论文查询系统（三）

DBUtil

package DBUtil;
import java.sql.*;
public class DBUtil {
    
    
     static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; //数据库驱动名
        static final String url = "jdbc:mysql://localhost:3306/python?serverTimezone=UTC";//数据库地址
        static final String user = "root";
        static final String password = "152486";
        
        
        
//连接数据库
        public static Connection getConn () {
            Connection conn = null;
            
            try {
                Class.forName("com.mysql.cj.jdbc.Driver");//加载驱动
                conn = DriverManager.getConnection(url, user, password);
            } catch (Exception e) {
                e.printStackTrace();
            }
            
            return conn;
        }
    
    
    //关闭连接
        public static void close (PreparedStatement preparedState, Connection conn) {
            if (preparedState != null) {
                try {
                    preparedState.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            
            if (conn != null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
        
        public static void close (ResultSet rs, PreparedStatement preparedState, Connection conn) {
            if (rs != null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            
            if (preparedState != null) {
                try {
                    preparedState.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            
            if (conn != null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }

        /**
         * 关闭连接
         * @param state
         * @param conn
         */
        public static void close (Statement state, Connection conn) {
            if (state != null) {
                try {
                    state.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            
            if (conn != null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
        
        public static void close (ResultSet rs, Statement state, Connection conn) {
            if (rs != null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            
            if (state != null) {
                try {
                    state.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            
            if (conn != null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
        //测试是否连接成功
        public static void main(String[] args) throws SQLException {
            Connection conn = getConn();
            PreparedStatement preparedStatement = null;
            ResultSet rs = null;
            String sql ="select * from pachong";//数据库名称
            preparedStatement = conn.prepareStatement(sql);
            rs = preparedStatement.executeQuery();
            if(rs.next()){
                System.out.println("数据库不为空");
            }
            else{
                System.out.println("数据库为空");
            }
        }
        






}
    
    

servlet

package Servlet;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
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.bean;
import Dao.Dao;


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


    private void update(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        int id = Integer.parseInt(request.getParameter("id"));
        String name = request.getParameter("name");
        String pdf = request.getParameter("pdf");
        String author = request.getParameter("author");
        String title = request.getParameter("title");
        String booktitle = request.getParameter("booktitle");
        String date = request.getParameter("date");
        bean bean=new bean(id,name,pdf,author,title,booktitle,date);
        Dao.update(bean);
        request.setAttribute("message", "修改成功");
        request.getRequestDispatcher("servlet?method=list").forward(request, response);
    }

    private void delete(HttpServletRequest request, HttpServletResponse response) throws Exception, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("UTF-8");
        int id=Integer.parseInt(request.getParameter("id"));
        Dao.delete(id); //进行数据库的删除操作
        request.setAttribute("message", "删除成功");
        request.getRequestDispatcher("servlet?method=list").forward(request, response);
    }

    private void insert(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        int id = Integer.parseInt(request.getParameter("id"));
        String name = request.getParameter("name");
        String pdf = request.getParameter("pdf");
        String author = request.getParameter("author");
        String title = request.getParameter("title");
        String booktitle = request.getParameter("booktitle");
        String date = request.getParameter("date");
        bean bean=new bean(id,name,pdf,author,title,booktitle,date);
        if(Dao.insert(bean)) {
            request.setAttribute("message", "添加成功");
            request.getRequestDispatcher("index.jsp").forward(request, response);
        }
    }
    
    

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        String method=request.getParameter("method");
        if("insert".equals(method)) {
            insert(request,response);
            
        }
        else if("delete".equals(method)) {
            try {
                delete(request,response);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            
        }
        else if("update".equals(method)) {
            update(request,response);
        }
        /*else if("list".equals(method)) {
            try {
                list(request,response);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }*/
        
    }

    /**
     * @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);
    }

}