This question already has answers here:
Executing another java program from our java program [duplicate]
(3 answers)
How to save a shell script's echo output within Java [duplicate]
(2 answers)
Closed 5 years ago.
I was tried to get OSM data from my local overpass API. There are four steps to get OSM data.
run the binary file /srv/osm3s/bin/osm3s_query
once the osm3s_query is running, you'll see this messageencoding remark: Please enter your query and terminate it with CTRL+D.
input your query <query type="node"><bbox-query n="51.0" s="50.9" w="6.9" e="7.0"/><has-kv k="amenity" v="pub"/></query><print/>
press ctrl+D and get the OSM results
my code as below:
try
{
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("/srv/osm3s/bin/osm3s_query");
InputStream stderr = proc.getErrorStream();
InputStreamReader isr = new InputStreamReader(stderr);
BufferedReader br = new BufferedReader(isr);
String line = null;
while ( (line = br.readLine()) != null)
System.out.println(line);
int exitVal = proc.waitFor();
System.out.println("Process exitValue: " + exitVal);
} catch (Throwable t)
{
t.printStackTrace();
}
The process will hang on step 2 after shown the message encoding remark: Please enter your query and terminate it with CTRL+D.. I have no idea how to give the process the query string.
Anybody has some idea?
OutputStreamWriter output = proc.getOutputStream();
output.write(yourQuery);
output.write(4); // that's ctrl-d
output.flush();
Firstly -- this is a pretty fragile way to interact with the Overpass API. Since Overpass is an XML-over-HTTP API, and Java has lots of XML and HTTP libraries, there are plenty of ways to do it in native Java. OpenStreetMap provides examples - for example http://wiki.openstreetmap.org/wiki/Java_Access_Example
This is probably easier, and certainly more robust, than calling an external command.
There are also higher level Java libraries: http://wiki.openstreetmap.org/wiki/Frameworks
For the general case of running a process, writing to its stdin and reading from its stdout, since Java 1.5 it's best to use ProcessBuilder to create your Process.
Once you have a process, you can use getInputStream(), getOutputSteam() and getErrorStream() to get the relevant streams (in the builder, if you like, you can make stderr go to stdout).
It's possible to get into a deadlock when reading and writing these streams - in many situations you'll need to either use non-blocking IO classes or create separate threads for reading and writing.
Related
This question already has answers here:
Bitlocker script to unlock drive
(8 answers)
Closed 6 years ago.
I am trying to unlock a drive secured by bitlocker from Java. As far as I know there are no libs which can help me to handle that, so I was trying it through cmd. Here's the code:
public static boolean unlockDisk(String pwd) throws IOException
{
String[] script =
{
"manage-bde.exe", "-unlock", "D:", "-password",
};
Process process = new ProcessBuilder(script).start();
InputStream inputStream = process.getInputStream();
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
final OutputStream outputStream = process.getOutputStream();
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream));
writer.write(pwd);
writer.newLine();
writer.close();
System.out.println("--------------------------------------");
System.out.println("Bitlocker log:");
String line;
while ((line = bufferedReader.readLine()) != null)
{
System.out.println(line);
}
bufferedReader.close();
BufferedReader stdError = new BufferedReader(new InputStreamReader(process.getErrorStream()));
System.out.println("Here is the standard error of the command (if any):\n");
String tmp;
while ((tmp = stdError.readLine()) != null)
{
System.out.println(tmp);
}
System.out.println("--------------------------------------");
return true;
}
My Problem
If I execute this java code I get The handle is invalid with Code 0x80070006.
What I already tried
Different JDK Version 32 and 64 Bit Java 8 and Java 7 (JDK 32 complains somehow that it can't find the command manage-bde)
Different combinations of output streams, with and without newline...
Another script command for the processbuilder like "cmd.exe", "/k", "manage-bde.exe", "-unlock", "D:", "-password", or with /c instead of /k
With and without admin rights
Simple *.bat with the command manage-bde.exe -unlock D: -password (which works perfectly)
Locking the drive through a java command (which works perfectly)
The command without -password (which let's bitlocker claim that I have to define how I want to unlock the drive)
I googled around for some time and found others having this problems but in a different way with other applications. So it seems like a very common error message.
My guess
I think it has something to do with how I handle my Java output as Bitlocker input. Maybe I am using the wrong streams to write to.
I can't provide the value of the password within the script variable, because Bitlocker want doesn't accept that way of entering the password. Usually you enter manage-bde -unlock D: -password within the command line and after a few lines of output Bitlocker asks you for the password.
Well I described it as good as I can and hope that someone knows what the problem is.
Any suggestion, even if it just leads to a more precise error message, would be appreciated. If you have any questions, just let me know!
Thanks in advance!
I encountered same problem recently. I did a lot search. It seems that mange-bde.exe doesn't read user input from stdin. Someone said ssh client and telent clent running on Linux doesn't read password from stdin. Another example Linux command passwd. It has a flag called -stdin which enable the shell to read password from stdin. Therefore, I guessed manage-bde.exe may works in a similar way.
My solution is simulating keyboard input. The awt package can do the job.
This question already has answers here:
Run fortran exe in java
(3 answers)
Closed 8 years ago.
I have a Fortran exe. What I need to do.... I need to call that exe through java in Linux. After that it should ask for input file and output file.
This is my code:
Process process = new ProcessBuilder("/home/admin/Documents/file.out",
"input","output").start();
InputStream is = process.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line;
System.out.printf("Output of running %s is:", Arrays.toString(args));
while ((line = br.readLine()) != null) {
System.out.println(line);
}
It is running but nit asking for input and output file
To call external programms in java you need the java.lang.Runtime package. If you want a more convenient API have a look at Apache Commons Exec.
None of the code you have shown us "asks" anything.
I can see where you are passing two names (are they file names?) to your fortran program. But then it would be up to the fortran program to open those files and do something with them. If that's not happening, then the problem is in the fortran code ...
On the other hand, if your intention is to open the files in the Java code, and pass the file handles to the fortran program (as its standard input and standard output), then your code doesn't attempt to do that. You need to read the javadocs for ProcessBuilder. Pay attention to the stuff about redirecting input and output for the child process.
I use the following code, for redirecting the output of a process I launch from my Java app:
ProcessBuilder builder = new ProcessBuilder("MyProcess.exe");
builder.redirectOutput(Redirect.INHERIT);
builder.redirectErrorStream(true);
Now, this works fine when I run the code from eclipse - I can see the output in Eclipse's console.
Yet when I create a jar file and run it from a cmd window, e.g. java -jar MyJar.jar, it doesn't print the output of the process. What could be the reason for this?
I know I'm late in answering, but I came across this question before coming across the answer, and wanted to save anybody else in the same boat some searching.
This is actually a known bug for Windows: https://bugs.openjdk.java.net/browse/JDK-8023130
You can get around it by redirecting the streams yourself:
Process p = pb.start();
BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = null;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
p.waitFor();
br.close();
It may be, that process is printing an error and exiting for some reason. So, the actual output goes into Err stream and not into the Out stream. Your code redirects Out stream only, so important process error information may be lost. I would suggest to inherit both Out and Err streams using this code:
ProcessBuilder builder = new ProcessBuilder("MyProcess.exe");
builder.inheritIO();
One more reason to redirect both streams is related to the output buffering for child process. If parent process (your java application) is not reading or redirecting standard streams (Out and Err) of the child process, then the latter may be blocked after a while, unable to make any further progress.
It definitely wouldn't hurt to have possible errors in the output anyway.
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Java external program
I am trying to wrtie a program to write a command on a command line,
for example;
ipconfig
and then get the response of the command so I want to both write command to a command line and get its response. I have searched about it on the net and saw that apache cli is used to do this in Java but actually I did not clearly get how it can be done. Can you please help me about my situation with a few line of codes or tutorials about both writing and reading commands please?
Thank you all very much
You could start it as a Process and capture the InputStream of the process as described here:
Runtime runtime = Runtime.getRuntime();
Process process = runtime.exec("ipconfig"); // you might need the full path
InputStream is = process.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
Edit: I copied this code from above link, but the code seems wrong. Don't you need the output stream for this? Edit2: no.
getInputStream()
Gets the input stream of the subprocess. The stream obtains data
piped from the standard output stream of the process represented by
this Process object.
Nice naming convention...
See Process and ProcessBuilder classes.
Specifically, you would create a Process. Process.getOutputStream() gives an InputStream, from which you read what the process's output. You also need to read Process.getErrorStream() for any errors that the process reports.
Try this for inputting the user value.
java.util.Scanner input = new Scanner( System.in);
System.out.println("Please Enter your Name: ");
String empName = input.nextLine();
I'm launching wkhtmltopdf from within my Java app (part of a Tomcat server, running in debug mode within Eclipse Helios on Win7 64-bit): I'd like to wait for it to complete, then Do More Stuff.
String cmd[] = {"wkhtmltopdf", htmlPathIn, pdfPathOut};
Process proc = Runtime.getRuntime().exec( cmd, null );
proc.waitFor();
But waitFor() never returns. I can still see the process in the Windows Task Manager (with the command line I passed to exec(): looks fine). AND IT WORKS. wkhtmltopdf produces the PDF I'd expect, right where I'd expect it. I can open it, rename it, whatever, even while the process is still running (before I manually terminate it).
From the command line, everything is fine:
c:\wrk>wkhtmltopdf C:\Temp\foo.html c:\wrk\foo.pdf
Loading pages (1/6)
Counting pages (2/6)
Resolving links (4/6)
Loading headers and footers (5/6)
Printing pages (6/6)
Done
The process exits just fine, and life goes on.
So what is it about runtime.exec() that's causing wkhtmltopdf to never terminate?
I could grab proc.getInputStream() and look for "Done", but that's... vile. I want something that is more general.
I've calling exec() with and without a working directory. I've tried with and without an empty "env" array. No joy.
Why is my process hanging, and what can I do to fix it?
PS: I've tried this with a couple other command line apps, and they both exhibit the same behavior.
Further exec woes.
I'm trying to read standard out & error, without success. From the command line, I know there's supposed to be something remarkably like my command line experience, but when I read the input stream returned by proc.getInputStream(), I immediately get an EOL (-1, I'm using inputStream.read()).
I checked the JavaDoc for Process, and found this
The parent process uses these streams to feed input to and get output from the subprocess. Because some native platforms only provide limited buffer size for standard input and output streams, failure to promptly write the input stream or read the output stream of the subprocess may cause the [b]subprocess to block, and even deadlock[/b].
Emphasis added. So I tried that. The first 'read()' on the Standard Out inputStream blocked until I killed the process...
WITH WKHTMLTOPDF
With the generic command line ap & no params so it should "dump usage and terminate", it sucks out the appropriate std::out, then terminates.
Interesting!
JVM version issue? I'm using 1.6.0_23. The latest is... v24. I just checked the change log and don't see anything promising, but I'll try updating anyway.
Okay. Don't let the Input Streams fill or they'll block. Check. .close() can also prevent this, but isn't terribly bright.
That works in general (including the generic command line apps I've tested).
In specific however, it falls down. It appears that wkhtmltopdf is using some terminal manipulation/cursor stuff to do an ASCII-graphic progress bar. I believe this is causing the inputStream to immediately return EOF rather than giving me the correct values.
Any ideas? Hardly a deal-breaker, but it would definitely be Nice To Have.
I had the same exact issue as you and I solved it. Here are my findings:
For some reason, the output from wkhtmltopdf goes to STDERR of the process and NOT STDOUT. I have verified this by calling wkhtmltopdf from Java as well as perl
So, for example in java, you would have to do:
//ProcessBuilder is the recommended way of creating processes since Java 1.5
//Runtime.getRuntime().exec() is deprecated. Do not use.
ProcessBuilder pb = new ProcessBuilder("wkhtmltopdf.exe", htmlFilePath, pdfFilePath);
Process process = pb.start();
BufferedReader errStreamReader = new BufferedReader(new InputStreamReader(process.getErrorStream()));
//not "process.getInputStream()"
String line = errStreamReader.readLine();
while(line != null)
{
System.out.println(line); //or whatever else
line = reader.readLine();
}
On a side note, if you spawn a process from java, you MUST read from the stdout and stderr streams (even if you do nothing with it) because otherwise the stream buffer will fill and the process will hang and never return.
To futureproof your code, just in case the devs of wkhtmltopdf decide to write to stdout, you can redirect stderr of the child process to stdout and read only one stream like this:
ProcessBuilder pb = new ProcessBuilder("wkhtmltopdf.exe", htmlFilePath, pdfFilePath);
pb.redirectErrorStream(true);
Process process = pb.start();
BufferedReader inStreamReader = new BufferedReader(new InputStreamReader(process.getInputStream()));
Actually, I do this in all the cases where I have to spawn an external process from java. That way I don't have to read two streams.
You should also read the streams of the spawned process in different threads if you dont want your main thread to block, since reading from streams is blocking.
Hope this helps.
UPDATE: I raised this issue in the project page and was replied that this is by design because wkhtmltopdf supports giving the actual pdf output in STDOUT. Please see the link for more details and java code.
A process has 3 streams: input, output and error. you can read both output and error stream at the same time using separate processes. see this question and its accepted answer and also this one for example.
You should read from the streams in a different thread.
final Semaphore semaphore = new Semaphore(numOfThreads);
final String whktmlExe = tmpwhktmlExePath;
int doccount = 0;
try{
File fileObject = new File(inputDir);
for(final File f : fileObject.listFiles()) {
if(f.getAbsolutePath().endsWith(".html")) {
doccount ++;
if(doccount >500 ) {
LOG.info(" done with conversion of 1000 docs exiting ");
break;
}
System.out.println(" inside for before "+semaphore.availablePermits());
semaphore.acquire();
System.out.println(" inside for after "+semaphore.availablePermits() + " ---" +f.getName());
new java.lang.Thread() {
public void run() {
try {
String F_ = f.getName().replaceAll(".html", ".pdf") ;
ProcessBuilder pb = new ProcessBuilder(whktmlExe , f.getAbsolutePath(), outPutDir + F_ .replaceAll(" ", "_") );//"wkhtmltopdf.exe", htmlFilePath, pdfFilePath);
pb.redirectErrorStream(true);
Process process = pb.start();
BufferedReader errStreamReader = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line = errStreamReader.readLine();
while(line != null)
{
System.err.println(line); //or whatever else
line = errStreamReader.readLine();
}
System.out.println("after completion for ");
} catch (Exception e) {
e.printStackTrace();
}finally {
System.out.println(" in finally releasing ");
semaphore.release();
}
}
}.start();
}
}
}catch (Exception ex) {
LOG.error(" *** Error in pdf generation *** ", ex);
}
while (semaphore.availablePermits() < numOfThreads) {//till all threads finish
LOG.info( " Waiting for all threads to exit "+ semaphore.availablePermits() + " --- " +( numOfThreads - semaphore.availablePermits()));
java.lang.Thread.sleep(10000);
}