輸出隨機圖片(CAPTCHA圖像):Completely Automated Public Turing Test to Tell Computers and Humans Apart (全自動區分計算機和人類的測試)
相關主要類(JDK 查看API)
BufferedImage:內存圖像
Graphics：畫筆
ImageIO：輸出圖像
放在html頁面上<img src/>
注意：瀏覽器默認會緩存圖片
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public static int WIDTH = 120; public static int HEIGHT = 25; public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); //創建內存圖像 BufferedImage image = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB); //勾勒圖像 Graphics graphics = image.getGraphics(); //設置背景 graphics.setColor(Color.WHITE); graphics.fillRect(0, 0, WIDTH, HEIGHT); //設置邊框 graphics.setColor(Color.BLUE); graphics.drawRect(1, 1, WIDTH-2, HEIGHT-2); //畫干擾線 graphics.setColor(Color.YELLOW); for(int i=0;i<8;i++){ int xStart = new Random().nextInt(WIDTH); int yStart = new Random().nextInt(HEIGHT); int xEnd = new Random().nextInt(WIDTH); int yEnd = new Random().nextInt(HEIGHT); graphics.drawLine(xStart, yStart, xEnd, yEnd); } //寫隨機數 graphics.setColor(Color.RED); int x = 5; for(int i=0;i<4;i++){ graphics.drawString(new Random().nextInt(9)+"", x, 20); x+=30; } response.setContentType("image/jpeg");//設置響應格式 ImageIO.write(image, "jpeg", response.getOutputStream()); } |
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原文鏈接：http://blog.csdn.net/alex_zhuang/article/details/7249850
