Play Framework/Scala example source code file (ClassFinder.scala)

This example Play Framework source code file (ClassFinder.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Play Framework (and Scala) source code examples by using tags.

All credit for the original source code belongs to Play Framework; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Play Framework tags/keywords

api, array, boolean, classfinder, classloader, jarentry, jarinputstream, lib, library, loading, play framework, set, string, url, web service, ws

The ClassFinder.scala Play Framework example source code

/*
 *
 *  * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 *
 */
package play.api.libs.ws.ssl.debug

import java.net.{ URLConnection, URL }
import java.util.jar.{ JarEntry, JarInputStream }

/**
 * Loads a set of classes from a package (including ones which are NOT already in the classloader)
 * and return the set that
 */
trait ClassFinder {

  def logger: org.slf4j.Logger

  /**
   * A resource (in a jar file, usually) in the format "/java/lang/String.class".  This returns
   * an initial URL that leads to the JAR file we search for classes.
   */
  def initialResource: String

  /**
   * Returns true if this is a "valid" class, i.e. one we want to return in a set.  Note that all
   * found classes are loaded into the current thread's classloader, even they are not returned.
   *
   * @param className
   * @return true if this class should be returned in the set of findClasses, false otherwise.
   */
  def isValidClass(className: String): Boolean

  def findClasses: Set[Class[_]] = {
    logger.debug(s"findClasses: using initialResource = ${initialResource}")

    val classSet = scala.collection.mutable.Set[Class[_]]()
    val classLoader: ClassLoader = Thread.currentThread.getContextClassLoader

    val urlToSource: URL = this.getClass.getResource(initialResource)
    logger.debug(s"findClasses: urlToSource = ${urlToSource}")

    val parts: Array[String] = urlToSource.toString.split("!")
    val jarURLString: String = parts(0).replace("jar:", "")

    logger.debug(s"findClasses: Loading from ${jarURLString}")

    val jar: URL = new URL(jarURLString)
    val jarConnection: URLConnection = jar.openConnection
    val jis: JarInputStream = new JarInputStream(jarConnection.getInputStream)
    try {
      var je: JarEntry = jis.getNextJarEntry
      while (je != null) {
        if (!je.isDirectory) {
          var className: String = je.getName.substring(0, je.getName.length - 6)
          className = className.replace('/', '.')
          if (isValidClass(className)) {
            //logger.debug(s"findClasses: adding valid class ${className}")

            val c: Class[_] = classLoader.loadClass(className)
            classSet.add(c)
          }
        }
        je = jis.getNextJarEntry
      }
    } finally {
      jis.close()
    }
    classSet.toSet
  }
}