src/be/nikiroo/fanfix/library/RemoteLibraryException.java

   1 package be.nikiroo.fanfix.library;
   2
   3 import java.io.IOException;
   4
   5 /**
   6  * Exceptions sent from remote to local.
   7  *
   8  * @author niki
   9  */
  10 public class RemoteLibraryException extends IOException {
  11         private static final long serialVersionUID = 1L;
  12
  13         private boolean wrapped;
  14
  15         @SuppressWarnings("unused")
  16         private RemoteLibraryException() {
  17                 // for serialization purposes
  18         }
  19
  20         /**
  21          * Wrap an {@link IOException} to allow it to pass across the network.
  22          *
  23          * @param cause
  24          *            the exception to wrap
  25          * @param remote
  26          *            this exception is used to send the contained
  27          *            {@link IOException} to the other end of the network
  28          */
  29         public RemoteLibraryException(IOException cause, boolean remote) {
  30                 this(null, cause, remote);
  31         }
  32
  33         /**
  34          * Wrap an {@link IOException} to allow it to pass across the network.
  35          *
  36          * @param message
  37          *            the error message
  38          * @param wrapped
  39          *            this exception is used to send the contained
  40          *            {@link IOException} to the other end of the network
  41          */
  42         public RemoteLibraryException(String message, boolean wrapped) {
  43                 this(message, null, wrapped);
  44         }
  45
  46         /**
  47          * Wrap an {@link IOException} to allow it to pass across the network.
  48          *
  49          * @param message
  50          *            the error message
  51          * @param cause
  52          *            the exception to wrap
  53          * @param wrapped
  54          *            this exception is used to send the contained
  55          *            {@link IOException} to the other end of the network
  56          */
  57         public RemoteLibraryException(String message, IOException cause,
  58                         boolean wrapped) {
  59                 super(message, cause);
  60                 this.wrapped = wrapped;
  61         }
  62
  63         /**
  64          * Return the actual exception we should return to the client code. It can
  65          * be:
  66          * <ul>
  67          * <li>the <tt>cause</tt> if {@link RemoteLibraryException#isWrapped()} is
  68          * TRUE</li>
  69          * <li><tt>this</tt> if {@link RemoteLibraryException#isWrapped()} is FALSE
  70          * (</li>
  71          * <li><tt>this</tt> if the <tt>cause</tt> is NULL (so we never return NULL)
  72          * </li>
  73          * </ul>
  74          * It is never NULL.
  75          *
  76          * @return the unwrapped exception or <tt>this</tt>, never NULL
  77          */
  78         public synchronized IOException unwrapException() {
  79                 Throwable ex = super.getCause();
  80                 if (!isWrapped() || !(ex instanceof IOException)) {
  81                         ex = this;
  82                 }
  83
  84                 return (IOException) ex;
  85         }
  86
  87         /**
  88          * This exception is used to send the contained {@link IOException} to the
  89          * other end of the network.
  90          * <p>
  91          * In other words, do not use <tt>this</tt> exception in client code when it
  92          * has reached the other end of the network, but use its cause instead (see
  93          * {@link RemoteLibraryException#unwrapException()}).
  94          *
  95          * @return TRUE if it is
  96          */
  97         public boolean isWrapped() {
  98                 return wrapped;
  99         }
 100 }