Package org.apache.commons.launcher
Class Launcher
java.lang.Object
org.apache.commons.launcher.Launcher
- All Implemented Interfaces:
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:
- You want to avoid having to determining where certain application paths are e.g. your application's home directory, etc. Determining this dynamically in a Windows batch scripts is very tricky on some versions of Windows or when softlinks are used on Unix platforms.
- You need to enforce certain properties e.g. java.endorsed.dirs when running with JDK 1.4.
- You want to allow users to pass in custom JVM arguments or system properties without having to parse and reorder arguments in your script. This can be tricky and/or messy in batch and shell scripts.
- You want to bootstrap Java properties from a configuration file instead hard-coding them in your batch and shell scripts.
- You want to provide localized error messages which is very tricky to do in batch and shell scripts.
- Author:
- Patrick Luby
-
Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionstatic void
Print a detailed error message and exit.static void
Print a detailed error message and exit.static File
Get the canonical directory of the class or jar file that this class was loaded.static File
Get the canonical directory or jar file that this class was loaded from.static String
Get the full path of the Java command to execute.static String
Get the full path of the JDB 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
Set the classpath to the current JVM's tools classes.static boolean
Get the started flag.static boolean
Get the stopped flag.static void
Iterate through the list of synchronous child process launched by all of theLaunchTask
instances.void
run()
Wrapper to allow thekillChildProcesses()
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 the launching process.static boolean
stop()
Interrupt thestart(String[])
method.
-
Field Details
-
SUPPORTED_ANT_TASKS
List of supported Ant tasks. -
SUPPORTED_ANT_TYPES
List of supported Ant types.
-
-
Constructor Details
-
Launcher
public Launcher()
-
-
Method Details
-
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
Start the launching process. This method is essential themain(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:
IllegalArgumentException
- if any error parsing the args parameter occurs
-
stop
public static boolean stop()Interrupt thestart(String[])
method. This is done by forcing the current or next scheduled invocation of theLaunchTask.execute()
method to throw an exception. In addition, this method will terminate any synchronous child processes that any instances of theLaunchTask
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 thestart(String[])
method.- Returns:
- true if this method completed without error and false if an error occurred or the launch process is already stopped
-
error
Print a detailed error message and exit.- Parameters:
message
- the message to be printedusage
- if true, print a usage statement after the message
-
error
Print a detailed error message and exit.- Parameters:
message
- the exception whose stack trace is to be printed.
-
getBootstrapDir
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:
IOException
- if the canonical directory or jar file cannot be found
-
getBootstrapFile
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:
IOException
- if the canonical directory or jar file cannot be found
-
getJavaCommand
Get the full path of the Java command to execute.- Returns:
- a string suitable for executing a child JVM
-
getJDBCommand
Get the full path of the JDB command to execute.- Returns:
- a string suitable for executing a child JDB debugger
-
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
Set the classpath to the current JVM's tools classes.- Returns:
- a string suitable for use as a JVM's -classpath argument
- Throws:
IOException
- if the tools classes cannot be found
-
getLocalizedString
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
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 retrieveclassName
- the name of the class to retrieve the property for- Returns:
- the localized and resolved property value
-
setLog
Set the PrintStream that all output should printed to.- Parameters:
a
- PrintStream instance to print output 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 theLaunchTask
instances. -
run
public void run()Wrapper to allow thekillChildProcesses()
method to be invoked in a shutdown hook.
-