Question

java servlet to run unix command

Asked by: usaperl


import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class t2 extends HttpServlet {
public void doGet (HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
{
res.setContentType("text/html");
Runtime runtime = Runtime.getRuntime();
Process process = runtime.exec( new String[] { "netstat -rn" } );
DataInputStream in = new DataInputStream( process.getInputStream() );
PrintWriter com_out = res.getWriter();
com_out.println("<pre>");
String line = null;
while ( ( line = in.readLine() ) != null ) {
com_out.println( line );
}
}
}



Hi,
  I compile the servlet above and receive the below
error.  Can someone help me fix the problem?
thanks in advance.


t2.java:16: Note: The method java.lang.String readLine() in class java.io.DataInputStream has been deprecated.
while ( ( line = in.readLine() ) != null ) {
                            ^
Note: t2.java uses or overrides a deprecated API.  Please consult the documentation for a better alternative.
1 warning

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Asked On
2001-12-04 at 16:35:08ID20243687
Tags

alternatives

,

command

,

running

,

servlet

Topics

Java Programming Language

,

Java Servlets

,

New to Java Programming

Participating Experts
4
Points
100
Comments
6

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Answers

 

by: objectsPosted on 2001-12-04 at 17:39:49ID: 6666563

Yes if you check the javadoc you'll see that the readLine method has been deprecated.
It's only a warning so your code will still have gotten compiled.

To get rid of the warning, replace the use of DataInputStream with a BufferedReader.

 

by: umargulPosted on 2001-12-04 at 23:12:04ID: 6666779

You can compile your existing code using the following command:
javac -deprecation <file name>
compile and enjoy servlets, OK

 

by: TimYatesPosted on 2001-12-05 at 03:09:02ID: 6666910

Dont forget to close all of your process streams as well!!!

 process.getErrorStream().close();
 process.getInputStream().close();
 process.getOutputStream().close();

Or else you will get a "too many open files" error after about 200 executions of the code...

Tim.

 

by: OviPosted on 2001-12-05 at 03:56:42ID: 6666967

Just change the DataInputStream to BufferedReader like this :

BufferedReader br = new BufferedReader(new InputStreamReader(process.getInputStream()));
PrintWriter com_out = res.getWriter();
com_out.println("<pre>");
String line = null;
while (( line = br.readLine()) != null ) {
  com_out.println( line );
}

 

by: usaperlPosted on 2001-12-05 at 10:57:16ID: 6667904

I successfully compile, but I got these errors when run
it from the netscape browser:




[05/Dec/2001:10:51:05] failure (13631): Internal error: exception thrown from the servlet service function (uri=/servlet/t2.class): java.io.IOException: netstat -rn: not found, Stack: java.io.IOException: netstat -rn: not found
        at java.lang.UNIXProcess.forkAndExec(Native Method)
        at java.lang.UNIXProcess.<init>(UNIXProcess.java:62)
        at java.lang.Runtime.execInternal(Native Method)
        at java.lang.Runtime.execInternal(Compiled Code)
        at java.lang.Runtime.exec(Compiled Code)
        at java.lang.Runtime.exec(Compiled Code)
        at t2.doGet(Compiled Code)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
        at com.iplanet.server.http.servlet.NSServletRunner.invokeServletService(NSServletRunner.java:891)
        at com.iplanet.server.http.servlet.NSServletRunner.Service(NSServletRunner.java:458)


 

by: usaperlPosted on 2001-12-05 at 11:36:52ID: 6667983

got it to work.

thanks

20120131-EE-VQP-002

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