org.apache.commons.launcher

Class Launcher

Implemented Interfaces:
Runnable

public class Launcher
extends java.lang.Object
implements Runnable

A class that is used to launch a Java process. The primary purpose of this class is to eliminate the need for a batch or shell script to launch a Java process. Some situations where elimination of a batch or shell script may be desirable are:

Author:
Patrick Luby

Field Summary

static Object[]
SUPPORTED_ANT_TASKS
List of supported Ant tasks.
static Object[]
SUPPORTED_ANT_TYPES
List of supported Ant types.

Method Summary

static void
error(String message, boolean usage)
Print a detailed error message and exit.
static void
error(Throwable t)
Print a detailed error message and exit.
static File
getBootstrapDir()
Get the canonical directory of the class or jar file that this class was loaded.
static File
getBootstrapFile()
Get the canonical directory or jar file that this class was loaded from.
static String
getJDBCommand()
Get the full path of the JDB command to execute.
static String
getJavaCommand()
Get the full path of the Java command to execute.
static String
getLocalizedString(String key)
Get a localized property.
static String
getLocalizedString(String key, String className)
Get a localized property.
static PrintStream
getLog()
Get the PrintStream that all output should printed to.
static String
getToolsClasspath()
Set the classpath to the current JVM's tools classes.
static boolean
isStarted()
Get the started flag.
static boolean
isStopped()
Get the stopped flag.
static void
killChildProcesses()
Iterate through the list of synchronous child process launched by all of the LaunchTask instances.
void
run()
Wrapper to allow the killChildProcesses() method to be invoked in a shutdown hook.
static void
setLog(PrintStream log)
Set the PrintStream that all output should printed to.
static void
setVerbose(boolean verbose)
Set the verbose flag.
static int
start(String[] args)
Start the launching process.
static boolean
stop()
Interrupt the start(String[]) method.

Field Details

SUPPORTED_ANT_TASKS

public static final Object[] SUPPORTED_ANT_TASKS
List of supported Ant tasks.


SUPPORTED_ANT_TYPES

public static final Object[] SUPPORTED_ANT_TYPES
List of supported Ant types.

Method Details

error

public static void error(String message,
                         boolean usage)
Print a detailed error message and exit.

Parameters:
message - the message to be printed
usage - if true, print a usage statement after the message


error

public static void error(Throwable t)
Print a detailed error message and exit.

Parameters:


getBootstrapDir

public static File getBootstrapDir()
            throws IOException
Get the canonical directory of the class or jar file that this class was loaded. This method can be used to calculate the root directory of an installation.

Returns:
the canonical directory of the class or jar file that this class file was loaded from


getBootstrapFile

public static File getBootstrapFile()
            throws IOException
Get the canonical directory or jar file that this class was loaded from.

Returns:
the canonical directory or jar file that this class file was loaded from


getJDBCommand

public static String getJDBCommand()
Get the full path of the JDB command to execute.

Returns:
a string suitable for executing a child JDB debugger


getJavaCommand

public static String getJavaCommand()
Get the full path of the Java command to execute.

Returns:
a string suitable for executing a child JVM


getLocalizedString

public static String getLocalizedString(String key)
Get a localized property. This method will search for localized properties and will resolve ${...} style macros in the localized string.

Parameters:
key - the localized property to retrieve

Returns:
the localized and resolved property value


getLocalizedString

public static String getLocalizedString(String key,
                                        String className)
Get a localized property. This method will search for localized properties and will resolve ${...} style macros in the localized string.

Parameters:
key - the localized property to retrieve
className - the name of the class to retrieve the property for

Returns:
the localized and resolved property value


getLog

public static PrintStream getLog()
Get the PrintStream that all output should printed to. The default PrintStream returned in System.err.

Returns:
the PrintStream instance to print output to


getToolsClasspath

public static String getToolsClasspath()
            throws IOException
Set the classpath to the current JVM's tools classes.

Returns:
a string suitable for use as a JVM's -classpath argument


isStarted

public static boolean isStarted()
Get the started flag.

Returns:
the value of the started flag


isStopped

public static boolean isStopped()
Get the stopped flag.

Returns:
the value of the stopped flag


killChildProcesses

public static void killChildProcesses()


run

public void run()
Wrapper to allow the killChildProcesses() method to be invoked in a shutdown hook.


setLog

public static void setLog(PrintStream log)
Set the PrintStream that all output should printed to.

Parameters:


setVerbose

public static void setVerbose(boolean verbose)
Set the verbose flag.

Parameters:
verbose - the value of the verbose flag


start

public static int start(String[] args)
            throws IllegalArgumentException
Start the launching process. This method is essential the main(String[]) method for this class except that this method never invokes System.exit(int). This method is designed for applications that wish to invoke this class directly from within their application's code.

Parameters:
args - command line arguments

Returns:
the exit value of the last synchronous child JVM that was launched or 1 if any other error occurs


stop

public static boolean stop()
Interrupt the start(String[]) method. This is done by forcing the current or next scheduled invocation of the LaunchTask.execute() method to throw an exception. In addition, this method will terminate any synchronous child processes that any instances of the LaunchTask class have launched. Note, however, that this method will not terminate any asynchronous child processes that have been launched. Accordingly, applications that use this method are encouraged to always set the LaunchTask.TASK_NAME task's "waitForChild" attribute to "true" to ensure that the application that you want to control can be terminated via this method. After this method has been executed, it will not return until is safe to execute the start(String[]) method.

Returns:
true if this method completed without error and false if an error occurred or the launch process is already stopped


Copyright (c) 2001-2002 - Apache Software Foundation