Java tutorial
/* The contents of this file are subject to the license and copyright terms * detailed in the license directory at the root of the source tree (also * available online at http://fedora-commons.org/license/). */ package fedora.client; import java.awt.Dimension; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.HashMap; import org.apache.commons.httpclient.HttpClient; import org.apache.commons.httpclient.HttpStatus; import org.apache.commons.httpclient.MultiThreadedHttpConnectionManager; import org.apache.commons.httpclient.UsernamePasswordCredentials; import org.apache.commons.httpclient.auth.AuthScope; import org.apache.commons.httpclient.methods.GetMethod; import fedora.server.utilities.StreamUtility; /** * A client for performing HTTP GET requests on a Fedora server (with * authentication) or any other server (without authentication). Each kind of * request can either request an InputStream or request that the Downloader * write the content directly to a provided OutputStream. * * @author Chris Wilper */ public class Downloader { private final MultiThreadedHttpConnectionManager m_cManager = new MultiThreadedHttpConnectionManager(); private final String m_fedoraUrlStart; private final AuthScope m_authScope; private final UsernamePasswordCredentials m_creds; /** * Construct a downloader for a certain repository as a certain user. */ public Downloader(String host, int port, String context, String user, String pass) throws IOException { m_fedoraUrlStart = Administrator.getProtocol() + "://" + host + ":" + port + "/" + context + "/" + "get/"; m_authScope = new AuthScope(host, AuthScope.ANY_PORT, AuthScope.ANY_REALM); m_creds = new UsernamePasswordCredentials(user, pass); } public void getDatastreamContent(String pid, String dsID, String asOfDateTime, OutputStream out) throws IOException { InputStream in = getDatastreamContent(pid, dsID, asOfDateTime); StreamUtility.pipeStream(in, out, 4096); } public InputStream getDatastreamContent(String pid, String dsID, String asOfDateTime) throws IOException { StringBuffer buf = new StringBuffer(); buf.append(m_fedoraUrlStart); buf.append(pid); buf.append('/'); buf.append(dsID); if (asOfDateTime != null) { buf.append('/'); buf.append(asOfDateTime); } return get(buf.toString()); } public void getDatastreamDissemination(String pid, String dsId, String asOfDateTime, OutputStream out) throws IOException { InputStream in = getDatastreamDissemination(pid, dsId, asOfDateTime); StreamUtility.pipeStream(in, out, 4096); } public InputStream getDatastreamDissemination(String pid, String dsId, String asOfDateTime) throws IOException { StringBuffer buf = new StringBuffer(); buf.append(m_fedoraUrlStart); buf.append(pid); buf.append('/'); buf.append(dsId); if (asOfDateTime != null) { buf.append('/'); buf.append(asOfDateTime); } return get(buf.toString()); } /** * Get data via HTTP and write it to an OutputStream, following redirects, * and supplying credentials if the host is the Fedora server. */ public void get(String url, OutputStream out) throws IOException { InputStream in = get(url); StreamUtility.pipeStream(in, out, 4096); } /** * Get data via HTTP as an InputStream, following redirects, and supplying * credentials if the host is the Fedora server. */ public InputStream get(String url) throws IOException { GetMethod get = null; boolean ok = false; try { m_cManager.getParams().setConnectionTimeout(20000); HttpClient client = new HttpClient(m_cManager); client.getState().setCredentials(m_authScope, m_creds); client.getParams().setAuthenticationPreemptive(true); // don't bother with challenges int redirectCount = 0; // how many redirects did we follow int resultCode = 300; // not really, but enter the loop that way Dimension d = null; while (resultCode > 299 && resultCode < 400 && redirectCount < 25) { get = new GetMethod(url); get.setDoAuthentication(true); get.setFollowRedirects(true); if (Administrator.INSTANCE != null) { d = Administrator.PROGRESS.getSize(); // if they're using Administrator, tell them we're downloading... Administrator.PROGRESS.setString("Downloading " + url + " . . ."); Administrator.PROGRESS.setValue(100); Administrator.PROGRESS.paintImmediately(0, 0, (int) d.getWidth() - 1, (int) d.getHeight() - 1); } resultCode = client.executeMethod(get); if (resultCode > 299 && resultCode < 400) { redirectCount++; url = get.getResponseHeader("Location").getValue(); } } if (resultCode != 200) { System.err.println(get.getResponseBodyAsString()); throw new IOException( "Server returned error: " + resultCode + " " + HttpStatus.getStatusText(resultCode)); } ok = true; if (Administrator.INSTANCE != null) { // cache it to a file File tempFile = File.createTempFile("fedora-client-download-", null); tempFile.deleteOnExit(); HashMap PARMS = new HashMap(); PARMS.put("in", get.getResponseBodyAsStream()); PARMS.put("out", new FileOutputStream(tempFile)); // do the actual download in a safe thread SwingWorker worker = new SwingWorker(PARMS) { @Override public Object construct() { try { StreamUtility.pipeStream((InputStream) parms.get("in"), (OutputStream) parms.get("out"), 8192); } catch (Exception e) { thrownException = e; } return ""; } }; worker.start(); // The following code will run in the (safe) // Swing event dispatcher thread. int ms = 200; while (!worker.done) { try { Administrator.PROGRESS.setValue(ms); Administrator.PROGRESS.paintImmediately(0, 0, (int) d.getWidth() - 1, (int) d.getHeight() - 1); Thread.sleep(100); ms = ms + 100; if (ms >= 2000) { ms = 200; } } catch (InterruptedException ie) { } } if (worker.thrownException != null) { throw worker.thrownException; } Administrator.PROGRESS.setValue(2000); Administrator.PROGRESS.paintImmediately(0, 0, (int) d.getWidth() - 1, (int) d.getHeight() - 1); try { Thread.sleep(100); } catch (InterruptedException ie) { } return new FileInputStream(tempFile); } return get.getResponseBodyAsStream(); } catch (Exception e) { throw new IOException(e.getMessage()); } finally { if (get != null && !ok) { get.releaseConnection(); } if (Administrator.INSTANCE != null) { Administrator.PROGRESS.setValue(0); Administrator.PROGRESS.setString(""); } } } /** * Test this class. */ public static void main(String[] args) { try { if (args.length == 8 || args.length == 9) { String host = args[0]; int port = Integer.parseInt(args[1]); String user = args[2]; String password = args[3]; String pid = args[4]; String dsid = args[5]; File outfile = new File(args[6]); String asOfDateTime = args.length == 8 ? args[7] : null; String context = args.length == 9 ? args[8] : null; FileOutputStream outStream = new FileOutputStream(outfile); Downloader downloader = new Downloader(host, port, context, user, password); downloader.getDatastreamContent(pid, dsid, asOfDateTime, outStream); } else { System.err.println( "Usage: Downloader host port user password pid dsid outfile [MMDDYYTHH:MM:SS] [context]"); } } catch (Exception e) { e.printStackTrace(); System.err.println("ERROR: " + e.getMessage()); } } }