/*
* Copyright 1998-2009 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
* and understandings on the user. The user is granted the right, without
* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
* supporting documentation. Further, UCAR requests that the user credit
* UCAR/Unidata in any publications that result from the use of this
* software or in any product that includes this software. The names UCAR
* and/or Unidata, however, may not be used in any advertising or publicity
* to endorse or promote any products or commercial entity unless specific
* written permission is obtained from UCAR/Unidata. The user also
* understands that UCAR/Unidata is not obligated to provide the user with
* any support, consulting, training or assistance of any kind with regard
* to the use, operation and performance of this software nor to provide
* the user with any updates, revisions, new versions or "bug fixes."
*
* THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package ucar.unidata.io.http;
import opendap.dap.http.HTTPMethod;
import opendap.dap.http.HTTPSession;
import org.apache.commons.httpclient.Header;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.channels.WritableByteChannel;
import java.nio.ByteBuffer;
/**
* Gives access to files over HTTP, using jakarta commons HttpClient library.
* This version uses a single instance of HttpClient, following performance guidelines at
* http://jakarta.apache.org/commons/httpclient/performance.html
* Plus other improvements.
*
* @author John Caron, based on work by Donald Denbo
*/
public class HTTPRandomAccessFile extends ucar.unidata.io.RandomAccessFile {
static public int defaultHTTPBufferSize = 20000;
///////////////////////////////////////////////////////////////////////////////////
private String url;
private HTTPSession session = null;
private long total_length = 0;
private boolean debug = false, debugDetails = false;
public HTTPRandomAccessFile(String url) throws IOException {
this(url, defaultHTTPBufferSize);
location = url;
}
public HTTPRandomAccessFile(String url, int bufferSize) throws IOException {
super(bufferSize);
file = null;
this.url = url;
location = url;
if (debugLeaks)
allFiles.add(location);
session = new HTTPSession();
boolean needtest = true;
HTTPMethod method = null;
try {
method = session.newMethodHead(url);
doConnect(method);
Header head = method.getResponseHeader("Accept-Ranges");
if (head == null) {
needtest = true; // header is optional - need more testing
} else if (head.getValue().equalsIgnoreCase("bytes")) {
needtest = false;
} else if (head.getValue().equalsIgnoreCase("none")) {
throw new IOException("Server does not support byte Ranges");
}
head = method.getResponseHeader("Content-Length");
if (head == null) {
throw new IOException("Server does not support Content-Length");
}
try {
total_length = Long.parseLong(head.getValue());
} catch (NumberFormatException e) {
throw new IOException("Server has malformed Content-Length header");
}
} finally {
if (method != null) method.close();
}
if (needtest && !rangeOk(url))
throw new IOException("Server does not support byte Ranges");
if (debugLeaks) openFiles.add(location);
}
public void close() {
if (debugLeaks)
openFiles.remove(location);
if (session != null) {
session.close();
session = null;
}
}
private boolean rangeOk(String url) {
HTTPMethod method = null;
try {
method = session.newMethodGet(url);
method.setFollowRedirects(true);
method.setRequestHeader("Range", "bytes=" + 0 + "-" + 1);
doConnect(method);
int code = method.getStatusCode();
if (code != 206)
throw new IOException("Server does not support Range requests, code= " + code);
// clear stream
method.close();
return true;
} catch (IOException e) {
return false;
} finally {
if (method != null) method.close();
}
}
private void doConnect(HTTPMethod method) throws IOException {
// Execute the method.
int statusCode = method.execute();
if (statusCode == 404)
throw new FileNotFoundException(url + " " + method.getStatusLine());
if (statusCode >= 300)
throw new IOException(url + " " + method.getStatusLine());
if (debugDetails) {
// request headers dont seem to be available until after execute()
printHeaders("Request: " + method.getName() + " " + method.getPath(), method.getRequestHeaders());
printHeaders("Response: " + method.getStatusCode(), method.getResponseHeaders());
}
}
private void printHeaders(String title, Header[] heads) {
System.out.println(title);
for (Header head : heads) {
System.out.print(" " + head.toString());
}
System.out.println();
}
/**
* Read directly from file, without going through the buffer.
* All reading goes through here or readToByteChannel;
*
* @param pos start here in the file
* @param buff put data into this buffer
* @param offset buffer offset
* @param len this number of bytes
* @return actual number of bytes read
* @throws IOException on io error
*/
@Override
protected int read_(long pos, byte[] buff, int offset, int len) throws IOException {
long end = pos + len - 1;
if (end >= total_length)
end = total_length - 1;
if (debug) System.out.println(" HTTPRandomAccessFile bytes=" + pos + "-" + end + ": ");
HTTPMethod method = null;
try {
method = session.newMethodGet(url);
method.setFollowRedirects(true);
method.setRequestHeader("Range", "bytes=" + pos + "-" + end);
doConnect(method);
int code = method.getStatusCode();
if (code != 206)
throw new IOException("Server does not support Range requests, code= " + code);
String s = method.getResponseHeader("Content-Length").getValue();
if (s == null)
throw new IOException("Server does not send Content-Length header");
int readLen = Integer.parseInt(s);
readLen = Math.min(len, readLen);
InputStream is = method.getResponseAsStream();
readLen = copy(is, buff, offset, readLen);
return readLen;
} finally {
if (method != null) method.close();
}
}
private int copy(InputStream in, byte[] buff, int offset, int want) throws IOException {
int done = 0;
while (want > 0) {
int bytesRead = in.read(buff, offset + done, want);
if (bytesRead == -1) break;
done += bytesRead;
want -= bytesRead;
}
return done;
}
@Override
public long readToByteChannel(WritableByteChannel dest, long offset, long nbytes) throws IOException {
int n = (int) nbytes;
byte[] buff = new byte[n];
int done = read_(offset, buff, 0, n);
dest.write(ByteBuffer.wrap(buff));
return done;
}
// override selected RandomAccessFile public methods
@Override
public long length() throws IOException {
long fileLength = total_length;
if (fileLength < dataEnd)
return dataEnd;
else
return fileLength;
}
}