Re: Passing variable to public/servlet

From:
Lew <lew@lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Mon, 12 Nov 2007 11:41:23 -0500
Message-ID:
<qt2dnfssh6OpH6XanZ2dnUVZ_qelnZ2d@comcast.com>
Clive_ wrote:

Hi,

Does anyone know an example showing how to pass a database variable to
a public variable??


One question mark would suffice.

I would like to run a java file or JSP, passing <%= rs.getInt(1)%> to
a servlet???


A JSP is a servlet, so you've already done that. What do you need the value for?

The servlet would store the data, which could be retrieved using
getAttribute.


Do you mean in a request attribute? Where do you intend to store the data?

You can set request attributes with the request setAttribute() method. Check
out the Javadocs.

<%


Do not put Java in JSPs. It's legal, but foolish.

 String connectionUrl =("jdbc:jtds:sqlserver://localhost:1032/");
 String dbName="Calibration";
 String driver="net.sourceforge.jtds.jdbc.Driver";
 String user="aaaa";
 String password="user";

   // Establish the connection.
   Class.forName(driver).newInstance();


You don't need to load the DB driver class again and again, and you certainly
don't need to create a throwaway instance of it.

   con = DriverManager.getConnection(connectionUrl
+dbName,user,password);


What if this fails? You have no Exception handling at all.

   stmt = con.createStatement() ;
   rs = stmt.executeQuery(querySQL) ;


 From where do you get the query?

  ResultSetMetaData rsmd = rs.getMetaData() ;


You assign the value then never refer to it again except to drive an empty
loop. Why?

  for(int i = 1 ; i <= rsmd.getColumnCount() ; i++) {
%>


Empty loop.

<% } %>

</tr>


Where's the opening <tr> tag? The enclosing <table>?

<% while(rs.next()) { %>
    <tr>
      <td> <%= rs.getInt(1)%> </td>
      <td> <%= rs.getString(2) %> </td>
    </tr>
    <br>

 <% }
  con.close();
  con = null;


What in the world do you expect to accomplish with setting con to null? It
goes out of scope anyway, so it's a useless action.

%>


There are tags in the JSTL for SQL access that likely would be much easier for
you. JSPs should do their action through separate server-side classes or tag
libs so that all this Java scriptlet doesn't cruft up your presentation artifacts.

You've already got the value in a servlet, so I am not clear what else you
need to accomplish.

--
Lew

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