MySQL database using JDBC connection operation CRUD

table of Contents

1. First of all the Myeclipse package name as well as some implementations of classes (written like this is my habit)
2. Next we create the database (MySQL)
3. Add the data in a database
4. First BaseDao, this is the most important, pay attention to the name of the database, where the emphasis on package name
5. This is the entity class, I believe we will write, pay attention to where the package name
6. Next we write BookingDao
7. Let's write Servlet
8. Configuration web.xml
9. once again write JSP page
10. Finally, the effect of this is displayed in the browser, this is the query results, query the whole table is as follows

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1. First of all the Myeclipse package name as well as some implementations of classes (written like this is my habit)

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2. Next we create the database (MySQL)

3. Add the data in a database

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4. First BaseDao, this is the most important, pay attention to the name of the database, where the emphasis on package name

package dao;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
 
public class BaseDao {
 
    /***
     * 
     * @author 数据库连接类
     *
     */
        private String driver ="com.mysql.jdbc.Driver";
        private String url="jdbc:mysql://localhost:3306/表名";        ---------自己写数据库表名，只要数据库的表名跟这里的一样就行
        private String name="数据库名称";      ----------你自己数据库的名称
        private String pwd="密码";        -----------你自己数据库的密码
          Connection conn=null;
          /***
           * 
           * @return 打开连接
           */
        /*  public Connection getconn(){
            Connection conn=null;
            Context ctx;
            try {
                ctx = new InitialContext();
                DataSource ds=(DataSource)ctx.lookup("java:comp/env/jdbc/news");    
                conn=ds.getConnection();
            }catch (Exception e) {
                e.printStackTrace();
            }
            return conn;
        }     */
        protected  Connection getconn(){
            conn=null;  
            try {
                Class.forName(driver);
                conn=DriverManager.getConnection(url,name,pwd);
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }       
            return conn;
        }
        
        /****
         * 
         * @param 关闭数据库连接
         */
        protected void closeAll(Connection conn ,PreparedStatement ps,ResultSet rs){        
            if(rs!=null)
                try {
                    if(rs!=null)
                    rs.close();
                    if(ps!=null)
                    ps.close();
                    if(conn!=null)
                    conn.close();
                } catch (SQLException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }               
        }
        /***
         * 
         * @param 增删改方法
         * @param 接受 参数为 SQL语句 和 对象数组
         * @return 返回受影响行数
         */
        public int executeUpdate(String sql ,Object []ob){
            conn=getconn();
            PreparedStatement ps=null;
            try {
                ps=prepareStatement(conn,sql,ob);
                int i=ps.executeUpdate();
                return i;   
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                //  e.printStackTrace();
                return 0;
            }finally{           
                closeAll(conn, ps, null);
            }
        
        }   
        /***
         * 查询方法
         */
        protected PreparedStatement prepareStatement(Connection conn,String sql,Object []ob){       
            PreparedStatement ps=null;
                    try {
                        int index=1;
                        ps = conn.prepareStatement(sql);
                            if(ps!=null&&ob!=null){
                                for (int i = 0; i < ob.length; i++) {           
                                        ps.setObject(index, ob[i]); 
                                        index++; 
                                }
                            }
                    } catch (SQLException e1) {
                        e1.printStackTrace();
                    }
             return ps;
        }
    
}

5. This is the entity class, I believe we will write, pay attention to where the package name

package entity;
 
public class Booking {
    private int id;
    private int categoryId;
    private String title;
    private String summary;
    private String uploaduser;
    private String createdate;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public int getCategoryId() {
        return categoryId;
    }
    public void setCategoryId(int categoryId) {
        this.categoryId = categoryId;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getSummary() {
        return summary;
    }
    public void setSummary(String summary) {
        this.summary = summary;
    }
    public String getUploaduser() {
        return uploaduser;
    }
    public void setUploaduser(String uploaduser) {
        this.uploaduser = uploaduser;
    }
    public String getCreatedate() {
        return createdate;
    }
    public void setCreatedate(String createdate) {
        this.createdate = createdate;
    }
    
    
}

6. Next we write BookingDao

package dao;
 
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import entity.Booking;
 
public class BookingDao extends BaseDao{
    
    public List<Booking> search(String sql,Object...params){
        List<Booking> list =new ArrayList<Booking>();
        Connection conn=this.getconn();
        PreparedStatement pst=null;
        ResultSet rs=null;
        try {
            pst=this.prepareStatement(conn, sql, params);
            rs=pst.executeQuery();
            while(rs.next()){
                Booking wor=new Booking();
                wor.setId(rs.getInt(1));
                wor.setCategoryId(rs.getInt(2));
                wor.setTitle(rs.getString(3));
                wor.setSummary(rs.getString(4));
                wor.setUploaduser(rs.getString(5));
                wor.setCreatedate(rs.getString(6));
                list.add(wor);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            closeAll(conn, pst, rs);
        }
        return list;
    }
    
    //查询表
    public List<Booking> findAll(){
        String sql="SELECT * FROM `Book`";
        return search(sql);
    }
    
    //添加方法
    public int insert(Booking t){
        String str="INSERT INTO `book`(categoryId,title,summary,uploaduser,createdate) VALUE(?,?,?,?,?)";
        return executeUpdate(str, new Object[]{t.getCategoryId(),t.getTitle(),t.getSummary(),t.getUploaduser(),t.getCreatedate()});
    }
    
    //修改方法
    public int update(Booking r){
        String sql="UPDATE `book` SET `categoryId`=?,`title`=?,`summary`=?,`uploaduser`=?,`createdate`=? WHERE id=?";
        return executeUpdate(sql, new Object[]{r.getCategoryId(),r.getTitle(),r.getSummary(),r.getUploaduser(),r.getCreatedate(),r.getId()});
    }
    
    //删除方法
    public int delete(Booking e){
        String sql="DELETE FROM `book` WHERE id=?";
        return executeUpdate(sql, new Object[]{e.getId()});
    }
    
    
}

7. Let's write Servlet

1. queries Servlet

package servlet;
 
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import dao.BookingDao;
import entity.Booking;
 
public class selectServlet extends HttpServlet {
 
    /**
     * Constructor of the object.
     */
    public selectServlet() {
        super();
    }
 
    /**
     * Destruction of the servlet. <br>
     */
    public void destroy() {
        super.destroy(); // Just puts "destroy" string in log
        // Put your code here
    }
 
    /**
     * The doGet method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to get.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
 
        doPost(request, response);
    }
 
    /**
     * The doPost method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to post.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
 
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        
        String opr=request.getParameter("opr");
        
    
        if(opr==null||opr.equals("list")){
            //刷新
            BookingDao goodsDao=new BookingDao();
            List<Booking> list=goodsDao.findAll();
            request.getSession().setAttribute("list", list);
            response.sendRedirect("index.jsp");
        }
        
        
        
        
        out.flush();
        out.close();
    }
 
    /**
     * Initialization of the servlet. <br>
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here
    }
 
}

2. Add the Servlet

package servlet;
 
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import dao.BookingDao;
import entity.Booking;
 
public class insertServlet extends HttpServlet {
 
    /**
     * Constructor of the object.
     */
    public insertServlet() {
        super();
    }
 
    /**
     * Destruction of the servlet. <br>
     */
    public void destroy() {
        super.destroy(); // Just puts "destroy" string in log
        // Put your code here
    }
 
    /**
     * The doGet method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to get.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
 
        doPost(request, response);
    }
 
    /**
     * The doPost method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to post.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
 
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();
        
        BookingDao rms=new BookingDao(); 
          int categoryId=Integer.parseInt(request.getParameter("categoryId"));
          String title=request.getParameter("title");
          String summary=request.getParameter("summary");
          String uploaduser=request.getParameter("uploaduser");
          String createdate=request.getParameter("createdate");
          Booking rm=new Booking();
              rm.setCategoryId(categoryId);
              rm.setTitle(title);
              rm.setSummary(summary);
              rm.setUploaduser(uploaduser);
              rm.setCreatedate(createdate);
             int i=rms.insert(rm);
             if(i>0){
                 out.print("true");
                //刷新
                    List<Booking> listrm=rms.findAll();
                    request.getSession().setAttribute("list", listrm);
             }else{
                 out.print("false");
             }
        
        out.flush();
        out.close();
    }
 
    /**
     * Initialization of the servlet. <br>
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here
    }
 
}

3. Modify the Servlet

package servlet;
 
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import dao.BookingDao;
import entity.Booking;
 
public class updateServlet extends HttpServlet {
 
    /**
     * Constructor of the object.
     */
    public updateServlet() {
        super();
    }
 
    /**
     * Destruction of the servlet. <br>
     */
    public void destroy() {
        super.destroy(); // Just puts "destroy" string in log
        // Put your code here
    }
 
    /**
     * The doGet method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to get.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
 
        doPost(request, response);
    }
 
    /**
     * The doPost method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to post.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
 
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        
        
        BookingDao booking=new BookingDao();
            int id=Integer.parseInt(request.getParameter("id"));
             int categoryId=Integer.parseInt(request.getParameter("categoryId"));
              String title=request.getParameter("title");
              String summary=request.getParameter("summary");
              String uploaduser=request.getParameter("uploaduser");
              String createdate=request.getParameter("createdate");
              Booking rm=new Booking();
                  rm.setId(id);
                  rm.setCategoryId(categoryId);
                  rm.setTitle(title);
                  rm.setSummary(summary);
                  rm.setUploaduser(uploaduser);
                  rm.setCreatedate(createdate);
            int i=booking.update(rm);
             if(i>0){
                //刷新
                    List<Booking> listrm=booking.findAll();
                    request.getSession().setAttribute("list", listrm);
                    out.print("<script>alert('修改成功！！！');location.href='index.jsp';</script>");
             }else{
                 out.print("<script>alert('修改失败！！！');location.href='Update.jsp';</script>");
             }
        
        out.flush();
        out.close();
    }
 
    /**
     * Initialization of the servlet. <br>
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here
    }
 
}

4. Delete the Servlet

package servlet;
 
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import dao.BookingDao;
import entity.Booking;
 
public class deleteServlet extends HttpServlet {
 
    /**
     * Constructor of the object.
     */
    public deleteServlet() {
        super();
    }
 
    /**
     * Destruction of the servlet. <br>
     */
    public void destroy() {
        super.destroy(); // Just puts "destroy" string in log
        // Put your code here
    }
 
    /**
     * The doGet method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to get.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
 
        doPost(request, response);
    }
 
    /**
     * The doPost method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to post.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
 
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        
        BookingDao rms=new BookingDao();
        Booking rm=new Booking();
        int id=Integer.parseInt(request.getParameter("id"));
        rm.setId(id);
        int i=rms.delete(rm);
        if(i>0){
            List<Booking> listrm=rms.findAll();
            request.getSession().setAttribute("list", listrm);
            out.print("<script>alert('删除成功！！！');location.href='index.jsp';</script>");
        }else{
            out.print("<script>alert('删除失败！！！');location.href='index.jsp';</script>");
        }
        
        out.flush();
        out.close();
    }
 
    /**
     * Initialization of the servlet. <br>
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here
    }
 
}

8. Configuration web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>selectServlet</servlet-name>
    <servlet-class>servlet.selectServlet</servlet-class>
  </servlet>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>insertServlet</servlet-name>
    <servlet-class>servlet.insertServlet</servlet-class>
  </servlet>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>updateServlet</servlet-name>
    <servlet-class>servlet.updateServlet</servlet-class>
  </servlet>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>deleteServlet</servlet-name>
    <servlet-class>servlet.deleteServlet</servlet-class>
  </servlet>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>idServlet</servlet-name>
    <servlet-class>servlet.idServlet</servlet-class>
  </servlet>
 
  <servlet-mapping>
    <servlet-name>selectServlet</servlet-name>
    <url-pattern>/selectServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>insertServlet</servlet-name>
    <url-pattern>/insertServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>updateServlet</servlet-name>
    <url-pattern>/updateServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>deleteServlet</servlet-name>
    <url-pattern>/deleteServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>idServlet</servlet-name>
    <url-pattern>/idServlet</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
 
</web-app>

Note that the following section, in the above comparison is below the web.xml,

Label declares the corresponding matching rules with the servlet, each Tag represents a matching rule. Containing the two sub-elements with ， Servlet name of the element must be given in Element declared the Servlet's name. Element specifies the Servlet corresponding to the URL path, the path is relative to the root of the Web application context path.

<servlet-mapping>
   <servlet-name></servlet-name>
   <url-pattern></url-pattern>
</servlet-mapping>

9. once again write JSP page

1.index.jsp initial interface

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib  uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title></title>
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
  </head>
  
  <body>
  
    <c:if test="${list==null}">
     <jsp:forward page="selectServlet"></jsp:forward>
    </c:if>
    <a href="insert.jsp"><input type="button" value="新增图书"></a>
    
    <table border="1">
        <tr><td>电子图书列表</td></tr>
        <tr><td>书品编号</td><td>书名</td><td>摘要</td><td>上传人</td><td>上传时间</td><td>操作</td></tr>
        <c:forEach items="${list}" var="gd">
          <tr>
            <td>${gd.categoryId}</td>
            <td>${gd.title}</td>
            <td>${gd.summary}</td>
            <td>${gd.uploaduser}</td>
            <td>${gd.createdate }</td>
            <td><a href="idServlet?id=${gd.id}"><input type="button" value="修改"></a></td>
            <td><a href="deleteServlet?id=${gd.id}"><input type="button" value="删除"></a></td>
          </tr>
       </c:forEach>
        
    </table>
  
  </body>
</html>

2.insert.jsp add pages

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title></title>
    
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
 
    <script type="text/javascript" src="js/jquery-1.12.4.js"></script>
    <script type="text/javascript">
    $(function(){
 
           $("#submit").click(function(){
                //非空验证
                    var $form=$("form").serialize();
                    alert($form);
                  $.get("insertServlet",$form,function(data){
                      if(data=="true"){
                         alert("新增成功");
                         window.location="index.jsp";
                      }else{
                       alert("新增失败");
                      }
                  });
       });
       });
    </script>
 
  </head>
  
  <body>
    <form action="">
        <h2>新增书本</h2>
        书本编号:<input type="text" name="categoryId"><br>
        书本名称:<input type="text" name="title"><br>
        摘要:<input type="text" name="summary"><br>
        上传人:<input type="text" name="uploaduser"><br>
        上传时间:<input type="text" name="createdate"><br>
        <input type="button" id="submit" value="提交"><input type="reset" value="重置">
    </form>
  
  </body>
</html>

3.Update.jsp modify the page

(1) This is a modified main

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title></title>
    
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
 
  </head>
  
  <body>
        <form action="updateServlet">
        <h2>修改书本</h2>
        <input type="hidden" value="${idid}" name="id">
        书本编号:<input type="text" name="categoryId"><br>
        书本名称:<input type="text" name="title"><br>
        摘要:<input type="text" name="summary"><br>
        上传人:<input type="text" name="uploaduser"><br>
        上传时间:<input type="text" name="createdate"><br>
        <input type="submit" id="submit" value="提交"><input type="reset" value="重置">
    </form>
  </body>
</html>

(2) This is BUG idServlet appeared behind me, I can only give but also added a Servlet

package servlet;
 
import java.io.IOException;
import java.io.PrintWriter;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
public class idServlet extends HttpServlet {
 
    /**
     * Constructor of the object.
     */
    public idServlet() {
        super();
    }
 
    /**
     * Destruction of the servlet. <br>
     */
    public void destroy() {
        super.destroy(); // Just puts "destroy" string in log
        // Put your code here
    }
 
    /**
     * The doGet method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to get.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
 
        doPost(request, response);
    }
 
    /**
     * The doPost method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to post.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
 
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        
        int id=Integer.parseInt(request.getParameter("id"));
        request.getSession().setAttribute("idid", id);
        response.sendRedirect("Update.jsp");
        
        out.flush();
        out.close();
    }
 
    /**
     * Initialization of the servlet. <br>
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here
    }
 
}

10. Finally, the effect of this is displayed in the browser, this is the query results, query the whole table is as follows

1. Inquiry

[Image dump outer link failure (img-wKfi8YM4-1567778008411) (https://cdn.jsdelivr.net/gh/Zevs6/blogimg/img/201803292306105211)]

2. Increase

3. Modify (where we just took us to add data modification)

4. Delete (this effect may not be obvious, but in order to interface I put it down to the screenshot)

I just add and modify our above operation to delete look at the results!

[Image dump outer link failure (img-UJdB1eFD-1567778008412) (https://cdn.jsdelivr.net/gh/Zevs6/blogimg/img/201803292353239561)]

Well, this project also Well done, is a complete, despite the Chinese garbled in time to the database transfer of data, but I'm going to tune this BUG, but at least functions to achieve, that's the project, though in some places we see the effect is not obvious now, if read this article to help everyone trouble you point a praise, thank you, if you have questions about Benpian or do you want me to show you step by step, add me QQ3506346737 (Note: CSDN blog + QQ name), am looking forward to your friend requests, we also expect some recommendations for improvement of this article, thank you

With source code acquiring Download: Baidu network disk. After downloading the code encounter problems in time to contact me, correct mistakes as soon as possible.

Link: https: //pan.baidu.com/s/1nlOSG10a0dW72qeeUKrS2g
extraction code: ycqr