这个博客也是补充之前的学习内容:

项目总述：这个增删改查我以，选课名称，选课教室，选课教师基本信息，作为主要的信息来源。主要对这些信息最基本的增删改查

详细的分析与说明：

1.首先在src文件里定义四个包，com.bean(定义类），com.dao(对数据进行处理，书写增删改查的函数），com.db(用于连接数据库），com.servlet(用于接受jsp中传输的值，并对其进行判断处理）

相关代码展示：

Bean.java:

package com.bean;

public class Bean {

    private String name;

    private String teacher;

    private String classroom;

    public Bean() {

        super();

    }

    public Bean(String name, String teacher, String classroom) {

        super();

        this.name = name;

        this.teacher = teacher;

        this.classroom = classroom;

    }

    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;

    }

    @Override

    public String toString() {

        return "Bean [name=" + name + ", teacher=" + teacher + ", classroom=" + classroom + "]";

    }

}

Dao.java:

package com.dao;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.Statement;

import java.util.ArrayList;

import java.util.List;

import java.sql.ResultSet;

import java.sql.SQLException;

import com.db.DB;

import com.servlet.selectNameServlet;

import com.servlet.updateServlet;

import com.db.DB;

import com.bean.Bean;

public class Dao {

    //增加

    @SuppressWarnings("static-access")

    public boolean add(Bean bean) {

        String tablename = "test";//表名

        DB db=new DB();

        Connection con = db.getCon();

        try {

            String sql="insert into "+tablename+"(name,teacher,classroom) values ('"+bean.getName()+"','"+bean.getTeacher()+"','"+bean.getClassroom()+"')";

            Statement stm = con.createStatement();

            System.out.println(sql);

            stm.execute(sql);

            db.close(stm, con);

        }catch(Exception e) {

            e.printStackTrace();

            System.out.println("add false");

            return false;

        }

        System.out.println("add true");

        return true;

    }

    //根据名称进行查询

    @SuppressWarnings("static-access")

    public static Bean selectName(String name) {

        String tablename = "test";

        System.out.println("select bean where name = "+name);

        Bean bean=null;

        DB db=new DB();

        Connection con = db.getCon();

        try {

            Statement stm = con.createStatement();

            ResultSet rs = stm.executeQuery("select * from "+tablename+" where name='" + name + "'");

            /*

             * ResultSet rs =stm.executeQuery("select value3 from "+tablename+" where value2="+i);

             */

            if(rs.next())

            {

                bean = new Bean();

                System.out.println("select the bean from mysql");

                bean.setName(rs.getString("name"));

                bean.setTeacher(rs.getString("teacher"));

                bean.setClassroom(rs.getString("classroom"));

                //bean.setValue2(Integer.parseInt(rs.getString("teacher")));

                //bean.setValue3(Boolean.parseBoolean(rs.getString("address")));

                System.out.println("name of the bean is "+rs.getString("name"));

            }

            db.close(rs,stm, con);

        }catch(Exception e) {

            e.printStackTrace();

        }

        return bean;

    }

    //删除

    @SuppressWarnings("static-access")

    public static boolean delete(String name)

    {

        //String tablename ="test";

        DB db=new DB();

        Connection con = db.getCon();

        //Connection con=null;

        PreparedStatement stm=null;

        try {

            con=DB.getCon();

            String sql="delete from test where name='"+name+"'";

            //String sql="delete from test where name='"+bean.getName()+"'";

            System.out.println(sql);

            stm=con.prepareStatement(sql);

            stm.executeUpdate();

            return true;

        }

        catch(SQLException e)

        {

            e.printStackTrace();

        }

        finally {

            db.close(stm, con);

        }

        return false;

    }

   //修改

    @SuppressWarnings("static-access")

    public boolean update(Bean bean) {

        Connection con=null;

        PreparedStatement stm=null;

        String tablename="test";

        DB db=new DB();

        try {

            con=DB.getCon();

            String sql="update "+tablename+" set teacher=?,classroom=? where name=?";

            //String sql="update "+tablename+"set teacher=?,classroom=? where name=?";

            stm=con.prepareStatement(sql);

            stm.setString(3,bean.getName());

            stm.setString(1, bean.getTeacher());

            stm.setString(2,bean.getClassroom());

            stm.executeUpdate();

        }

        catch(SQLException e)

        {

            e.printStackTrace();

            return false;

        }

        finally {

            db.close(stm, con);

            return true;

        }

    }

  //根据名字进行查找

     public  boolean findName(String name){

            boolean flag=false;

            Connection con=null;

            PreparedStatement psts=null;

            ResultSet rs=null;

            String tablename="test";

            DB db=new DB();

            try {

                con=db.getCon();

                String sql="select * from"+tablename+" where name=?";

                psts=con.prepareStatement(sql);

                psts.setString(1, name);

                rs=psts.executeQuery();

                while(rs.next()){

                    flag=true;

                }

            } catch (SQLException e) {

                e.printStackTrace();

            }

            return flag;

     }

    //

    @SuppressWarnings("static-access")

     public ArrayList<Bean> selectList(){

        Connection con=null;

        PreparedStatement stm=null;

        ResultSet rs=null;

        ArrayList<Bean> listbean=new ArrayList<Bean>();

        String tablename="test";

        DB db=new DB();

        try {

            con=db.getCon();

            String sql="select * from "+tablename;

            stm=con.prepareStatement(sql);

            rs=stm.executeQuery();

            while(rs.next()){

                String name=rs.getString("name");

                String teacher=rs.getString("teacher");

                String classroom=rs.getString("classroom");

                Bean bean=new Bean(name,teacher,classroom);

                listbean.add(bean);

            }

        }

        catch(SQLException e)

        {

            e.printStackTrace();

        }

        finally

        {

            db.close(stm, con);

        }

        return listbean;

    }

}

    //

//    public Bean login(String name,String password) {

//        String tablename = null;

//        DB db=new DB();

//        Connection con = db.getCon();

//        Bean bean = null;

//        try {

//            Statement stm = con.createStatement();

//            ResultSet rs = stm.executeQuery("select * from "+tablename+" where value1='" + name + "'");

//            if(rs.next()) {

//                if (rs.getString("password").equals(password)) {

//

//                }

//            }

//        }catch(Exception e) {

//

//        }

//    }

DB.java:

package com.db;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import org.junit.Test;

public class DB {

    private static String mysqlname = "database";//数据库名

    private static Connection con;

    private static Statement stm;

    private static ResultSet rs;

    private static String coursename = "com.mysql.jdbc.Driver";

    private static String url = "jdbc:mysql://127.0.0.1:3306/"+mysqlname+"?useUnicode=true&characterEncoding=GB18030&useSSL=false&serverTimezone=GMT&allowPublicKeyRetrieval=true";

    public static Connection getCon() {

        try {

            Class.forName(coursename);

            System.out.println("注册驱动成功");

        }catch(ClassNotFoundException e) {

            e.printStackTrace();

        }

        try {

            con = DriverManager.getConnection(url,"root","20000604");

            System.out.println("建立连接成功");

        }catch(Exception e){

            e.printStackTrace();

            con = null;

        }

        return con;

    }

    public static void close(Statement stm,Connection connection) {

        if(stm!=null) {

            try {

                stm.close();

            }catch(SQLException e) {

                e.printStackTrace();

            }

        }

        if(connection!=null) {

            try {

                connection.close();

            }catch(SQLException e) {

                e.printStackTrace();

            }

        }

    }

    //关闭

    public static void close(ResultSet rs,Statement stm,Connection connection) {

        if(rs!=null) {

            try {

                rs.close();

            }catch(SQLException e) {

            e.printStackTrace();

            }

        }

        if(stm!=null) {

            try {

                stm.close();

            }catch(SQLException e) {

                e.printStackTrace();

            }

        }

        if(connection!=null) {

            try {

                connection.close();

            }catch(SQLException e) {

                e.printStackTrace();

            }

        }

    }

    public static void main(String[] args)

    {

        getCon();

    }

}

addServlet.java:

package com.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.bean.Bean;

import com.dao.Dao;

/**

 * Servlet implementation class addServlet

 */

@WebServlet("/addServlet")

public class addServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // TODO Auto-generated method stub

        request.setCharacterEncoding("UTF-8");

        Bean bean = new Bean();

        bean.setName(request.getParameter("name"));

        bean.setTeacher(request.getParameter("teacher"));

        bean.setClassroom(request.getParameter("classroom"));

        Dao dao = new Dao();

        if(dao.add(bean)) {

            request.setAttribute("message", "添加成功");

            request.getRequestDispatcher("add.jsp").forward(request,response);

            //response.sendRedirect("index.jsp");

        }

        else {

            request.setAttribute("message","添加失败");

            request.getRequestDispatcher("add.jsp").forward(request,response);

            //response.sendRedirect("add.jsp");

        }

    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        doGet(request, response);

    }

}

deleteServlet.java:

package com.servlet;

import java.io.IOException;

import java.io.PrintWriter;

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.bean.Bean;

import com.dao.Dao;

/**

 * Servlet implementation class deleteServlet

 */

@WebServlet("/deleteServlet")

public class deleteServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        request.setCharacterEncoding("UTF-8");

        Dao dao=new Dao();

        if(dao.delete(request.getParameter("delete"))) {//response.sendRedirect("index.jsp");

            request.setAttribute("message", "删除成功");

            request.getRequestDispatcher("delete.jsp").forward(request,response);

            //response.sendRedirect("index.jsp");

        }

        else {

            request.setAttribute("message", "删除失败");

            request.getRequestDispatcher("delete.jsp").forward(request,response);

            //response.sendRedirect("index.jsp");//response.sendRedirect("delete.jsp");

        }

    }

    /**

     * @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);

    }

}

selectNameServlet.java:

package com.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.bean.Bean;

import com.dao.Dao;

/**

 * Servlet implementation class selectNameServlet

 */

@WebServlet("/selectNameServlet")

public class selectNameServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        request.setCharacterEncoding("UTF-8");

        Bean bean=new Bean();

        bean.setName(request.getParameter("selectname"));

        Dao dao=new Dao();

        bean = dao.selectName(bean.getName());

        if(bean!=null)

        {

            request.setAttribute("Bean",bean);

            request.getRequestDispatcher("select_show.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);

    }

}

showAllServlet.java:

package com.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.bean.Bean;

import com.dao.Dao;

/**

 * Servlet implementation class selectNameServlet

 */

@WebServlet("/selectNameServlet")

public class selectNameServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        request.setCharacterEncoding("UTF-8");

        Bean bean=new Bean();

        bean.setName(request.getParameter("selectname"));

        Dao dao=new Dao();

        bean = dao.selectName(bean.getName());

        if(bean!=null)

        {

            request.setAttribute("Bean",bean);

            request.getRequestDispatcher("select_show.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);

    }

}

updatenewServlet.java:

package com.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.bean.Bean;

import com.dao.Dao;

/**

 * Servlet implementation class updatenewServlet

 */

@WebServlet("/updatenewServlet")

public class updatenewServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // TODO Auto-generated method stub

        //response.getWriter().append("Served at: ").append(request.getContextPath());

        request.setCharacterEncoding("UTF-8");

        Bean beannew=new Bean();

        Dao dao=new Dao();

        beannew.setName(request.getParameter("updatename"));

        beannew.setTeacher(request.getParameter("updateteacher"));

        beannew.setClassroom(request.getParameter("updateclassroom"));

        //System.out.println("接受成功");

        //System.out.println(request.getParameter("updatename"));

        //bean.setValue2(Integer.parseInt(request.getParameter("value2")));

        //bean.setValue3(Boolean.parseBoolean(request.getParameter("value3")));

          if(dao.update(beannew)) {

             response.sendRedirect("index.jsp");

        }

        else {

            response.sendRedirect("update_show.jsp");

        }

    }

    /**

     * @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);

    }

}

updateServlet:

package com.servlet;

import java.io.IOException;

import java.io.PrintWriter;

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.bean.Bean;

import com.dao.Dao;

/**

 * Servlet implementation class updateServlet

 */

@WebServlet("/updateServlet")

public class updateServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        request.setCharacterEncoding("UTF-8");

        Bean bean=new Bean();

        Bean beanform=new Bean();

        Dao dao=new Dao();

        bean = dao.selectName(request.getParameter("selectname"));

         System.out.println(request.getParameter("selectname"));

        if(bean!=null)

        {

            request.setAttribute("Bean",bean);

            request.getRequestDispatcher("update_show.jsp").forward(request,response);

        }

//        else if(bean==null) {

//            request.setAttribute("Bean",bean);

//            request.getRequestDispatcher("delete.jsp").forward(request,response);

//            return ;

//        }

//        beanform.setName(request.getParameter("updatename"));

//        beanform.setTeacher(request.getParameter("updateteacher"));

//        beanform.setClassroom(request.getParameter("updateclassroom"));

//         //bean.setValue2(Integer.parseInt(request.getParameter("value2")));

//         //bean.setValue3(Boolean.parseBoolean(request.getParameter("value3")));

//          if(dao.update(beanform)) {//             response.sendRedirect("index.jsp");

//        }

//        else {//            response.sendRedirect("update.jsp");

//        }

    }

}

2.然后继续完成前端页面：

代码展示：

index.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>首界面</title>

</head>

<body>

           <div>

            <h1 align="center" color="blue"> 增删改查的主页面</h1>

            <hr/>

            <a href="add.jsp"><h2 align="center">添加课程信息</a></h2>

            <a href="delete.jsp"><h2 align="center">删除课程信息</a></h2>

            <a href="update.jsp"><h2 align="center">修改课程信息</h2></a>

            <a href="select.jsp"><h2 align="center">查询课程信息</h2></a>

            <a href="showAllServlet"  ><h2 align="center">浏览课程全部信息</h2></a>

           </div>

</body>

</html>

add.jsp:

<%@page import="java.util.jar.Attributes.Name"%>

<%@page import="com.servlet.addServlet" %>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>添加课程</title>

</head>

<body>

<%

  String mess=(String)request.getAttribute("message");

     if(mess!=null&&!"".equals(mess)){

         %>

         <script type="text/javascript">

         alert("<%=mess%>");

         </script>

         <%

     }

%>

<div align="center">

 <form action="addServlet" method="post">

   <a href="index.jsp"><h2>返回主界面</h2></a>

    <div >

    <table>

      <tr>

             <td>添加课程:</td>

             <td><input type="text" id="name" name="name"></td>

      </tr>

      <tr>

             <td>添加教师：</td>

             <td><input type="text" id="teacher" name="teacher"></td>

      </tr>

      <tr>

               <td>添加地点：</td>

               <td><input type="text" id="classroom" name="classroom"></td>

      </tr>

      <tr>

             <td><input align="center" type="submit" value="添加"></td>

      </tr>

          </table>

    </div>

   </form>

</div>

</body>

</html>

delete.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>删除课程</title>

</head>

<body>

<%

  String mess=(String)request.getAttribute("message");

     if(mess!=null&&!"".equals(mess)){

         %>

         <script type="text/javascript">

         alert("<%=mess%>");

         </script>

         <%

     }

%>

    <form align="center" action="deleteServlet" method="post">

      <div>

      <h4><a href="index.jsp">返回主界面</a></h4>

       <table>

          <tr>

            <td>根据名字进行删除：</td>

          </tr>

          <tr>

              <td>请输入需要删除课程的名字：</td>

              <td><input type="text" name="delete" value=""></td>

          </tr>

          <tr>

            <input type="submit" value="确定" id="">

          </tr>

       </table>

      </div>

    </form>

</body>

</html>

select.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>查询课程信息</title>

</head>

<body>

<%

  String mess=(String)request.getAttribute("message");

     if(mess!=null&&!"".equals(mess)){

         %>

         <script type="text/javascript">

         alert("<%=mess%>");

         </script>

         <%

     }

%>

 <h2 align="cneter">课程查询</h2>

 <hr/>

    <form align="center" action="selectNameServlet" method="post">

      <div>

       <table>

          <tr>

            <td>根据名字进行查询：</td>

          </tr>

          <tr>

              <td>请输入需要查询课程的名字：</td>

              <td><input type="text" name="selectname" value=""></td>

          </tr>

          <tr>

            <input type="submit" value="确定" id="">

          </tr>

          <a href="index.jsp">返回主页面</a>

       </table>

      </div>

    </form>

</body>

</html>

select_show.jsp:

<%@page import="com.bean.Bean"%>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>查询显示</title>

</head>

<body>

<%

 Bean b2=(Bean)request.getAttribute("Bean");

%>

  <form action="selectServlet" method="post">

  <table>

      <tr>

          <td>显示课程名字：</td>

          <td><input type="text" name="" value="<%=b2.getName()%>"></td>

      </tr>

      <tr>

          <td>显示课程教师：</td>

          <td><input type="text" name="" value="<%=b2.getTeacher()%>"></td>

      </tr>

      <tr>

          <td>显示课程地点：</td>

          <td><input type="text" naem="" value="<%= b2.getClassroom()%>"></td>

      </tr>

  </table>

 <a href="index.jsp">返回主界面</a>

 </form>

</body>

</html>

update.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>显示所要修改的课程</title>

</head>

<body>

 <form action="updateServlet" method="post">

          <tr>

               <td>请输入所要修改的课程的名字：</td>

               <td><input type="text" name="selectname" value=""></td>

          </tr>

          <tr>

              <input type="submit" value="确定" id="">

          </tr>

 </form>

</body>

</html>

update_show.jsp:

<%@page import="com.bean.Bean"%>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>修改课程信息</title>

</head>

   <%

      Bean b2=(Bean)request.getAttribute("Bean");

   %>

<body>

     <form action="updatenewServlet"  method="post">

  <table>

  <h4>修改前的课程信息：</h4>

      <tr>

          <td>课程名字：</td>

          <td><input type="text" name="" value="<%=b2.getName()%>"></td>

      </tr>

      <tr>

          <td>课程教师：</td>

          <td><input type="text" name="" value="<%=b2.getTeacher()%>"></td>

      </tr>

      <tr>

          <td>课程地点：</td>

          <td><input type="text" name="" value="<%= b2.getClassroom()%>"></td>

      </tr>

  </table>

  <hr/>

  <h4>修改后的课程信息</h4>

  <table>

    <tr>

        <td>请输入所要修改的课程名称：</td>

        <td><input type="text" name="updatename" value=""></td>

    </tr>

    <tr>

        <td>请输入修改后的课程教师：</td>

        <td><input type="text" name="updateteacher" value=""></td>

    <tr>

        <td>请输入修改后的上课地点：</td>

        <td><input type="text" name="updateclassroom" value=""></td>

    </tr>

     <tr>

            <input type="submit" value="确定" id="">

          </tr>

  </table>

  <a href="index.jsp">返回主页面</a>

  </form>

</body>

</html>

showall.jsp:

<%@page import="com.dao.Dao"%>

<%@page import="com.bean.Bean"%>

<%@page import="java.util.ArrayList"%>

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

<%-- <%@ page isELIgnored="false" %> --%>

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>显示全部信息</title>

</head>

<body>

<!-- <form  action="showAllServlet" method="post"> -->

 <tr><h3>所有课程信息：</h3></tr>

 <hr/>

   <table>

           <tr>

               <td>课程名称</td>

               <td>课程教师</td>

               <td>课程地点</td>

           </tr>

           <c:forEach items="${listbean}" var="item">

           <tr>

              <td>${item.name}</td>

              <td>${item.teacher}</td>

              <td>${item.classroom}</td>

           </tr>

             </c:forEach>

   </table>

        <a href="index.jsp">返回主界面</a>

        </form>

</html>

所遇到的问题：

1.在update_show.jsp的显示页面中，他的组成部分为两部分，一是显示需要修改之前的全部信息，二是输入修改之后的信息。界面如下所示

所遇问题是保存不成功修改后的信息，原因：在updatenewServlet.java没有接收到update_show.jsp所要传输的信息

2.在显示全部信息的时，不能全部的显示：

界面如下：

理应如下：

原因：自己对于forEach语句的不熟练照成，需要多多学习，多多练习。

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