Teach you how to use JSP to generate a color Chinese character verification code

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Some sites use letters and numbers to verify the code, numbers and letters add up to a total of more than 30, if the heart, or can be identified through the method.

I saw an article on the Internet "JSP Color Verification Code", I have been strengthened, the generated verification code content for Chinese characters, can be easily applied to Chinese netizens Web site certification.

Of course, I also see several ways that others consider:

1. Generate calculation questions, such as 20+34* (23-12) =?, the user must enter the correct answer to pass verification, this idea is very good, but the user must open calculator to calculate, increase the user's difficulty

2. Ask some common questions, such as the word "person" made up of several pens. This is also a good idea, the key is to have tens of thousands of questions, and the answer must be clear, simple and easy to compare, this difficulty is also greater.

The following is the code for the color Kanji verification code.

<%@ page contenttype= "JPEG" import= "java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"%>
<%!
Generate Random Colors
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);
}
%>
<%
Set Page Not Cached
Response.setheader ("Pragma", "No-cache");
Response.setheader ("Cache-control", "No-cache");
Response.setdateheader ("Expires", 0);

//Set the long width of the picture


int width=176, height=30;


//Set alternative Chinese characters, remove some indecent Chinese characters


String base = "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\ U5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\ U51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\ U4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\ U7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\ U800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\ U4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\ U5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\ U5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\ U513f\u5e38\u6c14\u4e94\U7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\ U5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\ U4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\ U6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\ U77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\ U96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\ U6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\ U52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\ U6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\ u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\ u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\ u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\ U5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\ U5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\ U7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\ U7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\ U7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\ U606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6 ";


//Alternative length of Chinese characters


int length = Base.length ();

Creating Memory Images
BufferedImage image = new BufferedImage (width, height, bufferedimage.type_int_rgb);
Get Graphics context
Graphics g = image.getgraphics ();

Create an instance of a random class
Random Random = new Random ();

Set the background color of the image (because it is a background, so light)
G.setcolor (Getrandcolor (random,200,250));
G.fillrect (0, 0, width, height);

Alternative fonts
String] Fonttypes = {"\u5b8b\u4f53", "\u65b0\u5b8b\u4f53", "\u9ed1\u4f53", "\u6977\u4f53", "\u96b6\u4e66"};
int fonttypeslength = Fonttypes.length;

Add noise to picture background
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));
}

Take a randomly generated authentication code (6 characters)

Save the generated character string
String srand= "";
for (int i=0;i<6;i++)
{
int start = random.nextint (length);
String rand=base.substring (start,start+1);
Srand+=rand;

Set the color of a font
G.setcolor (Getrandcolor (random,10,150));
Set font
G.setfont (New Font (Fonttypes[random.nextint (fonttypeslength)],font.bold,18 + random.nextint (6));
Draw the Chinese character to the picture
g.DrawString (rand,24*i+ + random.nextint (8), 24);
}

Save authentication Code in session
Session.setattribute ("Rand", SRand);

G.dispose ();

Output image to Page
Imageio.write (Image, "JPEG", Response.getoutputstream ());
%>