org.codehaus.plexus.classworlds.launcher.Launcher Maven / Gradle / Ivy
package org.codehaus.plexus.classworlds.launcher;
/*
* Copyright 2001-2006 Codehaus Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.net.MalformedURLException;
import java.net.URL;
import org.codehaus.plexus.classworlds.ClassWorld;
import org.codehaus.plexus.classworlds.realm.ClassRealm;
import org.codehaus.plexus.classworlds.realm.DuplicateRealmException;
import org.codehaus.plexus.classworlds.realm.NoSuchRealmException;
/**
* Command-line invokable application launcher.
*
* This launcher class assists in the creation of classloaders and ClassRealms
* from a configuration file and the launching of the application's main
* method from the correct class loaded through the correct classloader.
*
* The path to the configuration file is specified using the classworlds.conf
* system property, typically specified using the -D switch to
* java.
*
* @author bob mcwhirter
*/
public class Launcher
{
protected static final String CLASSWORLDS_CONF = "classworlds.conf";
protected static final String UBERJAR_CONF_DIR = "WORLDS-INF/conf/";
protected ClassLoader systemClassLoader;
protected String mainClassName;
protected String mainRealmName;
protected ClassWorld world;
private int exitCode = 0;
public Launcher()
{
this.systemClassLoader = Thread.currentThread().getContextClassLoader();
}
public void setSystemClassLoader( ClassLoader loader )
{
this.systemClassLoader = loader;
}
public ClassLoader getSystemClassLoader()
{
return this.systemClassLoader;
}
public int getExitCode()
{
return exitCode;
}
public void setAppMain( String mainClassName,
String mainRealmName )
{
this.mainClassName = mainClassName;
this.mainRealmName = mainRealmName;
}
public String getMainRealmName()
{
return this.mainRealmName;
}
public String getMainClassName()
{
return this.mainClassName;
}
public void setWorld( ClassWorld world )
{
this.world = world;
}
public ClassWorld getWorld()
{
return this.world;
}
/**
* Configure from a file.
*
* @param is The config input stream.
* @throws IOException If an error occurs reading the config file.
* @throws MalformedURLException If the config file contains invalid URLs.
* @throws ConfigurationException If the config file is corrupt.
* @throws org.codehaus.plexus.classworlds.realm.DuplicateRealmException If the config file defines two realms
* with the same id.
* @throws org.codehaus.plexus.classworlds.realm.NoSuchRealmException If the config file defines a main entry
* point in a non-existent realm.
*/
public void configure( InputStream is )
throws IOException, ConfigurationException, DuplicateRealmException, NoSuchRealmException
{
Configurator configurator = new Configurator( this );
configurator.configure( is );
}
/**
* Retrieve the main entry class.
*
* @return The main entry class.
* @throws ClassNotFoundException If the class cannot be found.
* @throws NoSuchRealmException If the specified main entry realm does not exist.
*/
public Class getMainClass()
throws ClassNotFoundException, NoSuchRealmException
{
return getMainRealm().loadClass( getMainClassName() );
}
/**
* Retrieve the main entry realm.
*
* @return The main entry realm.
* @throws NoSuchRealmException If the specified main entry realm does not exist.
*/
public ClassRealm getMainRealm()
throws NoSuchRealmException
{
return getWorld().getRealm( getMainRealmName() );
}
/**
* Retrieve the enhanced main entry method.
*
* @return The enhanced main entry method.
* @throws ClassNotFoundException If the main entry class cannot be found.
* @throws NoSuchMethodException If the main entry method cannot be found.
* @throws NoSuchRealmException If the main entry realm cannot be found.
*/
protected Method getEnhancedMainMethod()
throws ClassNotFoundException, NoSuchMethodException, NoSuchRealmException
{
Class cwClass = getMainRealm().loadClass( ClassWorld.class.getName() );
Method m = getMainClass().getMethod( "main", new Class[]{String[].class, cwClass} );
int modifiers = m.getModifiers();
if ( Modifier.isStatic( modifiers ) && Modifier.isPublic( modifiers ) )
{
if ( m.getReturnType() == Integer.TYPE || m.getReturnType() == Void.TYPE )
{
return m;
}
}
throw new NoSuchMethodException( "public static void main(String[] args, ClassWorld world)" );
}
/**
* Retrieve the main entry method.
*
* @return The main entry method.
* @throws ClassNotFoundException If the main entry class cannot be found.
* @throws NoSuchMethodException If the main entry method cannot be found.
* @throws NoSuchRealmException If the main entry realm cannot be found.
*/
protected Method getMainMethod()
throws ClassNotFoundException, NoSuchMethodException, NoSuchRealmException
{
Method m = getMainClass().getMethod( "main", new Class[]{String[].class} );
int modifiers = m.getModifiers();
if ( Modifier.isStatic( modifiers ) && Modifier.isPublic( modifiers ) )
{
if ( m.getReturnType() == Integer.TYPE || m.getReturnType() == Void.TYPE )
{
return m;
}
}
throw new NoSuchMethodException( "public static void main(String[] args) in " + getMainClass() );
}
/**
* Launch the application.
*
* @param args The application args.
* @throws ClassNotFoundException If the main entry class cannot be found.
* @throws IllegalAccessException If the method cannot be accessed.
* @throws InvocationTargetException If the target of the invokation is invalid.
* @throws NoSuchMethodException If the main entry method cannot be found.
* @throws NoSuchRealmException If the main entry realm cannot be found.
*/
public void launch( String[] args )
throws ClassNotFoundException, IllegalAccessException, InvocationTargetException, NoSuchMethodException,
NoSuchRealmException
{
try
{
launchEnhanced( args );
return;
}
catch ( NoSuchMethodException e )
{
// ignore
}
launchStandard( args );
}
/**
* Attempt to launch the application through the enhanced main method.
*
* This will seek a method with the exact signature of:
*
* public static void main(String[] args, ClassWorld world)
*
*
* @param args The application args.
* @throws ClassNotFoundException If the main entry class cannot be found.
* @throws IllegalAccessException If the method cannot be accessed.
* @throws InvocationTargetException If the target of the invokation is
* invalid.
* @throws NoSuchMethodException If the main entry method cannot be found.
* @throws NoSuchRealmException If the main entry realm cannot be found.
*/
protected void launchEnhanced( String[] args )
throws ClassNotFoundException, IllegalAccessException, InvocationTargetException, NoSuchMethodException,
NoSuchRealmException
{
ClassRealm mainRealm = getMainRealm();
Class mainClass = getMainClass();
Method mainMethod = getEnhancedMainMethod();
ClassLoader cl = mainRealm;
// ----------------------------------------------------------------------
// This is what the classloader for the main realm looks like when we
// boot from the command line:
// ----------------------------------------------------------------------
// [ AppLauncher$AppClassLoader ] : $CLASSPATH envar
// ^
// |
// |
// [ AppLauncher$ExtClassLoader ] : ${java.home}/jre/lib/ext/*.jar
// ^
// |
// |
// [ Strategy ]
// ----------------------------------------------------------------------
Thread.currentThread().setContextClassLoader( cl );
Object ret = mainMethod.invoke( mainClass, new Object[]{args, getWorld()} );
if ( ret instanceof Integer )
{
exitCode = ( (Integer) ret ).intValue();
}
Thread.currentThread().setContextClassLoader( systemClassLoader );
}
/**
* Attempt to launch the application through the standard main method.
*
* This will seek a method with the exact signature of:
*
* public static void main(String[] args)
*
*
* @param args The application args.
* @throws ClassNotFoundException If the main entry class cannot be found.
* @throws IllegalAccessException If the method cannot be accessed.
* @throws InvocationTargetException If the target of the invokation is
* invalid.
* @throws NoSuchMethodException If the main entry method cannot be found.
* @throws NoSuchRealmException If the main entry realm cannot be found.
*/
protected void launchStandard( String[] args )
throws ClassNotFoundException, IllegalAccessException, InvocationTargetException, NoSuchMethodException,
NoSuchRealmException
{
ClassRealm mainRealm = getMainRealm();
Class mainClass = getMainClass();
Method mainMethod = getMainMethod();
Thread.currentThread().setContextClassLoader( mainRealm );
Object ret = mainMethod.invoke( mainClass, new Object[]{args} );
if ( ret instanceof Integer )
{
exitCode = ( (Integer) ret ).intValue();
}
Thread.currentThread().setContextClassLoader( systemClassLoader );
}
// ------------------------------------------------------------
// Class methods
// ------------------------------------------------------------
/**
* Launch the launcher from the command line.
* Will exit using System.exit with an exit code of 0 for success, 100 if there was an unknown exception,
* or some other code for an application error.
*
* @param args The application command-line arguments.
*/
public static void main( String[] args )
{
try
{
int exitCode = mainWithExitCode( args );
System.exit( exitCode );
}
catch ( Exception e )
{
e.printStackTrace();
System.exit( 100 );
}
}
/**
* Launch the launcher.
*
* @param args The application command-line arguments.
* @return an integer exit code
* @throws Exception If an error occurs.
*/
public static int mainWithExitCode( String[] args )
throws Exception
{
String classworldsConf = System.getProperty( CLASSWORLDS_CONF );
InputStream is;
Launcher launcher = new Launcher();
ClassLoader cl = Thread.currentThread().getContextClassLoader();
launcher.setSystemClassLoader( cl );
if ( classworldsConf != null )
{
is = new FileInputStream( classworldsConf );
}
else
{
if ( "true".equals( System.getProperty( "classworlds.bootstrapped" ) ) )
{
is = cl.getResourceAsStream( UBERJAR_CONF_DIR + CLASSWORLDS_CONF );
}
else
{
is = cl.getResourceAsStream( CLASSWORLDS_CONF );
}
}
if ( is == null )
{
throw new Exception( "classworlds configuration not specified nor found in the classpath" );
}
launcher.configure( is );
is.close();
try
{
launcher.launch( args );
}
catch ( InvocationTargetException e )
{
ClassRealm realm = launcher.getWorld().getRealm( launcher.getMainRealmName() );
URL[] constituents = realm.getURLs();
System.out.println( "---------------------------------------------------" );
for ( int i = 0; i < constituents.length; i++ )
{
System.out.println( "constituent[" + i + "]: " + constituents[i] );
}
System.out.println( "---------------------------------------------------" );
// Decode ITE (if we can)
Throwable t = e.getTargetException();
if ( t instanceof Exception )
{
throw (Exception) t;
}
if ( t instanceof Error )
{
throw (Error) t;
}
// Else just toss the ITE
throw e;
}
return launcher.getExitCode();
}
}