圖片驗證碼jsp

前段時間項目中用的圖片驗證碼。有很多開源的圖片校正，用jquery寫的。但後來都沒採納，採納了一個最簡單的，拿出來和大家分享下

<%@ page language="java" contentType="image/jpeg" pageEncoding="utf-8"%><%@ page contentType="image/jpeg"import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"%><%@ page import="java.io.OutputStream"%><%!Color getRandColor(int fc, int bc)    {        //給定範圍獲得隨機顏色         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);    }%><%    try    {        //設定頁面不緩衝         response.setHeader("Pragma", "No-cache");        response.setHeader("Cache-Control", "no-cache");        response.setDateHeader("Expires", 0);        // 在記憶體中建立圖象         int width = 60, height = 20;        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);        OutputStream os = response.getOutputStream();        // 擷取圖形上下文         Graphics g = image.getGraphics();        //產生隨機類         Random random = new Random();        // 設定背景色         g.setColor(getRandColor(200, 250));        g.fillRect(0, 0, width, height);        //設定字型         g.setFont(new Font("Times New Roman", Font.PLAIN, 18));        //畫邊框         //g.setColor(new Color());         //g.drawRect(0,0,width-1,height-1);         // 隨機產生155條幹擾線，使圖象中的認證碼不易被其它程式探測到         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);        }        // 取隨機產生的認證碼(4位元字)         String sRand = "";        for (int i = 0; i < 4; i++ )        {            //String rand=String.valueOf(random.nextInt(10));  //數字             //String rand=String.valueOf((char)(Math.round(Math.random() * 25 + 65))); //字母大寫 http://www.itstudy.cn/             String rand = String.valueOf((char) (Math.round(Math.random() * 25 + 97))); //字母小寫             sRand += rand;            // 將認證碼顯示到圖象中             g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110),                20 + random.nextInt(110)));            //調用函數出來的顏色相同，可能是因為種子太接近，所以只能直接產生             g.drawString(rand, 13 * i + 6, 16);        }        // 將認證碼存入SESSION         session.setAttribute("rand", sRand);        // 圖象生效         g.dispose();        // 輸出圖象到頁面         ImageIO.write(image, "JPEG", os);        os.flush();        os.close();        os = null;        response.flushBuffer();        out.clear();        out = pageContext.pushBody();    }    catch (IllegalStateException e)    {        System.out.println(e.getMessage());        e.printStackTrace();    }%>