课后作业

//连接数据库
package util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class DBUtil {
    

    // 数据库连接地址
    private static String URL = "jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC";

    // 数据库的用户名
    private static String UserName = "root";
    // 数据库的密码
    private static String Password = "123456";

    public static Connection getConnection() {
        Connection Conn=null;

        try {

            Class.forName("com.mysql.cj.jdbc.Driver"); // 加载驱动

            System.out.println("加载驱动成功!!!");
        } catch (ClassNotFoundException e) {
            // TODO: handle exception
            e.printStackTrace();
        }

        try {

            //通过DriverManager类的getConenction方法指定三个参数,连接数据库
            Conn = DriverManager.getConnection(URL, UserName, Password);
            System.out.println("连接数据库成功!!!");

            //返回连接对象
            //return Conn;

        } catch (SQLException e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        return Conn;
    }
    public static void main(String[] args)throws SQLException {  //测试数据库是否连通
        Connection conn = getConnection();
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        String sql ="select * from teacher";
        pstmt = conn.prepareStatement(sql);
        rs = pstmt.executeQuery();
        System.out.println(getConnection());

        while(rs.next()){
            System.out.println("空");
        }

        }


}

　　

package j;

import util.DBUtil;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import service.Course;

public class CourseDao {
    public List<Course> getcourse(){
        List<Course>list=new ArrayList<Course>();
        Course course=null;
        Connection conn=DBUtil.getConnection();//连接数据库
        String sql="select * from teacher";
        Statement state = null;
        ResultSet rs = null;
        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            while(rs.next()) {
                course = new Course();
                course.setid(rs.getInt("id"));
                course.setname(rs.getString("name"));
                course.setteacher(rs.getString("teacher"));
                course.setclassroom(rs.getString("classroom"));
                list.add(course);
            }
        }
            catch(SQLException e) {
                e.printStackTrace();
            }        
        return list;
}
    public boolean addcourse(Course course) {
        String sql="insert into teacher('name','teacher','classroom')valus(?,?,?)";
        Connection conn=DBUtil.getConnection();
        try {
            PreparedStatement pst = conn.prepareStatement(sql);
             pst.setString(1, course.getname());
             pst.setString(2, course.getteacher());
             pst.setString(3, course.getclassroom());
             int count = pst.executeUpdate();
             pst.close();
             return count>0?true:false;
        }catch(SQLException e) {
            e.printStackTrace();
        }return false;
    }


    public boolean update(Course course) {
        String sql="update teacher set'name'=?,'teacher'=?,'classroom'=? where id=?";
        Connection conn = DBUtil.getConnection();
        try {
            PreparedStatement pst = conn.prepareStatement(sql);
             pst.setString(1, course.getname());
             pst.setString(2, course.getteacher());
             pst.setString(3, course.getclassroom());
             int count = pst.executeUpdate();
             pst.close();
             return count>0?true:false;
        }catch(SQLException e) {
            e.printStackTrace();
        }return false;    
    }
    public boolean delete(int id) {
        String sql = "delete from user where id = ?"; 
        Connection conn= DBUtil.getConnection();
        try {
            PreparedStatement pst= conn.prepareStatement(sql);
            pst.setInt(1,id);
            int count = pst.executeUpdate();
             pst.close();
             return count>0?true:false;
        }catch(SQLException e) {
            e.printStackTrace();
        }return false;    
    }
    public Course selectUserById(int id){  
        Connection conn = DBUtil.getConnection();
        String sql  = "select * from user where id = "+id;
        Course course = null;
        try {
            PreparedStatement pst = conn.prepareStatement(sql);
            ResultSet rst = pst.executeQuery();
            while (rst.next()) {
                course = new Course();
                course.setid(rst.getInt("id"));
                course.setname(rst.getString("name"));
                course.setteacher(rst.getString("teacher"));
                course.setclassroom(rst.getString ("classroom"));
            }
            rst.close();
            pst.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return course;  
    }

}

　　

package servlet;

import java.io.IOException;
import java.util.List;

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 dao.CourseDao;
import service.Course;

/**
 * Servlet implementation class servlet
 */
@WebServlet("/servlet")
public class ListServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ListServlet() {
        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());
        CourseDao dao =new CourseDao();
        List<Course> list=dao.getcourse();
        request.setAttribute("courseinfo", list);
        request.getRequestDispatcher("list.jsp").forward(request, response);
    }

    /**
     * @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);
    }

}

　　

<%@page import="dao.CourseDao"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
    <%@ page import="service.Course" %>
    <%@ page import="java.util.List" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>list</title>
</head>
<body>

<%
    CourseDao courseDao = new CourseDao();
    List<Course> list = courseDao.getcourse(); 
    if (list == null || list.size() < 1) {  
 %>
   <tr bgcolor="white"><td colspan="5" ><h4 align="center">没有数据</h4></td></tr>
<%
       }
    else {  
           // 遍历用户集合中的数据  
           for (Course course : list) {  
%>
    <tr align="center"  bgcolor="white">  
            <td><%=course.getid()%></td>  
            <td><%=course.getname()%></td>
            <td><%=course.getteacher()%></td>  
            <td><%=course.getclassroom() %></td>
            </tr>
            <%
            }
       }
            %>
    
</body>
</html>