Example of delegation

delegate.groovy

import org.apache.commons.fileupload.FileItem
import org.apache.commons.fileupload.FileItemHeaders

class StoredFile implements FileItem {
  String contentType = 'text/plain'
  File artifact
 
  @Override void            delete()         { throw new UnsupportedOperationException( 'Cannot call delete on a wrapped File' ) }
  @Override byte[]          get()            { artifact.bytes }
  @Override String          getContentType() { contentType }
  @Override String          getFieldName()   { null }
  @Override String          getName()        { artifact.name }
  @Override long            getSize()        { artifact.length() }
  @Override String          getString()      { artifact.text }
  @Override boolean         isFormField()    { false }
  @Override boolean         isInMemory()     { false }
  @Override FileItemHeaders getHeaders()     { null }

  @Override void setHeaders( FileItemHeaders pHeaders ) { }
  @Override void setFieldName( String s )               { }
  @Override void setFormField( boolean b )              { }

  @Override InputStream getInputStream() throws IOException {
    artifact.newInputStream()
  }
 
  @Override
  OutputStream getOutputStream() throws IOException {
    artifact.newOutputStream()
  }

  @Override
  String getString(String charset) throws UnsupportedEncodingException {
    artifact.getText( charset )
  }
 
  @Override
  void write(File file) throws Exception {
    file.withOutputStream { ous ->
      artifact.withInputStream { ins ->
        ous << ins
      }
    }
  }
}