1.数据库表如下

CREATE TABLE `employee` (`id` int(11) NOT NULL AUTO_INCREMENT,`name` varchar(40) NOT NULL,`note` varchar(200) DEFAULT NULL,PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;

2.项目的目录结构

5 个后端文件和 1 个前端文件。
controller 控制层，对业务逻辑的处理，响应给前端页面。
dao 数据接口层
entity 实体
impl 数据接口的实现，CRUD 语句
main.jsp 前端代码

简单前端页面，完整后端功能。

3.完整代码

实体类 Employee

/*** @author :hly* @github :https://github.com/huangliangyun* @blog :blog.csdn.net/Sirius_hly* @date :2018/11/29*/
public class Employee {private int id;private String name;private String note;public Employee() {}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getNote() {return note;}public void setNote(String note) {this.note = note;}@Overridepublic String toString() {return "Employee{" +"id=" + id +", name='" + name + '\'' +", note='" + note + '\'' +'}';}
}

数据库连接类 DBConnection

package com.hly.jsp.javaWeb.dao;import java.sql.*;/*** @author :hly* @github :https://github.com/huangliangyun* @blog :blog.csdn.net/Sirius_hly* @date :2018/10/31*/
public class DBConnection {private static final String driverName = "com.mysql.jdbc.Driver";private static final String url = "jdbc:mysql://localhost:3306/testDB?useUnicode=true&characterEncoding=UTF-8";private static final String user = "root";private static final String password = "roof";private static Connection connection = null;/*static {try {Class.forName(driverName);} catch (ClassNotFoundException e) {System.out.println("连接失败"+e.getMessage());}}
*/public static Connection getConnection() throws SQLException {try {Class.forName(driverName);connection = DriverManager.getConnection(url, user, password);;} catch (ClassNotFoundException e) {e.printStackTrace();}return connection;}public static void close(ResultSet rs, Statement st, Connection conn) {try {if (rs != null) {rs.close();}} catch (SQLException e) {e.printStackTrace();} finally {try {if (st != null) {st.close();}} catch (SQLException e) {e.printStackTrace();} finally {if (conn != null) {try {conn.close();} catch (SQLException e) {e.printStackTrace();}}}}}
}

EmployeeDao 数据接口层

package com.hly.jsp.javaWeb.dao;
import com.hly.jsp.javaWeb.entity.Employee;
import java.util.List;/*** @author :hly* @github :https://github.com/huangliangyun* @blog :blog.csdn.net/Sirius_hly* @date :2018/11/29*/
public interface EmployeeDao {//Cpublic int add(Employee employee);//Rpublic List<Employee> selectAll();public List<Employee> query(String name);//Upublic int  update(Employee employee);//Dpublic int delete (int id);}

dao 层实现类 EmployeeDaoImpl，SQL 语句的实现

package com.hly.jsp.javaWeb.impl;
import com.hly.jsp.javaWeb.dao.DBConnection;
import com.hly.jsp.javaWeb.dao.EmployeeDao;
import com.hly.jsp.javaWeb.entity.Employee;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;/*** @author :hly* @github :https://github.com/huangliangyun* @blog :blog.csdn.net/Sirius_hly* @date :2018/11/29*/
public class EmployeeDaoImpl implements EmployeeDao {//增@Overridepublic int add(Employee employee) {try {Connection con = DBConnection.getConnection();String sql = "insert into employee(name,note) values(?,?)";PreparedStatement ps = con.prepareStatement(sql);ps.setString(1, employee.getName());ps.setString(2, employee.getNote());ps.executeUpdate();DBConnection.close(null,ps,con);} catch (SQLException e) {e.printStackTrace();}return 1;}//查全部@Overridepublic List<Employee> selectAll() {List<Employee> list = new ArrayList<>();Employee employee = null;try {Connection con = DBConnection.getConnection();String sql = "select id,name,note from employee";PreparedStatement ps = con.prepareStatement(sql);ResultSet rs = ps.executeQuery();while (rs.next()){employee = new Employee();employee.setId(rs.getInt(1));employee.setName(rs.getString(2));employee.setNote(rs.getString(3));list.add(employee);}DBConnection.close(rs,ps,con);} catch (SQLException e) {e.printStackTrace();}return list;}//根据 id 查@Overridepublic List<Employee> query(String name) {Employee employee = null;List<Employee> list = new ArrayList<>();try {Connection con = DBConnection.getConnection();String sql = "select id,name,note from employee where name like ?";PreparedStatement ps = con.prepareStatement(sql);//模糊查询ps.setString(1,"%"+name+"%");ResultSet rs = ps.executeQuery();while (rs.next()){employee = new Employee();employee.setId(rs.getInt(1));employee.setName(rs.getString(2));employee.setNote(rs.getString(3));list.add(employee);}DBConnection.close(rs,ps,con);} catch (SQLException e) {e.printStackTrace();}return list;}//更新@Overridepublic int update(Employee employee) {try {Connection con = DBConnection.getConnection();String sql = "update employee set name = ?,note = ? where id = ?";PreparedStatement ps = con.prepareStatement(sql);ps.setString(1,employee.getName());ps.setString(2,employee.getNote());ps.setInt(3,employee.getId());ps.executeUpdate();DBConnection.close(null,ps,con);} catch (SQLException e) {e.printStackTrace();}return 1;}//删除@Overridepublic int delete(int id) {try {Connection con = DBConnection.getConnection();String sql = "delete from employee where id = ?";PreparedStatement ps = con.prepareStatement(sql);ps.setInt(1,id);ps.executeUpdate();DBConnection.close(null,ps,con);} catch (SQLException e) {e.printStackTrace();}return 1;}
}

控制层 Servlet

EmployeeServlet

package com.hly.jsp.javaWeb.controller;import com.hly.jsp.javaWeb.dao.EmployeeDao;
import com.hly.jsp.javaWeb.entity.Employee;
import com.hly.jsp.javaWeb.impl.EmployeeDaoImpl;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 java.io.IOException;
import java.lang.reflect.Method;
import java.util.List;
/*** @author :hly* @github :https://github.com/huangliangyun* @blog :blog.csdn.net/Sirius_hly* @date :2018/11/28*/@WebServlet(urlPatterns = { "*.do" })
public class EmployeeServlet extends HttpServlet {public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {response.setContentType("text/html;charset=UTF-8");doGet(request, response);}public void doGet(HttpServletRequest request, HttpServletResponse response) {response.setContentType("text/html;charset=utf-8");String url = request.getRequestURI();String methodName = url.substring(url.lastIndexOf("/")+1, url.lastIndexOf("."));Method method = null;try {// 使用反射机制获取在本类中声明了的方法method = getClass().getDeclaredMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);// 执行方法method.invoke(this, request, response);} catch (Exception e) {throw new RuntimeException("调用方法出错");}}//增加public void addEmp(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {Employee employee = new Employee();employee.setName(request.getParameter("addName"));employee.setNote(request.getParameter("addNote"));EmployeeDao employeeDao = new EmployeeDaoImpl();employeeDao.add(employee);selectAllEmp(request,response);}//查找全部public void selectAllEmp(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {EmployeeDao employeeDao = new EmployeeDaoImpl();List<Employee> list = employeeDao.selectAll();request.setAttribute("list", list);request.getRequestDispatcher("/javaWeb/manage/main.jsp").forward(request, response);}//模糊查询public void selectByEmpName(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String name = request.getParameter("selectName");EmployeeDao employeeDao = new EmployeeDaoImpl();List<Employee> list = employeeDao.query(name);System.err.println("list："+list);request.setAttribute("list", list);request.getRequestDispatcher("/javaWeb/manage/main.jsp").forward(request, response);}//更新数据public void updateEmp(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {Employee employee = new Employee();employee.setId(Integer.parseInt(request.getParameter("updateId")));employee.setName(request.getParameter("updateName"));employee.setNote(request.getParameter("updateNote"));System.err.println(employee);EmployeeDao employeeDao = new EmployeeDaoImpl();employeeDao.update(employee);selectAllEmp(request,response);}//删除public void deleteEmp(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String deleteId = request.getParameter("deleteId");EmployeeDao employeeDao = new EmployeeDaoImpl();employeeDao.delete(Integer.parseInt(deleteId));selectAllEmp(request,response);}
}

前端代码 main.js

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head><title>main</title><style>a, a:focus {text-decoration: none;}</style>
</head>
<body><a href="selectAllEmp.do">点击查询所有用户信息</a><br/><form action="selectByEmpName.do"><input type="text" name="selectName" placeholder="请输入名字"><input type="submit" value="模糊查询">
</form><form action="addEmp.do"><input type="text" name="addName" placeholder="请输入姓名"><input type="text" name="addNote" placeholder="请输入Note"><input type="submit" value="添加">
</form><form action="updateEmp.do"><input type="text" placeholder="需要修改的id"name="updateId" ><input type="text" placeholder="需要修改的name" name="updateName"><input type="text" placeholder="需要修改的note" name="updateNote"><input type="submit" value="修改">
</form><table border="1" cellpadding="3" cellspacing="0" width="400"><tr><th>id</th><th>name</th><th>note</th><th>delete</th></tr><c:forEach var="e" items="${list}"><tr><td>${e.id}</td><td>${e.name}</td><td>${e.note}</td><td><a href="deleteEmp.do?deleteId=${e.id}">删除</a></td></tr></c:forEach>
</table><script type="javascript"></script>
</body>
</html>

我的 Github：Github
个人网站: 天狼星的博客
代码下载：https://download.csdn.net/download/sirius_hly/10817983

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