JarCastingprocessoutput4j
Simple Java library for capturing stdout/stderr of processes launched from within Java.
Maven
Add the following artifact to your dependencies of your pom.xml:
<dependency>
<groupId>com.github.fracpete</groupId>
<artifactId>processoutput4j</artifactId>
<version>0.0.11</version>
</dependency>
Available schemes
The following schemes for capturing process output are available:
CollectingProcessOutput- collects all the output and makes it available once the process has finishedConsoleOutputProcessOutput- simply outputs the process' output from stdout and stderr to the Java process' stdout and stderr as it occurrs rather than waiting till the process finishes.StreamingProcessOutput- requires an owner object that implements theStreamingProcessOwnerinterface, as it will receive the output collected from stdout/stderr for further processing in the owner.
Stopping
The AbstractProcessOutput class offers the destroy() method, which allows a currently running process to be killed off from another thread (the monitor methods are waiting for the process to finish).
Extending
Adding a new scheme for capturing the process output is quite simple. You basically need to implement two classes:
- a reader class, derived from
AbstractProcessReaderthat does something with the data obtained from stdout and stderr of the process. - an output class, derived from
AbstractProcessOutputthat instantiates the appropriate readers for stdout and stderr.
Examples
The following executes the process and outputs any data from stdout/stderr once the process has finished:
import com.github.fracpete.processoutput4j.output.ConsoleOutputProcessOutput;
...
String[] cmd = new String[]{"/bin/ls", "-la", "/some/where"};
ProcessBuilder builder = new ProcessBuilder();
builder.command(cmd);
new ConsoleOutputProcessOutput().monitor(builder);
The following executes the process and outputs any data from stdout/stderr once the process has finished:
import com.github.fracpete.processoutput4j.output.CollectingProcessOutput;
...
String[] cmd = new String[]{"/bin/ls", "-la", "/some/where"};
ProcessBuilder builder = new ProcessBuilder();
builder.command(cmd);
CollectingProcessOutput output = new CollectingProcessOutput();
output.monitor(builder);
System.out.println("exit code: " + output.getExitCode());
System.out.println(output.getStdOut());
The following executes the process and outputs any data from stdout/stderr as it occurs, as well as setting a maximum execution time of 10 seconds:
import com.github.fracpete.processoutput4j.output.CollectingProcessOutput;
...
String[] cmd = new String[]{"/usr/bin/find", "/"};
ProcessBuilder builder = new ProcessBuilder();
builder.command(cmd);
ConsoleOutputProcessOutput output = new ConsoleOutputProcessOutput();
output.setTimeOut(10);
output.monitor(builder);
You can use the hasTimedOut() method to check whether the process timed out.
If you want to process the output (stdout/stderr) from the process yourself, then you can use StreamingProcessOutput instead of ConsoleOutputProcessOutput. You only need to supply an object of a class implementing the StreamingProcessOwner interface. Below is an example that simply prefixes the output with either [OUT] or [ERR]:
import com.github.fracpete.processoutput4j.core.StreamingProcessOutputType;
import com.github.fracpete.processoutput4j.core.StreamingProcessOwner;
import com.github.fracpete.processoutput4j.output.StreamingProcessOutput;
public static class Output implements StreamingProcessOwner {
public StreamingProcessOutputType getOutputType() {
return StreamingProcessOutputType.BOTH;
}
public void processOutput(String line, boolean stdout) {
System.out.println((stdout ? "[OUT] " : "[ERR] ") + line);
}
}
...
String[] cmd = new String[]{"/usr/bin/find", "/etc"};
ProcessBuilder builder = new ProcessBuilder();
builder.command(cmd);
StreamingProcessOutput output = new StreamingProcessOutput(new Output());
output.monitor(builder);
Instead of implementing StreamingProcessOwner yourself, you can use one of the following implementations:
-
com.github.fracpete.processoutput4j.core.impl.PrefixedStreamingProcessOwnerForwards the stdout/stderr output of the monitored process to this one's stdout, using either default prefixes for stdout/stderr or user-supplied ones (like the above example).
-
com.github.fracpete.processoutput4j.core.impl.SimpleStreamingProcessOwnerForwards the stdout/stderr output of the monitored process to this one's stdout/stderr.