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JSP randomly generated Verification Code

Source: Internet
Author: User
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Code:
  1. Code:
  2. 1. A. jsp
  4. <% @ Page contenttype = "text/html; charset = gb2312" %>
  5. <! Doctype HTML public "-// W3C // dtd html 4.01 transitional // en">
  6. <HTML>
  7. <Head>
  8. <Title> certificate code input page </title>
  9. <Meta http-equiv = "Content-Type" content = "text/html; charset = gb2312">
  10. <Meta HTTP-EQUIV = "Pragma" content = "no-Cache">
  11. <Meta HTTP-EQUIV = "cache-control" content = "no-Cache">
  12. <Meta HTTP-EQUIV = "expires" content = "0">
  13. </Head>
  14. <Body>
  15. <Form method = post action = "check. jsp">
  16. <Table>
  17. <Tr>
  18. <TD align = left> the verification code generated by the system: </TD>
  19. <TD> </TD>
  20. </Tr>
  21. <Tr>
  22. <TD align = left> enter the above verification code: </TD>
  23. <TD> <input type = text name = Rand maxlength = 4 value = ""> </TD>
  24. </Tr>
  25. <Tr>
  26. <TD colspan = 2 align = center> <input type = submit value = "Submit detection"> </TD>
  27. </Tr>
  28. </Form>
  29. </Body>
  30. </Html>
  33. 2. image. jsp
  36. <% @ Page contenttype = "image/JPEG; charset = gb18030" Import = "Java. AWT. *, Java. AWT. image. *, Java. util. *, javax. imageIO. * "%>
  37. <%!
  38. Color getrandcolor (int fc, int BC) {// obtain a random color from a given range
  39. Random random = new random ();
  40. If (FC> 255) fc = 255;
  41. If (BC> 255) BC = 255;
  42. Int r = FC + random. nextint (BC-Fc );
  43. Int G = FC + random. nextint (BC-Fc );
  44. Int B = FC + random. nextint (BC-Fc );
  45. Return new color (R, G, B );
  46. }
  47. %>
  48. <%
  49. // Set the page not to cache
  50. Response. setheader ("Pragma", "No-Cache ");
  51. Response. setheader ("cache-control", "No-Cache ");
  52. Response. setdateheader ("expires", 0 );
  54. // Create an image in memory
  55. Int width = 60, Height = 20;
  56. Bufferedimage image = new bufferedimage (width, height, bufferedimage. type_int_rgb );
  58. // Obtain the image Context
  59. Graphics G = image. getgraphics ();
  61. // Generate a random class
  62. Random random = new random ();
  64. // Set the background color
  65. G. setcolor (getrandcolor (200,250 ));
  66. G. fillrect (0, 0, width, height );
  68. // Set the font
  69. G. setfont (new font ("Times New Roman", Font. Plain, 18 ));
  71. // Draw a border
  72. // G. setcolor (new color ());
  73. // G. drawrect (0, 0, width-1, height-1 );
  76. // Generates 155 random interference lines, making the authentication code in the image hard to be detected by other programs.
  77. G. setcolor (getrandcolor (160,200 ));
  78. For (INT I = 0; I <155; I ++)
  79. {
  80. Int x = random. nextint (width );
  81. Int y = random. nextint (height );
  82. Int XL = random. nextint (12 );
  83. Int yl = random. nextint (12 );
  84. G. drawline (X, Y, x + XL, Y + yl );
  85. }
  87. // Obtain the random ID code (4 digits)
  88. String srand = "";
  89. For (INT I = 0; I <4; I ++ ){
  90. String Rand = string. valueof (random. nextint (10 ));
  91. Srand + = rand;
  92. // Display the authentication code to the image
  93. G. setcolor (new color (20 + random. nextint (110), 20 + random. nextint (110), 20 + random. nextint (110); // The color from the call function is the same, probably because the seed is too close, so it can only be generated directly.
  94. G. drawstring (RAND, 13 * I + 6, 16 );
  95. }
  97. // Save the authentication code to the session
  98. Session. setattribute ("RAND", srand );
  101. // The image takes effect
  102. G. Dispose ();
  104. // Output the image to the page
  105. ImageIO. Write (image, "Jpeg", response. getoutputstream ());
  108. %>
  111. 3. Check. jsp
  113. <% @ Page contenttype = "text/html; charset = gb2312" Language = "Java" Import = "Java. SQL. *" errorpage = "" %>
  114. <HTML>
  115. <Head>
  116. <Title> verification page </title>
  117. <Meta http-equiv = "Content-Type" content = "text/html; charset = gb2312">
  118. <Meta HTTP-EQUIV = "Pragma" content = "no-Cache">
  119. <Meta HTTP-EQUIV = "cache-control" content = "no-Cache">
  120. <Meta HTTP-EQUIV = "expires" content = "0">
  121. </Head>
  123. <Body>
  124. <%
  125. String Rand = (string) Session. getattribute ("RAND ");
  126. String input = request. getparameter ("RAND ");
  127. %>
  128. The verification code generated by the system is: <% = Rand %> <br>
  129. The verification code you entered is: <% = input %> <br>
  130. <Br>
  131. <%
  132. If (RAND. Equals (input )){
  133. %>
  134. <Font color = green> the input is the same and the authentication is successful! </Font>
  135. <%
  136. } Else {
  137. %>
  138. <Font color = Red> If the input is different, authentication fails! </Font>
  139. <%
  140. }
  141. %>
  142. </Body>
  143. </Html>

 

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Related Keywords:
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