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@@ -0,0 +1,476 @@
+```java
+package utils;
+
+import java.sql.*;
+
+public class DBUtil {
+    static String url = "jdbc:mysql:///CompanyManager?useSSL=false&useUnicode=true&characterEncoding=utf8";
+    static String user = "root";
+    static String pwd = "root";
+
+    static {
+        try {
+            Class.forName("com.mysql.jdbc.Driver");
+        } catch (ClassNotFoundException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public static Connection getConn() throws SQLException {
+        Connection conn = DriverManager.getConnection(url, user, pwd);
+        return conn;
+    }
+
+    // 查询
+    public static ResultSet query(String sql, Object... keys) {
+        ResultSet rs = null;
+        try {
+            Connection conn = getConn();
+            PreparedStatement pst = conn.prepareStatement(sql);
+            for (int i = 0; i < keys.length; i++) {
+                pst.setObject((i + 1), keys[i]);
+            }
+            rs = pst.executeQuery();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        return rs;
+    }
+
+    // update
+    public static int update(String sql, Object... keys) {
+        int rs = 0;
+        try {
+            Connection conn = getConn();
+            PreparedStatement pst = conn.prepareStatement(sql);
+            for (int i = 0; i < keys.length; i++) {
+                pst.setObject((i + 1), keys[i]);
+            }
+            rs = pst.executeUpdate();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        return rs;
+    }
+
+}
+
+```
+
+```java
+package bean;
+
+public class Dept {
+    private int deptId;
+    private String deptName;
+
+    @Override
+    public String toString() {
+        return "Dept{" +
+                "deptId=" + deptId +
+                ", deptName='" + deptName + '\'' +
+                '}';
+    }
+
+    public int getDeptId() {
+        return deptId;
+    }
+
+    public void setDeptId(int deptId) {
+        this.deptId = deptId;
+    }
+
+    public String getDeptName() {
+        return deptName;
+    }
+
+    public void setDeptName(String deptName) {
+        this.deptName = deptName;
+    }
+
+    public Dept() {
+    }
+
+    public Dept(int deptId, String deptName) {
+        this.deptId = deptId;
+        this.deptName = deptName;
+    }
+}
+
+```
+
+```java
+package bean;
+
+public class Emp {
+    private int empId; // 员工编号
+    private String empName; // 员工姓名
+    private String sex; //员工性别
+    private int age; //员工年龄
+    private String tel; //员工号码
+    private String passWord; //员工密码
+    private int deptId; // 员工部门编号
+    private String deptName; //员工部门名称
+
+    @Override
+    public String toString() {
+        return "Emp{" +
+                "empId=" + empId +
+                ", empName='" + empName + '\'' +
+                ", sex='" + sex + '\'' +
+                ", age=" + age +
+                ", tel='" + tel + '\'' +
+                ", passWord='" + passWord + '\'' +
+                ", deptId=" + deptId +
+                ", deptName='" + deptName + '\'' +
+                '}';
+    }
+
+    public int getEmpId() {
+        return empId;
+    }
+
+    public void setEmpId(int empId) {
+        this.empId = empId;
+    }
+
+    public String getEmpName() {
+        return empName;
+    }
+
+    public void setEmpName(String empName) {
+        this.empName = empName;
+    }
+
+    public String getSex() {
+        return sex;
+    }
+
+    public void setSex(String sex) {
+        this.sex = sex;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public String getTel() {
+        return tel;
+    }
+
+    public void setTel(String tel) {
+        this.tel = tel;
+    }
+
+    public String getPassWord() {
+        return passWord;
+    }
+
+    public void setPassWord(String passWord) {
+        this.passWord = passWord;
+    }
+
+    public int getDeptId() {
+        return deptId;
+    }
+
+    public void setDeptId(int deptId) {
+        this.deptId = deptId;
+    }
+
+    public String getDeptName() {
+        return deptName;
+    }
+
+    public void setDeptName(String deptName) {
+        this.deptName = deptName;
+    }
+
+    public Emp() {
+    }
+
+    public Emp(int empId, String empName, String sex, int age, String tel, String passWord, int deptId, String deptName) {
+        this.empId = empId;
+        this.empName = empName;
+        this.sex = sex;
+        this.age = age;
+        this.tel = tel;
+        this.passWord = passWord;
+        this.deptId = deptId;
+        this.deptName = deptName;
+    }
+
+
+}
+
+```
+
+```java
+package servlet;
+
+import bean.Dept;
+import bean.Emp;
+import utils.DBUtil;
+
+import javax.servlet.*;
+import javax.servlet.http.*;
+import javax.servlet.annotation.*;
+import java.io.IOException;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.ArrayList;
+
+@WebServlet("/add")
+public class AddServlet extends HttpServlet {
+    @Override
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        String sql="select * from emp";
+        ResultSet rs = DBUtil.query(sql);
+        ArrayList<Dept> list = new ArrayList<>();
+        try {
+            while (rs.next()){
+                int id = rs.getInt("id");
+                String deptName = rs.getString("deptName");
+                Dept dept = new Dept(id, deptName);
+                list.add(dept);
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        request.setAttribute("list",list);
+        request.getRequestDispatcher("/WEB-INF/from.jsp").forward(request,response);
+
+    }
+
+    @Override
+    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        request.setCharacterEncoding("utf-8");
+        String empName = request.getParameter("empName");
+        String sex = request.getParameter("sex");
+        int age = Integer.parseInt(request.getParameter("age"));
+        String tel = request.getParameter("tel");
+        String passWord = request.getParameter("passWord");
+        String deptId = request.getParameter("deptId");
+        String sql="insert into emp values (?,?,?,?,?,?,?)";
+        int i = DBUtil.update(sql, 0, empName, sex, age, tel, passWord, deptId);
+        if (i>0){
+            response.sendRedirect("/list");
+        }else{
+            request.setAttribute("msg","添加失败");
+            request.getRequestDispatcher("/WEB-INF/msg.jsp").forward(request,response);
+        }
+
+
+    }
+}
+
+```
+
+```java
+package servlet;
+
+import bean.Emp;
+import utils.DBUtil;
+
+import javax.servlet.*;
+import javax.servlet.http.*;
+import javax.servlet.annotation.*;
+import java.io.IOException;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.ArrayList;
+
+@WebServlet("/list")
+public class ListServlet extends HttpServlet {
+    @Override
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        String sql="select * from dept d ,emp e where d.DeptID=e.DeptID";
+        ResultSet rs = DBUtil.query(sql);
+        ArrayList<Emp> list = new ArrayList<>();
+        try {
+            while (rs.next()){
+                int deptId = rs.getInt(1);
+                String deptName = rs.getString(2);
+                int empId = rs.getInt(3);
+                String empName = rs.getString(4);
+                String sex = rs.getString(5);
+                int age = rs.getInt(6);
+                String tel = rs.getString(7);
+                String passWord = rs.getString(8);
+                Emp emp = new Emp(empId, empName, sex, age, tel, passWord, deptId, deptName);
+                list.add(emp);
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        request.setAttribute("list",list);
+        request.getRequestDispatcher("/WEB-INF/list.jsp").forward(request,response);
+
+
+    }
+
+    @Override
+    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        request.setCharacterEncoding("utf-8");
+        String user = request.getParameter("user");
+        String sql="select * from dept d ,emp e where d.DeptID=e.DeptID and empName like ?";
+        ResultSet rs = DBUtil.query(sql,"%"+user+"%");
+        ArrayList<Emp> list = new ArrayList<>();
+        try {
+            while (rs.next()){
+                int deptId = rs.getInt(1);
+                String deptName = rs.getString(2);
+                int empId = rs.getInt(3);
+                String empName = rs.getString(4);
+                String sex = rs.getString(5);
+                int age = rs.getInt(6);
+                String tel = rs.getString(7);
+                String passWord = rs.getString(8);
+                Emp emp = new Emp(empId, empName, sex, age, tel, passWord, deptId, deptName);
+                list.add(emp);
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        request.setAttribute("list",list);
+        request.getRequestDispatcher("/WEB-INF/list.jsp").forward(request,response);
+
+    }
+}
+
+```
+
+```jsp
+<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
+<%--
+  Created by IntelliJ IDEA.
+  User: Administrator
+  Date: 2023-06-10
+  Time: 16:22
+  To change this template use File | Settings | File Templates.
+--%>
+<%@ page contentType="text/html;charset=UTF-8" language="java" %>
+<html>
+<head>
+    <title>添加</title>
+</head>
+<body>
+<form action="/add" method="post">
+    <table>
+        <tr>
+            <th>姓名</th>
+            <td><input type="text" name="empName"></td>
+        </tr>
+        <tr>
+            <th>性别</th>
+            <td><input type="text" name="sex"></td>
+        </tr>
+        <tr>
+            <th>年龄</th>
+            <td><input type="text" name="age"></td>
+        </tr>
+        <tr>
+            <th>电话</th>
+            <td><input type="text" name="tel"></td>
+        </tr>
+        <tr>
+            <th>所属部门</th>
+            <td>
+                <select name="wu">
+                    <option>开发部</option>
+                    <c:forEach items="${list}" var="emp">
+                        <option value="${emp.deptId}"> ${emp.deptName} </option>
+                    </c:forEach>
+                </select>
+            </td>
+        </tr>
+        <tr>
+            <th>密码</th>
+            <td>
+                <input type="text" name="passWord">
+            </td>
+        </tr>
+        <tr>
+            <input type="submit">
+        </tr>
+    </table>
+</form>
+
+</body>
+</html>
+
+```
+
+```jsp
+<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
+<%--
+  Created by IntelliJ IDEA.
+  User: Administrator
+  Date: 2023-06-10
+  Time: 15:42
+  To change this template use File | Settings | File Templates.
+--%>
+<%@ page contentType="text/html;charset=UTF-8" language="java" %>
+<html>
+<head>
+    <title>Title</title>
+</head>
+<body>
+<form action="/list" method="post">
+    姓名:<input type="text" name="user">
+    <input type="submit" name="查询">
+</form>
+<a href="/add"><button>添加员工</button> </a>
+<table border="1">
+    <tr>
+        <th>编号</th>
+        <th>姓名</th>
+        <th>性别</th>
+        <th>年龄</th>
+        <th>电话</th>
+        <th>所属部门</th>
+    </tr>
+    <c:forEach items="${list}" var="emp">
+        <tr>
+            <td>${emp.empId}</td>
+            <td>${emp.empName}</td>
+            <td>${emp.sex}</td>
+            <td>${emp.age}</td>
+            <td>${emp.tel}</td>
+            <td>${emp.deptName}</td>
+        </tr>
+    </c:forEach>
+
+</table>
+
+
+</body>
+</html>
+
+```
+
+```jsp
+<%--
+  Created by IntelliJ IDEA.
+  User: Administrator
+  Date: 2023-06-10
+  Time: 16:39
+  To change this template use File | Settings | File Templates.
+--%>
+<%@ page contentType="text/html;charset=UTF-8" language="java" %>
+<html>
+<head>
+    <title>Title</title>
+</head>
+<body>
+${msg}
+<a href="/list">返回列表 </a>
+</body>
+</html>
+
+```
+