实例包括如下文件：
M部分：Student.java，包含了数据库访问代码，能够表示学生信息，封装了对学生操作的基本方法。
C部分：StudentServlet.java，完成增删改查的控制。
V部分：studentlist.jsp和edituser.jsp，前者显示学生列表，以及添加、删除、修改的入口，后者用于添加和修改。
配置文件：web.xml
下面分别给出相关文件。
----------------------------------------Student.java-----------------------------------------------------------
package javabean;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
public class Student {
private Connection con;
private Statement stmt;
private ResultSet rs;
private String sid;
private String sname;
private String sage;
/*
* 获取所有学生信息
*/
public List getAllStudents(){
List list = new ArrayList();
String sql = "select * from student";
try{
rs = executeQuery(sql);
while(rs.next()){
Student temp = new Student();
temp.setSid(rs.getString(1));
temp.setSname(rs.getString(2));
temp.setSage(rs.getString(3));
list.add(temp);
}
}catch(Exception e){
System.out.println(e.toString());
}finally{
close();
}
return list;
}
/*
* 添加学生
*/
public void add(Student stu){
String sql = "insert into student values('"+stu.getSid()+"','"+stu.getSname()+"',"+stu.getSage()+")";
try{
executeUpdate(sql);
}catch(Exception e){
System.out.println(e.toString());
}finally{
close();
}
}
/*
* 删除学生
*/
public void delete(String sid){
String sql = "delete from student where sid='"+sid+"'";
try{
executeUpdate(sql);
}catch(Exception e){
System.out.println(e.toString());
}finally{
close();
}
}
/*
* 修改学生
*/
public void edit(Student stu){
String sql = "update student set sname='"+stu.getSname()+"',sage="+stu.getSage()+" where sid='"+stu.getSid()+"'";
try{
int n = executeUpdate(sql);
System.out.println("--------------"+n);
}catch(Exception e){
System.out.println(e.toString());
}finally{
close();
}
}
/*
* 根据学号查询学生
*/
public Student findStudentById(String sid){
String sql = "select * from student where sid='"+sid+"'";
try{
rs = executeQuery(sql);
if(rs.next()){
Student temp = new Student();
temp.setSid(rs.getString(1));
temp.setSname(rs.getString(2));
temp.setSage(rs.getString(3));
return temp;
}
}catch(Exception e){
System.out.println(e.toString());
}finally{
close();
}
return null;
}
/*
* 执行更新等操作
*/
public int executeUpdate(String sql)throws SQLException,ClassNotFoundException{
return getStatement().executeUpdate(sql);
}
/*
* 关闭对象
*/
public void close(){
if(rs!=null)
try{rs.close();}catch(Exception e){}
if(stmt!=null)
try{stmt.close();}catch(Exception e){}
if(con!=null)
try{con.close();}catch(Exception e){}
}
/*
* 执行有结果集返回的查询
*/
public ResultSet executeQuery(String sql) throws SQLException,ClassNotFoundException{
return getStatement().executeQuery(sql);
}
/*
* 获取语句对象
*/
public Statement getStatement() throws SQLException,ClassNotFoundException{
if(stmt==null){
stmt = getConnection().createStatement();
}
return stmt;
}
/*
* 获取连接
*/
public Connection getConnection() throws SQLException,ClassNotFoundException{
if(con==null){
Class.forName("oracle.jdbc.driver.OracleDriver");
con = DriverManager.getConnection("jdbc:oracle:thin:@192.168.102.206:1521:orcl","training","123456");
}
return con;
}
public String getSid() {
return sid;
}
public void setSid(String sid) {
this.sid = sid;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public String getSage() {
return sage;
}
public void setSage(String sage) {
this.sage = sage;
}
public static void main(String[] args){
Student student = new Student();
}
}
----------------------------------------StudentServlet.java----------------- --------------------------------
package servlet;
import java.io.IOException;
import java.util.List;
import javabean.Student;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class StudentServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("gb2312");
String sid = request.getParameter("sid");
String sname = request.getParameter("sname");
String sage = request.getParameter("sage");
String action = request.getParameter("action");
// 调用业务方法
Student student = new Student();
if(action.equals("list")){ // 显示列表
List list = student.getAllStudents();
request.setAttribute("studentlist",list);
}else if(action.equals("add")){ //添加
Student info = new Student();
info.setSid(sid);
info.setSname(sname);
info.setSage(sage);
student.add(info);
}else if(action.equals("edit")){ // 修改
Student info = new Student();
info.setSid(sid);
info.setSname(sname);
info.setSage(sage);
student.edit(info);
}else if(action.equals("findedit")){ // 修改之前的查询
Student info = student.findStudentById(sid);
request.setAttribute("student",info);
}else if(action.equals("delete")){ // 删除学生
student.delete(sid);
}else if(action.equals("findadd")){
}
String forward;
if(action.equals("findedit")){
request.setAttribute("type","edit"); // 在界面上用于判断是添加界面还是修改界面
forward = "edituser.jsp";
}else if(action.equals("findadd")){
request.setAttribute("type","add"); // 在界面上用于判断是添加界面还是修改界面
forward = "edituser.jsp";
}else if(action.equals("list")){
forward = "studentlist.jsp";
}else{
forward = "student?action=list";
}
RequestDispatcher rd = request.getRequestDispatcher(forward);
rd.forward(request,response);
}
}
----------------------------------------studentlist.jsp---------------------------------------------------------
<%@ page contentType="text/html;charset=gb2312"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>
<title>所有学生信息</title>
</head>
<body>
<h1>学生列表</h1>
<table>
<tr>
<td>学号</td><td>姓名</td><td>年龄</td>
</tr>
<c:forEach var="student" items="${studentlist}">
<tr>
<td>${student.sid}</td>
<td>${student.sname}</td>
<td>${student.sage}</td>
<td><a href="student?action=delete&sid=${student.sid}">删除</a></td>
<td><a href="student?action=findedit&sid=${student.sid}">修改</a></td>
</tr>
</c:forEach>
</table>
<a href="student?action=findadd">添加学生</a>
</body>
</html>
----------------------------------------edituser.jsp -----------------------------------------------------------
<%@ page language="java" pageEncoding="gb2312" contentType="text/html;charset=gb2312"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'edituser.jsp' starting page</title>
</head>
<body>
<h2> <c:if test="${type==/"add/"}"> 添加学生</c:if> <c:if test="${type==/"edit/"}"> 修改学生</c:if> </h2>
<form action="student?action=${type}" method="post">
<table>
<tr>
<td>学号</td>
<td>
<c:if test="${ empty student }"> <input type="text" name="sid"></c:if>
<c:if test="${! empty student }"> <input type="hidden" name="sid" value="${student.sid}">${student.sid} </c:if>
</td>
</tr>
<tr>
<td>姓名</td><td><input type="text" name="sname" <c:if test="${! empty student }"> value="${student.sname}" </c:if> ></td>
</tr>
<tr>
<td>年龄</td><td><input type="text" name="sage" <c:if test="${! empty student }"> value="${student.sage}" </c:if>></td>
</tr>
<tr>
<td><input type="submit" value="确定"></td><td><input type="reset" value="重置"></td>
</tr>
</table>
</form>
</body>
</html>
----------------------------------------web.xml-----------------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>StudentServlet</servlet-name>
<servlet-class>servlet.StudentServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>StudentServlet</servlet-name>
<url-pattern>/student</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
该实例需要添加的内容：
1、增加验证部分。
2、增加异常处理部分。
3、增加日志部分。
4、增加国际化部分。
5、增加分页功能。
6、增加灵活的查询功能。