diff options
Diffstat (limited to 'simple/simple-transport/src/main/java/org/simpleframework/transport/TransportReader.java')
-rw-r--r-- | simple/simple-transport/src/main/java/org/simpleframework/transport/TransportReader.java | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/simple/simple-transport/src/main/java/org/simpleframework/transport/TransportReader.java b/simple/simple-transport/src/main/java/org/simpleframework/transport/TransportReader.java new file mode 100644 index 0000000..713c162 --- /dev/null +++ b/simple/simple-transport/src/main/java/org/simpleframework/transport/TransportReader.java @@ -0,0 +1,229 @@ +/* + * TransportReader.java February 2007 + * + * Copyright (C) 2007, Niall Gallagher <niallg@users.sf.net> + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or + * implied. See the License for the specific language governing + * permissions and limitations under the License. + */ + +package org.simpleframework.transport; + +import java.io.IOException; +import java.nio.ByteBuffer; + +/** + * The <code>TransportReader</code> object represents a reader that + * can read and buffer data from an underlying transport. If the + * number of bytes read from the reader is more than required for + * the HTTP request then those bytes can be pushed back in to the + * cursor using the <code>reset</code> method. This will only allow + * the last read to be reset within the cursor safely. + * + * @author Niall Gallagher + * + * @see org.simpleframework.transport.Transport + */ +class TransportReader implements ByteReader { + + /** + * This is the underlying transport to read the bytes from. + */ + private Transport transport; + + /** + * This is used to store the bytes read from the transport. + */ + private ByteBuffer buffer; + + /** + * This is used to determine if the transport has been closed. + */ + private boolean closed; + + /** + * This represents the number of bytes that are ready to read. + */ + private int count; + + /** + * Constructor for the <code>TransportReader</code> object. This + * requires a transport to read the bytes from. By default this + * will create a buffer of two kilobytes to read the input in to + * which ensures several requests can be read at once. + * + * @param transport this is the underlying transport to use + */ + public TransportReader(Transport transport) { + this(transport, 2048); + } + + /** + * Constructor for the <code>TransportReader</code> object. This + * requires a transport to read the bytes from. By default this + * will create a buffer of of the specified size to read the + * input in to which enabled bytes to be buffered internally. + * + * @param transport this is the underlying transport to use + * @param size this is the size of the internal buffer to use + */ + public TransportReader(Transport transport, int size) { + this.buffer = ByteBuffer.allocate(size); + this.transport = transport; + } + + /** + * Determines whether the source is still open. The source is + * considered open if there are still bytes to read. If there is + * still bytes buffered and the underlying transport is closed + * then the source is still considered open. + * + * @return true if there is nothing more to be read from this + */ + public boolean isOpen() throws IOException { + return count != -1; + } + + /** + * Determines whether the source is ready for reading. When the + * source is ready then it guarantees that some amount of bytes + * can be read from the underlying stream without blocking. + * + * @return true if some data can be read without blocking + */ + public boolean isReady() throws IOException { + return ready() > 0; + } + + /** + * Reads a block of bytes from the underlying stream. This will + * read up to the requested number of bytes from the underlying + * stream. If there are no ready bytes on the stream this can + * return zero, representing the fact that nothing was read. + * + * @param data this is the array to read the bytes in to + * + * @return this returns the number of bytes read from the stream + */ + public int read(byte[] data) throws IOException { + return read(data, 0, data.length); + } + + /** + * Reads a block of bytes from the underlying stream. This will + * read up to the requested number of bytes from the underlying + * stream. If there are no ready bytes on the stream this can + * return zero, representing the fact that nothing was read. + * + * @param data this is the array to read the bytes in to + * @param off this is the offset to begin writing the bytes to + * @param len this is the number of bytes that are requested + * + * @return this returns the number of bytes read from the stream + */ + public int read(byte[] data, int off, int len) throws IOException { + if(count <= 0) { // has the channel ended + return count; + } + int size = Math.min(len, count); // get the minimum + + if(size > 0) { + buffer.get(data, off, size); // get the bytes + count -= size; + } + return Math.max(0, size); + } + + /** + * Provides the number of bytes that can be read from the stream + * without blocking. This is typically the number of buffered or + * available bytes within the stream. When this reaches zero then + * the source may perform a blocking read. + * + * @return the number of bytes that can be read without blocking + */ + public int ready() throws IOException { + if(count < 0) { + return count; + } + if(count > 0) { // if the are ready bytes don't read + return count; + } + return peek(); + } + + /** + * Provides the number of bytes that can be read from the stream + * without blocking. This is typically the number of buffered or + * available bytes within the stream. When this reaches zero then + * the source may perform a blocking read. + * + * @return the number of bytes that can be read without blocking + */ + private int peek() throws IOException { + if(count <= 0) { // reset the buffer for filling + buffer.clear(); + } + if(count > 0) { + buffer.compact(); // compact the buffer + } + count += transport.read(buffer); // how many were read + + if(count > 0) { + buffer.flip(); // if there is something then flip + } + if(count < 0) { // close when stream is fully read + close(); + } + return count; + } + + /** + * Moves the source backward within the stream. This ensures + * that any bytes read from the last read can be pushed back + * in to the stream so that they can be read again. This will + * throw an exception if the reset can not be performed. + * + * @param size this is the number of bytes to reset back + * + * @return this is the number of bytes that have been reset + */ + public int reset(int size) throws IOException { + int mark = buffer.position(); + + if(size > mark) { + size = mark; + } + if(mark > 0) { + buffer.position(mark - size); + count += size; + } + return size; + } + + /** + * This is used to close the underlying transport. This is used + * when the transport returns a negative value, indicating that + * the client has closed the connection on the other side. If + * this is invoked the read method returns -1 and the reader + * is no longer open, further bytes can no longer be read. + */ + public void close() throws IOException { + if(!closed) { + transport.close(); + closed = true; + count = -1; + } + } +} + + |