JSP中文驗證碼

<%@ page  pageEncoding = "gb2312" contentType="image/jpeg" import = "javax.imageio.*,java.util.*,java.awt.image.*,java.awt.*" %><%!    //在此處 擷取並產生隨機顏色    Color getRandColor(Random random, int ff, int cc) {       if (ff > 255)           ff = 255;       if (cc > 255)           cc = 255;       int r = ff + random.nextInt(cc - ff);       int g = ff + random.nextInt(cc - ff);       int b = ff + random.nextInt(cc - ff);       return new Color(r, g, b);    } %><%    //在此處 設定JSP頁面無緩衝    response.setHeader( "Pragma" , "No-cache" );    response.setHeader( "Cache-Control" , "no-cache" );    response.setDateHeader( "Expires" , 0);    // 設定圖片的長寬    int width = 130;    int height = 30;    //設定被隨機選取的中文字，此處中文字內容過多，不一一列出，只是舉例說明下。     String base = "\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u538b\u6162\u53d4\u80cc\u7ec6" ;    //設定 備選隨機漢字的個數    int length = base.length();    //建立緩衝映像    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);    //擷取映像對象    Graphics g = image.getGraphics();    //建立隨機函數    Random random = new Random();    //設定映像背景色    g.setColor(getRandColor(random, 188, 235));    g.fillRect(0, 0, width, height);    //設定隨機備選的字型類型    String[] fontTypes = { "\u5b8b\u4f53" , "\u65b0\u5b8b\u4f53" ,           "\u9ed1\u4f53" , "\u6977\u4f53" , "\u96b6\u4e66" };    int fontTypesLength = fontTypes.length;    // 在圖片背景上增加噪點，增加圖片分析難度    g.setColor(getRandColor(random, 180, 199));    g.setFont( new Font( "Times New Roman" , Font.PLAIN, 14));    for ( int i = 0; i < 4; i++) {       g.drawString( "@*@*@*@*@*@*@*" ,       0, 5 * (i + 2));    }    // 取隨機產生的驗證碼 (4 個漢字 )    // 儲存產生的漢字字串    String sRand = "" ;    for ( int i = 0; i < 4; i++) {       int start = random.nextInt(length);       String rand = base.substring(start, start + 1);       sRand += rand;       // 設定圖片上字型的顏色       g.setColor(getRandColor(random, 10, 150));       // 設定字型格式       g.setFont( new Font(fontTypes[random.nextInt(fontTypesLength)],       Font.BOLD, 18 + random.nextInt(6)));       // 將此漢字畫到驗證圖片上面       g.drawString(rand, 24 * i + 10 + random.nextInt(8), 24);    }    // 將驗證碼存入S ession中    session.setAttribute( "rand" , sRand);    g.dispose();    //將 圖象輸出到JSP頁面中    ImageIO.write(image, "JPEG" , response.getOutputStream());    //關閉流    out.clear();    out=pageContext.pushBody();  %>