jsp中提供了el表达式，可以获取服务端域对象中的数据

    el表达式语法：${后端域对象中的key}

    JSTL：JSP标准标签库，也称为c标签

    jsp页面中导入jstl标签库

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

    用jstl标签对集合内容遍历并排版

    jsp语法

    1. <table></table>表格
    3. <tr></tr>  表格中的行
    5. <td></td>    tr的子标签，表示一行中的一个单元
    7. <c:forEach> </c:forEach>   jstl提供的遍历标签
    9. items  要遍历的对象。要遍历对象从域对象中获取，所以要通过el表达式从域对象中获取
    11. var 遍历的每个元素，用来存放当前指向的元素
    13. border 边框，表格的属性
    15. align="center" 表格居中
    17. <th></th> 会对内容进行加粗
    19. <h1 align="center"> 学生管理页面</h1>标题标签
    1. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    2. <%--导入jstl标签库--%>
    3. <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
    4. <html>
    5. <head>
    6.     <title>学生列表</title>
    7. </head>
    8. <body>
    10. <%--jsp中提供了el表达式，可以获取服务端域对象中的数据--%>
    11. <%--
    12.     el表达式语法
    13.     ${后端域对象中的key}
    14. --%>
    16. <%--在当前jsp页面中导入jstl标签(也称之为c标签)--%>
    18. <%--${stuList}--%>
    20. <h1 align="center"> 学生管理页面</h1>
    21. <table border="1px" align="center">
    23.     <tr>
    24.     <th>学生姓名</th>
    25.     <th>学生年龄</th>
    26.     <th>学生性别</th>
    27.     <th>学生地址</th>
    28.     <th>学生生日</th>
    29.     <th>学生爱好</th>
    31.     </tr>
    32.     <c:forEach items="${stuList}" var="stu">
    33.         <tr>
    34.             <td>${stu.sname}</td>
    35.             <td>${stu.age}</td>
    36.             <td>${stu.sex}</td>
    37.             <td>${stu.address}</td>
    38.             <td>${stu.birthday}</td>
    39.             <td>${stu.hobby}</td>
    41.         </tr>
    43.     </c:forEach>
    44. </table>
    45. </body>
    46. </html>

    运行结果如图
    Java学习十二——web案例（一） - 图1
    web具体代码如下：
    Student.java

    1. package com.jy.pojo;
    3. public class Student {
    5.     private Integer sid;
    7.     private String sname;
    9.     private Integer age;
    11.     private Integer sex;
    13.     private String address;
    15.     private String birthday;
    17.     private String hobby;
    19.     public Student(Integer sid, String sname, Integer age, Integer sex, String address, String birthday, String hobby) {
    20.         this.sid = sid;
    21.         this.sname = sname;
    22.         this.age = age;
    23.         this.sex = sex;
    24.         this.address = address;
    25.         this.birthday = birthday;
    26.         this.hobby = hobby;
    27.     }
    29.     public Student() {
    30.     }
    32.     public Integer getSid() {
    33.         return sid;
    34.     }
    36.     public String getSname() {
    37.         return sname;
    38.     }
    40.     public Integer getAge() {
    41.         return age;
    42.     }
    44.     public Integer getSex() {
    45.         return sex;
    46.     }
    48.     public String getAddress() {
    49.         return address;
    50.     }
    52.     public String getBirthday() {
    53.         return birthday;
    54.     }
    56.     public String getHobby() {
    57.         return hobby;
    58.     }
    60.     public void setSid(Integer sid) {
    61.         this.sid = sid;
    62.     }
    64.     public void setSname(String sname) {
    65.         this.sname = sname;
    66.     }
    68.     public void setAge(Integer age) {
    69.         this.age = age;
    70.     }
    72.     public void setSex(Integer sex) {
    73.         this.sex = sex;
    74.     }
    76.     public void setAddress(String address) {
    77.         this.address = address;
    78.     }
    80.     public void setBirthday(String birthday) {
    81.         this.birthday = birthday;
    82.     }
    84.     public void setHobby(String hobby) {
    85.         this.hobby = hobby;
    86.     }
    88.     @Override
    89.     public String toString() {
    90.         return "Student{" +
    91.                 "sid=" + sid +
    92.                 ", sname='" + sname + '\'' +
    93.                 ", age=" + age +
    94.                 ", sex=" + sex +
    95.                 ", address='" + address + '\'' +
    96.                 ", birthday='" + birthday + '\'' +
    97.                 ", hpbby='" + hobby + '\'' +
    98.                 '}';
    99.     }
    100. }

    StudentServlet.java

    1. package com.jy.servlet;
    3. import com.jy.pojo.Student;
    4. import com.jy.util.JDBCUtils;
    5. import org.apache.taglibs.standard.tag.common.core.ChooseTag;
    6. import org.omg.CosNaming.NamingContextExtPackage.StringNameHelper;
    8. import javax.servlet.RequestDispatcher;
    9. import javax.servlet.ServletException;
    10. import javax.servlet.http.HttpServlet;
    11. import javax.servlet.http.HttpServletRequest;
    12. import javax.servlet.http.HttpServletResponse;
    13. import java.io.IOException;
    14. import java.sql.*;
    15. import java.util.ArrayList;
    17. public class StudentServlet extends HttpServlet {
    19.     @Override
    20.     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    23.         doPost(req,resp);
    24.     }
    26.     @Override
    27.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    29.         //处理中文乱码
    30.         request.setCharacterEncoding("utf-8");
    31.         //接收前端传递的标识，决定具体执行的方法
    32.         String flag = request.getParameter("flag");
    34.         if(flag != null && flag.equals("list")){
    36.             getList(request,response);
    37.         }else if(flag != null &&flag.equals("add")){
    38.             getAdd(request,response);
    39.         }else if(flag != null && flag.equals("delete")){
    40.             getDelete(request,response);
    42.     }
    43.     }
    44. /*
    45. * 根据id进行删除
    46. * */
    47.     private void getDelete(HttpServletRequest request, HttpServletResponse response) {
    50.         //接收id值
    51.         String id = request.getParameter("id");
    53.         Connection connection =null;
    54.         PreparedStatement preparedStatement = null;
    56.         //jdbc执行访问数据库执行删除
    57.         try {
    59.             connection = JDBCUtils.getConnection();
    61.             preparedStatement = connection.prepareStatement("delete  from tb_student  where id= ?");
    63.             preparedStatement.setInt(1,Integer.parseInt(id));
    65.             int i = preparedStatement.executeUpdate();
    67.             if(i>0){
    68.                 System.out.println("删除成功");
    70.                 response.sendRedirect("http://localhost:8080/managerWeb/stu?flag=list");
    71.             }else{
    72.                 System.out.println("删除失败");
    73.             }
    75.         }catch(Exception e){
    76.             e.printStackTrace();
    77.         }finally {
    78.             JDBCUtils.JDBCClose(connection,preparedStatement,null);
    79.         }
    82.     }
    85.     //执行添加的方法
    86.     public void getAdd(HttpServletRequest request, HttpServletResponse response) {
    88.         //接收客户端数据
    89.         String sname = request.getParameter("sname");
    91.         String age = request.getParameter("age");
    93.         String sex = request.getParameter("sex");
    95.         String address = request.getParameter("address");
    97.         String birthday = request.getParameter("birthday");
    99.         //接收多个值
    100.         String[] hobbies = request.getParameterValues("hobby");
    102.         //测试数据
    103.        // System.out.println(sname+" " +age+ " "+sex+" "+ address+" "+birthday);
    104.         String hobbys = "";
    107.         //遍历爱好数组
    108.         for (String hobby : hobbies) {
    110.             hobbys += ","+hobby;
    112.         }
    113.         //字符串切割
    114.         hobbys=hobbys.substring(1);
    116.         Connection connection = null;
    117.         PreparedStatement preparedStatement = null;
    119.         //使用jdbc保存数据到数据库
    120.         try {
    121.             //获取数据库连接
    122.             connection = JDBCUtils.getConnection();
    124.             //
    125.             String sql = "insert tb_student(sname,age,sex,address,birthday,hobby) 
    126.                 values(?,?,?,?,?,?)";
    127.             //获取数据库操作对象
    128.             preparedStatement = connection.prepareStatement(sql);
    130.             //给占位符赋值
    131.             preparedStatement.setString(1,sname);
    133.             preparedStatement.setInt(2,Integer.parseInt(age));
    135.             preparedStatement.setInt(3,Integer.parseInt(sex));
    137.             preparedStatement.setString(4,address);
    139.             preparedStatement.setString(5,birthday);
    141.             int i = preparedStatement.executeUpdate();
    143.             if(i>0){
    145.                 System.out.println("success");
    147.                 //请求重定向
    148.                 response.sendRedirect("http://localhost:8080/managerWeb/stu?flag=list");
    149.             }else {
    150.                 System.out.println("defeat");
    151.             }
    153.       } catch (ClassNotFoundException e) {
    155.             e.printStackTrace();
    157.         } catch (SQLException throwables) {
    159.             throwables.printStackTrace();
    160.         } catch (IOException e) {
    161.             e.printStackTrace();
    162.         } finally {
    163.             JDBCUtils.JDBCClose(connection,preparedStatement,null);
    164.         }
    167.     }
    169.     //具体实现学生列表的方法
    170.     public void getList(HttpServletRequest request, HttpServletResponse response){
    172.         /**
    173.          * 1、通过jdbc访问数据库
    174.          */
    177.         Connection connection =null;
    179.         PreparedStatement preparedStatement = null;
    181.         ResultSet resultSet = null;
    182.         try{
    184.             //注册驱动
    185.             Class.forName("com.mysql.cj.jdbc.Driver");
    187.             //获取数据库连接对象
    188.             connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/test_stu?serverTimezone=GMT", "root", "root");
    190.             //获取数据库操作对象，并预编译sql
    191.             preparedStatement = connection.prepareStatement("select * from tb_student");
    193.             //执行SQL语句
    194.             resultSet = preparedStatement.executeQuery();
    196.             ArrayList<Student> stuList = new ArrayList<>();
    198.             //遍历结果集
    199.             while(resultSet.next()){
    201.                 //根据表字段取出数据
    202.                 String sname = resultSet.getString("sname");
    204.                 int age = resultSet.getInt("age");
    206.                 int sex = resultSet.getInt("sex");
    208.                 String address = resultSet.getString("address");
    210.                 String birthday = resultSet.getString("birthday");
    212.                 String hobby = resultSet.getString("hobby");
    214.                 //取出ID，用于删除与修改
    215.                 int id = resultSet.getInt("id");
    217.                 System.out.println(sname+ " "+ age+" "+sex+ " "+ address+" "+birthday+" "+hobby);
    219.                 //创建学生对象
    220.                 Student student = new Student();
    222.                 //给对象赋值
    223.                 student.setSname(sname);
    224.                 student.setAge(age);
    225.                 student.setSex(sex);
    226.                 student.setBirthday(birthday);
    227.                 student.setAddress(address);
    228.                 student.setHobby(hobby);
    230.                 student.setSid(id);
    232.                 //添加学生对象到集合
    233.                 stuList.add(student);
    234.             }
    235.             //System.out.println("集合的长度为 "+stuList.size());
    237.             //遍历集合数据
    238.             for (Student student:stuList){
    240.                 System.out.println(student);
    242.             }
    244.             /**
    245.              * 二、响应对象到客户端
    246.              * 1、把集合对象存放到域中
    247.              * 2、请求转发跳转资源
    248.              */
    250.             //存放集合对象到域中
    251.             request.setAttribute("stuList",stuList);
    253.             //请求转发
    254.             RequestDispatcher requestDispatcher = request.getRequestDispatcher("/jsp/list.jsp");
    256.             //走向具体的资源
    257.             requestDispatcher.forward(request,response);
    260.         }catch(Exception e){
    263.             e.printStackTrace();
    264.         }finally {
    265.             //关闭数据库资源
    266.             if(resultSet !=null){
    267.                 try {
    268.                     resultSet.close();
    270.                 } catch (SQLException throwables) {
    272.                     throwables.printStackTrace();
    273.                 }
    274.             }
    276.             if(preparedStatement!=null){
    277.                 try {
    278.                     preparedStatement.close();
    280.                 } catch (SQLException throwables) {
    282.                     throwables.printStackTrace();
    283.                 }
    284.             }
    286.             if(connection !=null){
    287.                 try {
    288.                     connection.close();
    290.                 } catch (SQLException throwables) {
    292.                     throwables.printStackTrace();
    293.                 }
    294.             }
    296.         }
    298.     }
    299. }

    JDBCUtils.java

    1. package com.jy.util;
    3. import java.sql.*;
    5. /**
    6.  *
    7.  * 封装jdbc工具类
    8.  * 1、构造方法私有化，不希望工具类可以实例化对象
    9.  *
    10.  * 2、所有调用的方法都用static关键字修饰
    11.  */
    13. public class JDBCUtils {
    15.     private JDBCUtils(){}
    17.     /**
    18.      *
    19.      * 把注册驱动写在静态代码块，静态代码块在类加载器的时候执行且只执行一次
    20.      */
    22.     static {
    24.         //注册驱动
    25.         try {
    26.             Class.forName("com.mysql.cj.jdbc.Driver");
    28.         } catch (ClassNotFoundException e) {
    30.             e.printStackTrace();
    31.         }
    33.     }
    34.     /**
    35.      * 获取数据库连接
    36.      */
    38.     public static Connection getConnection() throws ClassNotFoundException, SQLException {
    42.         //获取连接
    43.         Connection connection =
    44.                 DriverManager.getConnection("jdbc:mysql://localhost:3306/test_stu?serverTimezone=GMT","root","root");
    47.         return connection;
    48.     }
    50.     /**
    51.      *
    52.      * 关闭数据库资源
    53.      */
    55.     public static void JDBCClose(Connection connection, Statement statement, ResultSet resultSet)  {
    57.         //关闭结果集对象
    58.         if(resultSet !=null){
    60.             try {
    61.                 resultSet.close();
    63.             } catch (SQLException throwables) {
    65.                 throwables.printStackTrace();
    66.             }
    67.         }
    68.         //关闭数据库操作对象
    69.         if(statement != null){
    70.             try {
    71.                 statement.close();
    73.             } catch (SQLException throwables) {
    75.                 throwables.printStackTrace();
    76.             }
    77.         }
    79.         //关闭数据库连接对象
    80.         if(connection != null){
    81.             try {
    82.                 connection.close();
    83.             } catch (SQLException throwables) {
    84.                 throwables.printStackTrace();
    85.             }
    86.         }
    88.     }
    90. }

    list.jsp

    1. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    2. <%--导入jstl标签库--%>
    3. <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
    4. <html>
    5. <head>
    6.     <title>学生列表</title>
    7. </head>
    8. <body>    
    10. <h1 align="center"> 学生管理页面</h1>
    11. <table border="1px" align="center">
    13.     <tr>
    14.         <td colspan="8" align="center">
    15.             <a href="http://localhost:8080/managerWeb/jsp/add.jsp">添加学生</a></td>
    16.     </tr>
    17.     <tr>
    18.     <th>学生姓名</th>
    19.     <th>学生年龄</th>
    20.     <th>学生性别</th>
    21.     <th>学生地址</th>
    22.     <th>学生生日</th>
    23.     <th>学生爱好</th>
    24.     <th>操作</th>
    26.     </tr>
    27.     <c:forEach items="${stuList}" var="stu">
    28.         <tr>
    29.             <td>${stu.sname}</td>
    30.             <td>${stu.age}</td>
    31.             <td>${stu.sex}</td>
    32.             <td>${stu.address}</td>
    33.             <td>${stu.birthday}</td>
    34.             <td>${stu.hobby}</td>
    35.             <td>
    36.                 <a href="http://localhost:8080/managerWeb/stu?flag=delete&id=${stu.sid}">删除记录</a>
    37.                 <a href="http://localhost:8080/managerWeb/stu?flag=delete">编辑</a>
    38.             </td>
    40.         </tr>
    42.     </c:forEach>
    43. </table>
    44. </body>
    45. </html>

    add.jsp

    2. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    3. <html>
    4. <head>
    5.     <title>添加学生</title>
    6. </head>
    7. <body>
    8. <h1 align="center"> 学生添加页面</h1>
    9. <%--
    10. <input type="radio"> 单选框
    11. <input type="checkbox">  多选框
    12. <input type="date"> 日期选择
    13. name 用于分组
    14. 文本输入框的name属性将作为获取数据的key
    15. --%>
    17. <form action="http://localhost:8080/managerWeb/stu?flag=add" method="post">
    18. <table align="center">
    19.     <tr>
    20.         <td>学生姓名:</td>
    21.         <td>
    22.             <input type="text" name="sname">
    23.         </td>
    24.     </tr>
    25.     <tr>
    26.         <td>学生年龄:</td>
    27.         <td>
    28.             <input type="text" name="age">
    29.         </td>
    30.     </tr>
    31.     <tr>
    32.     <td>学生性别:</td>
    33.     <td>
    34.         男:<input type="radio" name="sex" value="1">
    35.         女:<input type="radio" name="sex" value="2">
    36.     </td>
    37.     </tr>
    38.     <tr>
    39.     <td>学生住址:</td>
    40.     <td>
    41.         <input type="text" name="address">
    42.     </td>
    43.     </tr>
    44.     <tr>
    45.     <td>生日:</td>
    46.     <td>
    47.         <input type="date" name="birthday">
    48.     </td>
    49.     </tr>
    50.     <tr>
    51.     <td>爱好:</td>
    52.     <td>
    53.         下棋:<input type="checkbox" name="hobby" value="下棋">
    54.         舞剑:<input type="checkbox" name="hobby" value="舞剑">
    55.         论道:<input type="checkbox" name="hobby" value="论道">
    56.         布阵:<input type="checkbox" name="hobby" value="布阵">
    57.         弄枪:<input type="checkbox" name="hobby" value="弄枪">
    58.     </td>
    59.     </tr>
    61.     <tr align="center">
    62.         <td colspan="10"><input type="submit" value="添加" ></td>
    63.     </tr>
    64. </table>
    65. </form>
    67. </body>
    68. </html>