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jsp实现简单图片验证码功能

本文实例为大家分享了jsp实现简单图片验证码的具体代码，供大家参考，具体内容如下

一、实现的功能分析

（1）在登陆页面加验证码的功能，起到一定的安全性 。在输入正确的验证码，用户名和密码的情况下，才可以实现登录 。
（2）实现查询数据库的功能 。在登陆后的页面中，显示用户名和密码，并且设置有一个超链接，实现查询数据库的功能 。
（3）代码核心是：随机生成验证码，并且显示在页面上 。同时要和输入框中的输入验证码进行校验 。
（4）主页面使用img标签的src属性引入验证页面的jsp文件 。
（5）验证码的实现页面使用BufferedImage类的方法产生图片 。
（6）使用Graphics类的各种方法实现验证码的构成 。

二、代码实现

（1）登录页面：index.jsp文件 。

<%@ page language="java" contentType="text/html; charset=utf-8"
? ? pageEncoding="utf-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>登录页面</title>
</head>
<body>
<form action="LoginServlet" method="post">
? ? ? ?用户名：<input name="username" type="text" value=""/><br/><br/>
? ? ? ?密码：<input name="password" type="password" value=""/><br/><br/>
? ? ? ?
? ? ? ?
? ? ? ? 验证码: <input type="text" name="checkCode" height="20px " value=""/>
? ? ? <img src="CodeServlet"/><span>${error_code}</span><br/>
? ? ? ?<input type="submit" value="提交">

</form>
</body>
</html>

（2）登录后的页面：user.jsp文件 。

<%@ page language="java" contentType="text/html; charset=utf-8"
? ? pageEncoding="utf-8"%>
<%@ ?page import = "com.entity.Author"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>显示登录用户的用户名和密码页面</title>
</head>
<body>
<% ?
? ? //内置对象
? ? request.setCharacterEncoding("utf-8");
? ? //获取交互层放入session中的obj
? ? Author obj = (Author)session.getAttribute("authorInfo");
? ??
? ? if(obj != null){
? ? ?? ?out.print("<p>用户名："+obj.getName()+"</p>");
? ? ?? ?out.print("<p>密码："+obj.getId()+"</p>");
? ? }
? ? else{
? ? ?? ?response.sendRedirect("index.jsp");
? ? }
%>
<br/>
<a href="AuthorServlet">用户信息查询 </a>
</body>
</html>

（3）实现数据查询页面：ueslist.jsp文件 。

<%@ page language="java" contentType="text/html; charset=utf-8"
? ? pageEncoding="utf-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>查询信息显示页面</title>
</head>
<body>
<table border="1">
? <tr>
? ? ? ? ?<td>编号</td>
? ? ? ? ?<td>名称</td>
? ? ? ? ?<td>价格</td>
? ? ? ? ?<td>数量</td>
? ? ? ? ?<td>日期</td>
? ? ? ? ?<td>风格</td>
? </tr>
??
? ?<c:forEach items="${authorList}" var="author">
? <tr>
? ? <td>${author.id}</td>
? ? <td>${author.name }</td>
? ? <td>${author.price }</td>
? ? <td>${author.num }</td>
? ? <td>${author.dates}</td>
? ? <td>${author.style}</td>
? </tr>
? </c:forEach>
</table>
</body>
</html>

（4）定义一个Author类，用于接收数据库中的元素 。

package com.entity;
//用于获取数据库中的元素对象
public class Author {
?? ?private int id;
?? ?private String name;
?? ?private int price ;
?? ?private int num;
?? ?private String dates;
?? ?private String style;
?? ?public int getId() {
?? ??? ?return id;
?? ?}
?? ?public void setId(int id) {
?? ??? ?this.id = id;
?? ?}
?? ?public String getName() {
?? ??? ?return name;
?? ?}
?? ?public void setName(String name) {
?? ??? ?this.name = name;
?? ?}
?? ?public int getPrice() {
?? ??? ?return price;
?? ?}
?? ?public void setPrice(int price) {
?? ??? ?this.price = price;
?? ?}
?? ?public int getNum() {
?? ??? ?return num;
?? ?}
?? ?public void setNum(int num) {
?? ??? ?this.num = num;
?? ?}
?? ?public String getDates() {
?? ??? ?return dates;
?? ?}
?? ?public void setDates(String dates) {
?? ??? ?this.dates = dates;
?? ?}
?? ?public String getStyle() {
?? ??? ?return style;
?? ?}
?? ?public void setStyle(String style) {
?? ??? ?this.style = style;
?? ?}

}

（5）登录页面的交互层：LoginServlet.java文件 。用于登录检验和验证码匹配 。

//交互层（客户端和服务器的交互）
package com.servlet;

import java.io.IOException;
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 javax.servlet.http.HttpSession;

import com.dao.AuthorDao;
import com.entity.Author;

/**
?* Servlet implementation class LoginServlet
?*/
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
?? ?private static final long serialVersionUID = 1L;
? ? ? ?
? ? /**
? ? ?* @see HttpServlet#HttpServlet()
? ? ?*/
? ? public LoginServlet() {
? ? ? ? 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
?? ??? ?//内置对象request，response
?? ??? ?request.setCharacterEncoding("utf-8");
?? ??? ?
?? ??? ?HttpSession session = request.getSession();
?? ??? ?
?? ??? ?//获取用户输入验证码
?? ??? ?String checkCode = request.getParameter("checkCode");
?? ??? ?//获取session中的验证码,也就是CodeServlet中生成的四个字符
?? ??? ?String sessionCode = (String)session.getAttribute("sCode");
?? ??? ?
?? ??? ?
?? ??? ?//验证码正确
?? ??? ?if(checkCode.equals(sessionCode)) {
?? ??? ??? ?//获取表单数据
?? ??? ??? ?String username = request.getParameter("username");
?? ??? ??? ?int password = Integer.valueOf(request.getParameter("password"));
?? ??? ??? ?
?? ??? ??? ?//判断用户信息是否正确，查询数据库获取用户信息
?? ??? ??? ? AuthorDao ad = new AuthorDao();
?? ??? ? ? ? Author obj = ad.check(username, password);
?? ??? ? ? ??
?? ??? ? ? ? //判断
?? ??? ? ? ? if(obj != null) {
?? ??? ? ? ??? ??
?? ??? ? ? ??? ? //重新放入用户信息
?? ??? ? ? ?//?? ? HttpSession session = request.getSession();
?? ??? ? ? ??? ? session.setAttribute("authorInfo", obj);
?? ??? ? ? ??? ? //设置session的有效期为10秒
?? ??? ? ? ??? ? session.setMaxInactiveInterval(10);
?? ??? ? ? ??? ??
?? ??? ? ? ??? ? //页面转发
?? ??? ? ? ??? ? response.sendRedirect("user.jsp");
?? ??? ? ? ? }
?? ??? ? ? ? else {
?? ??? ? ? ??? ??
?? ??? ? ? ??? ? //页面重定向到登录页面
?? ??? ? ? ??? ? response.sendRedirect("index.jsp");
?? ??? ? ? ? }
?? ??? ?}
?? ??? ?else {
?? ??? ??? ?//验证码不正确
?? ??? ??? ?request.setAttribute("error_code", "验证码不匹配");
?? ??? ??? ?request.getRequestDispatcher("index.jsp").forward(request, response);
?? ??? ?}
?? ?}?? ?
?? ?/**
?? ? * @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);
?? ?}

}

（6）数据库查询的交互层：AuthorServlet.java文件 。

package com.servlet;

import java.io.IOException;
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 com.dao.AuthorDao;
import com.entity.Author;

/**
?* Servlet implementation class AuthorServlet
?*/
@WebServlet("/AuthorServlet")
public class AuthorServlet extends HttpServlet {
?? ?private static final long serialVersionUID = 1L;
? ? ? ?
? ? /**
? ? ?* @see HttpServlet#HttpServlet()
? ? ?*/
? ? public AuthorServlet() {
? ? ? ? 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
?? ??? ?//设置编码方式
?? ??? ? request.setCharacterEncoding("utf-8");
?? ??? ??
?? ??? ? //查询用户列表
?? ??? ? AuthorDao ad = new AuthorDao();
?? ??? ? //将Dao层中的结果放入list中
?? ??? ? List<Author> list = ad.queryAuthorList();
?? ??? ? request.setAttribute("authorList", list);
?? ??? ??
?? ??? ? //请求转发的方式将查询结果放入request中，再将超链接直接访问AuthorServlet就将信息显示出来了 。
?? ??? ? request.getRequestDispatcher("uselist.jsp").forward(request, response);
?? ??? ??
?? ??? ??
?? ?}

?? ?/**
?? ? * @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);
?? ?}

}

（7）定义一个AuthorDao类实现查询数据库和检验登录的用户名和密码 。

//用于检验登录页面所填入信息是否正确
package com.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 com.entity.Author;

public class AuthorDao {
?? ?
?? ?public Author check(String username ,int password)
?? ?{
?? ??? ?Author obj = null ;
?? ??? ?try {
?? ??? ??? ??? ?DBConnection db = new DBConnection();
?? ??? ??? ??? ?//获取数据库连接
?? ??? ??? ??? ?Connection conn = db.getConn();
?? ??? ??? ??? ?//设置要执行的数据库语句
?? ??? ??? ??? ?String sql = "select *from furnitures where name = ? and id = ?";
?? ??? ??? ??? ?
?? ??? ??? ??? ?PreparedStatement ps = ?conn.prepareStatement(sql);
?? ??? ??? ??? ?//设置用户名和密码放入sql语句
?? ??? ??? ??? ?ps.setString(1, username);
?? ??? ??? ??? ?ps.setInt(2, password);
?? ??? ??? ??? ?
?? ??? ??? ??? ?//执行sql查询语句 , 并将执行结果放入结果集中
?? ??? ??? ? ? ?ResultSet rs = ps.executeQuery();
?? ??? ??? ??? ?
?? ??? ??? ? ? ?//用户名和密码都正确
?? ??? ??? ? ? ?if(rs.next()) {
?? ??? ??? ? ? ??? ?
?? ??? ??? ? ? ??? ?//新创建一个obj 将查询结果放入
?? ??? ??? ? ? ??? ?obj = new Author();
?? ??? ??? ? ? ??? ?obj.setId(rs.getInt(1));
?? ??? ??? ? ? ??? ?obj.setName(rs.getString(2));
?? ??? ??? ? ? ??? ?obj.setPrice(rs.getInt(3));
?? ??? ??? ? ? ??? ?obj.setNum(rs.getInt(4));
?? ??? ??? ? ? ??? ?obj.setDates(rs.getString(5));
?? ??? ??? ? ? ??? ?obj.setStyle(rs.getString(6));
?? ??? ??? ? ? ?}
?? ? ??
?? ??? ?} catch (SQLException e) {
?? ??? ??? ?// TODO Auto-generated catch block
?? ??? ??? ?e.printStackTrace();
?? ??? ?}
?? ??? ?
?? ??? ?return obj;
? }
?? ?
?? ?public List<Author> queryAuthorList(){
?? ??? ?
?? ??? ?
?? ??? ?Author obj = null;
?? ??? ?//定义一个list集合，用于存放查询结果
?? ??? ?List<Author> list = new ArrayList<Author>() ;
?? ??? ?try {
?? ??? ??? ?
?? ??? ??? ?
?? ??? ??? ?DBConnection db = new DBConnection();
?? ??? ??? ?//获取数据库连接
?? ??? ??? ?Connection conn = db.getConn();
?? ??? ??? ?//设置数据库要查询的语句
?? ??? ??? ?String sql = "select *from furnitures ";
?? ??? ??? ?
?? ??? ??? ?PreparedStatement ps = conn.prepareStatement(sql);
?? ??? ??? ?
?? ??? ??? ?//执行数据库查询语句,并将查询结果放入结果集
?? ??? ??? ?ResultSet rs = ps.executeQuery();
?? ??? ??? ?
?? ??? ??? ?//利用循环将obj放入list集合中
?? ??? ??? ?while(rs.next()) {
?? ??? ??? ??? ?obj = new Author();
?? ??? ??? ??? ?
?? ??? ??? ??? ?obj.setId(rs.getInt(1));
?? ??? ??? ??? ?obj.setName(rs.getNString(2));
?? ??? ??? ??? ?obj.setPrice(rs.getInt(3));
?? ??? ??? ??? ?obj.setNum(rs.getInt(4));
?? ??? ??? ??? ?obj.setDates(rs.getString(5));
?? ??? ??? ??? ?obj.setStyle(rs.getString(6));
?? ??? ??? ??? ?
?? ??? ??? ??? ?//将obj加入到list
?? ??? ??? ??? ?
?? ??? ??? ??? ?list.add(obj);
?? ??? ??? ??? ?
?? ??? ??? ?}
?? ??? ??? ?
?? ??? ??? ?
?? ??? ?} catch (SQLException e) {
?? ??? ??? ?// TODO Auto-generated catch block
?? ??? ??? ?e.printStackTrace();
?? ??? ?}
?? ??? ?
?? ??? ?
?? ??? ?return list;
?? ?}
?? ?
}

（8）定义一个验证码生成CodeServlet类，用于生成验证码 。

package com.servlet;

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

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

@WebServlet("/CodeServlet")
public class CodeServlet extends HttpServlet{
?? ?
?? ?//定义验证码的源码
?? ?private static final String str ="abcdefghijklmnopqrstuvwxyaABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
?? ?
?? ?//定义随机数
?? ?private Random random = new Random();
?? ?
?? ?//随机生成四个字符
?? ?public String getStr()
?? ?{
?? ??? ?String s = "";
?? ??? ?int len = str.length();
?? ??? ?for(int i=0;i<4;i++) {
?? ??? ??? ?s+=str.charAt(random.nextInt(len));
?? ??? ?}
?? ??? ?return s;
?? ?}
?? ?
?? ?//随机颜色
?? ?public Color getColor() {
?? ??? ?
?? ??? ?int red = random.nextInt(256);
?? ??? ?int green = random.nextInt(256);
?? ??? ?int blue = random.nextInt(256);
?? ??? ?Color color = new Color(red,green,blue);
?? ??? ?
?? ??? ?return color;
?? ?}
?? ?@Override
?? ?protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
?? ??? ?// TODO Auto-generated method stub
?? ??? ?
?? ??? ?
?? ??? ?//生成验证码图片
?? ??? ?//画板
?? ??? ?BufferedImage image = new BufferedImage(70,20,BufferedImage.TYPE_INT_RGB );
?? ??? ?//画笔
?? ??? ?Graphics pen = ?image.getGraphics();
?? ??? ?//矩形
?? ??? ?pen.fillRect(0, 0, 70, 20);
?? ??? ?//字体
?? ??? ?pen.setFont(new Font("微软雅黑",Font.BOLD,20));
?? ??? ?
?? ??? ?//获取4个字符
?? ??? ?String code = getStr();
?? ??? ?
?? ??? ?//绘制图片
?? ??? ?for(int i=0;i<code.length();i++) {
?? ??? ??? ?pen.setColor(getColor());
?? ??? ??? ?pen.drawString(String.valueOf(code.charAt(i)), i*15+5, 20);;
?? ??? ?}
?? ??? ?
?? ??? ?//response对象绘制图片到页面,Servle输出流进行图片的输出
?? ??? ?ServletOutputStream sos = resp.getOutputStream();
?? ??? ?ImageIO.write(image, "png", sos);
?? ??? ?
?? ??? ?sos.flush();
?? ??? ?sos.close();
?? ??? ?
?? ??? ?//验证码放入session
?? ??? ?HttpSession session = req.getSession();
?? ??? ?session.setAttribute("sCode", code);
?? ??? ?
?? ?}

?? ?@Override
?? ?protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
?? ??? ?// TODO Auto-generated method stub
?? ??? ?doPost(req, resp);
?? ?}
}

（9）创建DBConnectoin.java类用户获取数据库连接 。（我用的是mysql）

//获取数据库连接
package com.dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBConnection {
?? ?private static String username="填入自己的数据库名";
?? ?private static String password="填入自己的数据库密码";
?? ?private static String driver = "com.mysql.jdbc.Driver";
?? ?private static String url="jdbc:mysql://localhost:3306/已经创建数据库名";
?? ?
?? ?private Connection conn;
?? ?
?? ?static {
?? ??? ?try {
?? ??? ??? ?//加载驱动，捕获异常
?? ??? ??? ?Class.forName(driver);
?? ??? ?} catch (ClassNotFoundException e) {
?? ??? ??? ?// TODO Auto-generated catch block
?? ??? ??? ?e.printStackTrace();
?? ??? ?}
?? ?}
?? ?
?? ?public DBConnection () throws SQLException {
?? ??? ?//连接数据库
?? ??? ?conn = DriverManager.getConnection(url,username,password);
?? ?}
?? ?
?? ?//用于获取conn
?? ?public Connection getConn() {
?? ??? ?return conn;
?? ?}

?? ?public void setConn(Connection conn) {
?? ??? ?this.conn = conn;
?? ?}?
?? ?

}

三、页面

（1）登录页面

（2）数据查询页面

（3）查询结果显示页面

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持 。