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"/>${error_code}<br/>
<input type="submit" value="提交">
</form>
</body>
</html>（2）登录后的页面：user.jsp文件。
<%@ page language="java" contenttype="text/html; charset=utf-8"
pageencoding="utf-8"%>
<%@ page import = "com.entity.author"%>
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>显示登录用户的用户名和密码页面</title>
</head>
<body>
<%
//内置对象
request.setcharacterencoding("utf-8");
//获取交互层放入session中的obj
author obj = (author)session.getattribute("authorinfo");
if(obj != null){
out.print("<p>用户名："+obj.getname()+"</p>");
out.print("<p>密码："+obj.getid()+"</p>");
}
else{
response.sendredirect("index.jsp");
}
%>
<br/>
<a href="authorservlet">用户信息查询 </a>
</body>
</html>（3）实现数据查询页面：ueslist.jsp文件。
<%@ page language="java" contenttype="text/html; charset=utf-8"
pageencoding="utf-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>查询信息显示页面</title>
</head>
<body>
<table border="1">
<tr>
<td>编号</td>
<td>名称</td>
<td>价格</td>
<td>数量</td>
<td>日期</td>
<td>风格</td>
</tr>
<c:foreach items="${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硕编程。
JSP实战