On Wed, 8 Feb 2006, Nelson Brandon K A1C AFWA/SCSA wrote:
> Robb,
>
>
>
> Is there anyway to use an http URL as the file source when
> making the random access file?
Nelson,
yes, i also attached the HTTPRandomAccessFile3 file and the tomcat lib
that's needed.
if (uriString.startsWith("http:")) { // open through URL
raf = new ucar.unidata.io.http.HTTPRandomAccessFile3(uriString);
robb...
>
>
>
> Ex:
>
> Grib1Indexer g1d = new Grib1Indexer();
>
>
>
> //RandomAccessFile for faster reading of the index file
>
> ===>RandomAccessFile raf = new RandomAccessFile(gribFile, "r");
>
> raf.order(RandomAccessFile.BIG_ENDIAN);
>
>
>
> //File stream for writing of the index file
>
> PrintStream ps = new PrintStream(new FilterOutputStream(
>
> new FileOutputStream(outfile, false)));
>
>
>
> //Writes the index file
>
> g1d.writeFileIndex(raf, ps, false);
>
> } catch (Exception e) {
>
> e.printStackTrace();
>
> }
>
>
>
> V/r
>
> A1C Nelson, Brandon K
>
> Communications-Computer Systems Programmer
>
> HQ AFWA/SCSA (402) 294-1404
>
>
>
>
===============================================================================
Robb Kambic Unidata Program Center
Software Engineer III Univ. Corp for Atmospheric Research
address@hidden WWW: http://www.unidata.ucar.edu/
===============================================================================// $Id: HTTPRandomAccessFile3.java,v 1.6 2005/10/11 19:39:51 caron Exp $
/*
* Copyright 1997-2000 Unidata Program Center/University Corporation for
* Atmospheric Research, P.O. Box 3000, Boulder, CO 80307,
* address@hidden.
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at
* your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
* General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* HTTPRandomAccessFile.java.
* @author John Caron, based on work by Donald Denbo
*/
package ucar.unidata.io.http;
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.methods.*;
import java.io.FileNotFoundException;
import java.io.FileDescriptor;
import java.io.IOException;
import java.io.InputStream;
/**
* Gives access to files over HTTP, using jakarta commons HttpClient.
* @author John Caron
*/
public class HTTPRandomAccessFile3 extends ucar.unidata.io.RandomAccessFile {
static public int defaultHTTPBufferSize = 20000;
static public int timeoutMsecs = 5000;
private String url;
private HttpClient client;
private long total_length = 0;
private boolean debug = false, debugDetails = false;
public HTTPRandomAccessFile3(String url) throws IOException {
this( url, defaultHTTPBufferSize);
location = url.toString();
}
public HTTPRandomAccessFile3(String url, int bufferSize) throws IOException {
super( bufferSize);
file = null;
this.url = url;
location = url.toString();
client = new HttpClient();
client.setConnectionTimeout(timeoutMsecs); //establish a connection within
this time
HttpMethod method = new HeadMethod(url);
method.setFollowRedirects(true);
method.setStrictMode(false);
doConnect( method);
/* Header head = method.getResponseHeader("Accept-Ranges");
if (head == null || !head.getValue().equalsIgnoreCase("bytes")) {
throw new IOException("Server does not support byte Ranges");
} */
Header head = method.getResponseHeader("Content-Length");
if (head == null) {
throw new IOException("Server does not support Content-Length");
}
try {
total_length = Integer.parseInt( head.getValue());
} catch ( NumberFormatException e) {
throw new IOException("Server has malformed Content-Length header");
}
method.releaseConnection();
// header[0] = new NVPair("User-Agent", "HTTPnetCDF;"); ??
if (debugLeaks) openFiles.add( location);
}
private void doConnect(HttpMethod method) throws IOException {
// Execute the method.
int statusCode = -1;
// We will retry up to 3 times.
for (int attempt = 0; statusCode == -1 && attempt < 3; attempt++) {
try {
statusCode = client.executeMethod(method);
} catch (HttpRecoverableException e) {
if (attempt == 2) throw new IOException( e.getMessage());
System.err.println("A recoverable exception occurred, retrying." +
e.getMessage());
}
}
if (statusCode == 404)
throw new FileNotFoundException( url+" "+method.getStatusLine());
if (statusCode >= 300)
throw new IOException( url+" "+method.getStatusLine());
if (debugDetails) {
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 (int i = 0; i < heads.length; i++) {
Header head = heads[i];
System.out.print(" "+head.toString());
}
System.out.println();
}
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 = new GetMethod(url); // LOOK: can we resuse?
method.setFollowRedirects(true);
method.setStrictMode(false);
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();
int readLen = Integer.parseInt( s);
readLen = Math.min( len, readLen);
InputStream is = method.getResponseBodyAsStream();
readLen = copy( is, buff, offset, readLen);
return readLen;
} finally {
if (method != null) method.releaseConnection();
}
}
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;
}
public long length( ) throws IOException {
long fileLength = total_length;
if( fileLength < dataEnd )
return dataEnd;
else
return fileLength;
}
/**
* override the rest of the RandomAccessFile public methods
*/
public void close() {
client = null;
if (debugLeaks) openFiles.remove( location);
}
public FileDescriptor getFD() {
return null;
}
}
Attachment:
HTTPClient.jar
Description: Zip archive