org.springframework.boot.loader.Launcher Maven / Gradle / Ivy
/*
* Copyright 2012-2014 the original author or authors.
*
* 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.
*/
package org.springframework.boot.loader;
import java.io.File;
import java.lang.reflect.Constructor;
import java.net.URI;
import java.net.URL;
import java.security.CodeSource;
import java.security.ProtectionDomain;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;
import org.springframework.boot.loader.archive.Archive;
import org.springframework.boot.loader.archive.ExplodedArchive;
import org.springframework.boot.loader.archive.JarFileArchive;
import org.springframework.boot.loader.jar.JarFile;
/**
* Base class for launchers that can start an application with a fully configured
* classpath backed by one or more {@link Archive}s.
*
* @author Phillip Webb
* @author Dave Syer
*/
public abstract class Launcher {
protected Logger logger = Logger.getLogger(Launcher.class.getName());
/**
* The main runner class. This must be loaded by the created ClassLoader so cannot be
* directly referenced.
*/
private static final String RUNNER_CLASS = Launcher.class.getPackage().getName()
+ ".MainMethodRunner";
/**
* Launch the application. This method is the initial entry point that should be
* called by a subclass {@code public static void main(String[] args)} method.
* @param args the incoming arguments
*/
protected void launch(String[] args) {
try {
JarFile.registerUrlProtocolHandler();
ClassLoader classLoader = createClassLoader(getClassPathArchives());
launch(args, getMainClass(), classLoader);
}
catch (Exception ex) {
ex.printStackTrace();
System.exit(1);
}
}
/**
* Create a classloader for the specified archives.
* @param archives the archives
* @return the classloader
* @throws Exception
*/
protected ClassLoader createClassLoader(List archives) throws Exception {
List urls = new ArrayList(archives.size());
for (Archive archive : archives) {
// Add the current archive at end (it will be reversed and end up taking
// precedence)
urls.add(archive.getUrl());
}
return createClassLoader(urls.toArray(new URL[urls.size()]));
}
/**
* Create a classloader for the specified URLs
* @param urls the URLs
* @return the classloader
* @throws Exception
*/
protected ClassLoader createClassLoader(URL[] urls) throws Exception {
return new LaunchedURLClassLoader(urls, getClass().getClassLoader());
}
/**
* Launch the application given the archive file and a fully configured classloader.
* @param args the incoming arguments
* @param mainClass the main class to run
* @param classLoader the classloader
* @throws Exception
*/
protected void launch(String[] args, String mainClass, ClassLoader classLoader)
throws Exception {
Runnable runner = createMainMethodRunner(mainClass, args, classLoader);
Thread runnerThread = new Thread(runner);
runnerThread.setContextClassLoader(classLoader);
runnerThread.setName(Thread.currentThread().getName());
runnerThread.start();
}
/**
* Create the {@code MainMethodRunner} used to launch the application.
* @param mainClass the main class
* @param args the incoming arguments
* @param classLoader the classloader
* @return a runnable used to start the application
* @throws Exception
*/
protected Runnable createMainMethodRunner(String mainClass, String[] args,
ClassLoader classLoader) throws Exception {
Class runnerClass = classLoader.loadClass(RUNNER_CLASS);
Constructor constructor = runnerClass.getConstructor(String.class,
String[].class);
return (Runnable) constructor.newInstance(mainClass, args);
}
/**
* Returns the main class that should be launched.
* @return the name of the main class
* @throws Exception
*/
protected abstract String getMainClass() throws Exception;
/**
* Returns the archives that will be used to construct the class path.
* @return the class path archives
* @throws Exception
*/
protected abstract List getClassPathArchives() throws Exception;
protected final Archive createArchive() throws Exception {
ProtectionDomain protectionDomain = getClass().getProtectionDomain();
CodeSource codeSource = protectionDomain.getCodeSource();
URI location = (codeSource == null ? null : codeSource.getLocation().toURI());
String path = (location == null ? null : location.getSchemeSpecificPart());
if (path == null) {
throw new IllegalStateException("Unable to determine code source archive");
}
File root = new File(path);
if (!root.exists()) {
throw new IllegalStateException(
"Unable to determine code source archive from " + root);
}
return (root.isDirectory() ? new ExplodedArchive(root) : new JarFileArchive(root));
}
}