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  /*
  * JBoss, Home of Professional Open Source
  * Copyright 2005, JBoss Inc., and individual contributors as indicated
  * by the @authors tag. See the copyright.txt in the distribution for a
  * full listing of individual contributors.
  *
  * This is free software; you can redistribute it and/or modify it
  * under the terms of the GNU Lesser General Public License as
  * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
 
 package org.jboss.remoting.stream;
 
 import  org.jboss.logging.Logger;
 
This is the server side proxy back to the orginal stream on the client side. It implements InputStream, so can be passed and acted on by the server handler as a regular InputStream type. For all the InputStream methods, it should behave EXACTLY like a local InputStream with the one exception being that it will sometimes throw IOExceptions based on network exceptions or in the case when the method does not throw an IOException, throwing a RuntimeException if network problem (however none of the method signatures are changed).

Internally, it will use remoting to callback to the client.

Author(s):
Tom Elrod
 
 public class StreamHandler extends InputStream //implements InvocationHandler
 {
    private InvokerLocator streamServerLocator = null;
    private Client streamClient = null;
 
    private static final Logger log = Logger.getLogger(StreamHandler.class);
 
    // The remoting invocation methods the match the InputStream metnhods.
    public static final String READ = "read()";
    public static final String AVAILABLE = "available()";
    public static final String CLOSE = "close()";
    public static final String RESET = "reset()";
    public static final String MARKSUPPORTED = "markSupported()";
    public static final String MARKREADLIMIT = "mark(int readlimit)";
    public static final String SKIP = "skip(long n)";
    public static final String READBYTEARRAY = "read(byte b[])";
    public static final String READOFFSET = "read(byte b[], int off, int len)";

   
Constructor requiring the locator url back to the client's StreamServer connector (actually the connector's server invoker).

Parameters:
locatorURL
Throws:
Exception
 
    //private StreamHandler(String locatorURL) throws Exception
    public StreamHandler(String locatorURLthrows Exception
    {
        = new InvokerLocator(locatorURL);
        = new Client();
       .connect();
    }

   
Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream. The next caller might be the same thread or or another thread.

The available method for class InputStream always returns 0.

This method should be overridden by subclasses.

Returns:
the number of bytes that can be read from this input stream without blocking.
Throws:
java.io.IOException if an I/O error occurs.
 
    public int available() throws IOException
    {
       int readInt = 0;
 
       try
      {
         Integer retInt = (Integer.invoke(new StreamCallPayload());
         if(retInt != null)
         {
            readInt = retInt.intValue();
         }
      }
      catch(Throwable throwable)
      {
         .debug("Error getting available from client stream."throwable);
         throw new IOException(throwable.getMessage());
      }
      return readInt;
   }

   
Closes this input stream and releases any system resources associated with the stream.

The close method of InputStream does nothing.

Throws:
java.io.IOException if an I/O error occurs.
   public void close() throws IOException
   {
      try
      {
         .invoke(new StreamCallPayload());
      }
      catch(Throwable throwable)
      {
         .debug("Error closing client stream."throwable);
         throw new IOException(throwable.getMessage());
      }
   }

   
Repositions this stream to the position at the time the mark method was last called on this input stream.

The general contract of reset is:

  • If the method markSupported returns true, then:

    • If the method mark has not been called since the stream was created, or the number of bytes read from the stream since mark was last called is larger than the argument to mark at that last call, then an IOException might be thrown.

    • If such an IOException is not thrown, then the stream is reset to a state such that all the bytes read since the most recent call to mark (or since the start of the file, if mark has not been called) will be resupplied to subsequent callers of the read method, followed by any bytes that otherwise would have been the next input data as of the time of the call to reset.

  • If the method markSupported returns false, then:

    • The call to reset may throw an IOException.

    • If an IOException is not thrown, then the stream is reset to a fixed state that depends on the particular type of the input stream and how it was created. The bytes that will be supplied to subsequent callers of the read method depend on the particular type of the input stream.

The method reset for class InputStream does nothing and always throws an IOException.

Throws:
java.io.IOException if this stream has not been marked or if the mark has been invalidated.
See also:
java.io.InputStream.mark(int)
java.io.IOException
   public synchronized void reset() throws IOException
   {
      try
      {
         .invoke(new StreamCallPayload());
      }
      catch(Throwable throwable)
      {
         .debug("Error reseting client stream."throwable);
         throw new IOException(throwable.getMessage());
      }
   }

   
Tests if this input stream supports the mark and reset methods. Whether or not mark and reset are supported is an invariant property of a particular input stream instance. The markSupported method of InputStream returns false.

Returns:
true if this stream instance supports the mark and reset methods; false otherwise.
See also:
java.io.InputStream.mark(int)
java.io.InputStream.reset()
   public boolean markSupported()
   {
      boolean supported = false;
      try
      {
         Boolean bSupported = (Boolean.invoke(new StreamCallPayload());
         if(bSupported != null)
         {
            supported = bSupported.booleanValue();
         }
      }
      catch(Throwable throwable)
      {
         .debug("Error getting markSupported from client stream."throwable);
         throw new RuntimeException(throwable.getMessage(), throwable);
      }
      return supported;
   }

   
Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

The readlimit arguments tells this input stream to allow that many bytes to be read before the mark position gets invalidated.

The general contract of mark is that, if the method markSupported returns true, the stream somehow remembers all the bytes read after the call to mark and stands ready to supply those same bytes again if and whenever the method reset is called. However, the stream is not required to remember any data at all if more than readlimit bytes are read from the stream before reset is called.

The mark method of InputStream does nothing.

Parameters:
readlimit the maximum limit of bytes that can be read before the mark position becomes invalid.
See also:
java.io.InputStream.reset()
   public synchronized void mark(int readlimit)
   {
      try
      {
         StreamCallPayload payload = new StreamCallPayload();
         payload.setParams(new Object[]{new Integer(readlimit)});
         .invoke(payload);
      }
      catch(Throwable throwable)
      {
         .debug("Error marking with read limit on client stream."throwable);
         throw new RuntimeException(throwable.getMessage(), throwable);
      }
   }

   
Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped.

The skip method of InputStream creates a byte array and then repeatedly reads into it until n bytes have been read or the end of the stream has been reached. Subclasses are encouraged to provide a more efficient implementation of this method.

Parameters:
n the number of bytes to be skipped.
Returns:
the actual number of bytes skipped.
Throws:
java.io.IOException if an I/O error occurs.
   public long skip(long nthrows IOException
   {
      long numSkipped = -1;
      try
      {
         StreamCallPayload payload = new StreamCallPayload();
         payload.setParams(new Object[]{new Long(n)});
         Long ret = (Long.invoke(payload);
         if(ret != null)
         {
            numSkipped = ret.longValue();
         }
      }
      catch(Throwable throwable)
      {
         .debug("Error skipping on client stream."throwable);
         throw new IOException(throwable.getMessage());
      }
      return numSkipped;
   }

   
Reads some number of bytes from the input stream and stores them into the buffer array b. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown. If the length of b is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[0], the next one into b[1], and so on. The number of bytes read is, at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be stored in elements b[0] through b[k-1], leaving elements b[k] through b[b.length-1] unaffected.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

The read(b) method for class InputStream has the same effect as:

 read(b, 0, b.length) 

Parameters:
b the buffer into which the data is read.
Returns:
the total number of bytes read into the buffer, or -1 is there is no more data because the end of the stream has been reached.
Throws:
java.io.IOException if an I/O error occurs.
NullPointerException if b is null.
See also:
java.io.InputStream.read(byte[], int, int)
   public int read(byte b[]) throws IOException
   {
      if(b == null)
      {
         throw new NullPointerException("can not read for a null byte array.");
      }
      else
      {
         if(b.length == 0)
         {
            return 0;
         }
      }
      int retByte = -1;
      try
      {
         StreamCallPayload payload = new StreamCallPayload();
         payload.setParams(new Object[]{b});
         StreamCallPayload ret = (StreamCallPayload.invoke(payload);
         if(ret != null)
         {
            Object[] retVals = ret.getParams();
            byte[] retBytes = (byte[]) retVals[0];
            Integer retInt = (IntegerretVals[1];
            retByte = retInt.intValue();
            if(retByte != -1)
            {
               System.arraycopy(retBytes, 0, b, 0, retByte);
            }
         }
      }
      catch(Throwable throwable)
      {
         .debug("Error reading from client stream."throwable);
         throw new IOException(throwable.getMessage());
      }
      return retByte;
   }

   
Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read, possibly zero. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown.

If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. Subclasses are encouraged to provide a more efficient implementation of this method.

Parameters:
b the buffer into which the data is read.
off the start offset in array b at which the data is written.
len the maximum number of bytes to read.
Returns:
the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
Throws:
java.io.IOException if an I/O error occurs.
NullPointerException if b is null.
See also:
java.io.InputStream.read()
   public int read(byte b[], int offint lenthrows IOException
   {
      if(b == null)
      {
         throw new NullPointerException("can not read for a null byte array.");
      }
      else
      {
         if(b.length == 0)
         {
            return 0;
         }
         else
         {
            if(off < 0 || len < 0 || off + len > b.length)
            {
               throw new IndexOutOfBoundsException("Either off or len is negative or off+len is greater than length of b.");
            }
            if(len == 0)
            {
               return 0;
            }
         }
      }
      int retByte = -1;
      try
      {
         byte[] payloadArray = new byte[len];
         StreamCallPayload payload = new StreamCallPayload();
         payload.setParams(new Object[]{payloadArray});
         StreamCallPayload ret = (StreamCallPayload.invoke(payload);
         if(ret != null)
         {
            Object[] retVals = ret.getParams();
            byte[] retBytes = (byte[]) retVals[0];
            Integer retInt = (IntegerretVals[1];
            retByte = retInt.intValue();
            if(retByte != -1)
            {
               System.arraycopy(retBytes, 0, boffretByte);
            }
         }
      }
      catch(Throwable throwable)
      {
         .debug("Error reading with offset from client stream."throwable);
         throw new IOException(throwable.getMessage());
      }
      return retByte;
   }

   
Reads the next byte of data from the input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

A subclass must provide an implementation of this method.

Returns:
the next byte of data, or -1 if the end of the stream is reached.
Throws:
java.io.IOException if an I/O error occurs.
   public int read() throws IOException
   {
      int readInt = -1;
      try
      {
         Integer retInt = (Integer.invoke(new StreamCallPayload());
         if(retInt != null)
         {
            readInt = retInt.intValue();
         }
      }
      catch(Throwable throwable)
      {
         .debug("Error reading from client stream."throwable);
         throw new IOException(throwable.getMessage());
      }
      return readInt;
   }
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