The
'jdom.jar' archive can be downloaded from the following
web-site:
http://www.jdom.org/dist/binary
:
Unfortunately,
the requiered file is in compressed format.
Click onto
'jdom-1.0.tar.gz' to inspect the contents.
Leave the prposed
application 'file-roller' and click the [ OK ] button.
Move
to the folder /jdom-1.0/build to see the requested 'jdom.jar'
Use
>Edit>Copy
Use
the File Browser to 'paste' the file onto its final destination.
I
used the directory '/usr/java/j2sdk1.4.2_08/lib/extern' - and will
refer to it in further steps.
This directory can only be
write-accessed with rights as 'root'.
Now
it is time to incorporate the file into the libraries.
Mark the
project 'JS_Base02', right click with the mouse and select
>Properties
On
the window that just openend select 'Java Build Path' (on the left
side) and the tab 'Libraries'.
Then click the button [ Add
External JARs... ].
Manouvre
to the directory '/usr/java/j2sdk1.4.2_08/lib/extern' and select the
file 'jdom.jar'.
Then click the button [ OK ].
The
incorporation of the selected JAR into the Java Build Path is shown.
Click the button [ OK ].
First,
as the text-area txt_Report
should display the progress-status, it must allow to be called from
other methods within the package - i.e. it must
be defined as protected.
At
the same time, the area will be set as not 'Editable'. This prevents
entering data by the user.
protected
JTextArea get_txt_Report {
/* The code of
this method auto-creates the element if it is not already defined
*/
if
(txt_Report ==
null) {
try
{
txt_Report
= new
JTextArea();
txt_Report.setName(“txt_Report“);
txt_Report.setToolTipText(“Report“);
txt_Report.setMargin(new
Insets(3,3,3,3));
txt_Report.setEditable(false);
}
catch
(Throwable Exc) {
The
next task is, to implement amethod to be called when the button
'Start SQL execution' is clicked.
protected
static void handleEvent(JS_DBLoad parmCallingFrame,
ActionEvent parmActionEvent){
/*
*
Extract the action-command (in form of a String) that triggered the
Event from the Event */
String
cmd = parmActionEvent.getActionCommand().trim();
/*
*
Compare the String with the action-command and call the adjacent
method */
if(cmd.equals(„btn_Select“))
processSelectFile(parmCallingFrame);
if(cmd.equals(„btn_Start“))
processDBLoad(parmCallingFrame);
As
the code to be executed will get voluminous, the subtasks are coded
in several methods.
More calls will be added later on - first the
method to read the parameters from the XML-file is
coded.
protected
static void processDBLoad(JS_DBLoad
parmCallingFrame){
/*
*
Define an array that holds the parameters for the database-access */
String[]
array_DBParms;
array_DBParms
= processGetDBParms(parmCallingFrame);
}
To
explain the following code, some assumptions were made:
* The
XML-file with the parameters to connect to the database is in the
same directory as the input-file with the SQL-commands.
* The
file-name of the XML-file is 'DBParms.xml' with the exact
case-sensitivity.
protected
static String[]
processGetDBParm(JS_DBLoad
parmCallingFrame){
/*
Define the return-value holding the parameters */
String[]
array_DBParms = new String[4];
/*
Get the selected input-file to derive the directory in the next step
*/
String
strDirectory = parmCallingFrame.get_txt_InputFile().getText();
/*
Get the (system-specific) character that separates directories and
files */
String
strDirectorySeparator = System.getProperty(„file.separator“);
/*
Get the position of the last DirectorySeparator, the one were the
file-name is therafter */
int
intLastDirectorySeparator =
strDirectory.lastIndexOf(strDirectorySeparator);
/*
If there is not separator, e.g. no input-file selected
write
an error message to the text-area and return an empty array */
if
(intLastDirectorySeparator < 1)
{
parmCallingFrame.get_txt_Report().append(„Invalid
selection: “ + strDirectory + „\n“);
return
new String[0];
}
/*
Build the String with the complete directory and file-name and
display it in the text-area */
String
strDBParmDirectoryAndFile =
strDirectory.substring(1, intLastDirectorySwparator + 1) + „DBParms.xml“;
parmCallingFrame.get_txt_Report().append(„DB-Parameters will be read from file: “ + strDBParmDirectoryAndFile+ „\n“);
/*
Return the array with the parameters */
return
array_DBParms;
}
It
is a good time now to see an intermediate result before coding is
continued - but first:
Please remind to save the code just
typed.
Run
the application again by selecting
>Run>Run
As>Java Application.
The result of the shown screenshot is
after doing the following:
* First click the button 'Start SQL
execution' without previous selection of a file.
* Then selection
the correct input-file and click the button
'Start
SQL execution' thereafter.
For
the next steps of coding, the import of some packages for
XML-handling have to be included.
package
js_base02.application;
import
java.awt.*;
import
java.awt.event.*;
import
org.jdom.*;
import
org.jdom.input.*;
/**
*
* @author kurt@javascout.biz
*
@date 2006-02-10
First
(as for every reading of a file ;-) ), the file has to be
opened.
The org.jdom package offers a simple method to open and
check a file with data in XML-format.
(If you do not fully
understand what is going on there - just take it as given that this
code has to be like it is ;-) ).
/*
Build the String with the complete directory and file-name and
display it in the text-area /
String
strDBParmDirectoryAndFile =
strDirectory.substring(1, intLastDirectorySwparator + 1) + „DBParms.xml“;
parmCallingFrame.get_txt_Report().append(„DB-Parameters will be read from file: “ + strDBParmDirectoryAndFile+ „\n“);
/*
*
Open the file with methods provided by the org.jdom.input package
*/
try
{
SAXBuilder
parser = new
SAXBuilder();
Document
document =
parser.build(strDBParmDirectoryAndFile);
Element
XML_RootElement =
document.getRootElement();
}
catch(JDOMException
e)
{
parmCallingFrame.get_txt_Report().append(„'Not well formed exception' opening: „ + strDBParmDirectoryAndFile + „\n“);
return
new String[0];
}
catch(Exception
e)
{
parmCallingFrame.get_txt_Report().append(„'Unknown error' opening: „ + strDBParmDirectoryAndFile + „\n“);
return
new String[0];
}
/*
*
File could be opened and contains a 'well-formed' XML-structure
*/
parmCallingFrame.get_txt_Report().append(„XML-Root-Element found in: „ + strDBParmDirectoryAndFile + „\n“);
/*
Return the array with the parameters */
return
array_DBParms;
}
To
see what happens at this point you may save and run the application
again by selecting >Run>Run
As>Java Application.
As a result you will see, that a 'Not
well formed exception' occured when opening the file.
The reason
is, that the file is empty; i.e. the data does not represent a
XML-structure.
To
save some space, a screenshot is not included.
