jdbc操作数据库 and 一个商品管理页面

岳轩子2024-04-23 18:14

文章目录

  • [1. 介绍](#1. 介绍)
    • [1.1 应用知识介绍](#1.1 应用知识介绍)
    • [1.2 项目介绍](#1.2 项目介绍)
  • [2. 文件目录](#2. 文件目录)
    • [2.1 目录](#2.1 目录)
    • [2.2 介绍以下（从上到下）](#2.2 介绍以下（从上到下）)
  • [3. 相关代码](#3. 相关代码)
    • [3.1 DBConnection.java](#3.1 DBConnection.java)
    • [3.2 MysqlUtil.java](#3.2 MysqlUtil.java)
    • [3.3 AddServlet.java](#3.3 AddServlet.java)
    • [3.4 CommodityServlet.java](#3.4 CommodityServlet.java)
    • [3.5 DelectServlet.java](#3.5 DelectServlet.java)
    • [3.6 SelectByIdServlet.java](#3.6 SelectByIdServlet.java)
    • [3.7 SelectServlet.java](#3.7 SelectServlet.java)
    • [3.8 UpdataServlet.java](#3.8 UpdataServlet.java)
    • [3.9 style.css](#3.9 style.css)
    • [3.10 index.js](#3.10 index.js)
    • [3.11 jquery-3.7.1.min.js（略）](#3.11 jquery-3.7.1.min.js（略）)
    • [3.12 index.html](#3.12 index.html)
  • [4. 效果展示](#4. 效果展示)
  • [5. 链接](#5. 链接)
  • [6. 思考](#6. 思考)

很丑，主要学习方法

1. 介绍

1.1 应用知识介绍

基础知识：mySQL，jbdc，JQuery，ajax

mySQL中对于表的增删改查

jQuery对于前端元素的获取

ajax传递数据和获取数据

1.2 项目介绍

是一个商品管理系统，需要自己先创建好一个表如图：

其中类型就不多说了。

前端交互界面设计：

对商品数据进行增删改查

2. 文件目录

2.1 目录

2.2 介绍以下（从上到下）

DBConnection.java：用于连接数据库

MysqlUtil.java：操作数据库

AddServlet.java：增加商品

CommodityServlet.java：初始化时候进行查询

DelectServlet.java：删除数据库中的相关数据

SelectByIdServlet.java：通过id获取数据

SelectServlet.java：通过名字获取数据，用于查询

UpdataServlet.java：更新数据

style.css：样式

index.js：写js

jquery-3.7.1.min.js：引入jquery

index.html：写界面

3. 相关代码

3.1 DBConnection.java

java 复制代码 
package com.qcby.db;

import java.sql.Connection;
import java.sql.DriverManager;

public class DBConnection {

	public static void main(String[] args) {

	}

	String driver = "com.mysql.jdbc.Driver";
	String url = "jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC&useSSL=false";
	String user = "root";
	String password = "root";

	public Connection conn;

	public DBConnection() {

		try {
			Class.forName(driver);
			conn = (Connection) DriverManager.getConnection(url, user, password);//

			// if(!conn.isClosed())
			// System.out.println("Succeeded connecting to the Database!");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public void close() {
		try {
			this.conn.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}

3.2 MysqlUtil.java

java 复制代码 
package com.qcby.db;

import java.rmi.StubNotFoundException;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MysqlUtil {

	public static void main(String[] args) {
		
//		String sqlcount = "select count(*) from admin";
//		String sql = "select * from admin";
//		String[] colums = {"id","account","password"};
//		String json = getJsonBySql(sqlcount, sql, colums);
//		System.out.println(json);
		
		/*String sql = "insert into t_student(name,age,sex) values(\"张三\",21,\"男\")";
        System.out.println(add(sql));*/
		
		
		/*String sqldel = "delete from gq_user where id=11";
        System.out.println(del(sqldel));*/

		/*
		 * String sqlupdate ="update user set age = 60 where name=\"you\"";
		 * System.out.println(update(sqlupdate));
		 */

		/*String sql = "select count(*) from gq_user";
		System.out.println(getCount(sql));*/
		
		/*String[] col = {"id","name","age"};
		String sql = "select * from t_student";
		String sqlCount = "select count(*) from t_student";
		String strJson = getJsonBySql(sqlCount,sql,col);
        System.out.println(strJson);*/
		
		/*String sqlcount = "select count(*) from gq_user";
		String sql="select * from gq_user";
		String[] col = {"username","age","id","sex","salary"};
		System.out.println(getJsonBySql(sqlcount, sql, col));*/

		/*
		 * String sql = "select * from user"; String[] column =
		 * {"id","name","age","entrydate"}; ArrayList<String[]> strings =
		 * MysqlUtil.showUtil(sql, column); for (String[] string : strings) {
		 * System.out.println(Arrays.toString(string)); }
		 */
	}
	/*添加*/
	public static int add(String sql) {
		// System.out.println("sql语句是：" + sql);
        int i=0;
        //数据库连接
        DBConnection db = new DBConnection();
        try {        
            PreparedStatement preStmt = (PreparedStatement) db.conn.prepareStatement(sql);
            i=preStmt.executeUpdate();
            preStmt.close();
            db.close();//关闭连接 
            System.out.println("数据插入成功，sql语句是：" + sql);
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println(i);
        return i;//返回影响的行数，1为执行成功;
    }



   /*修改数据*/
    public static int update(String sql) {
        int i =0;
        DBConnection db = new DBConnection();
        try {
            PreparedStatement preStmt = (PreparedStatement) db.conn.prepareStatement(sql);
            i = preStmt.executeUpdate();
            preStmt.close();
            db.close();
            System.out.println("数据更新成功，sql语句是：" + sql);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return i;
    }
    

    /*删除*/
    public static int del(String delstr) {
        int i=0;
        DBConnection db = new DBConnection();
        try {    
            PreparedStatement preStmt = (PreparedStatement) db.conn.prepareStatement(delstr);
            i=preStmt.executeUpdate();
            //executeUpdate()返回受影响的行数
            preStmt.close();
            db.close();
            System.out.println("数据删除成功，sql语句是：" + delstr);
        } catch (SQLException e){
            e.printStackTrace();
        }
        return i;
    }

    /*查询数量*/
    public static int getCount(String sql) {
        int sum = 0;
        DBConnection db = new DBConnection();
        try {
            Statement stmt = (Statement) db.conn.createStatement();
            ResultSet rs = (ResultSet) stmt.executeQuery(sql);
            while (rs.next()) {
                sum += rs.getInt(1);
            }
            rs.close();
            db.close();
        } catch (Exception e) {
            // TODO: handle exception
        }
        return sum;
    }

    /**
     *功能描述 查询json数据带数据总量
     * @author 郭帅
     * @date 2021-03-22 10:30
     * @param sqlcount 查询数量的sql
     * @param sql 查询具体数据的sql
     * @param colums 查询的字段
     * @return java.lang.String
     */
    public static String getJsonBySqlDataGrid( String sqlcount,String sql,String[] colums){
        int count = getCount(sqlcount);
        System.err.println("标红信息展示sql:" + sql);
        ArrayList<String[]>  result = new ArrayList<String[]>();
        DBConnection db = new DBConnection();
        try {
            Statement stmt = (Statement) db.conn.createStatement();
            ResultSet rs = (ResultSet) stmt.executeQuery(sql);
            while(rs.next()){
                String[] dataRow = new String[colums.length];
                for( int i = 0; i < dataRow.length; i++ ) {
                    dataRow[i] = rs.getString( colums[i] );
                }
                result.add(dataRow);
            }
            rs.close();
            db.close();//
        } catch (SQLException e) {
            e.printStackTrace();
        }

        return listToJsonDataGrid(result,colums,count);
    }
    
    /**
     *功能描述 查询json数据
     * @author 郭帅
     * @date 2021-03-22 10:30
     * @param sql 查询具体数据的sql
     * @param colums 查询的字段
     * @return java.lang.String
     */
    public static String getJsonBySql( String sql,String[] colums){
       
        System.err.println("标红信息展示sql:" + sql);
        ArrayList<String[]>  result = new ArrayList<String[]>();
        DBConnection db = new DBConnection();
        try {
            Statement stmt = (Statement) db.conn.createStatement();
            ResultSet rs = (ResultSet) stmt.executeQuery(sql);
            while(rs.next()){
                String[] dataRow = new String[colums.length];
                for( int i = 0; i < dataRow.length; i++ ) {
                    dataRow[i] = rs.getString( colums[i] );
                }
                result.add(dataRow);
            }
            rs.close();
            db.close();//
        } catch (SQLException e) {
            e.printStackTrace();
        }

        return listToJson(result,colums);
    }

    /**
     *功能描述 查询数据
     * @author 郭帅
     * @date 2021-03-22 10:38
     * @param sql 查询具体数据的sql
     * @param colums  查询的字段
     * @return java.util.ArrayList<java.lang.String[]>
     */
    public static ArrayList<String[]> showUtil( String sql, String[] colums){

        ArrayList<String[]>  result = new  ArrayList<String[]>();
        DBConnection db = new DBConnection();
        try {
            Statement stmt = (Statement) db.conn.createStatement();
            ResultSet rs = (ResultSet) stmt.executeQuery(sql);

            while(rs.next()){
                String[] dataRow = new String[colums.length];
                for( int i = 0; i < dataRow.length; i++ ) {
                    dataRow[i] = rs.getString( colums[i] );
                }
                result.add(dataRow);
            }
            rs.close();
            db.close();//
        } catch (SQLException e) {
            e.printStackTrace();
        }

        return result;
    }

    /**
     * 转化为json数据字符串
     * @param
     * @return
     */
    public static String listToJsonDataGrid( ArrayList<String[]> list,String[] colums,int count) {

    	String jsonStr = "{\"code\":0,\"msg\":\"成功了\",\"count\":"+count+",\"data\":[";
    			for(int i = 0; i < list.size(); i++) {
    				String arr = "{";
    				for( int j = 0; j < list.get(0).length; j++) {
    					
    					if( list.get(i)[j] == null || "NULL".equals(list.get(i)[j])) {
    						arr += "\"" + colums[j] + "\":\"\"";
    					}else {
    						arr += "\"" + colums[j] + "\""+":" ;
    						arr +=  "\"" + list.get(i)[j].replace("\"","\\\"") + "\"";
    					}
    					
    					if( j < list.get(0).length - 1 ) {
    						arr += ",";
    					}
    				}
    				arr += "}";
    				if( i < list.size() - 1 ) {
						arr += ",";
					}
    				
    				jsonStr += arr;
    			}
    			jsonStr += "]}";
    	
    	return jsonStr;
    }
    
    /**
     * 转化为json数据字符串
     * @param
     * @return
     */
    public static String listToJson( ArrayList<String[]> list,String[] colums) {

    	String jsonStr = "{\"code\":0,\"msg\":\"成功了\",\"data\":[";
    			for(int i = 0; i < list.size(); i++) {
    				String arr = "{";
    				for( int j = 0; j < list.get(0).length; j++) {
    					
    					if( list.get(i)[j] == null || "NULL".equals(list.get(i)[j])) {
    						arr += "\"" + colums[j] + "\":\"\"";
    					}else {
    						arr += "\"" + colums[j] + "\""+":" ;
    						arr +=  "\"" + list.get(i)[j].replace("\"","\\\"") + "\"";
    					}
    					
    					if( j < list.get(0).length - 1 ) {
    						arr += ",";
    					}
    				}
    				arr += "}";
    				if( i < list.size() - 1 ) {
						arr += ",";
					}
    				
    				jsonStr += arr;
    			}
    			jsonStr += "]}";
    	
    	return jsonStr;
    }

}

3.3 AddServlet.java

java 复制代码 
package com.qcby.servlet;

import java.io.IOException;
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 com.qcby.db.MysqlUtil;

/**
 * Servlet implementation class AddServlet
 */
@WebServlet("/add")
public class AddServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public AddServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setCharacterEncoding("utf-8");
		request.setCharacterEncoding("utf-8");
		String name = request.getParameter("name");
		String number = request.getParameter("num");
		String price = request.getParameter("price");
		String sql = "insert into commodity(name, num, price) VALUES ('"+ name + "', " + number + ", "+ price + ");";
		int num = MysqlUtil.add(sql);
		response.getWriter().write(num + "");
	}
}

3.4 CommodityServlet.java

java 复制代码 
package com.qcby.servlet;

import java.io.IOException;
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 com.qcby.db.MysqlUtil;

/**
 * Servlet implementation class CommodityServlet
 */
@WebServlet("/commodity")
public class CommodityServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public CommodityServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setCharacterEncoding("utf-8");
		request.setCharacterEncoding("utf-8");
		//设置返回数据的格式
		response.setContentType("text/json;charset:utf-8");
		String sql = "select * from commodity";
		String[] column ={"id","name","num","price"};
		String res = MysqlUtil.getJsonBySql(sql, column);
		System.out.println(res);
		// 响应数据
		response.getWriter().write(res);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

3.5 DelectServlet.java

java 复制代码 
package com.qcby.servlet;

import java.io.IOException;
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 com.qcby.db.MysqlUtil;

/**
 * Servlet implementation class DelectServlet
 */
@WebServlet("/del")
public class DelectServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public DelectServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		// 接受参数
		String id = request.getParameter("id");
		String sql = "delete from commodity where id = " + id;
		int num = MysqlUtil.del(sql);
		response.getWriter().write(num);
	}

}

3.6 SelectByIdServlet.java

java 复制代码 
package com.qcby.servlet;

import java.io.IOException;
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 com.qcby.db.MysqlUtil;

/**
 * Servlet implementation class SelectByIdServlet
 */
@WebServlet("/selectById")
public class SelectByIdServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public SelectByIdServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		String id = request.getParameter("id");
		String sql = "select * from commodity where id ='" + id +"';";
		response.setCharacterEncoding("utf-8");
		request.setCharacterEncoding("utf-8");
		//设置返回数据的格式
		response.setContentType("text/json;charset:utf-8");
		String[] column ={"id","name","num","price"};
		String res = MysqlUtil.getJsonBySql(sql, column);
		System.out.println(res);
		// 响应数据
		response.getWriter().write(res);
	}

}

3.7 SelectServlet.java

java 复制代码 
package com.qcby.servlet;

import java.io.IOException;
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 com.qcby.db.MysqlUtil;

/**
 * Servlet implementation class SelectServlet
 */
@WebServlet("/select")
public class SelectServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public SelectServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		String name = request.getParameter("name");
		String sql = "select * from commodity where name ='" + name +"';";
		response.setCharacterEncoding("utf-8");
		request.setCharacterEncoding("utf-8");
		//设置返回数据的格式
		response.setContentType("text/json;charset:utf-8");
		String[] column ={"id","name","num","price"};
		String res = MysqlUtil.getJsonBySql(sql, column);
		System.out.println(res);
		// 响应数据
		response.getWriter().write(res);
	}

}

3.8 UpdataServlet.java

java 复制代码 
package com.qcby.servlet;

import java.io.IOException;
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 com.qcby.db.MysqlUtil;

/**
 * Servlet implementation class UpdataServlet
 */
@WebServlet("/updata")
public class UpdataServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public UpdataServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setCharacterEncoding("utf-8");
		request.setCharacterEncoding("utf-8");
		String id = request.getParameter("id");
		String name = request.getParameter("name");
		String number = request.getParameter("num");
		String price = request.getParameter("price");
		String sql = "update commodity set  name = '" + name + "', num = "+ number +", price="+ price +" where id = " + id +";";
		int num = MysqlUtil.update(sql);
		response.getWriter().write(num + "");
	}

}

3.9 style.css

css 复制代码 
*{
    margin: 0;
    padding: 0;
}
@font-face {
    font-family: YUZ;
    src: url(./YXZ.ttf);
}
body{
	position: relative;
	padding-top: 100px;
}
#todo {
    width: 500px;
    min-width: 500px;
    padding: 5px;
    background:linear-gradient(red,blue);
    background:-moz-linear-gradient(left,#ace,#f96);
    background:-webkit-gradient(linear,0 50%,100% 50%,from(#ace),to(#f96));
    background:-webkit-linear-gradient(left,#ace,#f96);
    background:-o-linear-gradient(left,#ace,#f96);
    margin: auto;
    border-radius: 10px;
    border: solid 1px wheat;
}
#todo .cmmodityName{
	width: 50%;
    height:25px;
    line-height:30px;
    border-radius: 10px 10px 10px 10px;
    border: solid 1px rgb(255, 255, 255);
    margin-bottom: 10px;
    padding-left: 10px;
    font-size: 20px;
}

#todo .add, #todo .select{
    width: 15%;
    height:30px;
    line-height:30px;
    border-radius: 10px 10px 10px 10px;
    background-color: rgb(39, 160, 225);
    border: solid 1px rgb(255, 255, 255);
    margin-bottom: 10px;
}
#todo #add{
    width: 40%;
    border-radius: 0px 10px 10px 0px;
    background-color: rgb(39, 160, 225);
    border: 0;
    cursor: pointer;
    color: rgb(255, 255, 255);
}
#todoList{
    width: 100%;
    border-radius: 10px;
    overflow: hidden;
    color: white;
}
#todoList thead {
    background-color: rgb(39, 160, 225);
}
#todoList thead td:first-child {
    width: 20%;
    border-radius: 10px 0px 0px 0px;
}
#todoList thead td:last-child {
    border-radius: 0px 10px 0px 0px;
}
#todoList tr{
    width: 100%;
    height: 40px;
    text-align: center;
    color: rgb(51, 51, 51);
}
#todoList td{
    border: solid 1px white ; 
}
#todoList tr td input{
    width: 45px;
    height: 25px;
    line-height: 25px;
    font-family: Arial, Helvetica, sans-serif;
    background-color: #ace;
    border: solid 1px white;
    color: rgb(67, 67, 67);
}
#todoList tr td input:first-child{
    border-radius: 5px 0 0 5px;
}
#todoList tr td input:last-child{
    border-radius: 0 5px 5px 0;
    border-left: 0;
}
#add_div, #add_div2{
	position: absolute;
	top: 0;
    left: 0;
    background-color: rgba(255, 255, 255, 0.95);
    width: 100%;
    height: 100vh;
}
#add_div .add_div{
    margin: auto;
    padding: 5px;
    border: solid 2px #ac0f0f;
    border-radius: 3px;
    position: absolute;
    width: 20%;
    height: 20%;
    top: 40%;
    left: 40%;
}
#add_div .add_div input{
    height: 20px;
    width: 150px;
    padding-left: 5px;
}
#add_div2 .add_div{
    margin: auto;
    padding: 5px;
    border: solid 2px #ac0f0f;
    border-radius: 3px;
    position: absolute;
    width: 20%;
    height: 20%;
    top: 40%;
    left: 40%;
}
#add_div2 .add_div tr th{
    width: 100px;
    height: 30px;
}
#add_div2 .add_div span{
    height: 20px;
    width: 100px;
    padding-left: 5px;
}
#add_div2 .add_div input{
    height: 20px;
    width: 200px;
}

3.10 index.js

js 复制代码 
// 初始化
$.ajax({
	url:"commodity",
	type: "get",
	success:function(value){
		console.log(value);
		var arr = value.data;
		for(let i = 0 ; i < arr.length; i ++){
			$("#one").append("<tr>" + 
				"<td>" + arr[i].name +"</td>"+
				"<td>" + arr[i].num +"</td>"+
				"<td>" + arr[i].price +"</td>"+
                "<td>" + "<input type=\"button\" value=\"修改\" class=\"reUpdata\" index = \"" + arr[i].id + "\">" + 
    			"<input type=\"button\" class = \"del\" value=\"删除\" index = \""+ arr[i].id +"\">" + "</td>")
		}
	},
	error:function(){
		alert("失败了！！");
	}
})
// 删除
$("tbody").on("click",".del", function(){
	var id = $(this).attr("index");
	$.ajax({
		url:"del",
		type:"post",
		data:{
			id
		},
		success:function(value){
			location.reload();
		},
		error: function(){
			alert("失败了！！");
		}
	})
})
var flag = 1;
// 点击添加
$(".add").on("click",function(){
	$("#add_div").css("display","block");
	$(".name").val("");
	$(".num").val("");
	$(".price").val("");
	$(".upData").val("添加商品");
	flag = 1;
})
// 点击取消
$(".back").on("click", function(){
	$("#add_div").css("display","none");
})
// 取消查找
$(".back2").on("click", function(){
	$("#add_div2").css("display","none");
})
// 点击查找
$(".select").on("click",function(){
	var name = $(".cmmodityName").val();
	if(name==""){
		alert("输入正确的格式！！！");
		return;
	}
	$.ajax({
		url:"select",
		type:"post",
		data:{
			name
		},
		success:function(value){
			if(value.data.length == 0){
				alert("不存在该物品");
				return;
			}
			var arr = value.data[0];
			$(".Cname").text(arr.name);
			$(".Cnum").text(arr.num);
			$(".Cprice").text(arr.price);
			$("#add_div2").css("display","block");
		},
		error:function(){
			alert("不存在该物品");
		}
	});
	
})
// 点击第二个添加，更新数据
$(".upData").on("click", function(){
	// 是1，就是添加
	if(flag ==1){
		var name = $(".name").val();
		var num = $(".num").val();
		var price = $(".price").val();
		$.ajax({
			url:"add",
			type:"post",
			data:{
				name,num,price
			},
			success:function(value){
				console.log(value);
				if(value=="0"){
					alert("请输入正确格式！！！");
				}else{
					location.reload();
					alert("添加成功！！！");
				}
			},
			error:function(){
				alert("失败了")
			}
		})
	}else{
		var id = $(".Cid").val();
		var name = $(".name").val();
		var num = $(".num").val();
		var price = $(".price").val();
		$.ajax({
			url:"updata",
			type:"post",
			data:{
				id, name, num, price
			},
			success:function(value){
				console.log(value);
				if(value=="0"){
					alert("请输入正确格式！！！");
				}else{
					location.reload();
					alert("修改成功！！！")
				}
			},
			error:function(){
				alert("失败了");
			}
		})
	}
})
// 点击修改
$("tbody").on("click",".reUpdata", function(){
	$("#add_div").css("display","block");
	id = $(this).attr("index");
	$.ajax({
		url:"selectById",
		type:"post",
		data:{
			id
		},
		success:function(value){
			flag = 0;
			var arr = value.data[0];
			$(".Cid").val(arr.id);
			$(".name").val(arr.name);
			$(".num").val(arr.num);
			$(".price").val(arr.price);
			$(".upData").val("修改");
		},
		error: function(){
			alert("失败了！！");
		}
	})
})

3.11 jquery-3.7.1.min.js（略）

3.12 index.html

html 复制代码 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>表</title>
    <link rel="stylesheet" href="css/style.css">
    <script src="js/jquery-3.7.1.min.js"></script>
    <script src="js/index.js" defer></script>
</head>
<body>
    <!-- <div>demo</div>
    <a href="test">你好</a> -->
    <div id="todo">
    商品名称：<input type="text" class="cmmodityName"><input type="button"  class="select" value="查找"><input type="button"  class="add" value="添加">
        <table id="todoList" cellpadding="0" cellspacing="0" >
            <thead>
                <td>商品名字</td>
                <td>数量</td>
                <td>价格</td>
                <td>操作</td>
            </thead>
            <tbody id ="one">
                
            </tbody>
        </table>
    </div>
    <div id="add_div" style="display:none">
        <table class="add_div">
            <tr>
                <th>商品名称：</th>
                <th><input type="text" class="name"></th>
            </tr>
            <tr>
                <th>商品数量：</th>
                <th><input type="text" class="num"></th>
            </tr>
            <tr>
                <th>商品价格：</th>
                <th><input type="text" class="price"></th>
            </tr>
            <tr>
                <th> <input type="button" value="添加" class="upData"></th>
                <th><input type="button" value="取消" class="back"></th>
            </tr>
        </table>
    </div>
    <div id="add_div2" style="display:none">
        <span class="Cid" style="display:none">1</span>
        <table class="add_div">
            <tr>
                <th>商品名称：</th>
                <th><span class="Cname">XXX</span></th>
            </tr>
            <tr>
                <th>商品数量：</th>
                <th><span class="Cnum">XXX</span></th>
            </tr>
            <tr>
                <th>商品价格：</th>
                <th><span class="Cprice">XXX</span></th>
            </tr>
            <tr>
                <th colspan="2"><input type="button" value="取消" class="back2"></th>
            </tr>
        </table>
    </div>
    
    
</body>
</html>

4. 效果展示

查找不存在的物品：

查找成功：

点击添加：

添加成功：

添加失败：

点击删除就直接没了

点击修改：


5. 链接

javaWeb项目创建

史上最全MySQL基本操作（这一篇就够用了！！！）

6. 思考

目前还是不完美的，当添加商品时，商品已经存在表里，仍然能添加上，就交给你去修改了。（因为我比较懒。。。。）

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