Re: converting some VB code to Java..
"maya" <fdr58@yahoo.com> wrote...
Bjorn Abelli wrote:
A simple Google gives plenty of sites with AJAX connected to Java:
http://tinyurl.com/pmypd
Why not from the horses mouth, Sun:
http://developers.sun.com/ajax/
Plenty of examples there... ;-)
thank you Bjorn, I HAD searched in Google, and had found some stuff (among
others sun-pg you mention above) but can't find a step-by-step java-based
tutorial like the one here..
http://www.w3schools.com/ajax/default.asp
since you seem to know about AJAX I was wondering,
Actually, I had only heard of it, but never used it, before you asked for
it... ;-)
am looking for AJAX 'docs'...
I don't think anyone "owns" the concept. That would be Adaptive Path who
coined the expression:
http://www.adaptivepath.com/publications/essays/archives/000385.php
closest thing I found is here...
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/xmlsdk/html/7924f6be-c035-411f-acd2-79de7a711b38.asp
why does XMLHTTPRequest have an "I" at the beginning here? (it's referred
to as "IXMLHTTPRequest")
Microsoft has a naming standard where interfaces "always" starts with an
"I".
That IXMLHTTPRequest is not "exactly" the same as XMLHTTPRequest, but as it
started in IE, MSDN is one source:
http://tinyurl.com/n8n7p
Other pages that explain the concepts are:
http://en.wikipedia.org/wiki/XMLHttpRequest
http://www.xulplanet.com/references/objref/XMLHttpRequest.html
http://developer.mozilla.org/en/docs/AJAX:Getting_Started
http://developer.apple.com/internet/webcontent/xmlhttpreq.html
I would like to know what all the objs are that these properties & methods
can be applied to (is XMLHttpRequest the only obj here? or are there
others? I just need to get the "big picture" here....:)
So I'd suggest you get your hands dirty with JDBC, ResultSets,
PreparedStatements, etc... ;-)
I do know how to do db-stuff w/Java, Bjorn (probably not as much as you
do, but I do know how to connect to db, insert stuff into tables, do
updates and queries, etc..) right now I just need to figure out how to do
this in java:
response.write("<table>")
do until rs.EOF
for each x in rs.Fields
response.write("<tr><td><b>" & x.name & "</b></td>")
response.write("<td>" & x.value & "</td></tr>")
next
rs.MoveNext
loop
rs.EOF?? (resultSet EndOfFile? what does this mean?)
Yes, ADO has a slightly different approach than JDBC... ;-)
Other than that, the code would look quite similar, e.g.:
out.print("<table>");
while (rs.next ())
{
for (int i = 0; i < columnCount; i++)
{
out.print(
"<tr><td><b>" +
rsMetaData.getColumnName(i+1) +
"</b></td>");
out.print(
"<td>" +
rs.getString (i+1) +
"</td></tr>");
}
}
....should be corresponding to the code you extracted.
ok, no more on AJAX questions (unless it's an AJAX/Java-related
question....:), since this is not an AJAX group.. have more JS/AJAX code
questions (xmlHttp.readyState=="complete" -- what is "complete"..), I
guess I need to switch to JS ng (I guess no AJAX-ng yet..)
Yep, that's on the client side...
again, many thanks for yr help..
You're welcome.
// Bjorn A
---------------------------------
Appendix
---------------------------------
The servlet, not tested though...
import java.sql.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class AjaxDatabaseServlet extends HttpServlet
{
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException
{
PrintWriter out = response.getWriter();
String sql =
"SELECT * FROM CUSTOMERS WHERE CUSTOMERID=" +
request.getParameter("q");
// You might want to fix the path to the database
String url =
"jdbc:odbc:DRIVER={Microsoft Access Driver (*.mdb)};DBQ=" +
"/db/northwind.mdb";
try
{
DriverManager.registerDriver(
new sun.jdbc.odbc.JdbcOdbcDriver());
Connection conn = DriverManager.getConnection (url);
Statement stmt = conn.createStatement ();
ResultSet rs = stmt.executeQuery (sql);
ResultSetMetaData rsMetaData = rs.getMetaData();
int columnCount = rsMetaData.getColumnCount();
out.print("<table>");
while (rs.next ())
{
for (int i = 0; i < columnCount; i++)
{
out.print(
"<tr><td><b>" +
rsMetaData.getColumnName(i+1) +
"</b></td>");
out.print(
"<td>" +
rs.getString (i+1) +
"</td></tr>");
}
}
out.print("</table>");
// cleanup...
rs.close();
stmt.close();
conn.close();
}
catch (SQLException ex)
{
ex.printStackTrace(out);
}
}
}
/// Bjorn A
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