Launcher (Commons Launcher 1.2-SNAPSHOT API)

java.lang.Object
- org.apache.commons.launcher.Launcher

All Implemented Interfaces:

Runnable
```
public class Launcher
extends 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:
- 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
Modifier and Type Field and Description

static Object[] SUPPORTED_ANT_TASKS
List of supported Ant tasks.

static Object[] SUPPORTED_ANT_TYPES
List of supported Ant types.

Fields
Modifier and Type	Field and Description
`static Object[]`	`SUPPORTED_ANT_TASKS` List of supported Ant tasks.
`static Object[]`	`SUPPORTED_ANT_TYPES` List of supported Ant types.

Constructor Summary

Constructors
Constructor and Description

Launcher()

Constructors
Constructor and Description
`Launcher()`

Method Summary

Methods
Modifier and Type	Method and Description
`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`	`getJavaCommand()` Get the full path of the Java command to execute.
`static String`	`getJDBCommand()` 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`	`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.

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 Object[] SUPPORTED_ANT_TASKS
```
    List of supported Ant tasks.
  - SUPPORTED_ANT_TYPES
```
public static final 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(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 Throws: 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(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: t - the exception whose stack trace is to be printed. 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 Throws: IOException - if the canonical directory or jar file cannot be found 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 Throws: IOException - if the canonical directory or jar file cannot be found getJavaCommand public static String getJavaCommand() Get the full path of the Java command to execute. Returns: a string suitable for executing a child JVM 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 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 Throws: IOException - if the tools classes cannot be found 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 setLog public static void setLog(PrintStream log) Set the PrintStream that all output should printed to. Parameters: log - 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 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 Runnable

Class Launcher

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

SUPPORTED_ANT_TASKS

SUPPORTED_ANT_TYPES

Constructor Detail

Launcher

Method Detail

isStarted

isStopped

start

stop

error

error

getBootstrapDir

getBootstrapFile

getJavaCommand

getJDBCommand

getLog

getToolsClasspath

getLocalizedString

getLocalizedString

setLog

setVerbose

killChildProcesses

run