应用jsp生成彩色汉字验证码

<% ... @?page?language = " java " ?import = " java.util.* " ?pageEncoding = " utf-8 " %>
<% ... @?page?contentType = " image/jpeg "
????import = " java.awt.*,java.awt.image.*,java.util.*,javax.imageio.* " %>
?
<! DOCTYPE?HTML?PUBLIC?"-//W3C//DTD?HTML?4.01?Transitional//EN" >
< html >
???? < head >
?????????

???????? < title > My?JSP?'index.jsp'?starting?page </ title >
???????? < meta? http-equiv ="pragma" ?content ="no-cache" >
???????? < meta? http-equiv ="cache-control" ?content ="no-cache" >
???????? < meta? http-equiv ="expires" ?content ="0" >
???????? < meta? http-equiv ="keywords" ?content ="keyword1,keyword2,keyword3" >
???????? < meta? http-equiv ="description" ?content ="This?is?my?page" >
?
???? </ head >

???? < body >
???????? <% ... ! // 生成随机颜色?
????Color?getRandColor(Random?random,? int ?fc,? int ?bc)?{
???????? 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);
????} %>
???????? <% ...
???????????? // 设置页面不缓存?
????????????response.setHeader( " Pragma " ,? " No-cache " );
????????????response.setHeader( " Cache-Control " ,? " no-cache " );
????????????response.setDateHeader( " Expires " ,? 0 );

???????????? // ?设置图片的长宽?
???????????? int ?width? = ? 176 ,?height? = ? 30 ;
???????????? // 设置备选汉字，剔除一些不雅的汉字?
???????????? String ?base? = ? " 的 一了是我不在人们有来他这上着个地到大里说就去子得也和那要下看天时过出小么起你都把好还多没为又可家学只以主会样年想生同老中十从自面前头道它后然走很 像见两用她国动进成回什边作对开而己些现山民候经发工向事命给长水几义三声于高手知理眼志点心战二问但身方实吃做叫当住听革打呢真全才四已所敌之最光产情 路分总条白话东席次亲如被花口放儿常气五第使写军吧文运再果怎定许快明行因别飞外树物活部门无往船望新带队先力完却站代员机更九您每风级跟笑啊孩万少直意 夜比阶连车重便斗马哪化太指变社似士者干石满日决百原拿群究各六本思解立河村八难早论吗根共让相研今其书坐接应关信觉步反处记将千找争领或师结块跑谁草越 字加脚紧爱等习阵怕月青半火法题建赶位唱海七女任件感准张团屋离色脸片科倒睛利世刚且由送切星导晚表够整认响雪流未场该并底深刻平伟忙提确近亮轻讲农古黑 告界拉名呀土清阳照办史改历转画造嘴此治北必服雨穿内识验传业菜爬睡兴形量咱观苦体众通冲合破友度术饭公旁房极南枪读沙岁线野坚空收算至政城劳落钱特围弟 胜教热展包歌类渐强数乡呼性音答哥际旧神座章帮啦受系令跳非何牛取入岸敢掉忽种装顶急林停息句区衣般报叶压慢叔背细 " ;
???????????? // 备选汉字的长度?
???????????? int ?length? = ?base.length();

???????????? // 创建内存图像?
????????????BufferedImage?image? = ? new ?BufferedImage(width,?height,
????????????????????BufferedImage.TYPE_INT_RGB);
???????????? // ?获取图形上下文?
????????????Graphics?g? = ?image.getGraphics();

???????????? // 创建随机类的实例?
????????????Random?random? = ? new ?Random();

???????????? // ?设定图像背景色(因为是做背景，所以偏淡)?
????????????g.setColor(getRandColor(random,? 200 ,? 250 ));
????????????g.fillRect( 0 ,? 0 ,?width,?height);

???????????? // 备选字体?
???????????? String []?fontTypes? = ?{? " 宋体 " ,? " 新宋体 " ,
???????????????????? " 黑体 " ,? " 楷体 " ,? " 隶书 " ?};
???????????? int ?fontTypesLength? = ?fontTypes.length;

???????????? // 在图片背景上增加噪点?
????????????g.setColor(getRandColor(random,? 160 ,? 200 ));
????????????g.setFont( new ?Font( " Times?New?Roman " ,?Font.PLAIN,? 14 ));
???????????? for ?( int ?i? = ? 0 ;?i? < ? 6 ;?i ++ )?{
????????????????g.drawString( " ********************************************* " ,
???????????????????????? 0 ,? 5 ? * ?(i? + ? 2 ));
????????????}

???????????? // 取随机产生的认证码(6个汉字)?

???????????? // 保存生成的汉字字符串?
???????????? String ?sRand? = ? "" ;
???????????? for ?( int ?i? = ? 0 ;?i? < ? 6 ;?i ++ )?{
???????????????? int ?start? = ?random.nextInt(length);
???????????????? String ?rand? = ?base.substring(start,?start? + ? 1 );
????????????????sRand? += ?rand;

???????????????? // 设置字体的颜色?
????????????????g.setColor(getRandColor(random,? 10 ,? 150 ));
???????????????? // 设置字体?
????????????????g.setFont( new ?Font(fontTypes[random.nextInt(fontTypesLength)],
????????????????????????Font.BOLD,? 18 ? + ?random.nextInt( 6 )));
???????????????? // 将此汉字画到图片上?
????????????????g.drawString(rand,? 24 ? * ?i? + ? 10 ? + ?random.nextInt( 8 ),? 24 );
????????????}

???????????? // 将认证码存入session?
????????????session.setAttribute( " rand " ,?sRand);

????????????g.dispose();

???????????? // 输出图象到页面?
????????????ImageIO.write(image,? " JPEG " ,?response.getOutputStream());
????????????out.clear();
????????????out = pageContext.pushBody();
????????????
???????? %>

???? </ body >
</ html >