org.fife.rsta.ac.IOUtil Maven / Gradle / Ivy
/*
* 05/11/2010
*
* Copyright (C) 2010 Robert Futrell
* robert_futrell at users.sourceforge.net
* http://fifesoft.com/rsyntaxtextarea
*
* This library is distributed under a modified BSD license. See the included
* LICENSE.md file for details.
*/
package org.fife.rsta.ac;
import java.io.IOException;
import java.io.InputStream;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* I/O related utility methods. We should think of a better location for
* these methods.
*
* @author Robert Futrell
* @version 1.0
*/
public final class IOUtil {
private static Map defaultEnv;
/**
* Private constructor to prevent instantiation.
*/
private IOUtil() {
}
/**
* Gets the environment of the current process.
*
* @return A mapping of environment variable names to values.
*/
private static Map getDefaultEnvMap() {
// If we've already created it...
if (defaultEnv !=null) {
return defaultEnv;
}
try {
defaultEnv = System.getenv();
} catch (SecurityException e) { // In an applet perhaps?
defaultEnv = Collections.emptyMap();
}
return defaultEnv;
}
/**
* Returns the value of an environment variable. This method is here so
* we don't get an exception when calling System.getenv() in Java
* 1.4 (which we support).
*
* @param var The environment variable.
* @return The value of the variable, or null if it is not
* defined.
*/
public static String getEnvSafely(String var) {
String value = null;
try {
value = System.getenv(var);
} catch (SecurityException e) { // In an applet perhaps?
// Swallow
}
return value;
}
/**
* Returns the environment of the current process, with some variables
* possibly added/overwritten. This method works even with Java 1.4.
*
* @param toAdd The environment variables to add/overwrite in the returned
* array. This array should have an even length, with even indices
* containing variable names and odd indices containing the variable
* values.
* @return The environment variables. This array's entries will be of the
* form "name=value", so it can be passed directly
* into Runtime.exec().
*/
public static String[] getEnvironmentSafely(String[] toAdd) {
Map env = getDefaultEnvMap();
// Put any vars they want to explicitly specify
if (toAdd!=null) {
Map temp = new HashMap<>(env);
for (int i=0; i entry : env.entrySet()) {
vars[i++] = entry.getKey() + "=" + entry.getValue();
}
return vars;
}
/**
* Runs a process, possibly capturing its stdout and/or stderr.
*
* @param p The process.
* @param stdout A buffer in which to put stdout, or null if
* you don't want to keep it.
* @param stderr A buffer in which to keep stderr, or null
* if you don't want to keep it.
* @return The return code of the process.
* @throws IOException If an IO error occurs.
*/
// TODO: Allow a timeout to be passed in
public static int waitForProcess(Process p, StringBuilder stdout,
StringBuilder stderr) throws IOException {
InputStream in = p.getInputStream();
InputStream err = p.getErrorStream();
Thread t1 = new Thread(new OutputCollector(in, stdout));
Thread t2 = new Thread(new OutputCollector(err, stderr));
t1.start();
t2.start();
int rc = -1;
try {
rc = p.waitFor();
t1.join();
t2.join();
} catch (InterruptedException ie) {
p.destroy();
} finally {
in.close();
err.close();
}
return rc;
}
/**
* Utility testing method.
*
* @param args Command line arguments.
*/
public static void main(String[] args) {
for (String arg : args) {
String value = IOUtil.getEnvSafely(arg);
System.out.println(arg + "=" + value);
}
}
}