package  test;

 import  java.io.*;

 public   class  ReadFileToArray {
   public   static   void  main(String[] args)  throws  IOException {
    ByteArrayOutputStream baos =  new  ByteArrayOutputStream();

    File file =  new  File("c:\\test.gif");
    FileInputStream fis =  new  FileInputStream(file);
     byte [] buf =  new   byte [ 1024 ];
     int  readed;
     while  ((readed = fis.read(buf)) != - 1 ) {
      baos.write(buf,  0 , readed);
    }
    fis.close();

     byte [] data = baos.toByteArray();
    System.out.println(data.length);
  }
}

      class  NetworkClassLoader  extends  ClassLoader {
         String host;
          int  port;

          public   Class  findClass(String name) {
              byte [] b = loadClassData(name);
              return  defineClass(name, b,  0 , b.length);
         }

          private   byte [] loadClassData(String name) {
             // load the class data from the connection
              . . .
         }
     }