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CSE 305 Theory of Database
Tutorial on Connecting with Sybase from Java program and Developing GUI
Jalal Mahmud, TA , CSE 305
Main topics in this tutorial Setting Environment in your account Connecting with Sybase from a Java program
(applet/application) using JDBC. Executing queries from Java program
(applet/application) Developing a GUI using html, java script Working from Home
Set the Environment ….Step 1
Create a directory called html under your home directory. Your html pages and java class files should reside in the html directory.
Copy the com folder under c:\program files\sybase\jConnect-4_5\classes to your html directory to make JDBC working
Set the Environment ….Step 2 Make sure that the CLASSPATH variable is set.
set CLASSPATH=%CLASSPATH%;.;c:\Program Files\sybase\jConnect-4_5\classes;c:\Program Files\jdk\lib;
set path=%path%;c:\Program Files\jdk\bin
You can download a batch file which sets the CLASSPATH from here .
CLASSPATH : More… Once the CLASSPATH variable is set, it
remains set until the DOS windows is closed.
The CLASSPATH variable is only required for compiling the java file. It is not required to connect to Sybase through the www server (assuming you have copied the com directory to your html directory).
Remember…. Make sure that you have the com directories located
in c:\program files\jdbc\classes in your html folder.
The com directory has to be in the same directory as the connection applet.
e.g. if your applet connect.class is located in h:\myproject\html\, then the com directory should be in h:\myproject\html\.
How to compile a Java source code
Open a DOS window
Compile your java source code by typing javac source.java on the command prompt.
Where to get JDBC
a new version of JDBC in the lab. The current version is now 4.5. It is installed locally on every machine. The path is c:\Program Files\sybase\jConnect-4_5.
Set the Property First String USER = “smith”; // replace with your sybase user id String Password = “abcd”; // replace with your password Properties prop = new Properties(); prop.put("user",USER); prop.put("password",Password);
// The proxy is setup to the TDS Tunneling servlet
prop.put("proxy","http://www.translab.cs.sunysb.edu/proxy/ servlet/TDSTunnelServlet");
Connect to the JDBC database.try{ Class.forName("com.sybase.jdbc.SybDriver"); conn = DriverManager.getConnection("jdbc:sybase:Tds:rdb. translab.cs.sunysb.edu:5000",prop); System.out.println(conn);}catch (Exception e) { e.printStackTrace();
return false; }
Now you are connected , how to execute a query ? 1. Create a statement object from the connection object 2. Execute the statement object.
Create a statement object from the connection Object try { stmt =conn.createStatement(); } catch (SQLException sqle) {
}
Execute the statement object.
try
{
sSelectStml=“Select * from test“ result_status=stmt.executeUpdate(sSelectStmt);
}
catch (SQLException sqle)
{
}
Develop your HTML Page You need to develop some ( at least one ) html page
for your GUI.
The html page should contain appropriate elements ( like textbox, button , selection, check box ) so that you can take user inputs and also display the result.
You may use Microsoft Front Page or any html editor for developing html pages.
You also need Java Script Java script is very easy ! The functions are almost similar to Java
functions. For Java script syntax : click the following
http://www.javascript.com You need to link java script functions to some
input elements in your GUI, specially submit button.
Add Java Script function to your GUI elements
Q. How to link a button with a JavaScript function?
<SCRIPT LANGUAGE="Javascript1.1"> function verify() { … } </SCRIPT> … <INPUT TYPE="button" VALUE="Send" onClick="verify();"> …
How to get the values of fields on the current window in a JavaScript function?
var user = document.forms[0].elements[1].value;
var password = document.forms[0].elements[2].value;
Parameter Passing from Java script Now you have collected parameter, ( say username
and password) from your html page .
When user presses submit it directly goes to java script function..
You can call Java applet function from here which will take care the remaining
Q. How to pass parameters from JavaScript function to Java Applet method?
<javascript>
function verify(){
var user = document.forms[0].elements[1].value; var password = document.forms[0].elements[2].value; document.applets[0].connectSybase(user, password); …
} </javascript>
<APPLET code=“connect.class" name="connect" codebase=. height=850 width = 600 MAYSCRIPT></APPLET>
Displaying Result from Javascript Now you can pass parameters to applet using
Java script function .. You also need to display your results…
You can use Java script to set value of a particular field of your GUI.
But , you also need java applet which will calculate the result for you !
How to get the result and display it ? function showResult() {
... var result = String(document.applets[0].getOneRow()); while(result != "" && result != null){
msg += result; result = String(document.applets[0].getOneRow());
} document.oper.result.value = msg; ... }
Getting and Processing result from a Java Applet public String getOneRow()
{ ... rs=stmt.executeUpdate(sSelectStmt);
String name = rs.getString(1); String desc = rs.getString(2); int length = rs.getInt(3); int access = rs.getInt(4); result= new String(name + " " + desc + " " + length
+ " " + access); return result; }
How html, JavaScript, JAVA Applet, JDBC work together? You need to develop your html page for the GUI.
You will write the java script code in your html file that will be responsible for verifying, parameter passing and displaying result.
Java Applet should be embedded in the html file within <applet>…</applet> tag
Within Java applet, you will write functions to connect to Sybase, executing Queries and calculating results….
Good Practice to Disconnect !!
<SCRIPT type="text/javascript" language="JavaScript1.2">
function doDisconnect() { var output;
output = parent.samplehtml.document.connect.disconnect(); if(output == 0){
alert("Not disconnected"); return true; } if(output == 1) { alert("disconnected sucessfully"); return true; }
} </SCRIPT>
Disconnect Code public int disconnect() { if (conn != null){ try { conn.close(); } catch (SQLException sqle) { } } }
How to work at home?
Download and install Java from JavaSoft (JDK 1.1) on your own machine
Download and install JDBC from Sybase (jConnect) on your own machine
For more information, see dbcourse
You need Sybase To interact with Sybase, you can do so by
either using the gateway applet, located at: http://www.translab.cs.sunysb.edu/gateway/gateway or
by installing JConnect from Sybase, and installing Sybase's jisql. Instructions for installing jisql can be found here.
Also JDBC JDBC or JConnect from Sybase: You can
download JConnect from the Sybase website at http://www.sybase.com . Make sure that you use the same version as in the lab or else you will have compatibility issues.
Also, you need to have the com directory tree in your html folder within your account. The Jconnect that you install on your home machine should be used only to compile your code. Avoid setting the CLASSPATH variable.
You also need JDK Java Development Kit (or JDK). You can download
it from Sun's Website at http://www.sun.com or go to http://www.sun.com/download . Make sure that you use the same version of JDK as in the lab.
An HTML editor. You can download one from http://www.evrsoft.com (1st Page 2000) which is installed in the lab or you could simply use wordpad or notepad or use the editors which come with IE or Netscape.
And a SSH2 client A SSH2 client. You will need to upload the
files to the transaction lab file server. You can download a free windows SSH2 client from http://www.ssh.com . The ssh2 server for the TRANSLAB is www.translab.cs.sunysb.edu .
Useful resources HTML
http://www.w3.org/TR/REC-html32.html HTTP
http://www.w3.org/Protocols/HTTP/1.0/spec.html JavaScript
http://developer.netscape.com/docs/manuals/communicator/jsguide4/contents.htm
Java http://java.sun.com/docs/books/tutorial/
JDBC http://java.sun.com/docs/books/tutorial/
Sybase & SQL http://sybooks.sybase.com/onlinebooks/group-as/srg1100e/sqlref
