Get Array value from JSP page to external JavaScript page

Question

I want to display the databases in MySQL in a tree structure.

I have a JSP page to get the database name and JavaScript page to display it in tree format.

As I am new to web application development I don't know how to get the database name from JSP page to JavaScript page without using jQuery. Do I need to use jQuery for this purpose?

demoframeset.html

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<HEAD>

    <!-- This is the <STYLE> block for the default styles.  If   -->
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    <STYLE>
        BODY {
            background-color: white;}
        TD {
            font-size: 10pt; 
            font-family: verdana,helvetica; 
            text-decoration: none;
            white-space:nowrap;}
        A {
            text-decoration: none;
            color: black;}
        .specialClass {
            font-family:garamond; 
            font-size:12pt;
            color:green;
            font-weight:bold;
            text-decoration:underline}
        </STYLE>

        <!-- If you want the black background, replace the contents  -->
        <!-- of the <STYLE> tag above with the following...
          BODY {
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        <!-- This is the end of the <STYLE> contents.                -->

        <!-- Code for browser detection. DO NOT REMOVE.              -->
        <SCRIPT src="ua.js"></SCRIPT>

        <!-- Infrastructure code for the TreeView. DO NOT REMOVE.    -->
        <SCRIPT src="ftiens4.js"></SCRIPT>

        <!-- Scripts that define the tree. DO NOT REMOVE.            -->
        <SCRIPT src="demoFramesetNodes.js"></SCRIPT>

    </HEAD>

    <BODY topmargin="16" marginheight="16">

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        <DIV style="position:absolute; top:0; left:0;"><TABLE border=0><TR><TD><FONT size=-2><A style="font-size:7pt;text-decoration:none;color:silver" href="http://www.treemenu.net/" target=_blank>Javascript Tree Menu</A></FONT></TD></TR></TABLE></DIV>

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    A tree for site navigation will open here if you enable JavaScript in your browser.
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</BODY>

demoFrameSetNodes.js

  USETEXTLINKS = 1
  STARTALLOPEN = 0
   ICONPATH = ''
  foldersTree = gFld("<i>Databases</i>", "demoFramesetRightFrame.html")
  foldersTree.treeID = "Frameset" 
  aux11 = insFld(foldersTree, gFld("New", "Databases.jsp"))

  var xmlHttp 
 function create()
  { 
      xmlHttp=CreateXmlHttpObject()
      if (xmlHttp==null)
      {
         alert ("Browser does not support HTTP Request")
         return
      } 

       var url="new1.jsp"
      url=url+"?dbname="+str

      url=url+"&sid="+Math.random()
     //  out.print(url)
       xmlHttp.onreadystatechange=stateChanged 
       xmlHttp.open("GET",url,true)
       xmlHttp.send()

   }
  function stateChanged() 
   { 
      if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
      { 
          document.getElementById("div").innerHTML=xmlHttp.responseText 
     } 
  } 
  function CreateXmlHttpObject()
  { 
       var objXMLHttp=null
       if (window.XMLHttpRequest)
       {
              objXMLHttp=new XMLHttpRequest()
         }
          else if (window.ActiveXObject)
         {
          objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP")
        }
         return objXMLHttp
  }

new1.jsp

try {
    String responseText = "";
    String text = "";
    Class.forName("com.mysql.jdbc.Driver").newInstance();
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/", "root", "");

    DatabaseMetaData dbmd = conn.getMetaData();

    ResultSet ctlgs = dbmd.getCatalogs();
    while (ctlgs.next()) {
        text += ctlgs.getString(1) + ",";
    }
} catch (Exception e) {
    out.println(e);
}

tmarwen · Accepted Answer · 2014-11-14 08:19:00Z

You should be able to retrieve the dbname from the request query string parmaters. This can be done using:

request.getParameter("your-param");

In your case, it should be the dbname parameter, which you are injecting in URL within your JS file:

try {
    String dbName = request.getParameter("dbname"); // Retrive the dbname parameter
    String responseText = "";
    String text = "";
    Class.forName("com.mysql.jdbc.Driver").newInstance();
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/" + dbName /*Use the dbName in the schema URL*/, "root", "");

    DatabaseMetaData dbmd = conn.getMetaData();

    ResultSet ctlgs = dbmd.getCatalogs();
    while (ctlgs.next()) {
        text += ctlgs.getString(1) + ",";
    }
} catch (Exception e) {
    out.println(e);
}

Edit:

Otherwise you can simply show your database names within your JSP without any external requests calls, since you are already populating your db names to a String delimited by a comma, you can use the <c:forTokens> tag to iterate over a splitted array from you String; text:

<c:forTokens items="${text}" delims="," var="dbname"> 
  <c:out value="${dbname}"/><p> 
</c:forTokens>

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