
===================================================
package com.stone.study.validate; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.ByteArrayOutputStream; import java.io.IOException; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class ImgValidateServlet2 extends HttpServlet { private static int WIDTH = 90; private static int HEIGHT = 20; private static int LENGTH = 6; @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { HttpSession session = request.getSession(); response.setContentType("image/jpeg"); ServletOutputStream sos = response.getOutputStream(); //設置瀏覽器不要緩存此圖片 response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0); //創建內存圖象并獲得其圖形上下文 BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); //產生隨機的認證碼 char [] rands = generateCheckCode(); //產生圖像 drawBackground(g); drawRands(g,rands); //結束圖像的繪制過程,完成圖像 g.dispose(); //將圖像輸出到客戶端 ByteArrayOutputStream bos = new ByteArrayOutputStream(); ImageIO.write(image, "JPEG", bos); byte [] buf = bos.toByteArray(); response.setContentLength(buf.length); //下面的語句也可寫成:bos.writeTo(sos); sos.write(buf); bos.close(); sos.close(); //將當前驗證碼存入到Session或者數據庫中,下一個表單處理中驗證客戶端提交的驗證碼是否正確 session.setAttribute("check_code",new String(rands)); } private static char [] generateCheckCode() { //定義驗證碼的字符表 String chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; char [] rands = new char[LENGTH]; for(int i=0; i<LENGTH; i++) { int rand = (int)(Math.random() * 36); rands[i] = chars.charAt(rand); } return rands; } private void drawRands(Graphics g , char [] rands) { g.setColor(Color.BLACK); g.setFont(new Font(null,Font.ITALIC|Font.BOLD,18)); //在不同的高度上輸出驗證碼的每個字符 g.drawString("" + rands[0],1,17); g.drawString("" + rands[1],16,15); g.drawString("" + rands[2],31,18); g.drawString("" + rands[3],46,16); g.drawString("" + rands[4],61,14); g.drawString("" + rands[5],76,19); System.out.println(rands); } private void drawBackground(Graphics g) { //畫背景 g.setColor(new Color(0xDCDCDC)); g.fillRect(0, 0, WIDTH, HEIGHT); //隨機產生120個干擾點 for(int i=0; i<120; i++) { int x = (int)(Math.random() * WIDTH); int y = (int)(Math.random() * HEIGHT); int red = (int)(Math.random() * 255); int green = (int)(Math.random() * 255); int blue = (int)(Math.random() * 255); g.setColor(new Color(red,green,blue)); g.drawOval(x,y,1,0); } //加兩條干擾線 g.drawLine(0, 5, 90, 5); g.drawLine(0, 15, 90, 15); } public static void main(String args[]) { char[] chars = generateCheckCode(); System.out.println(chars); } }
代碼出處:《深入體驗Java Web開發內幕——核心基礎》
更多文章、技術交流、商務合作、聯系博主
微信掃碼或搜索:z360901061

微信掃一掃加我為好友
QQ號聯系: 360901061
您的支持是博主寫作最大的動力,如果您喜歡我的文章,感覺我的文章對您有幫助,請用微信掃描下面二維碼支持博主2元、5元、10元、20元等您想捐的金額吧,狠狠點擊下面給點支持吧,站長非常感激您!手機微信長按不能支付解決辦法:請將微信支付二維碼保存到相冊,切換到微信,然后點擊微信右上角掃一掃功能,選擇支付二維碼完成支付。
【本文對您有幫助就好】元
