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在写图书管理系统的时候,登录、借书和还书都报了同样的错误,错误和目录结构如图
这里我列出我觉得和借书有关的代码:
- <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
- <html>
- <head>
- <title>一般用户页面</title>
- </head>
- <body>
- <label><a href="chabook.jsp" style="text-decoration: none;">查询所有图书信息</a></label><br><br>
- <label><a href="jiebook.jsp" style="text-decoration: none">借阅图书</a></label><br><br>
- <label><a href="huanbook.jsp" style="text-decoration: none">归还图书</a></label>
- </body>
- </html>
- <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
- <html>
- <head><title></title></head>
- <!-- 根据图书编号和图书名字借阅图书 -->
- <body>
- <form action="borrow" method="post">
- 请输入所借阅书籍的编号<input type="text" name="bid"><br><br>
- 请输入所借阅书籍的书名<input type="text" name="bname"><br><br>
- 请输入借阅本数(注意,你总共只能借阅8本)<input type="text" name="bbeizhu"><br><br>
- <input type="submit" value="确定">
- <input type="reset" value="重填">
- </form>
- </body>
- </html>
- 这里是web.xml的部分配置
- <servlet>
- <servlet-name>Borrow</servlet-name>
- <servlet-class>servlets.Borrow</servlet-class>
- </servlet>
- <servlet-mapping>
- <servlet-name>Borrow</servlet-name>
- <url-pattern>/borrow</url-pattern>
- </servlet-mapping>
- servlets包下的Borrow.java类
- /**
- *
- */
- package servlets;
- import java.io.IOException;
- import java.sql.SQLException;
- import javax.servlet.RequestDispatcher;
- import javax.servlet.ServletException;
- import javax.servlet.http.HttpServlet;
- import javax.servlet.http.HttpServletRequest;
- import javax.servlet.http.HttpServletResponse;
- import beans.JdbcUtil;
- /**
- * @author SwordJM
- * @date:2019-5-3
- * @ClassName
- * @Description 借书,相应书籍本数减
- */
- public class Borrow extends HttpServlet{
- public void doPost(HttpServletRequest request,HttpServletResponse response)
- throws ServletException, IOException{
- request.setCharacterEncoding("UTF-8");
- int bid = 0;
- int bbeizhu = 0;
- try {
- bid = Integer.parseInt(request.getParameter("bid"));
- bbeizhu = Integer.parseInt(request.getParameter("bbeizhu"));//书籍本数
- } catch (NumberFormatException e) {
- // TODO: handle exception
- e.printStackTrace();
- }
-
- String bname = request.getParameter("bname");
-
- String sql = "update book set bbeizhu = bbeizhu - ? where bid = ? and bname = ?";
- int i = 0;
- try {
- i = JdbcUtil.executeDML(sql,bbeizhu,bid,bname);
- } catch (SQLException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- } catch (ClassNotFoundException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- }
- RequestDispatcher dis = null;
- if(i > 0){
- dis = request.getRequestDispatcher("../../WebRoot/success.jsp");//提示操作成功
- }
- else {
- dis = request.getRequestDispatcher("../../WebRoot/fail.jsp");//提示操作失败
- }
- dis.forward(request, response);
-
-
- }
- public void doGet(HttpServletRequest request,HttpServletResponse response)
- throws ServletException,IOException{
- doPost(request, response);
- }
- }
- 这里是Borrow.java中用到的beans报下的JdbcUtil.java类的部分函数
- //封装DML(针对增删改)
- public static int executeDML(String sql,Object...objs) throws SQLException, ClassNotFoundException{
- Connection conn = Connect.getConnection();
-
- PreparedStatement ps = getPreparedStatement(conn, sql);
- //给占位符赋值
- try {
- conn.setAutoCommit(false);
- for(int i = 0;i < objs.length;i++){
- ps.setObject(i+1, objs[i]);
- }
- int i = ps.executeUpdate();
- conn.commit();
- return i;
- } catch (SQLException e) {
- try {
- conn.rollback();
- } catch (SQLException e1) {
- // TODO Auto-generated catch block
- e1.printStackTrace();
- }
- }finally{
- //关闭资源
- Connect.closeAll(null, ps, conn);
- }
- return -1;
- }
复制代码 |
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目录结构
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报错
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