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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。
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JSP
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