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Calling a Java class from a batch file and returning the response

Joe San

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posted 12 years ago

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I'm not sure if it is possible to do the following:

1. Call a Java class from a batch file - I can do this
2. The Java class does something and has a response - I can do this
3. I want to pass this response to the batch file - Is this possible???

Any ideas?

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Jesper de Jong

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posted 12 years ago

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What kind of response does the Java class produce?

If it's just an integer, you can call System.exit(...); in the Java code; the value that you pass to exit(...) is returned to the batch file as the exit code.

If it's something more complicated, you could let the Java program write the response to a file, and then work with that file in the rest of the batch script.

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Joe San

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posted 12 years ago

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It will just be an integer response! either 0 or -1!

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fred rosenberger

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posted 12 years ago

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I believe the exact syntax would vary depending on what your OS is, but basically in the script you'd have a variable that would catch the value, just like you do in any other programming language. Alternatively, it may be a pseudo environment variable that gets set in the shell your job is running in.

So I guess the question is what OS are you using?

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Joe San

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It will just be windows!

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Joanne Neal

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posted 12 years ago

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In Windows the return code is set in the ERRORLEVEL environment variable.
So if you did something like
java -cp ...
and your code contained
System.exit(2);
then putting
echo %ERRORLEVEL%
straight after the java call in your batch file would print 2.

Joanne

doug mccann

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posted 12 years ago

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If you need to capture standard output you can get an input stream from the process (Process p = Runtime.getRuntime().exec( ...);). Then write the data to a file as was suggested by Joe.

Joe San

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Thanks for that. Based on your inputs, here is what I have so far. I'm checking for ERRORLEVEL and if it is not 0, I'm restarting my server.

The batch file

I have made my program ServerHealthTest to return -1 in case of any exception and 0 for success. When I tried running this, I get the following when something fails:

java.util.concurrent.ExecutionException: java.net.ConnectException: Connection refused: no further information to ws://localhost:9999/getData
        at com.ning.http.client.providers.netty.NettyResponseFuture.abort(NettyResponseFuture.java:297)
        at com.ning.http.client.providers.netty.NettyConnectListener.operationComplete(NettyConnectListener.java:104)
        at org.jboss.netty.channel.DefaultChannelFuture.notifyListener(DefaultChannelFuture.java:399)
        at org.jboss.netty.channel.DefaultChannelFuture.notifyListeners(DefaultChannelFuture.java:390)
        at org.jboss.netty.channel.DefaultChannelFuture.setFailure(DefaultChannelFuture.java:352)
        at org.jboss.netty.channel.socket.nio.NioClientSocketPipelineSink$Boss.connect(NioClientSocketPipelineSink.java:409)
        at org.jboss.netty.channel.socket.nio.NioClientSocketPipelineSink$Boss.processSelectedKeys(NioClientSocketPipelineSink.java:366)
        at org.jboss.netty.channel.socket.nio.NioClientSocketPipelineSink$Boss.run(NioClientSocketPipelineSink.java:282)
        at org.jboss.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:102)
        at org.jboss.netty.util.internal.DeadLockProofWorker$1.run(DeadLockProofWorker.java:42)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)
Caused by: java.net.ConnectException: Connection refused: no further information to ws://localhost:9999/getData
        at com.ning.http.client.providers.netty.NettyConnectListener.operationComplete(NettyConnectListener.java:100)
        ... 11 more
Caused by: java.net.ConnectException: Connection refused: no further information
        at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
        at sun.nio.ch.SocketChannelImpl.finishConnect(Unknown Source)
        at org.jboss.netty.channel.socket.nio.NioClientSocketPipelineSink$Boss.connect(NioClientSocketPipelineSink.java:404)
        at org.jboss.netty.channel.socket.nio.NioClientSocketPipelineSink$Boss.processSelectedKeys(NioClientSocketPipelineSink.java:366)
        at org.jboss.netty.channel.socket.nio.NioClientSocketPipelineSink$Boss.run(NioClientSocketPipelineSink.java:282)
        ... 3 more
[b]0 was unexpected at this time.[/b]

I don't get the last line! What is it?

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Jesper de Jong

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posted 12 years ago

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I'm not an expert in writing Windows batch files, but are you sure the syntax of this line is correct?

Maybe it should be something like %ERRORLEVEL% = 0 or == 0 or whatever, instead of just %ERRORLEVEL% 0.

Lookup the syntax.

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Joe San

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posted 12 years ago

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Ok. I made some changes and the batch file looks as below:

It looks all good now!

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Joe San

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Maybe another question that is somewhat related to what I'm trying to do here. How can I pass a parameter to a batch file. For example:

How can I get the value of -Dhttp.port in my batch file? Any ideas?

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fred rosenberger

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posted 12 years ago

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a quick google search returned this page, which looks like it would have what you need.

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Joe San

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posted 12 years ago

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Thanks for that. I have another question. I have a call to a Java process like this in my batch file:

How can I make the above call return control to the batch file that it is running from? The reason is that I want to run some additional Java processes in the same batch file.

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Joe San

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posted 12 years ago

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I think I have the solution now. I prefixed the call to the java process with start. So the call now effectively looks like below:

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Joe San

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I did not want to open another thread, I have another question which is pretty much same to what I have been doing with calling batch files. In the following call:

How to I get the value of -Dhttp.port in my start.bat file?

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Paul Clapham

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posted 12 years ago

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It's the first parameter, so %1 would be how.

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Joe San

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I tried it, echo %1 prints only -Dhttp.port. Do I pass the -Dhttp.port=8080 within double quotes? Is there a way to get it without double quotes?

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fred rosenberger

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Joe Harry wrote:I tried it, echo %1 prints only -Dhttp.port. Do I pass the -Dhttp.port=8080 within double quotes? Is there a way to get it without double quotes?

What's wrong with double quotes, if they work?

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Joe San

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posted 12 years ago

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The call to the batch file will be configured in the Windows scheduler and I'm not sure if we could use double quotes there. I've never configured something on the Windows scheduler. Is there a way without the quotes?

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Paul Clapham

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Instead of solving problems which may or may not exist, why not see if there's a problem first? Personally I would expect the Windows scheduler to support obvious things like quote characters in the command string, but I could be wrong. Haven't ever used it.

Joe San

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If I had a windows machine, I could have tried it. I have to check with the operations team to see if that works with the double quotes.

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