一. 新建数据表
在mysql中新建一个名为course的数据库，并在其中新建一个course数据表，包含四个字段，id，name，teacher，classname如图
注意：将id设为自动递增，否则后面新增会出错。id设为自增，新增时就只需关注course的其它属性。
二. 新建web项目
1. eclipse新建一个名为MyServlet的Dynamic Web Project
修改class的默认输出目录为：WebContent/WEB-INF/classes
勾选自动生成web.xml
生成的项目在java EE透视图中的结构如下，
2. 将连接mysql的驱动jar包（mysql-connector-java-5.1.7-bin.jar）copy到WEB-INF下的lib目录下
3. 新建五个包，entity存放实体类(User)，dao存放数据库操作类(UserDao)，servlet存放控制类(addServlet,updateServlet,deleteServlet,listServlet)，util存放开发帮助类service是算法实现(这里是数据库操作帮助类，封装了数据库连接部分代码，避免大量重复代码)
4. 新建类(最愉快的搬砖环节 -.-)，java类放在对应包中，jsp页面放在WebContent目录下，替换web.xml中内容，结构如图
五：代码
//Course.javapackage com.hjf.entity;public class Course { private int id; private String name; private String teacher; private String classroom; 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 getTeacher() { return teacher; } public void setTeacher(String teacher) { this.teacher = teacher; } public String getClassroom() { return classroom; } public void setClassroom(String classroom) { this.classroom = classroom; } public Course() {} public Course(int id, String name, String teacher, String classroom) { this.id = id; this.name = name; this.teacher = teacher; this.classroom = classroom; } public Course(String name, String teacher, String classroom) { this.name = name; this.teacher = teacher; this.classroom = classroom; }}
//CourseDao.java package com.hjf.dao;import java.sql.Connection;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.ArrayList;import java.util.List;import com.hjf.entity.Course;import com.hjf.util.DBUtil;/** * 课程Dao * Dao层操作数据 * @author Hu * */public class CourseDao { /** * 添加 * @param course * @return */ public boolean add(Course course) { String sql = "insert into course(name, teacher, classroom) values('" + course.getName() + "','" + course.getTeacher() + "','" + course.getClassroom() + "')"; //创建数据库链接 Connection conn = DBUtil.getConn(); Statement state = null; boolean f = false; int a = 0; try { state = conn.createStatement(); state.executeUpdate(sql); } catch (Exception e) { e.printStackTrace(); } finally { //关闭连接 DBUtil.close(state, conn); } if (a > 0) { f = true; } return f; } /** * 删除 * * @param id * @return */ public boolean delete (int id) { boolean f = false; String sql = "delete from course where id='" + id + "'"; Connection conn = DBUtil.getConn(); Statement state = null; int a = 0; try { state = conn.createStatement(); a = state.executeUpdate(sql); } catch (SQLException e) { e.printStackTrace(); } finally { DBUtil.close(state, conn); } if (a > 0) { f = true; } return f; } /** * 修改 * @param name * @param pass */ public boolean update(Course course) { String sql = "update course set name='" + course.getName() + "', teacher='" + course.getTeacher() + "', classroom='" + course.getClassroom() + "' where id='" + course.getId() + "'"; Connection conn = DBUtil.getConn(); Statement state = null; boolean f = false; int a = 0; try { state = conn.createStatement(); a = state.executeUpdate(sql); } catch (SQLException e) { e.printStackTrace(); } finally { DBUtil.close(state, conn); } if (a > 0) { f = true; } return f; } /** * 验证课程名称是否唯一 * true --- 不唯一 * @param name * @return */ public boolean name(String name) { boolean flag = false; String sql = "select name from course where name = '" + name + "'"; Connection conn = DBUtil.getConn(); Statement state = null; ResultSet rs = null; try { state = conn.createStatement(); rs = state.executeQuery(sql); while (rs.next()) { flag = true; } } catch (SQLException e) { e.printStackTrace(); } finally { DBUtil.close(rs, state, conn); } return flag; } /** * 通过ID得到课程信息 * @param id * @return */ public Course getCourseById(int id) { String sql = "select * from course where id ='" + id + "'"; Connection conn = DBUtil.getConn(); Statement state = null; ResultSet rs = null; Course course = null; try { state = conn.createStatement(); rs = state.executeQuery(sql); while (rs.next()) { String name = rs.getString("name"); String teacher = rs.getString("teacher"); String classroom = rs.getString("classroom"); course = new Course(id, name, teacher, classroom); } } catch (Exception e) { e.printStackTrace(); } finally { DBUtil.close(rs, state, conn); } return course; } /** * 通过name得到Course * @param name * @return */ public Course getCourseByName(String name) { String sql = "select * from course where name ='" + name + "'"; Connection conn = DBUtil.getConn(); Statement state = null; ResultSet rs = null; Course course = null; try { state = conn.createStatement(); rs = state.executeQuery(sql); while (rs.next()) { int id = rs.getInt("id"); String teacher = rs.getString("teacher"); String classroom = rs.getString("classroom"); course = new Course(id, name, teacher, classroom); } } catch (Exception e) { e.printStackTrace(); } finally { DBUtil.close(rs, state, conn); } return course; } /** * 查找 * @param name * @param teacher * @param classroom * @return */ public List search(String name, String teacher, String classroom) { String sql = "select * from course where "; if (name != "") { sql += "name like '%" + name + "%'"; } if (teacher != "") { sql += "teacher like '%" + teacher + "%'"; } if (classroom != "") { sql += "classroom like '%" + classroom + "%'"; } List list = new ArrayList<>(); Connection conn = DBUtil.getConn(); Statement state = null; ResultSet rs = null; try { state = conn.createStatement(); rs = state.executeQuery(sql); Course bean = null; while (rs.next()) { int id = rs.getInt("id"); String name2 = rs.getString("name"); String teacher2 = rs.getString("teacher"); String classroom2 = rs.getString("classroom"); bean = new Course(id, name2, teacher2, classroom2); list.add(bean); } } catch (SQLException e) { e.printStackTrace(); } finally { DBUtil.close(rs, state, conn); } return list; } /** * 全部数据 * @param name * @param teacher * @param classroom * @return */ public List list() { String sql = "select * from course"; List list = new ArrayList<>(); Connection conn = DBUtil.getConn(); Statement state = null; ResultSet rs = null; try { state = conn.createStatement(); rs = state.executeQuery(sql); Course bean = null; while (rs.next()) { int id = rs.getInt("id"); String name2 = rs.getString("name"); String teacher2 = rs.getString("teacher"); String classroom2 = rs.getString("classroom"); bean = new Course(id, name2, teacher2, classroom2); list.add(bean); } } catch (SQLException e) { e.printStackTrace(); } finally { DBUtil.close(rs, state, conn); } return list; }} //CourseService.javapackage com.hjf.service;import java.util.List;import com.hjf.dao.CourseDao;import com.hjf.entity.Course;/** * CourseService * 服务层 * @author Hu * */public class CourseService { CourseDao cDao = new CourseDao(); /** * 添加 * @param course * @return */ public boolean add(Course course) { boolean f = false; if(!cDao.name(course.getName())) { cDao.add(course); f = true; } return f; } /** * 删除 */ public void del(int id) { cDao.delete(id); } /** * 修改 * @return */ public void update(Course course) { cDao.update(course); } /** * 通过ID得到一个Course * @return */ public Course getCourseById(int id) { return cDao.getCourseById(id); } /** * 通过Name得到一个Course * @return */ public Course getCourseByName(String name) { return cDao.getCourseByName(name); } /** * 查找 * @return */ public List search(String name, String teacher, String classroom) { return cDao.search(name, teacher, classroom); } /** * 全部数据 * @return */ public List list() { return cDao.list(); }} //CourseServlet.javapackage com.hjf.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 com.hjf.entity.Course;import com.hjf.service.CourseService;@WebServlet("/CourseServlet")public class CourseServlet extends HttpServlet { private static final long serialVersionUID = 1L; CourseService service = new CourseService(); /** * 方法选择 */ protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setCharacterEncoding("utf-8"); String method = req.getParameter("method"); if ("add".equals(method)) { add(req, resp); } else if ("del".equals(method)) { del(req, resp); } else if ("update".equals(method)) { update(req, resp); } else if ("search".equals(method)) { search(req, resp); } else if ("getcoursebyid".equals(method)) { getCourseById(req, resp); } else if ("getcoursebyname".equals(method)) { getCourseByName(req, resp); } else if ("list".equals(method)) { list(req, resp); } } /** * 添加 * @param req * @param resp * @throws IOException * @throws ServletException */ private void add(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException { req.setCharacterEncoding("utf-8"); //获取数据 String name = req.getParameter("name"); String teacher = req.getParameter("teacher"); String classroom = req.getParameter("classroom"); Course course = new Course(name, teacher, classroom); //添加后消息显示 if(service.add(course)) { req.setAttribute("message", "添加成功"); req.getRequestDispatcher("add.jsp").forward(req,resp); } else { req.setAttribute("message", "课程名称重复，请重新录入"); req.getRequestDispatcher("add.jsp").forward(req,resp); } } /** * 全部 * @param req * @param resp * @throws ServletException */ private void list(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{ req.setCharacterEncoding("utf-8"); List courses = service.list(); req.setAttribute("courses", courses); req.getRequestDispatcher("list.jsp").forward(req,resp); } /** * 通过ID得到Course * @param req * @param resp * @throws ServletException */ private void getCourseById(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{ req.setCharacterEncoding("utf-8"); int id = Integer.parseInt(req.getParameter("id")); Course course = service.getCourseById(id); req.setAttribute("course", course); req.getRequestDispatcher("detail2.jsp").forward(req,resp); } /** * 通过名字查找 * 跳转至删除 * @param req * @param resp * @throws IOException * @throws ServletException */ private void getCourseByName(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{ req.setCharacterEncoding("utf-8"); String name = req.getParameter("name"); Course course = service.getCourseByName(name); if(course == null) { req.setAttribute("message", "查无此课程！"); req.getRequestDispatcher("del.jsp").forward(req,resp); } else { req.setAttribute("course", course); req.getRequestDispatcher("detail.jsp").forward(req,resp); } } /** * 删除 * @param req * @param resp * @throws IOException * @throws ServletException */ private void del(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{ req.setCharacterEncoding("utf-8"); int id = Integer.parseInt(req.getParameter("id")); service.del(id); req.setAttribute("message", "删除成功！"); req.getRequestDispatcher("del.jsp").forward(req,resp); } /** * 修改 * @param req * @param resp * @throws IOException * @throws ServletException */ private void update(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{ req.setCharacterEncoding("utf-8"); int id = Integer.parseInt(req.getParameter("id")); String name = req.getParameter("name"); String teacher = req.getParameter("teacher"); String classroom = req.getParameter("classroom"); Course course = new Course(id, name, teacher, classroom); service.update(course); req.setAttribute("message", "修改成功"); req.getRequestDispatcher("CourseServlet?method=list").forward(req,resp); } /** * 查找 * @param req * @param resp * @throws ServletException */ private void search(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{ req.setCharacterEncoding("utf-8"); String name = req.getParameter("name"); String teacher = req.getParameter("teacher"); String classroom = req.getParameter("classroom"); List courses = service.search(name, teacher, classroom); req.setAttribute("courses", courses); req.getRequestDispatcher("searchlist.jsp").forward(req,resp); }} //DBUtil.javapackage com.hjf.util;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;/** * 数据库连接工具 * @author Hu * */public class DBUtil { public static String db_url = "jdbc:mysql://localhost:3306/course"; public static String db_user = "root"; public static String db_pass = "root"; public static Connection getConn () { Connection conn = null; try { Class.forName("com.mysql.jdbc.Driver");//加载驱动 conn = DriverManager.getConnection(db_url, db_user, db_pass); } catch (Exception e) { e.printStackTrace(); } return conn; } /** * 关闭连接 * @param state * @param conn */ public static void close (Statement state, Connection conn) { if (state != null) { try { state.close(); } catch (SQLException e) { e.printStackTrace(); } } if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } public static void close (ResultSet rs, Statement state, Connection conn) { if (rs != null) { try { rs.close(); } catch (SQLException e) { e.printStackTrace(); } } if (state != null) { try { state.close(); } catch (SQLException e) { e.printStackTrace(); } } if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } public static void main(String[] args) throws SQLException { Connection conn = getConn(); PreparedStatement pstmt = null; ResultSet rs = null; String sql ="select * from course"; pstmt = conn.prepareStatement(sql); rs = pstmt.executeQuery(); if(rs.next()){ System.out.println("空"); }else{ System.out.println("不空"); } }} //add.jsp<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>Insert title here <% Object message = request.getAttribute("message"); if(message!=null && !"".equals(message)){ %> <%} %>课程信息录入
返回主页
//del.jsp<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>Insert title here <% Object message = request.getAttribute("message"); if(message!=null && !"".equals(message)){ %> <%} %>课程信息删除
返回主页
//detail.jap<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>Insert title here
//detail2.jsp<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>Insert title here <% Object message = request.getAttribute("message"); if(message!=null && !"".equals(message)){ %> <%} %>课程信息修改
返回主页
//index.jsp
//list.jsp<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>Insert title here <% Object message = request.getAttribute("message"); if(message!=null && !"".equals(message)){ %> <%} %>
//search.jsp<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>Insert title here 课程信息查询
返回主页
//searchlist.jsp<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>Insert title here