org.apache.commons.launcher
Class Launcher

java.lang.Object
  |
  +--org.apache.commons.launcher.Launcher
All Implemented Interfaces:
java.lang.Runnable

public class Launcher
extends java.lang.Object
implements java.lang.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 java.lang.Object[] SUPPORTED_ANT_TASKS
          List of supported Ant tasks.
static java.lang.Object[] SUPPORTED_ANT_TYPES
          List of supported Ant types.
 
Constructor Summary
Launcher()
           
 
Method Summary
static void error(java.lang.String message, boolean usage)
          Print a detailed error message and exit.
static void error(java.lang.Throwable t)
          Print a detailed error message and exit.
static java.io.File getBootstrapDir()
          Get the canonical directory of the class or jar file that this class was loaded.
static java.io.File getBootstrapFile()
          Get the canonical directory or jar file that this class was loaded from.
static java.lang.String getJavaCommand()
          Get the full path of the Java command to execute.
static java.lang.String getJDBCommand()
          Get the full path of the JDB command to execute.
static java.lang.String getLocalizedString(java.lang.String key)
          Get a localized property.
static java.lang.String getLocalizedString(java.lang.String key, java.lang.String className)
          Get a localized property.
static java.io.PrintStream getLog()
          Get the PrintStream that all output should printed to.
static java.lang.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(java.io.PrintStream log)
          Set the PrintStream that all output should printed to.
static void setVerbose(boolean verbose)
          Set the verbose flag.
static int start(java.lang.String[] args)
          Start the launching process.
static boolean stop()
          Interrupt the start(String[]) method.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

SUPPORTED_ANT_TASKS

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


SUPPORTED_ANT_TYPES

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

Constructor Detail

Launcher

public Launcher()
Method Detail

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

start

public static int start(java.lang.String[] args)
                 throws java.lang.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
Throws:
java.lang.IllegalArgumentException - if any error parsing the args parameter 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

error

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


getBootstrapDir

public static java.io.File getBootstrapDir()
                                    throws java.io.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
Throws:
java.io.IOException - if the canonical directory or jar file cannot be found

getBootstrapFile

public static java.io.File getBootstrapFile()
                                     throws java.io.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
Throws:
java.io.IOException - if the canonical directory or jar file cannot be found

getJavaCommand

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

Returns:
a string suitable for executing a child JVM

getJDBCommand

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

Returns:
a string suitable for executing a child JDB debugger

getLog

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

Returns:
a string suitable for use as a JVM's -classpath argument
Throws:
java.io.IOException - if the tools classes cannot be found

getLocalizedString

public static java.lang.String getLocalizedString(java.lang.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 java.lang.String getLocalizedString(java.lang.String key,
                                                  java.lang.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

setLog

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


setVerbose

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

Parameters:
verbose - the value of the verbose flag

killChildProcesses

public static void killChildProcesses()
Iterate through the list of synchronous child process launched by all of the LaunchTask instances.


run

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

Specified by:
run in interface java.lang.Runnable


Copyright (c) 2001-2002 - Apache Software Foundation