| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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.apache.tomcat.util.http.fileupload; |
| |
| import java.io.IOException; |
| import java.io.OutputStream; |
| |
| |
| /** |
| * An output stream which triggers an event when a specified number of bytes of |
| * data have been written to it. The event can be used, for example, to throw |
| * an exception if a maximum has been reached, or to switch the underlying |
| * stream type when the threshold is exceeded. |
| * <p> |
| * This class overrides all <code>OutputStream</code> methods. However, these |
| * overrides ultimately call the corresponding methods in the underlying output |
| * stream implementation. |
| * <p> |
| * NOTE: This implementation may trigger the event <em>before</em> the threshold |
| * is actually reached, since it triggers when a pending write operation would |
| * cause the threshold to be exceeded. |
| */ |
| public abstract class ThresholdingOutputStream |
| extends OutputStream |
| { |
| |
| // ----------------------------------------------------------- Data members |
| |
| |
| /** |
| * The threshold at which the event will be triggered. |
| */ |
| private final int threshold; |
| |
| |
| /** |
| * The number of bytes written to the output stream. |
| */ |
| private long written; |
| |
| |
| /** |
| * Whether or not the configured threshold has been exceeded. |
| */ |
| private boolean thresholdExceeded; |
| |
| |
| // ----------------------------------------------------------- Constructors |
| |
| |
| /** |
| * Constructs an instance of this class which will trigger an event at the |
| * specified threshold. |
| * |
| * @param threshold The number of bytes at which to trigger an event. |
| */ |
| public ThresholdingOutputStream(final int threshold) |
| { |
| this.threshold = threshold; |
| } |
| |
| |
| // --------------------------------------------------- OutputStream methods |
| |
| |
| /** |
| * Writes the specified byte to this output stream. |
| * |
| * @param b The byte to be written. |
| * |
| * @throws IOException if an error occurs. |
| */ |
| @Override |
| public void write(final int b) throws IOException |
| { |
| checkThreshold(1); |
| getStream().write(b); |
| written++; |
| } |
| |
| |
| /** |
| * Writes <code>b.length</code> bytes from the specified byte array to this |
| * output stream. |
| * |
| * @param b The array of bytes to be written. |
| * |
| * @throws IOException if an error occurs. |
| */ |
| @Override |
| public void write(final byte b[]) throws IOException |
| { |
| checkThreshold(b.length); |
| getStream().write(b); |
| written += b.length; |
| } |
| |
| |
| /** |
| * Writes <code>len</code> bytes from the specified byte array starting at |
| * offset <code>off</code> to this output stream. |
| * |
| * @param b The byte array from which the data will be written. |
| * @param off The start offset in the byte array. |
| * @param len The number of bytes to write. |
| * |
| * @throws IOException if an error occurs. |
| */ |
| @Override |
| public void write(final byte b[], final int off, final int len) throws IOException |
| { |
| checkThreshold(len); |
| getStream().write(b, off, len); |
| written += len; |
| } |
| |
| |
| /** |
| * Flushes this output stream and forces any buffered output bytes to be |
| * written out. |
| * |
| * @throws IOException if an error occurs. |
| */ |
| @Override |
| public void flush() throws IOException |
| { |
| getStream().flush(); |
| } |
| |
| |
| /** |
| * Closes this output stream and releases any system resources associated |
| * with this stream. |
| * |
| * @throws IOException if an error occurs. |
| */ |
| @Override |
| public void close() throws IOException |
| { |
| try |
| { |
| flush(); |
| } |
| catch (final IOException ignored) |
| { |
| // ignore |
| } |
| getStream().close(); |
| } |
| |
| |
| // --------------------------------------------------------- Public methods |
| |
| |
| /** |
| * Determines whether or not the configured threshold has been exceeded for |
| * this output stream. |
| * |
| * @return {@code true} if the threshold has been reached; |
| * {@code false} otherwise. |
| */ |
| public boolean isThresholdExceeded() |
| { |
| return written > threshold; |
| } |
| |
| |
| // ------------------------------------------------------ Protected methods |
| |
| |
| /** |
| * Checks to see if writing the specified number of bytes would cause the |
| * configured threshold to be exceeded. If so, triggers an event to allow |
| * a concrete implementation to take action on this. |
| * |
| * @param count The number of bytes about to be written to the underlying |
| * output stream. |
| * |
| * @throws IOException if an error occurs. |
| */ |
| protected void checkThreshold(final int count) throws IOException |
| { |
| if (!thresholdExceeded && written + count > threshold) |
| { |
| thresholdExceeded = true; |
| thresholdReached(); |
| } |
| } |
| |
| // ------------------------------------------------------- Abstract methods |
| |
| |
| /** |
| * Returns the underlying output stream, to which the corresponding |
| * <code>OutputStream</code> methods in this class will ultimately delegate. |
| * |
| * @return The underlying output stream. |
| * |
| * @throws IOException if an error occurs. |
| */ |
| protected abstract OutputStream getStream() throws IOException; |
| |
| |
| /** |
| * Indicates that the configured threshold has been reached, and that a |
| * subclass should take whatever action necessary on this event. This may |
| * include changing the underlying output stream. |
| * |
| * @throws IOException if an error occurs. |
| */ |
| protected abstract void thresholdReached() throws IOException; |
| } |