JSP中文验证码

<%@ page  pageEncoding = "gb2312" contentType="image/jpeg" import = "javax.imageio.*,java.util.*,java.awt.image.*,java.awt.*" %><%!    //在此处 获取并生成随机颜色    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);    } %><%    //在此处 设置JSP页面无缓存    response.setHeader( "Pragma" , "No-cache" );    response.setHeader( "Cache-Control" , "no-cache" );    response.setDateHeader( "Expires" , 0);    // 设置图片的长宽    int width = 130;    int height = 30;    //设定被随机选取的中文字，此处中文字内容过多，不一一列出，只是举例说明下。     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" ;    //设置 备选随机汉字的个数    int length = base.length();    //创建缓存图像    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);    //获取图像对象    Graphics g = image.getGraphics();    //创建随机函数    Random random = new Random();    //设定图像背景色    g.setColor(getRandColor(random, 188, 235));    g.fillRect(0, 0, width, height);    //设置随机备选的字体类型    String[] fontTypes = { "\u5b8b\u4f53" , "\u65b0\u5b8b\u4f53" ,           "\u9ed1\u4f53" , "\u6977\u4f53" , "\u96b6\u4e66" };    int fontTypesLength = fontTypes.length;    // 在图片背景上增加噪点，增加图片分析难度    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));    }    // 取随机产生的验证码 (4 个汉字 )    // 保存生成的汉字字符串    String sRand = "" ;    for ( int i = 0; i < 4; i++) {       int start = random.nextInt(length);       String rand = base.substring(start, start + 1);       sRand += rand;       // 设置图片上字体的颜色       g.setColor(getRandColor(random, 10, 150));       // 设置字体格式       g.setFont( new Font(fontTypes[random.nextInt(fontTypesLength)],       Font.BOLD, 18 + random.nextInt(6)));       // 将此汉字画到验证图片上面       g.drawString(rand, 24 * i + 10 + random.nextInt(8), 24);    }    // 将验证码存入S ession中    session.setAttribute( "rand" , sRand);    g.dispose();    //将 图象输出到JSP页面中    ImageIO.write(image, "JPEG" , response.getOutputStream());    //关闭流    out.clear();    out=pageContext.pushBody();  %>