[FMG]两个简单的JSP+servlet小程序

周末啦，最后一天，问了一下妹子，你作业写完了没有，妹子说，木有，我就傻眼了。。。

好吧，妹子，我来帮你写。

于是乎，把作业ppt下载下来，看了看，还可以，不算难，于是就帮妹子写完了这一个作业。虽然说还有一个作业ppt连我都看不懂布置的老师是想要干什么，真心想吐槽一句，老师，不给力啊。

好了，先上一个代码结构图吧：

主要代码分为java代码部分和WebContent代码部分：

java代码部分主要分成了3个包：BEAN(实体类包)，DAO(数据库访问类包)，Servlet(Servlet类包)

BEAN包包含了2个实体：user.java(用户实体)，vote.java(参选人信息实体)

DAO包含了3个类：BaseDao.java(提供数据库连接的基本类)，UserDao.java(访问用户表的DAO)，VoteDao.java(访问参选人信息表的DAO)

Servlet包含了5个类：RandCode.java,YZMServlet.java(这两个类提供了验证码的功能)，addVoteNumber.java(提供了投票的功能，即被选中的人票数+1)，login.java(用户登录验证)，reg.java(用户注册功能)

 

WebContent包含了4个html页面和4个JSP页面：

ShowAllVoteInfo.jsp页面：显示所有参选人的简略信息，并提供前往投票界面的通道。
addVoteNumber.jsp页面：显示被选中的那个参选人的详细信息，并提供投票功能

UserLogin.jsp页面：提供用户登录功能，并提供前往注册的通道

UserReg.jsp页面：提供新用户注册的功能。

剩下4个html页面都是简单的成功失败信息提示页面，无需过多说明。

 

先说一下，做这个练习的思路。我是先把实*作好了先的人。

要制作实体，先要有对应的数据库及表，

所以，第一步是创库创表加数据

create database vote
go

use vote
go

create table voteInfo
(
    id int primary key identity,
    pname varchar(20) not null,
    voteNumber int not null default 0,
    pImgSrc varchar(200) ,--图片路径
    achievement1 text,--事迹
    achievement2 text
)

insert voteInfo values('张三',100,'1.jpg','他姓张','排行老三')
insert voteInfo values('马云',111,'2.jpg','淘宝','天猫')
insert voteInfo values('李连杰',33,'3.jpg','非常能打','')

select * from voteInfo

create table userInfo
(
    id int primary key identity,
    uaccount varchar(20) not null,
    upwd varchar(20) not null
)

insert userInfo values('qiu','123456')
insert userInfo values('yangmei','520.')

 

第二步，对应数据库的表制作实体：

user.java，用户实体

package BEAN;

public class user {
    private int id;
    private String uaccount;
    private String upwd;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getUaccount() {
        return uaccount;
    }
    public void setUaccount(String uaccount) {
        this.uaccount = uaccount;
    }
    public String getUpwd() {
        return upwd;
    }
    public void setUpwd(String upwd) {
        this.upwd = upwd;
    }
}

vote.java，参选人信息实体

package BEAN;

public class vote {
    private int id;
    private String pname;
    private int voteNumber;
    private String pImgSrc;
    private String achievement1;
    private String achievement2;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getPname() {
        return pname;
    }
    public void setPname(String pname) {
        this.pname = pname;
    }
    public int getVoteNumber() {
        return voteNumber;
    }
    public void setVoteNumber(int voteNumber) {
        this.voteNumber = voteNumber;
    }
    public String getpImgSrc() {
        return pImgSrc;
    }
    public void setpImgSrc(String pImgSrc) {
        this.pImgSrc = pImgSrc;
    }
    public String getAchievement1() {
        return achievement1;
    }
    public void setAchievement1(String achievement1) {
        this.achievement1 = achievement1;
    }
    public String getAchievement2() {
        return achievement2;
    }
    public void setAchievement2(String achievement2) {
        this.achievement2 = achievement2;
    }
    
}

 

第三步，查看信息，列出所有需要提供的功能，并为功能编写DAO

BaseDao.java，数据库连接Dao

package DAO;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class BaseDao {
    private static String username = "sa";
    private static String password = "123456";
    private static String url = "jdbc:sqlserver://localhost:1433;databaseName=vote";
    private static String classname = "com.microsoft.sqlserver.jdbc.SQLServerDriver";
    private static Connection conn;  
    PreparedStatement stat;
    
    static{
        try {
            Class.forName(classname);
            System.out.print("forName");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }    
    
    public static Connection getCon() {
        try {
             conn = DriverManager.getConnection(url, username, password);
             System.out.print("getConnection");
        } catch (SQLException e) {
            e.printStackTrace();
        }        
        return conn;
    }
    
    public static void closeAll(Connection conn,PreparedStatement ps,ResultSet rs){
    
    
            try {
                if(rs != null)
                    rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        
            try {
                if(ps != null)
                    ps.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        
            try {
                if(conn != null)
                    conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        
        
    }
}

UserDao.java ，用户Dao

package DAO;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;


import BEAN.user;
import BEAN.vote;

public class UserDao {
　　//提供根据实体类对象来判断是否登录成功的方法
    public Boolean login(user u) throws SQLException{
        Connection conn = BaseDao.getCon();
        PreparedStatement statement =null;
        ResultSet rest = null;
        try {
            String sql = "select * from userInfo where uaccount='"+u.getUaccount()
                    +"' and upwd='"+u.getUpwd()+"'";
            statement = conn.prepareStatement(sql);                    
            rest = statement.executeQuery();
            if (rest.next()) {
                return true;
            }
            else
                return false;
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            conn.close();
        }
        return false;
    }
　　//判断用户注册的账号是否已经存在
    public Boolean hasUser(String uaccount) throws SQLException{
        Connection conn = BaseDao.getCon();
        PreparedStatement statement =null;
        ResultSet rest = null;
        try {
            String sql = "select * from userInfo where uaccount='"+uaccount+"'";
            statement = conn.prepareStatement(sql);                    
            rest = statement.executeQuery();
            if (rest.next()) {
                return true;
            }
            else
                return false;
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            conn.close();
        }
        return false;
    }
    //添加用户
    public boolean addUser(user     u)
    {
        Boolean result=false;
        Connection conn = BaseDao.getCon();
        PreparedStatement statement =null;
        String sql = "insert userInfo values(?,?);";
        
        try {            
            statement = conn.prepareStatement(sql);
            statement.setString(1, u.getUaccount());
            statement.setString(2, u.getUpwd());
            int rows=statement.executeUpdate();
            
            if(rows>0)
                result=true;
            else
                result=false;
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            BaseDao.closeAll(conn, statement, null);
        }
        return result;
    }
}

VoteDao.java,参选人信息Dao

package DAO;
import java.sql.*;
import java.util.*;


import BEAN.vote;


public class VoteDao {
　　//得到一个List集合，该集合包含所有参选人的信息
    public List<vote> selectAll() throws SQLException{
        List<vote> list = new ArrayList<vote>();
        Connection conn = BaseDao.getCon();
        vote voteInfo = null;
        PreparedStatement statement =null;
        ResultSet rest = null;
        try {
            String sql = "select * from voteInfo";
            statement = conn.prepareStatement(sql);                    
            rest = statement.executeQuery();
            while (rest.next()) {
                voteInfo = new vote();
                voteInfo.setId(rest.getInt("id"));
                voteInfo.setPname(rest.getString("pname"));
                voteInfo.setVoteNumber(rest.getInt("voteNumber"));
                voteInfo.setpImgSrc(rest.getString("pImgSrc"));
                voteInfo.setAchievement1(rest.getString("achievement1"));
                voteInfo.setAchievement2(rest.getString("achievement2"));
                list.add(voteInfo);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            conn.close();
        }
        return list;
    }
    //为特定编号的参选人选票+1
    public boolean addVoteNumber(String id)
    {
        Boolean result=false;
        Connection conn = BaseDao.getCon();
        PreparedStatement statement =null;
        String sql = "update voteInfo set voteNumber=voteNumber+1 where id="+id;
        
        try {            
            statement = conn.prepareStatement(sql);

            int rows=statement.executeUpdate();
            
            if(rows>0)
                result=true;
            else
                result=false;
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            BaseDao.closeAll(conn, statement, null);
        }
        return result;
    }
}

第四步，编写JSP页面，JSP页面相对来说要简单许多，因为在ppt里有提供，依葫芦画瓢就好啦。

ShowAllVoteInfo.jsp页面：显示所有参选人的简略信息，并提供前往投票界面的通道。

效果图：

代码部分如下：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import="DAO.VoteDao" %>
<%@ page import="BEAN.vote" %>
<%@ page import="java.util.*" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<% 
VoteDao dao=new VoteDao(); 
List<vote> voteInfo=dao.selectAll();
%>
<table width="100%" height="768">
    <%
        //for(int i=0;i<voteInfo.size()/3+1;i++)
        for(int i=0;i<voteInfo.size();i++)
        {
            vote v=voteInfo.get(i);
            if(i%3==0)
            {
    %>
    <tr>
        <td><img src="/vote/<%=v.getpImgSrc()%>" width=250 height=350><br><%=v.getPname() %>(<%=v.getVoteNumber() %>)票<br>
            <a href="/vote/addVoteNumber.jsp?id=<%=v.getId() %>" >我要投票</a></td>
            <%}
            else if(i%3<2){%>
            <td><img src="/vote/<%=v.getpImgSrc()%>" width=250 height=350><br><%=v.getPname() %>(<%=v.getVoteNumber() %>)票<br>
            <a href="/vote/addVoteNumber.jsp?id=<%=v.getId() %>" >我要投票</a></td>
            <%}
            else{%>
            <td><img src="/vote/<%=v.getpImgSrc()%>" width=250 height=350 ><br><%=v.getPname() %>(<%=v.getVoteNumber() %>)票<br>
            <a href="/vote/addVoteNumber.jsp?id=<%=v.getId() %>" >我要投票</a></td>
    </tr>
        <%} %>
    <%} %>
</table>
</body>
</html>

 

addVoteNumber.jsp页面：显示被选中的那个参选人的详细信息，并提供投票功能

效果图：

代码部分如下：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import="DAO.VoteDao" %>
<%@ page import="BEAN.vote" %>
<%@ page import="java.util.*" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<% 
VoteDao dao=new VoteDao(); 
List<vote> voteInfo=dao.selectAll();
String str=request.getParameter("id");

//for(int i=0;i<voteInfo.size()/3+1;i++)
for(int i=0;i<voteInfo.size();i++)
{
    vote v=voteInfo.get(i);
    if(str.equals(v.getId()+""))
    {
        %>
        <img src="/vote/<%=v.getpImgSrc()%>" width=250 height=350>
        <br><%=v.getPname() %>(<%=v.getVoteNumber() %>)票
        <br><br>主要事迹：<br>1.<%=v.getAchievement1() %><br>2.<%=v.getAchievement2() %><br><br>
        <% 
    }
}
%>
<form action="addVoteNumber" method="post">
    <input type=hidden name=id value=<%=str %> />
    <input type=submit value="我要投票" />&nbsp;<a href="ShowAllVoteInfo.jsp">返回首页</a>
</form>
</body>
</html>

 

UserLogin.jsp页面：提供用户登录功能，并提供前往注册的通道

效果图：

代码部分如下：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1 >用户登录</h1>
<form action="login" method=post name=frm>
账号：<input type=text name=account /><br>
密码：<input type=password name=pwd /><br>
验证码:<input type="text" name='myYZM'><img src="yzm" onclick="this.src='yzm?parm='+new Date()"><br>
<input type=submit value="登录" />&nbsp;<a href="UserReg.jsp">新用户注册</a>
</form>
</body>
</html>

 

UserReg.jsp页面：提供新用户注册的功能。

效果图：

代码如下：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>新用户注册</h1>
<form action="reg" method=post name=frm onsubmit="return checkData()">
账号：<input type=text name=account /><br>
密码：<input type=password name=pwd /><br>
密码：<input type=password name=pwd2 /><br>
验证码:<input type="text" name='myYZM'><img src="yzm" onclick="this.src='yzm?parm='+new Date()"><br>
<input type=submit value="注册" />
</form>

<script type="text/javascript">
    function checkData(){
        if(frm.account.value==""){
            alert("用户名不能为空!");
            return false;    
        }
        if(frm.pwd.value==""){
            alert("密码不能为空!");
            return false;    
        }
        if(frm.pwd.value!=frm.pwd2.value){
            alert("两次密码不一致!");
            return false;
        }
        return true;
    }

</script>
</body>
</html>

 

最后一步，为特定的功能制作servlet：

其实，一开始我看到验证码的时候我是很蛋疼的，但是妹子直接发给了我功能代码，因为我拿来主义，研究一下，使用了一下，duang,duang,duang,验证码功能就好了

哈哈，就是搞笑一下，其实验证码的功能还挺麻烦的，首先你的有两个文件：

RandCode.java,YZMServlet.java(这两个类提供了验证码的功能)

当添加了这两个类以后，需要在JSP页面和功能servlet页面添加对应的代码，才能正确实现验证。

RandCode.java文件代码作用是设置会产生的字符范围，并且产生4位的随机文字，如下：

package Servlet;

import java.util.Random;

public class RandCode {
    String code="";
    public RandCode(){
        Random rand = new Random();
        String tmp = "@ABCDPghijkmnopqyz0123rsEFKLMNQRSTUVWXYZabcdeGHIJftuvwx456789";
        code="";
        for(int i=0; i<4; i++){
            int index = rand.nextInt(tmp.length());
            code+=tmp.substring(index, index+1);
        }
    }

    public String getCode() {
        return code;
    }
}

YZMServlet.java文件，提供了servlet功能来产生一个验证码图片，代码部分如下：

package Servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.jws.WebService;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/yzm")
public class YZMServlet extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        RandCode yzm = new RandCode();
        BufferedImage bi = new BufferedImage(80,30,BufferedImage.TYPE_INT_RGB);
        Graphics g = bi.getGraphics();
        
        g.setColor(new Color(120,200,50));
        g.setFont(new Font("Tw Cen MT",Font.ROMAN_BASELINE, 24));
        g.fillRect(0, 0, 80, 30);
        
        g.setColor(Color.RED);
        g.drawLine(20, 15, 80, 0);
        g.setColor(Color.PINK);
        g.fillRoundRect(50, 20, 5, 10, 15, 20);
        
        //设置随机验证码字符串
        g.setColor(Color.blue);
        g.drawString(yzm.getCode(), 0, 20);
        
        //将验证码保存在session对象中
        request.getSession().setAttribute("yzm", yzm.getCode());
        //将生成的图片以jpg格式发送到客户端        
        ImageIO.write(bi, "JPG", response.getOutputStream());
    }

    
}

addVoteNumber.java文件(提供了投票的功能，即被选中的人票数+1)，这是一个servlet文件，代码如下：

package Servlet;

import java.io.IOException;
import java.io.PrintWriter;

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 DAO.VoteDao;

/**
 * 实现为某一个参选者投票的功能
 */
@WebServlet("/addVoteNumber")
public class addVoteNumber extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public addVoteNumber() {
        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
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();//得到打印对象
        
        String str=request.getParameter("id");
        VoteDao dao=new VoteDao();
        Boolean result = dao.addVoteNumber(str);
        if(result==true)
        {//投票成功
            String js= "<script>location.href='succ.html';</script>";
            out.print(js);
        }
        else
        {//投票失败
            String js= "<script>location.href='fail.html';</script>";
            out.print(js);
        }
    }

}

login.java(用户登录验证),这是一个servlet文件，代码如下：

package Servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;

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.user;
import DAO.UserDao;

/**
 * Servlet implementation class login
 */
@WebServlet("/login")
public class login extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public login() {
        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
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();//得到打印对象
        
        String innerYzm = (String) request.getSession().getAttribute("yzm");//得到服务器端验证码
        String userYzm = request.getParameter("myYZM");//得到用户填写的验证码
        
        if (innerYzm.equals(userYzm)) 
        {
            String uaccount=request.getParameter("account");
            String upwd=request.getParameter("pwd");
            UserDao dao=new UserDao();
            user u=new user();
            u.setUaccount(uaccount);
            u.setUpwd(upwd);
            try {
                if(dao.login(u))//查询数据里是否有一致的账号密码，有则登录成功，没有则失败
                {
                    String js= "<script>location.href='UserSucc.html';</script>";
                    out.print(js);
                }
                else
                {//插入失败
                    String js= "<script>location.href='UserFail.html';</script>";
                    out.print(js);
                }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        else
        {
            String js = "<script>alert('登录失败，验证码出错!');location.href='UserLogin.jsp';</script>";
            out.print(js);
        }
    }

}

reg.java(用户注册功能)，提供新用户注册功能的servlet，代码如下：

package Servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;

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.user;
import DAO.UserDao;

/**
 * Servlet implementation class reg
 */
@WebServlet("/reg")
public class reg extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public reg() {
        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
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();//得到打印对象
        
        String innerYzm = (String) request.getSession().getAttribute("yzm");
        String userYzm = request.getParameter("myYZM");
        if (innerYzm.equals(userYzm)) {
            String uaccount=request.getParameter("account");
            String upwd=request.getParameter("pwd");
            UserDao dao=new UserDao();
            user u=new user();
            u.setUaccount(uaccount);
            u.setUpwd(upwd);
            
            
            
            try {
                if(dao.hasUser(uaccount))
                {
                    String js= "<script>location.href='UserFail.html';</script>";
                    out.print(js);
                    return;
                }
                
                if(dao.addUser(u))
                {
                    String js= "<script>location.href='UserSucc.html';</script>";
                    out.print(js);
                }
                else
                {//插入失败
                    String js= "<script>location.href='UserFail.html';</script>";
                    out.print(js);
                }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        else
        {
            String js = "<script>alert('登录失败，验证码出错!');location.href='UserReg.jsp';</script>";
            out.print(js);
        }
    }

}

 

 

 

在制作整个练习的时候，遇到过一些问题。也抓了不少头发，但是终究还是给我做出来了，来，为自己喝彩。。。

1.需要显示的图片不要使用中文名的图片文件，会找不到图片文件的

2.在JSP页面中导入包使用的是<% page命令，示例：<%@ page import="java.util.*" %>

3.在JSP页面中如果写普通的服务器代码可以使用<%%>将它们括起来。

4.借鉴代码的时候一点都不要改，要不然就请理解透彻，要不然就是bug地狱。

5.其实java真的比oc好太多。。。