package com.atlassian.gzipfilter.util;
   
   import com.atlassian.gzipfilter.flushable.FlushableGZIPOutputStream;
   
   import java.io.IOException;
   import java.io.OutputStream;
   import java.lang.reflect.Constructor;
   import java.lang.reflect.InvocationTargetException;
   import java.util.zip.GZIPOutputStream;
  
  /**
   * Factory for creating flushable GZIP output streams. Easy in JDK7+, more difficult in earlier JDKs.
   */
  public class FlushableGZIPOutputStreamFactory
  {
      private static final Constructor JDK7_CONSTRUCTOR;
      static
      {
          Constructor ctor = null;
          try
          {
              ctor = GZIPOutputStream.class.getConstructor(OutputStream.class, Integer.TYPE, Boolean.TYPE);
          }
          catch (NoSuchMethodException e) {
              // that's fine, we'll fall back
          }
          JDK7_CONSTRUCTOR = ctor;
      }
      public static GZIPOutputStream makeFlushableGZIPOutputStream(OutputStream out, int bufferSize) throws IOException
      {
          if (JDK7_CONSTRUCTOR == null)
          {
              return new FlushableGZIPOutputStream(out, bufferSize);
          }
          else
          {
              try {
                  return (GZIPOutputStream) JDK7_CONSTRUCTOR.newInstance(out, bufferSize, true);
              } catch (InstantiationException e) {
                  throw new IOException(e);
              } catch (IllegalAccessException e) {
                  throw new IOException(e);
              } catch (InvocationTargetException e) {
                  throw new IOException(e);
              }
          }
      }
  }