scala.reflect.internal.util.ScalaClassLoader.scala Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of scala-reflect Show documentation
Show all versions of scala-reflect Show documentation
Compiler for the Scala Programming Language
/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Paul Phillips
*/
package scala
package reflect.internal.util
import scala.language.implicitConversions
import java.lang.{ ClassLoader => JClassLoader }
import java.lang.reflect.Modifier
import java.net.{ URLClassLoader => JURLClassLoader }
import java.net.URL
import scala.reflect.runtime.ReflectionUtils.{ show, unwrapHandler }
import ScalaClassLoader._
import scala.util.control.Exception.{ catching }
import scala.reflect.{ ClassTag, classTag }
trait HasClassPath {
def classPathURLs: Seq[URL]
}
/** A wrapper around java.lang.ClassLoader to lower the annoyance
* of java reflection.
*/
trait ScalaClassLoader extends JClassLoader {
/** Executing an action with this classloader as context classloader */
def asContext[T](action: => T): T = {
val saved = contextLoader
try { setContext(this) ; action }
finally setContext(saved)
}
def setAsContext() { setContext(this) }
/** Load and link a class with this classloader */
def tryToLoadClass[T <: AnyRef](path: String): Option[Class[T]] = tryClass(path, initialize = false)
/** Load, link and initialize a class with this classloader */
def tryToInitializeClass[T <: AnyRef](path: String): Option[Class[T]] = tryClass(path, initialize = true)
private def tryClass[T <: AnyRef](path: String, initialize: Boolean): Option[Class[T]] =
catching(classOf[ClassNotFoundException], classOf[SecurityException]) opt
Class.forName(path, initialize, this).asInstanceOf[Class[T]]
/** Create an instance of a class with this classloader */
def create(path: String): AnyRef =
tryToInitializeClass[AnyRef](path).map(_.newInstance()).orNull
/** Create an instance with ctor args, or invoke errorFn before throwing. */
def create[T <: AnyRef : ClassTag](path: String, errorFn: String => Unit)(args: AnyRef*): T = {
def fail(msg: String) = error(msg, new IllegalArgumentException(msg))
def error(msg: String, e: Throwable) = { errorFn(msg) ; throw e }
try {
val clazz = Class.forName(path, /*initialize =*/ true, /*loader =*/ this)
if (classTag[T].runtimeClass isAssignableFrom clazz) {
val ctor = {
val maybes = clazz.getConstructors filter (c => c.getParameterCount == args.size &&
(c.getParameterTypes zip args).forall { case (k, a) => k isAssignableFrom a.getClass })
if (maybes.size == 1) maybes.head
else fail(s"Constructor must accept arg list (${args map (_.getClass.getName) mkString ", "}): ${path}")
}
(ctor.newInstance(args: _*)).asInstanceOf[T]
} else {
errorFn(s"""Loader for ${classTag[T]}: [${show(classTag[T].runtimeClass.getClassLoader)}]
|Loader for ${clazz.getName}: [${show(clazz.getClassLoader)}]""".stripMargin)
fail(s"Not a ${classTag[T]}: ${path}")
}
} catch {
case e: ClassNotFoundException =>
error(s"Class not found: ${path}", e)
case e @ (_: LinkageError | _: ReflectiveOperationException) =>
error(s"Unable to create instance: ${path}: ${e.toString}", e)
}
}
/** The actual bytes for a class file, or an empty array if it can't be found. */
def classBytes(className: String): Array[Byte] = classAsStream(className) match {
case null => Array()
case stream => scala.reflect.io.Streamable.bytes(stream)
}
/** An InputStream representing the given class name, or null if not found. */
def classAsStream(className: String) = getResourceAsStream {
if (className endsWith ".class") className
else s"${className.replace('.', '/')}.class" // classNameToPath
}
/** Run the main method of a class to be loaded by this classloader */
def run(objectName: String, arguments: Seq[String]) {
val clsToRun = tryToInitializeClass(objectName) getOrElse (
throw new ClassNotFoundException(objectName)
)
val method = clsToRun.getMethod("main", classOf[Array[String]])
if (!Modifier.isStatic(method.getModifiers))
throw new NoSuchMethodException(objectName + ".main is not static")
try asContext(method.invoke(null, Array(arguments.toArray: AnyRef): _*)) // !!! : AnyRef shouldn't be necessary
catch unwrapHandler({ case ex => throw ex })
}
}
/** Methods for obtaining various classloaders.
* appLoader: the application classloader. (Also called the java system classloader.)
* extLoader: the extension classloader.
* bootLoader: the boot classloader.
* contextLoader: the context classloader.
*/
object ScalaClassLoader {
/** Returns loaders which are already ScalaClassLoaders unaltered,
* and translates java.net.URLClassLoaders into scala URLClassLoaders.
* Otherwise creates a new wrapper.
*/
implicit def apply(cl: JClassLoader): ScalaClassLoader = cl match {
case cl: ScalaClassLoader => cl
case cl: JURLClassLoader => new URLClassLoader(cl.getURLs.toSeq, cl.getParent)
case _ => new JClassLoader(cl) with ScalaClassLoader
}
def contextLoader = apply(Thread.currentThread.getContextClassLoader)
def appLoader = apply(JClassLoader.getSystemClassLoader)
def setContext(cl: JClassLoader) =
Thread.currentThread.setContextClassLoader(cl)
def savingContextLoader[T](body: => T): T = {
val saved = contextLoader
try body
finally setContext(saved)
}
class URLClassLoader(urls: Seq[URL], parent: JClassLoader)
extends JURLClassLoader(urls.toArray, parent)
with ScalaClassLoader
with HasClassPath {
private var classloaderURLs: Seq[URL] = urls
def classPathURLs: Seq[URL] = classloaderURLs
/** Override to widen to public */
override def addURL(url: URL) = {
classloaderURLs :+= url
super.addURL(url)
}
override def close(): Unit = {
super.close()
classloaderURLs = null
}
}
def fromURLs(urls: Seq[URL], parent: ClassLoader = null): URLClassLoader =
new URLClassLoader(urls, parent)
/** True if supplied class exists in supplied path */
def classExists(urls: Seq[URL], name: String): Boolean =
(fromURLs(urls) tryToLoadClass name).isDefined
/** Finding what jar a clazz or instance came from */
def originOfClass(x: Class[_]): Option[URL] =
Option(x.getProtectionDomain.getCodeSource) flatMap (x => Option(x.getLocation))
}