jsp图片验证码
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发布时间：2022-04-27 03:35
共3个回答
懂视网
时间：2022-05-15 14:39
项目结构如下，MyEclipse中新建一个Web Project，取名servlet
1、src下new一个servlet类
package com.servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
public class IdentityServlet extends HttpServlet {
public static final char[] chars={'2','3','4','5','6','7','8','9','A'};//自定义验证码池
public static Random random=new Random(); //随机数
public static String getRandomString(){ //获取6位随机数，放在图片里
StringBuffer buffer=new StringBuffer();
for(int i=0;i<6;i++){
buffer.append(chars[random.nextInt(chars.length)]);
}
return buffer.toString();
}
public static Color getRandomColor(){ //获取随机的颜色
return new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255));
}
public static Color getReverseColor(Color c){ //返回某颜色的反色
return new Color(255 - c.getRed(), 255 - c.getGreen(), 255 - c.getBlue());
}
/**
* Constructor of the object.
*/
public IdentityServlet() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("image/jpeg"); //设置输出类型
String randomString = getRandomString(); //随机字符串
request.getSession(true).setAttribute("randomString", randomString);//放到session里
int width=100; //图片宽度
int height=30; //图片高度
Color color=getRandomColor(); //随机颜色，用于背景色
Color reverse=getReverseColor(color);//反色，用于前景色
//创建一个彩色图片
BufferedImage bi=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics2D g=bi.createGraphics(); //绘图对象
g.setFont(new Font(Font.SANS_SERIF,Font.BOLD,16));//设置字体
g.setColor(color);//设置颜色
g.fillRect(0, 0, width, height);//绘制背景
g.setColor(reverse);
g.drawString(randomString, 18, 20);//绘制随机字符
for(int i=0,n=random.nextInt(100);i<n;i++){ //画最多100个噪音点
g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);
}
ServletOutputStream out= response.getOutputStream();//转成JPEG格式
JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(out);//编码器
encoder.encode(bi); //对图片进行编码
out.flush(); //输出到客户端
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}2、web.xml，会自动生成servlet和servlet-mapping的配置：
<?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name></display-name> <servlet> <servlet-name>IdentityServlet</servlet-name> <servlet-class>com.servlet.IdentityServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>IdentityServlet</servlet-name> <url-pattern>/servlet/IdentityServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
3、WebRoot下新建一个html，展示验证码
<!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>
<script type="text/javascript">
function reloadImage(){
document.getElementById('btn').disabled=true;
document.getElementById('identity').src='servlet/IdentityServlet?ts='+new Date().getTime();
}
</script>
</head>
<body>
<img src="servlet/IdentityServlet" id="identity" onload="btn.disabled=false;" />
<input type=button value="换个图片" onclick="reloadImage()" id="btn">
</body>
</html>启动Tomcat，输入网址：http://localhost:8080/servlet/identity.html，效果如下：
点击‘换个图片'，会生成新的验证码。
热心网友
时间：2022-05-15 11:47
<%!
Color getRandColor(int fc,int bc){//给定范围获得随机颜色
Random random = new Random();
if(fc>255) fc=255;
if(bc>255) bc=255;
int r=fc+random.nextInt(bc-fc);
int g=fc+random.nextInt(bc-fc);
int b=fc+random.nextInt(bc-fc);
return new Color(r,g,b);
}
%>
<%
//设置页面不缓存
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
// 在内存中创建图象
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
//生成随机类
Random random = new Random();
// 设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
//设定字体
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
//画边框
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);
// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160,200));
for (int i=0;i<155;i++)
{
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x,y,x+xl,y+yl);
}
// 取随机产生的认证码(4位数字)
String sRand="";
for (int i=0;i<4;i++){
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
// 将认证码显示到图象中
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
g.drawString(rand,13*i+6,16);
}
// 将认证码存入SESSION
session.setAttribute("rand",sRand);
// 图象生效
g.dispose();
// 输出图象到页面
ImageIO.write(image, "JPEG", response.getOutputStream());
%>
保存成image.jsp,调用的时候用<img src="image.jsp" width="60" height="20">就可以了
热心网友
时间：2022-05-15 13:05
<%@ page contentType="image/jpeg" import="java.awt.*,
java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
Color getRandColor(int fc,int bc)
{
Random random = new Random();
if(fc>255) fc=255;
if(bc>255) bc=255;
int r=fc+random.nextInt(bc-fc);
int g=fc+random.nextInt(bc-fc);
int b=fc+random.nextInt(bc-fc);
return new Color(r,g,b);
}
%>
<%
out.clear();//这句针对resin服务器，如果是tomacat可以不要这句
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
g.setColor(getRandColor(160,200));
for (int i=0;i<155;i++)
{
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x,y,x+xl,y+yl);
}
String sRand="";
for (int i=0;i<4;i++){
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
g.drawString(rand,13*i+6,16);
}
// 将认证码存入SESSION
session.setAttribute("rand",sRand);
g.dispose();
ImageIO.write(image, "JPEG", response.getOutputStream());
%>
