javaweb之删除功能

对数据库的删除，主要是通过表中的一个数据查询来进行逐个删除，否则会清空整张表。

一.dao层

在dao层加入删除方法

public boolean delete(Course n) {
    boolean f=false;
    int a=0;
    String sql="delete from submitcourse where teachername=?";//通过老师姓名来删除
    try {
         Connection conn=DBUtil.getConnection();
         PreparedStatement pstmt=conn.prepareStatement(sql);        
         pstmt.setString(1,n.getTeachername());
          a=pstmt.executeUpdate();
          System.out.println("fuck you");
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    if(a>0) f=true;
    return f;
}

二.servlet层

package servlet;

import java.io.IOException;
import java.util.ArrayList;
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 Bean.Course;
import dao.daoCourse;

/**
 * Servlet implementation class course_servlet
 */
@WebServlet("/course_servlet")
public class course_servlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       daoCourse gooddao=new daoCourse();
    /**
     * @see HttpServlet#HttpServlet()
     */
    public course_servlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doPost(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        String method=request.getParameter("method");
        if("add".equals(method))
        {
        String teachername=request.getParameter("teachername");
        String classname=request.getParameter("classname");
        String place=request.getParameter("place");
        Course n=new Course(classname,teachername,place);
        gooddao.add(n);
        request.setAttribute("message", "添加成功");
        request.getRequestDispatcher("NewFile2.jsp").forward(request, response);
        }
        
        else if("delete".equals(method)) {
            String teachername=request.getParameter("teachername");
            Course n=new Course();
            n.setTeachername(teachername);
            gooddao.delete(n);
            request.setAttribute("message", "删除成功");
            request.getRequestDispatcher("course_servlet?method=looklist").forward(request, response);
        }
        else if("looklist".equals(method)) {            
            List<Course> nt= gooddao.list();
            request.setAttribute("nt", nt);
            System.out.println("王建民");
            request.getRequestDispatcher("NewFile3.jsp").forward(request, response);
        }
    }

}