Read classes from pageckage

PackageClassReader

package rel


object PackageClassReaderDemo extends App{

  println(PackageClassReader.getClassNamesFromPackage("org.apache.spark.examples","/Users/xfwu/hadoop/workspace/app/app.jar").mkString("\n"))
}

object PackageClassReader {
  def getClassNamesFromPackage(packageName: String,file:String): Seq[String] = {
    val names = new scala.collection.mutable.ListBuffer[String]

    val packagePath = packageName.replace(".", "/")
    if(file.endsWith("jar")){

      // build jar file name, then loop through zipped entries
      val jf = new java.util.jar.JarFile(file)
      val jarEntries = jf.entries()
      while(jarEntries.hasMoreElements()){
        val entryName = jarEntries.nextElement().getName()
        if(entryName.startsWith(packagePath) && entryName.length()>packagePath.length()+5 && !entryName.endsWith("/")){
          names += entryName//entryName.substring(packagePath.length()+1,entryName.lastIndexOf('.'))
        }
      }

      // loop through files in classpath
    } else{
      val folder = new java.io.File(file+"/"+packagePath);
      // won't work with path which contains blank (%20)
      // File folder = new File(packageURL.getFile());
      val clzs =
        folder.listFiles().map{ actual =>
          actual.getName
          //entryName.substring(0, entryName.lastIndexOf('.'))
        }
      names ++= clzs
    }

    names
  }
}