Java随机验证吗

<span style="font-size:18px;">package com.java.process.jsp;import java.awt.Color;import java.awt.Font;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.Servlet;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;</span>

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<span style="font-size:18px;"></span><pre name="code" class="java">

<span style="font-size:18px;">//servlet3.0之前必须是在web.xml中配置</span>

<span style="font-size:18px;"></span><pre name="code" class="html"> <servlet>    <servlet-name>validateColorServlet</servlet-name>    <servlet-class>com.atguigu.javaweb.ValidateColorServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>validateColorServlet</servlet-name>    <url-pattern>/validateColorServlet</url-pattern>  </servlet-mapping>

<span style="font-size: 18px;">//servlet3.0以后就是可以直接用@WebServlet,</span>

<span style="font-size:18px;">@WebServlet("/validateColorServlet")public class ValidateColorServlet extends HttpServlet {public static final String CHECK_CODE_KEY = "CHECK_CODE_KEY";private static final long serialVersionUID = 1L;//设置验证图片的宽度, 高度, 验证码的个数private int width = 152;private int height = 40;private int codeCount = 6;//验证码字体的高度private int fontHeight = 4;//验证码中的单个字符基线. 即：验证码中的单个字符位于验证码图形左上角的 (codeX, codeY) 位置处private int codeX = 0;private int codeY = 0;//验证码由哪些字符组成char [] codeSequence = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz23456789".toCharArray();//初始化验证码图形属性public void init(){fontHeight = height - 2;codeX = width / (codeCount + 2);codeY = height - 4;}public void service(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//定义一个类型为 BufferedImage.TYPE_INT_BGR 类型的图像缓存BufferedImage buffImg = null;buffImg = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);//在 buffImg 中创建一个 Graphics2D 图像Graphics2D graphics = null;graphics = buffImg.createGraphics();//设置一个颜色, 使 Graphics2D 对象的后续图形使用这个颜色graphics.setColor(Color.WHITE);//填充一个指定的矩形: x - 要填充矩形的 x 坐标; y - 要填充矩形的 y 坐标; width - 要填充矩形的宽度; height - 要填充矩形的高度graphics.fillRect(0, 0, width, height);//创建一个 Font 对象: name - 字体名称; style - Font 的样式常量; size - Font 的点大小Font font = null;font = new Font("", Font.BOLD, fontHeight);//使 Graphics2D 对象的后续图形使用此字体graphics.setFont(font);graphics.setColor(Color.BLACK);//绘制指定矩形的边框, 绘制出的矩形将比构件宽一个也高一个像素graphics.drawRect(0, 0, width - 1, height - 1);//随机产生 15 条干扰线, 使图像中的认证码不易被其它程序探测到Random random = null;random = new Random();graphics.setColor(Color.GREEN);for(int i = 0; i < 55; i++){int x = random.nextInt(width);int y = random.nextInt(height);int x1 = random.nextInt(20);int y1 = random.nextInt(20);graphics.drawLine(x, y, x + x1, y + y1);}//创建 randomCode 对象, 用于保存随机产生的验证码, 以便用户登录后进行验证StringBuffer randomCode;randomCode = new StringBuffer();for(int i = 0; i < codeCount; i++){//得到随机产生的验证码数字String strRand = null;strRand = String.valueOf(codeSequence[random.nextInt(36)]);//把正在产生的随机字符放入到 StringBuffer 中randomCode.append(strRand);//用随机产生的颜色将验证码绘制到图像中graphics.setColor(Color.BLUE);graphics.drawString(strRand, (i + 1)* codeX, codeY);}//再把存放有所有随机字符的 StringBuffer 对应的字符串放入到 HttpSession 中request.getSession().setAttribute(CHECK_CODE_KEY, randomCode.toString());//禁止图像缓存response.setHeader("Pragma", "no-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expires", 0);//将图像输出到输出流中ServletOutputStream sos = null;sos = response.getOutputStream();ImageIO.write(buffImg, "jpeg", sos); sos.close();}}</span>