| /* |
| * 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.commons.io.input; |
| |
| import static org.apache.commons.io.IOUtils.EOF; |
| |
| import java.io.FilterInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| import org.apache.commons.io.IOUtils; |
| |
| /** |
| * A Proxy stream which acts as expected, that is it passes the method |
| * calls on to the proxied stream and doesn't change which methods are |
| * being called. |
| * <p> |
| * It is an alternative base class to FilterInputStream |
| * to increase reusability, because FilterInputStream changes the |
| * methods being called, such as read(byte[]) to read(byte[], int, int). |
| * </p> |
| * <p> |
| * See the protected methods for ways in which a subclass can easily decorate |
| * a stream with custom pre-, post- or error processing functionality. |
| * </p> |
| */ |
| public abstract class ProxyInputStream extends FilterInputStream { |
| |
| /** |
| * Constructs a new ProxyInputStream. |
| * |
| * @param proxy the InputStream to delegate to |
| */ |
| public ProxyInputStream(final InputStream proxy) { |
| super(proxy); |
| // the proxy is stored in a protected superclass variable named 'in' |
| } |
| |
| /** |
| * Invoked by the {@code read} methods after the proxied call has returned |
| * successfully. The number of bytes returned to the caller (or -1 if |
| * the end of stream was reached) is given as an argument. |
| * <p> |
| * Subclasses can override this method to add common post-processing |
| * functionality without having to override all the read methods. |
| * The default implementation does nothing. |
| * </p> |
| * <p> |
| * Note this method is <em>not</em> called from {@link #skip(long)} or |
| * {@link #reset()}. You need to explicitly override those methods if |
| * you want to add post-processing steps also to them. |
| * </p> |
| * |
| * @since 2.0 |
| * @param n number of bytes read, or -1 if the end of stream was reached. |
| * @throws IOException if the post-processing fails in a subclass. |
| */ |
| @SuppressWarnings("unused") // Possibly thrown from subclasses. |
| protected void afterRead(final int n) throws IOException { |
| // no-op |
| } |
| |
| /** |
| * Invokes the delegate's {@code available()} method. |
| * |
| * @return the number of available bytes |
| * @throws IOException if an I/O error occurs. |
| */ |
| @Override |
| public int available() throws IOException { |
| try { |
| return super.available(); |
| } catch (final IOException e) { |
| handleIOException(e); |
| return 0; |
| } |
| } |
| |
| /** |
| * Invoked by the {@code read} methods before the call is proxied. The number |
| * of bytes that the caller wanted to read (1 for the {@link #read()} |
| * method, buffer length for {@link #read(byte[])}, etc.) is given as |
| * an argument. |
| * <p> |
| * Subclasses can override this method to add common pre-processing |
| * functionality without having to override all the read methods. |
| * The default implementation does nothing. |
| * </p> |
| * <p> |
| * Note this method is <em>not</em> called from {@link #skip(long)} or |
| * {@link #reset()}. You need to explicitly override those methods if |
| * you want to add pre-processing steps also to them. |
| * </p> |
| * |
| * @since 2.0 |
| * @param n number of bytes that the caller asked to be read. |
| * @throws IOException if the pre-processing fails in a subclass. |
| */ |
| @SuppressWarnings("unused") // Possibly thrown from subclasses. |
| protected void beforeRead(final int n) throws IOException { |
| // no-op |
| } |
| |
| /** |
| * Invokes the delegate's {@code close()} method. |
| * |
| * @throws IOException if an I/O error occurs. |
| */ |
| @Override |
| public void close() throws IOException { |
| IOUtils.close(in, this::handleIOException); |
| } |
| |
| /** |
| * Handles any IOExceptions thrown; by default, throws the given exception. |
| * <p> |
| * This method provides a point to implement custom exception |
| * handling. The default behavior is to re-throw the exception. |
| * </p> |
| * |
| * @param e The IOException thrown |
| * @throws IOException if an I/O error occurs. |
| * @since 2.0 |
| */ |
| protected void handleIOException(final IOException e) throws IOException { |
| throw e; |
| } |
| |
| /** |
| * Invokes the delegate's {@code mark(int)} method. |
| * |
| * @param readLimit read ahead limit |
| */ |
| @Override |
| public synchronized void mark(final int readLimit) { |
| in.mark(readLimit); |
| } |
| |
| /** |
| * Invokes the delegate's {@code markSupported()} method. |
| * |
| * @return true if mark is supported, otherwise false |
| */ |
| @Override |
| public boolean markSupported() { |
| return in.markSupported(); |
| } |
| |
| /** |
| * Invokes the delegate's {@code read()} method. |
| * |
| * @return the byte read or -1 if the end of stream |
| * @throws IOException if an I/O error occurs. |
| */ |
| @Override |
| public int read() throws IOException { |
| try { |
| beforeRead(1); |
| final int b = in.read(); |
| afterRead(b != EOF ? 1 : EOF); |
| return b; |
| } catch (final IOException e) { |
| handleIOException(e); |
| return EOF; |
| } |
| } |
| |
| /** |
| * Invokes the delegate's {@code read(byte[])} method. |
| * |
| * @param b the buffer to read the bytes into |
| * @return the number of bytes read or EOF if the end of stream |
| * @throws IOException if an I/O error occurs. |
| */ |
| @Override |
| public int read(final byte[] b) throws IOException { |
| try { |
| beforeRead(IOUtils.length(b)); |
| final int n = in.read(b); |
| afterRead(n); |
| return n; |
| } catch (final IOException e) { |
| handleIOException(e); |
| return EOF; |
| } |
| } |
| |
| /** |
| * Invokes the delegate's {@code read(byte[], int, int)} method. |
| * |
| * @param b the buffer to read the bytes into |
| * @param off The start offset |
| * @param len The number of bytes to read |
| * @return the number of bytes read or -1 if the end of stream |
| * @throws IOException if an I/O error occurs. |
| */ |
| @Override |
| public int read(final byte[] b, final int off, final int len) throws IOException { |
| try { |
| beforeRead(len); |
| final int n = in.read(b, off, len); |
| afterRead(n); |
| return n; |
| } catch (final IOException e) { |
| handleIOException(e); |
| return EOF; |
| } |
| } |
| |
| /** |
| * Invokes the delegate's {@code reset()} method. |
| * |
| * @throws IOException if an I/O error occurs. |
| */ |
| @Override |
| public synchronized void reset() throws IOException { |
| try { |
| in.reset(); |
| } catch (final IOException e) { |
| handleIOException(e); |
| } |
| } |
| |
| /** |
| * Invokes the delegate's {@code skip(long)} method. |
| * |
| * @param n the number of bytes to skip |
| * @return the actual number of bytes skipped |
| * @throws IOException if an I/O error occurs. |
| */ |
| @Override |
| public long skip(final long n) throws IOException { |
| try { |
| return in.skip(n); |
| } catch (final IOException e) { |
| handleIOException(e); |
| return 0; |
| } |
| } |
| |
| } |