课堂练习-增加信息

1、练习设计思想

编web应用有两种，一种纯JSP，一种是JSP+JavaBean,由于对后者了解不深，这道题先使用JSP，后者方法在以后的博客中实现。

先使用jsp制作课程添加web页面，使用request内置命令获得客户端提交的HTTP协议数据，getParameter（String name）获得URL中的第一个name参数对应的值，setAttribute（String key，object value）设置map映射中键key对应的值对象value，在jsp读取时判断课程名称，任课教师，上课地点是否符合要求，不符合要求时，输出信息，并调转返回，否则，添加course；需要建立course类，包含get，set函数；需要建立ICourseDao的接口，用于增加课程；需要调用补充接口，sql创建语句传输对象，preparedStatement接收结果集；在Util中创建DBUtil创建连接对象connection，与数据库连接，并创建CourseException.java文件继承RuntimeException，用于处理异常信息。创建数据库时在命令行输入create database name;建立名为“name”的数据库，（也可以直接在Navicat Premium（数据库管理工具）中建立）点开数据库，输入“Ctrl q”，进入编辑框，输入命令，表建立成功。

create table t_user(

id int(10) primary key auto_increment,

       username varchar(255),

       password varchar(255),

       nickname varchar(255),

       type int(2),

       status int(2)

//仅是个范例，与本题建立数据库无关。

);

2、源程序代码

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 7 <title>增加信息</title>
 8 </head>
 9 <body>
10 <%=request.getAttribute("error") %>
11     <form action="add.jsp" method="get">
12         <table align="center" border="1" width="500">
13             <tr>
14                 <td>课程名称 : </td>
15                 <td>
16                     <input type="text" name="coursename" />
17                 </td>
18             </tr>
19                 <tr>
20                 <td>任课教师:</td>
21                 <td>
22                     <input type="text" name="teacher" />
23                 </td>
24             </tr>
25             <tr>
26                 <td>上课地点:</td>
27                 <td>
28                     <input type="text" name="place" />
29                 </td>
30             </tr>
31             <tr align="center">
32                 <td colspan="2">
33                     <input type="submit" value="保存" />
34                 </td>
35             </tr>
36         </table>
37     </form>
38 </body>
39 </html>

addInput.jsp

 1 <%@page import="com.jaovo1.msg.model.Course" %>
 2 <%@page import="com.jaovo1.msg.dao.*" %>
 3 <%@page import="com.jaovo1.msg.Util.DBUtil" %>
 4 <%@page import="com.jaovo1.msg.Util.CourseException" %>
 5 <%@ page language="java" contentType="text/html; charset=UTF-8"
 6     pageEncoding="UTF-8"%>
 7 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 8 <html>
 9 <%
10 String coursename=request.getParameter("coursename");
11 String teacher=request.getParameter("teacher");
12 String place=request.getParameter("place");
13 if(coursename==null||"".equals(coursename.trim())){
14     request.setAttribute("error","请输入课程名称");
15     %>
16     <jsp:forward page="addInput.jsp"></jsp:forward>
17 <%
18 }
19 if((!teacher.equals("王建民")&&!teacher.equals("刘立嘉")&&!teacher.equals("刘丹")&&!teacher.equals("王辉")&&!teacher.equals("杨子光"))&&(!place.startsWith("一教")&&!place.startsWith("二教")&&!place.startsWith("三教")&&!place.startsWith("基教"))){
20     request.setAttribute("error", "上课地点、任课老师错误");
21     %>
22     <jsp:forward page="addInput.jsp"></jsp:forward>
23 <%
24 }
25 if(!teacher.equals("王建民")&&!teacher.equals("刘立嘉")&&!teacher.equals("刘丹")&&!teacher.equals("王辉")&&!teacher.equals("杨子光")){
26     request.setAttribute("error", "任课老师错误");
27     %>
28     <jsp:forward page="addInput.jsp"></jsp:forward>
29     <%
30 }
31 if(!place.startsWith("一教")&&!place.startsWith("二教")&&!place.startsWith("三教")&&!place.startsWith("基教")){
32     request.setAttribute("error", "上课地点错误");
33 %>
34     <jsp:forward page="addInput.jsp"></jsp:forward>
35 <%
36 }
37 Course course=new Course();
38 course.setCoursename(coursename);
39 course.setTeacher(teacher);
40 course.setPlace(place);
41 CourseImpl courseDao=new CourseImpl();
42 try{
43     courseDao.add(course);
44 %>
45 <body>
46 课程保存成功！！<br>
47 <a href="addInput.jsp">继续添加</a>
48 </body>
49 
50 <%
51 }catch(CourseException e){
52 %>
53 <h2 style="color:red ; font-size:50px">发生错误 <%=e.getMessage() %></h2>
54 <%
55 } 
56 %>
57 </html>

add.jsp

 1 package com.jaovo1.msg.model;
 2 public class Course {
 3 private String coursename;
 4 private String teacher;
 5 private String place;
 6 public String getCoursename() {
 7     return coursename;
 8 }
 9 public void setCoursename(String coursename) {
10     this.coursename = coursename;
11 }
12 public String getTeacher() {
13     return teacher;
14 }
15 public void setTeacher(String teacher) {
16     this.teacher = teacher;
17 }
18 public String getPlace() {
19     return place;
20 }
21 public void setPlace(String place) {
22     this.place = place;
23 }
24 
25 }

Course.java

1 package com.jaovo1.msg.dao;
2 import com.jaovo1.msg.model.Course;
3 public interface ICourseDao {
4     public void add(Course course);
5 
6 }

ICourseDao.java

 1 package com.jaovo1.msg.dao;
 2 import java.sql.Connection;
 3 import java.sql.PreparedStatement;
 4 import java.sql.ResultSet;
 5 import java.sql.SQLException;
 6 
 7 import com.jaovo1.msg.Util.CourseException;
 8 import com.jaovo1.msg.Util.DBUtil;
 9 import com.jaovo1.msg.model.Course;
10 import sun.net.www.content.text.plain;
11 public class CourseImpl implements ICourseDao{
12 
13     @Override
14     public void add(Course course) {
15         Connection connection=DBUtil.getConnection();
16         String sql="select count(*)from t_user where coursename=?";
17         //创建语句传输对象
18         PreparedStatement preparedStatement=null;
19         ResultSet resultSet=null;
20         try {
21             preparedStatement=(PreparedStatement) connection.prepareStatement(sql);
22             preparedStatement.setString(1, course.getCoursename());
23             //接收结果集
24             resultSet=preparedStatement.executeQuery();
25             while(resultSet.next()) {
26                 if(resultSet.getInt(1)>0) {
27                     throw new CourseException("课程名已存在");
28                 }
29             }
30             sql="insert into t_user(coursename,teacher,place) value(?,?,?)";
31             preparedStatement = connection.prepareStatement(sql);
32             preparedStatement.setString(1, course.getCoursename());
33             preparedStatement.setString(2, course.getTeacher());
34             preparedStatement.setString(3, course.getPlace());
35             preparedStatement.executeUpdate();
36         } catch (SQLException e) {
37             // TODO Auto-generated catch block
38             e.printStackTrace();
39         }finally {
40             DBUtil.close(resultSet);
41             DBUtil.close(connection);
42             DBUtil.close(preparedStatement);
43         }
44         
45     }
46 
47 }

CourseImpl.java

 1 package com.jaovo1.msg.Util;
 2 
 3 public class CourseException extends RuntimeException{
 4 
 5     public CourseException() {
 6         super();
 7         // TODO Auto-generated constructor stub
 8     }
 9 
10     public CourseException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
11         super(message, cause, enableSuppression, writableStackTrace);
12         // TODO Auto-generated constructor stub
13     }
14 
15     public CourseException(String message, Throwable cause) {
16         super(message, cause);
17         // TODO Auto-generated constructor stub
18     }
19 
20     public CourseException(String message) {
21         super(message);
22         // TODO Auto-generated constructor stub
23     }
24 
25     public CourseException(Throwable cause) {
26         super(cause);
27         // TODO Auto-generated constructor stub
28     }
29 
30 }

CourseException.java

 1 package com.jaovo1.msg.Util;
 2 
 3 import java.sql.DriverManager;
 4 import java.sql.PreparedStatement;
 5 import java.sql.ResultSet;
 6 import java.sql.SQLException;
 7 
 8 import com.mysql.jdbc.Connection;
 9 
10 public class DBUtil {
11     public static Connection getConnection() {
12             //1加载驱动
13             try {
14                 Class.forName("com.mysql.jdbc.Driver").newInstance();
15             } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
16                 // TODO Auto-generated catch block
17                 e.printStackTrace();
18             }
19         String user ="root";
20         String password="root";
21         String url="jdbc:mysql://localhost:3306/javo_msg";
22         //test
23         Connection connection=null;
24         try {
25             //2创建连接对象connection
26             connection=(Connection) DriverManager.getConnection(url, user, password);
27         } catch (SQLException e) {
28             // TODO Auto-generated catch block
29             e.printStackTrace();
30         }
31         return connection;
32         }
33     //关闭资源方法
34     public static void close(java.sql.Connection connection) {
35         try {
36             if(connection!=null)
37             {
38             connection.close();
39             }
40         } catch (SQLException e) {
41             // TODO Auto-generated catch block
42             e.printStackTrace();
43         }
44     }
45     public static void close(PreparedStatement preparedStatement) {
46         try
47         {if(preparedStatement!=null)
48         {
49             preparedStatement.close();
50         }
51         }catch(SQLException e)
52         {
53             e.printStackTrace();
54         }
55     }
56     public static void close(ResultSet resultSet) {
57         try
58         {if(resultSet!=null)
59         {
60             resultSet.close();
61         }
62         }catch(SQLException e)
63         {
64             e.printStackTrace();
65         }
66     }
67     
68 
69 }

DBUtil.java

3、运行结果截图

（输错后报错，页面将跳到重新输入的空白格里，为了显示错误结果，截图使两者同框）

4、按照PSP0级的要求记录开发过程中的项目计划日志、时间记录日志、缺陷记录日志

5、总结

目前调试程序，易出现404，500，空指针异常，jsp异常，乱码等问题，大多数情况下由于自己编写代码粗心，而且这种错误难找，因此，尽量少犯下这些错误，在今后学习中学会总结各种错误的原因。本程序存在一些细节性问题，判断语句在jsp中写，安全性降低，在后来学习中，学会将判断打包，增强安全性。学会总结，化为自己的东西，一切不要着急，慢慢来，bug慢慢改，大不了重修呗，你又不是没勇气。软工之路漫漫长道，扎实走好每一步，急于求成，反而不进。相信自己，学计算机的孩子不认输。