http.Cookie;
  15. import javax.servlet.http.HttpServlet;
  16. import javax.servlet.http.HttpServletRequest;
  17. import javax.servlet.http.HttpServletResponse;
  18. import javax.servlet.http.HttpSession;
  19.  
  20. /**
  21.  * Servlet implementation class LoginServlet
  22.  */
  23. @WebServlet("/LoginServlet")
  24. public class LoginServlet extends HttpServlet {
  25.     private static final long serialVersionUID = 1L;
  26.  
  27.     /**
  28.      * @see HttpServlet#HttpServlet()
  29.      */
  30.     public LoginServlet() {
  31.         super();
  32.         // TODO Auto-generated constructor stub
  33.     }
  34.  
  35.     /**
  36.      * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
  37.      */
  38.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  39.         // TODO Auto-generated method stub
  40.         doPost(request,response);
  41.     }
  42.  
  43.     /**
  44.      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  45.      */
  46.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  47.         // TODO Auto-generated method stub
  48.         request.setCharacterEncoding("GBK");
  49.         response.setContentType("text/html;charset = GBK");
  50.         PrintWriter out = response.getWriter();
  51.         String username = request.getParameter("username");
  52.         String userpass = request.getParameter("userpass");
  53.         ServletContext ctx = request.getServletContext();
  54.         String server = ctx.getInitParameter("server");
  55.         String dbname = ctx.getInitParameter("dbname");
  56.         String dbuser = ctx.getInitParameter("dbuser");
  57.         String dbpwd = ctx.getInitParameter("dbpwd");       
  58.         DBOper db = new DBOper();
  59.         db.getConn(server, dbname, dbuser, dbpwd);
  60.         String sql = "SELECT username,userpass,role FROM tb_user WHERE username = ? AND userpass = ?";
  61.         ResultSet rs = db.executeQuery(sql,new String[]{username,userpass});
  62.         try {
  63.             if(rs != null && rs.next()){
  64.                 HttpSession session = request.getSession();
  65.                 session.setAttribute("username",username);
  66.                 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
  67.                 String logtime = sdf.format(new Date()); 
  68.                 session.setAttribute("logtime",logtime);
  69.                 Cookie cookie = new Cookie("username",username);
  70.                 cookie.setMaxAge(60*60*24*30);
  71.                 response.addCookie(cookie);
  72.                 RequestDispatcher dispatcher = request.getRequestDispatcher("MainServlet");
  73.                 dispatcher.forward(request,response);
  74.             }else{
  75.                 out.print("登录失败");
  76.                 out.print("<br><a href = 'login.jsp'>重新登陆</a>");
  77.             }
  78.         } catch (SQLException e) {
  79.             // TODO Auto-generated catch block
  80.             e.printStackTrace();
  81.         }
  82.     }
  83.  
  84.     public void init()throws ServletException {
  85.  
  86.     }
  87.  
  88. }

==========================================================================================

LoginServlet里的MianServlet用来显示登陆成功的信息，登陆失败则跳转到login.jsp重新登陆，MainServlet的代码如下：

  1. package com.szx.jnmc;
  2.  
  3. import java.io.IOException;
  4. import java.io.PrintWriter;
  5.  
  6. import javax.servlet.ServletException;
  7. import javax.servlet.annotation.WebServlet;
  8. import javax.servlet.http.HttpServlet;
  9. import javax.servlet.http.HttpServletRequest;
  10. import javax.servlet.http.HttpServletResponse;
  11. import javax.servlet.http.HttpSession;
  12.  
  13. /**
  14.  * Servlet implementation class MainServlet
  15.  */
  16. @WebServlet("/MainServlet")
  17. public class MainServlet extends HttpServlet {
  18.     private static final long serialVersionUID = 1L;
  19.  
  20.     /**
  21.      * @see HttpServlet#HttpServlet()
  22.      */
  23.     public MainServlet() {
  24.         super();
  25.         // TODO Auto-generated constructor stub
  26.     }
  27.  
  28.     /**
  29.      * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
  30.      */
  31.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  32.         // TODO Auto-generated method stub
  33.         doPost(request,response);
  34.     }
  35.  
  36.     /**
  37.      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  38.      */
  39.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  40.         // TODO Auto-generated method stub
  41.         request.setCharacterEncoding("GBK");
  42.         response.setContentType("text/html;charaset = GBK");
  43.         PrintWriter out = response.getWriter();
  44.         HttpSession session = request.getSession();
  45.         String username = (String)session.getAttribute("username");
  46.         String logtime = (String)session.getAttribute("logtime");
  47.         out.println("登录名:"+username+"&nbsp;&nbsp;&nbsp;&nbsp;登陆时间:"+logtime);
  48.         out.println("欢迎"+username);
  49.     }
  50.  
  51. }

===============================================================================================

到此我们还有最重要的一步，就是在web.xml里配置我们的项目，web.xml代码如下：

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  3.   <display-name>20170512</display-name>
  4.   <welcome-file-list>
  5.     <welcome-file>index.html</welcome-file>
  6.     <welcome-file>index.htm</welcome-file>
  7.     <welcome-file>index.jsp</welcome-file>
  8.     <welcome-file>default.html</welcome-file>
  9.     <welcome-file>default.htm</welcome-file>
  10.     <welcome-file>default.jsp</welcome-file>
  11.   </welcome-file-list>
  12.   <context-param>
  13.     <param-name>server</param-name>
  14.     <param-value>localhost</param-value>
  15.   </context-param>
  16.   <context-param>
  17.     <param-name>dbname</param-name>
  18.     <param-value>A20170512</param-value>
  19.   </context-param>
  20.   <context-param>
  21.     <param-name>dbuser</param-name>
  22.     <param-value>root</param-value>
  23.   </context-param>
  24.   <context-param>
  25.     <param-name>dbpwd</param-name>
  26.     <param-value>123456</param-value>
  27.   </context-param>
  28.   <servlet>
  29.     <display-name>AddUserServlet</display-name>
  30.     <servlet-name>AddUSerServlet</servlet-name>
  31.     <servlet-class>com.szx.jnmc.AddUserServlet</servlet-class>
  32.   </servlet>
  33.    <servlet>
  34.   <display-name>LoginServlet</display-name>
  35.   <servlet-name>LoginServlet</servlet-name>
  36.   <servlet-class>com.szx.jnmc.LoginServlet</servlet-class>
  37.   </servlet>
  38. </web-app>

转载于：https://blog.csdn.net/ITcreater000/article/details/71759744

 

 

 

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