Servlet（七）生成验证码

时间：2023-03-17 20:10:32

1、ImageCode.java

package com.hunhun.utils;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.io.OutputStream;

import java.util.Random;

import javax.imageio.ImageIO;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

 * Servlet implementation class ImageCode

 */

@WebServlet("/ImageCode")

public class ImageCode extends HttpServlet {

	private static final long serialVersionUID = 1L;

    /**

     * @see HttpServlet#HttpServlet()

     */

    public ImageCode() {

        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

		//禁止浏览器缓存随机图片

		response.setDateHeader("Expires", -1);

		response.setHeader("Cache-Control", "no-cache");

		response.setHeader("Pragma", "no-cache");

		//通知浏览器以图片方式显示数据

		response.setHeader("Content-Type", "image/png");

		//在内存中创建图片

		BufferedImage image = new BufferedImage(75,20,BufferedImage.TYPE_INT_RGB);

		//获取图片上下文

		Graphics g = image.getGraphics();

		//设置背景色

		  g.setColor(Color.black);

		  g.fillRect(0, 0, 75, 20);

		  //生成随机类

		  Random r = new Random();

		  //生成4位验证码

		  String srcChars ="abcdefghijklmnopqrstuvwxyz1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ";

		  String number = "";

		  for(int i=0;i<4;i++){

		   number +=srcChars.charAt(r.nextInt(srcChars.length()));

		  }

		  //设置字体、颜色

		  g.setFont(new Font("Arial",Font.BOLD|Font.ITALIC,16));//new Font(name, style, size)

		  g.setColor(new Color(r.nextInt(255),r.nextInt(255),r.nextInt(255)));

		// 随机产生15条干扰线。使图象中的认证码不易被其他程序探測到

	        for (int i = 0; i < 15; i++) {

	            int x = r.nextInt(75);

	            int y = r.nextInt(20);

	            int xl = r.nextInt(12);

	            int yl = r.nextInt(12);

	            g.drawLine(x, y, x + xl, y + yl);

	        }

	        g.setColor(new Color(r.nextInt(255),r.nextInt(255),r.nextInt(255)));

		  g.drawString(number,10,15);

		  //保存session

		  request.getSession().setAttribute("code",number);

		  OutputStream os = response.getOutputStream();

		  ImageIO.write(image, "png", os);

		//  JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(os);

		//  encoder.encode(image);

	}

	/**

	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

	 */

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		// TODO Auto-generated method stub

		this.doGet(request, response);

	}

}

2.login.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"

    pageEncoding="utf-8"%>

<!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>

</head>

<body>

<form action="/LittleMall/LoginCServlet" method="post">

<input type="text" name="code" value=""><img alt="code" src="/LittleMall/ImageCode"><br/>

<input type="submit" value="登录">

</form>

</body>

</html>

图片样式：

Servlet（七）生成验证码

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