www.pudn.com > StudentDBServlet_java.rar > StudentDBServlet.java

import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.sql.*;
import java.io.*;

/**
 * Title:        三层结构数据库应用系统
 * Description:  Java语言演示程序：三层结构数据库应用系统，用于北京师范大学计算机系Java课程教学示范。
 * Copyright:    Copyright (c) 2002
 * Company:      北京师范大学计算机系
 * @author 孙一林
 * @version 1.0
 */

public class StudentDBServlet extends HttpServlet{
    protected Connection dbConnection;
    protected PreparedStatement displayStatement;
    protected PreparedStatement registerStatement;
    private static final String CONTENT_TYPE = "text/html;charset=gb2312";
    protected String driverName = "sun.jdbc.odbc.JdbcOdbcDriver";
    protected String dbURL = "jdbc:odbc:student";
    protected String userID = "student";
    protected String passwd = "123456";
    protected String CR = "\n";
    protected final int NUMBER_POSITION = 1;
    protected final int NAME_POSITION = 2;
    protected final int AGE_POSITION = 3;
    protected final int SEX_POSITION = 4;
    protected final int DEPARTMENT_POSITION = 5;
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        try {
            System.out.println("开始初始化");
            System.out.println("加载数据库驱动程序");
            Class.forName(driverName);
            System.out.println("开始连接数据库：" + dbURL);
            dbConnection = DriverManager.getConnection(dbURL, userID, passwd);
            System.out.println("准备显示数据库数据");
            displayStatement = dbConnection.prepareStatement("select * from studentbase");
            System.out.println("准备添加数据库记录");
            registerStatement = dbConnection.prepareStatement("insert into Studentbase" + "(学号, 姓名, 年龄, 性别, 系别)" + " values ( ?, ?, ?, ?, ?)");
            System.out.println("初始化准备工作结束");
        }
        catch (Exception e){
            cleanUp();
            e.printStackTrace();
        }
    }
    public void service(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
        String userOption = null;
        userOption = request.getParameter("Register");
        if (userOption != null){
            registerStudent(request, response);
        }
        else{
            displayStudents(request, response);
        }
    }
    public void displayStudents(HttpServletRequest request,HttpServletResponse response){
        Student aStudent = null;
        try {
            String htmlHead = "" + CR;
            String htmlBody = "" + CR;
            htmlBody += "
学生记录
" + CR;
            htmlBody += "
" + CR;
            String tableHead = "
" + CR;
            tableHead += "" + CR;
            tableHead += "" + CR;
            tableHead += "" + CR;
            tableHead += "" + CR;
            tableHead += "" + CR;
            tableHead += "" + CR;
            tableHead += "" + CR;
            tableHead += "" + CR;
            ResultSet dataResultSet = displayStatement.executeQuery();
            String tableBody = "";
            int rowNumber = 1;
            while (dataResultSet.next()){
                aStudent = new Student(dataResultSet);
                tableBody += aStudent.toTableString(rowNumber);
                rowNumber++;
            }
            dataResultSet.close();
            String tableBottom = "
 
学号
姓名
年龄
性别
系别";
            String htmlBottom = "";
            htmlBody += tableHead + tableBody + tableBottom;
            htmlBody += "
";
            htmlBody += "返回首页";
            htmlBody += "
" + this.getServletInfo() + "";
            htmlBody += "";
            String htmlPage = htmlHead + htmlBody + htmlBottom;
            PrintWriter outputToBrowser =  new PrintWriter(response.getOutputStream());
            response.setContentType(CONTENT_TYPE);
            outputToBrowser.println(htmlPage);
            outputToBrowser.close();
        }
        catch (Exception e)
        {
            cleanUp();
            e.printStackTrace();
        }
    }
    public void registerStudent(HttpServletRequest request,HttpServletResponse response){
        try {
            Student aStudent = new Student(request);
            registerStatement.setString(NUMBER_POSITION, aStudent.getNumber());
            registerStatement.setString(NAME_POSITION, aStudent.getName());
            registerStatement.setString(AGE_POSITION, aStudent.getAge());
            registerStatement.setString(SEX_POSITION, aStudent.getSex());
            registerStatement.setString(DEPARTMENT_POSITION, aStudent.getDepartment());
            registerStatement.executeUpdate();
            String htmlPage = "";

            htmlPage += "";
            htmlPage += "
确认正确与否
";
            htmlPage += "以下为输入的信息";
            htmlPage += aStudent.toWebString();
            htmlPage += "
";
            htmlPage += "返回首页 | ";
            htmlPage += "查看记录";
            htmlPage += "
" + this.getServletInfo() + "";
            htmlPage += "";
            PrintWriter outputToBrowser =  new PrintWriter(response.getOutputStream());
            response.setContentType(CONTENT_TYPE);
            outputToBrowser.println(htmlPage);
            outputToBrowser.close();
        }
        catch (Exception e) {
            cleanUp();
            e.printStackTrace();
        }
    }
    public void cleanUp(){
        try {
            System.out.println("关闭数据库连接");
            dbConnection.close();
        }
        catch (SQLException e){
            e.printStackTrace();
        }
    }
    public void destroy() {
        System.out.println("撤消StudentDBServlet程序");
        cleanUp();
    }
    public String getServletInfo(){
        return "在线学生注册系统 v1.0";
    }
}