Java tutorial
/* ********************************************************************** ** ** Copyright notice ** ** ** ** (c) 2005-2009 RSSOwl Development Team ** ** http://www.rssowl.org/ ** ** ** ** All rights reserved ** ** ** ** This program and the accompanying materials are made available under ** ** the terms of the Eclipse Public License v1.0 which accompanies this ** ** distribution, and is available at: ** ** http://www.rssowl.org/legal/epl-v10.html ** ** ** ** A copy is found in the file epl-v10.html and important notices to the ** ** license from the team is found in the textfile LICENSE.txt distributed ** ** in this package. ** ** ** ** This copyright notice MUST APPEAR in all copies of the file! ** ** ** ** Contributors: ** ** RSSOwl Development Team - initial API and implementation ** ** ** ** ********************************************************************** */ package org.rssowl.core.connection; import org.apache.commons.httpclient.Header; import org.apache.commons.httpclient.HttpMethodBase; import org.apache.commons.httpclient.URIException; import org.eclipse.core.runtime.IProgressMonitor; import java.io.FilterInputStream; import java.io.IOException; import java.io.InputStream; import java.net.URI; import java.net.URISyntaxException; /** * <p> * This kind of FilterInputStream makes sure that the HTTP Method responsible * for the given InputStream is releasing its connection after the stream has * been closed. This class is also keeping two important headers to be used for * the Conditional GET Mechanism of HTTP. * </p> * <p> * Passing an instance of <code>IProgressMonitor</code> into the class allows * for early cancelation by throwing an Exception from the various * stream-methods as soon as the monitor is canceled. * </p> * * @author bpasero */ public class HttpConnectionInputStream extends FilterInputStream implements IConditionalGetCompatible, IAbortable { /* Response Header */ private static final String HEADER_RESPONSE_ETAG = "ETag"; //$NON-NLS-1$ private static final String HEADER_RESPONSE_LAST_MODIFIED = "Last-Modified"; //$NON-NLS-1$ private static final String HEADER_RESPONSE_CONTENT_LENGTH = "Content-Length"; //$NON-NLS-1$ private static final String HEADER_RESPONSE_CONTENT_TYPE = "Content-Type"; //$NON-NLS-1$ private static final String HEADER_RESPONSE_CONTENT_DISPOSITION = "Content-Disposition"; //$NON-NLS-1$ private static final String HEADER_RESPONSE_CONTENT_ENCODING = "Content-Encoding"; //$NON-NLS-1$ private final HttpMethodBase fMethod; private final IProgressMonitor fMonitor; private String fIfModifiedSince; private String fIfNoneMatch; private final URI fLink; /** * Creates a <code>HttpConnectionInputStream</code> by assigning the argument * <code>inS</code> to the field <code>this.in</code> so as to remember it for * later use. * * @param link the {@link URI} that was used to create the Stream. * @param method The Method holding the connection of the given Stream. * @param monitor A ProgressMonitor to support early cancelation, or * <code>NULL</code> if no monitor is being used. * @param inS the underlying input Stream. */ public HttpConnectionInputStream(URI link, HttpMethodBase method, IProgressMonitor monitor, InputStream inS) { super(inS); fLink = link; fMethod = method; fMonitor = monitor; /* Keep some important Headers */ Header headerLastModified = method.getResponseHeader(HEADER_RESPONSE_LAST_MODIFIED); if (headerLastModified != null) setIfModifiedSince(headerLastModified.getValue()); Header headerETag = method.getResponseHeader(HEADER_RESPONSE_ETAG); if (headerETag != null) setIfNoneMatch(headerETag.getValue()); } /** * @return the actual {@link URI} used to open this stream. */ public URI getLink() { try { return new URI(fMethod.getURI().toString()); } catch (URIException e) { return fLink; } catch (URISyntaxException e) { return fLink; } } /* * @seeorg.rssowl.core.connection.internal.http.IConditionalGetCompatible# * getIfModifiedSince() */ public String getIfModifiedSince() { return fIfModifiedSince; } /* * @seeorg.rssowl.core.connection.internal.http.IConditionalGetCompatible# * getIfNoneMatch() */ public String getIfNoneMatch() { return fIfNoneMatch; } /* * @seeorg.rssowl.core.connection.internal.http.IConditionalGetCompatible# * setIfModifiedSince(java.lang.String) */ public void setIfModifiedSince(String ifModifiedSince) { fIfModifiedSince = ifModifiedSince; } /* * @seeorg.rssowl.core.connection.internal.http.IConditionalGetCompatible# * setIfNoneMatch(java.lang.String) */ public void setIfNoneMatch(String ifNoneMatch) { fIfNoneMatch = ifNoneMatch; } /* * @see org.rssowl.core.connection.IAbortable#abort() */ public void abort() { fMethod.abort(); fMethod.releaseConnection(); } /* * @see java.io.FilterInputStream#close() */ @Override public void close() throws IOException { super.close(); fMethod.releaseConnection(); } /* * @see java.io.FilterInputStream#read() */ @Override public int read() throws IOException { /* Support early cancelation */ if (fMonitor != null && fMonitor.isCanceled()) throw new MonitorCanceledException(Messages.HttpConnectionInputStream_ERROR_CONNECTION_CANCELED); return super.read(); } /* * @see java.io.FilterInputStream#read(byte[], int, int) */ @Override public int read(byte[] b, int off, int len) throws IOException { /* Support early cancelation */ if (fMonitor != null && fMonitor.isCanceled()) throw new MonitorCanceledException(Messages.HttpConnectionInputStream_ERROR_CONNECTION_CANCELED); return super.read(b, off, len); } /* * @see java.io.FilterInputStream#available() */ @Override public int available() throws IOException { /* Support early cancelation */ if (fMonitor != null && fMonitor.isCanceled()) throw new MonitorCanceledException(Messages.HttpConnectionInputStream_ERROR_CONNECTION_CANCELED); return super.available(); } /** * @return the content length of the content served by this stream or -1 if * not available. */ public int getContentLength() { Header header = fMethod.getResponseHeader(HEADER_RESPONSE_CONTENT_LENGTH); if (header != null) { String value = header.getValue(); try { return Integer.parseInt(value); } catch (NumberFormatException e) { return -1; } } return -1; } /** * @return the content type of the content served by this stream or null if * not available. */ public String getContentType() { Header header = fMethod.getResponseHeader(HEADER_RESPONSE_CONTENT_TYPE); if (header != null) return header.getValue(); return null; } /** * @return the content disposition of the content served by this stream or * null if not available. */ public String getContentDisposition() { Header header = fMethod.getResponseHeader(HEADER_RESPONSE_CONTENT_DISPOSITION); if (header != null) return header.getValue(); return null; } /** * @return the content encoding of the content served by this stream or * null if not available. */ public String getContentEncoding() { Header header = fMethod.getResponseHeader(HEADER_RESPONSE_CONTENT_ENCODING); if (header != null) return header.getValue(); return null; } }