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Create a JSP + JavaScript level-2 cascade drop-down menu

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Then let's start JSP + JavaScript to create a level-2 cascade drop-down menu:

Create a variable definition for the JSP JavaScript level-2 cascade drop-down menu:

◆ Class (first-level column information ):

◆ ClassId (automatic ID)

◆ ClassName (topic name)

◆ Nclass (second-level column information)

◆ NclassId (automatic ID)

◆ NclassName (topic name)

◆ ParentId (first-level column id, associated with classId in the class table)

 
 
    
  
  
  1. ﹤%@ page contentType=text/html; charset=GB2312 language=java errorPage=../error.jsp %﹥  
    2. 
  
  
  2. ﹤%@ include file=../conn.jsp%﹥  
    3. 
  
  
  3. ﹤%@ include file=../ds.jsp%﹥  
    4. 
  
  
  4. ﹤%@ taglib uri=http://java.sun.com/jsp/jstl/sql divfix=sql %﹥  
    5. 
  
  
  5. ﹤%request.setCharacterEncoding(gb2312); %﹥ 
    6.

Create a cascading menu for JSP + JavaScript level-2 cascading drop-down menus

 
 
    
  
  
  1. <HTML> <HEAD>
    2. 
  
  
  2. <META.Http-equiv=Content-TypeContent=Text/Html;Charset=Gb2312>
    3. 
  
  
  3.  
    4. 
  
  
  4. <TITLE> cascade menu </TITLE>
    5. 
  
  
  5. <LINKRel=Stylesheet Type=Text/CssHref=Style. Css>
    6. 
  
  
  6. </HEAD>
    7.

◆ Obtain the second-level column information from the database

 
 
    
  
  
  1. ﹤%String sql=select * from Nclass order by NclassId asc;  
    2. 
  
  
  2. ResultSet rs=stmt.executeQuery(sql);  
    3. 
  
  
  3. %﹥  
    4.


◆ Save the second-level column information to the array subcat

 
 
    
  
  
  1. ﹤script. type=text/javascript﹥  
    2. 
  
  
  2. var onecount;  
    3. 
  
  
  3. onecount=0;  
    4. 
  
  
  4. subcat = new Array();  
    5. 
  
  
  5.         ﹤%  
    6. 
  
  
  6.         int count = 0;  
    7. 
  
  
  7.         while(rs.next()){  
    8. 
  
  
  8.         %﹥  
    9. 
  
  
  9. subcat[﹤%=count%﹥] = new Array(﹤%=rs.getString(NclassName)%﹥,  
    10. 
  
  
  10. ﹤%=rs.getString(NclassId)%﹥,﹤%=rs.getString(parentId)%﹥);  
    11. 
  
  
  11.         ﹤%  
    12. 
  
  
  12.         count++;  
    13. 
  
  
  13.         }  
    14. 
  
  
  14.         rs.close();  
    15. 
  
  
  15.         %﹥  
    16. 
  
  
  16. onecount=﹤%=count%﹥;  
    17.

◆ Determines the function displayed by the Select statement.

 
 
    
  
  
  1.  
    2. 
  
  
  2. function changelocation(locationid)  
    3. 
  
  
  3.     {  
    4. 
  
  
  4.     document.myform.NclassId.length = 0;  
    5. 
  
  
  5.  
    6. 
  
  
  6.     var locationidlocationid=locationid;  
    7. 
  
  
  7.     var i;  
    8. 
  
  
  8.     for (i=0;i ﹤ onecount; i++)  
    9. 
  
  
  9.         {  
    10. 
  
  
  10.             if (subcat[i][2] == locationid)  
    11. 
  
  
  11.             {  
    12. 
  
  
  12.                 document.myform.NclassId.options[document.myform.NclassId.length] = new  
    13. 
  
  
  13. Option(subcat[i][0], subcat[i][1]);  
    14. 
  
  
  14.             }         
    15. 
  
  
  15.         }  
    16. 
  
  
  16.          
    17. 
  
  
  17.     }     
    18. 
  
  
  18. ﹤/script﹥  
    19.

◆ JSP JavaScript level-2 cascade menu Creation

 
 
    
  
  
  1. <FORM.Method=POST Name=Myform.Action=Adminsave. Jsp?Action=Add>
    2. 
  
  
  2. <TABLE>
    3. 
  
  
  3. 
  
  
  4. <TR>
    5. 
  
  
  5. <TD> Level 1 Classification </TD>
    6. 
  
  
  6. <TD>
    7. 
  
  
  7. <SELECTName=ClassId NChange=Changelocation(Document. myform. classId. options
    8. 
  
  
  8. [Document. myform. classId. selectedIndex]. value)Size=1>
    9. 
  
  
  9. <OPTION selected value >== select a level-1 category ==</ OPTION>
    10. 
  
  
  10. <SQL: queryVar=Query DataSource=﹥>
    11. 
  
  
  11. SELECT * FROM class
    12. 
  
  
  12. </SQL: query>
    13. 
  
  
  13. <C: forEachVar=Row Items=﹥>
    14. 
  
  
  14. <OptionValue=$ >$ </Option>
    15. 
  
  
  15. </C: forEach>
    16. 
  
  
  16. </Select>
    17. 
  
  
  17. </TD>
    18. 
  
  
  18. <TD> Select secondary category </TD>
    19. 
  
  
  19. <TD>
    20. 
  
  
  20. <SELECTName=NclassId>
    21. 
  
  
  21. <OPTION selected value >== select Level 2 Category ==</ OPTION>
    22. 
  
  
  22. </SELECT>
    23. 
  
  
  23. </TD>
    24. 
  
  
  24. </TR>
    25. 
  
  
  25. </TABLE>
    26. 
  
  
  26. 
  
  
  27. </FORM>
    28. 
  
  
  28. </BODY>
    29. 
  
  
  29. </HTML>
    30. 
  
  
  30. <%@ PageContentType=Text/Html;Charset=GB2312 Language=Java ErrorPage= ../Error. jsp %>
    31. 
  
  
  31. <%@ IncludeFile= ../Conn. jsp %>
    32. 
  
  
  32. <%@ IncludeFile= ../Ds. jsp %>
    33. 
  
  
  33. <%@ TaglibUri=Http: // Java.sun.com/jsp/jstl/ SQLDivfix=SQL%>
    34. 
  
  
  34. <% Request. setCharacterEncoding (gb2312); %>
    35. 
  
  
  35. <HTML> <HEAD>
    36. 
  
  
  36. <META.Http-equiv=Content-TypeContent=Text/Html;Charset=Gb2312>
    37. 
  
  
  37.  
    38. 
  
  
  38. <TITLE> cascade menu </TITLE>
    39. 
  
  
  39. <LINKRel=Stylesheet Type=Text/CssHref=Style. Css>
    40. 
  
  
  40. </HEAD>
    41. 
  
  
  41. <! -- Obtain the second-level column information from the database -->
    42. 
  
  
  42. <%StringSQL=Select* From Nclass order by NclassId asc;
    43. 
  
  
  43. ResultSetRs=Stmt. ExecuteQuery (SQL );
    44. 
  
  
  44. %>
    45. 
  
  
  45. <! -- Save the second-level column information to the array subcat -->
    46. 
  
  
  46. <Script.Type=Text/Javascript>
    47. 
  
  
  47. Var onecount;
    48. 
  
  
  48. Onecount=0;
    49. 
  
  
  49. Subcat=NewArray ();
    50. 
  
  
  50. <%
    51. 
  
  
  51. IntCount=0;
    52. 
  
  
  52. While (rs. next ()){
    53. 
  
  
  53. %>
    54. 
  
  
  54. Subcat [<%= count %>] = new Array (<%= rs. getString (NclassName) %>,
    55. 
  
  
  55. <%= Rs. getString (NclassId) % >,<%= rs. getString (parentId) %> );
    56. 
  
  
  56. <%
    57. 
  
  
  57. Count ++;
    58. 
  
  
  58. }
    59. 
  
  
  59. Rs. close ();
    60. 
  
  
  60. %>
    61. 
  
  
  61. Onecount= <%= Count %>;
    62. 
  
  
  62. <! -- Determines the function displayed by select -->
    63. 
  
  
  63. Function changelocation (locationid)
    64. 
  
  
  64. {
    65. 
  
  
  65. Document. myform. NclassId. length=0;
    66. 
  
  
  66.  
    67. 
  
  
  67. VarLocationidLocationid= Locationid;
    68. 
  
  
  68. Var I;
    69. 
  
  
  69. For (I=0; I <onecount; I ++)
    70. 
  
  
  70. {
    71. 
  
  
  71. If (subcat [I] [2] = locationid)
    72. 
  
  
  72. {
    73. 
  
  
  73. Document. myform. NclassId. options [document. myform. NclassId. length] = new
    74. 
  
  
  74. Option (subcat [I] [0], subcat [I] [1]);
    75. 
  
  
  75. }
    76. 
  
  
  76. }
    77. 
  
  
  77. 
  
  
  78. }
    79. 
  
  
  79. </Script>
    80. 
  
  
  80.  
    81. 
  
  
  81. <FORM.Method=POST Name=Myform.Action=Adminsave. Jsp?Action=Add>
    82. 
  
  
  82. <TABLE>
    83. 
  
  
  83. 
  
  
  84. <TR>
    85. 
  
  
  85. <TD> Level 1 Classification </TD>
    86. 
  
  
  86. <TD>
    87. 
  
  
  87. <SELECTName=ClassId NChange=Changelocation(Document. myform. classId. options
    88. 
  
  
  88. [Document. myform. classId. selectedIndex]. value)Size=1>
    89. 
  
  
  89. <OPTION selected value >== select a level-1 category ==</ OPTION>
    90. 
  
  
  90. <SQL: queryVar=Query DataSource=﹥>
    91. 
  
  
  91. SELECT * FROM class
    92. 
  
  
  92. </SQL: query>
    93. 
  
  
  93. <C: forEachVar=Row Items=﹥>
    94. 
  
  
  94. <OptionValue=$ >$ </Option>
    95. 
  
  
  95. </C: forEach>
    96. 
  
  
  96. </Select>
    97. 
  
  
  97. </TD>
    98. 
  
  
  98. <TD> Select secondary category </TD>
    99. 
  
  
  99. <TD>
    100. 
  
  
  100. <SELECTName=NclassId>
    101. 
  
  
  101. <OPTION selected value >== select Level 2 Category ==</ OPTION>
    102. 
  
  
  102. </SELECT>
    103. 
  
  
  103. </TD>
    104. 
  
  
  104. </TR>
    105. 
  
  
  105. </TABLE>
    106. 
  
  
  106. 
  
  
  107. </FORM>
    108. 
  
  
  108. </BODY>
    109. 
  
  
  109. </HTML>
    110. 
  
  
  110.  
    111.

The above is how to build a level-2 cascade drop-down menu Using JSP JavaScript. Is it good after implementation? Is it helpful for JSP JavaScript development and design?

  1. A brief overview of embedded objects in JSP
  2. JSP entry-level website environment setup steps
  3. How to export Oracle Data Tables Using JSP
  4. Implement page Jump in JSP
  5. What is JSP and comparison with Servlet?

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