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Devmax。