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The Fedora Client is a Java Library that allows API access to a Fedora Repository. The client is typically one part of a full Fedora installation.
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/*
 * -----------------------------------------------------------------------------
 *
 * License and Copyright: The contents of this file are subject to 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.fedora-commons.org/licenses.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
 * the specific language governing rights and limitations under the License.
 *
 * The entire file consists of original code.
 * Copyright © 2008 Fedora Commons, Inc.

 * 
Copyright © 2002-2007 The Rector and Visitors of the University of 
 * Virginia and Cornell University
 
 * All rights reserved.
 *
 * -----------------------------------------------------------------------------
 */
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.auth.AuthScope;
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.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 [email protected]
 */
public class Downloader {

    private MultiThreadedHttpConnectionManager m_cManager=
            new MultiThreadedHttpConnectionManager();

    private String m_fedoraUrlStart;
    private AuthScope m_authScope;
    private UsernamePasswordCredentials m_creds;

    /**
     * Construct a downloader for a certain repository as a certain user.
     */
    public Downloader(String host, int port, String user, String pass)
            throws IOException {
        m_fedoraUrlStart=Administrator.getProtocol() + "://" + host + ":" + port + "/fedora/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) {
                    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==7 || args.length==8) {
                String asOfDateTime=null;
                if (args.length==8) {
                    asOfDateTime=args[7];
                }
                FileOutputStream out=new FileOutputStream(new File(args[6]));
                Downloader downloader=new Downloader(args[0], 
                        Integer.parseInt(args[1]), args[2], args[3]);
                downloader.getDatastreamContent(args[4], args[5], asOfDateTime, out);
            } else {
                System.err.println("Usage: Downloader host port user pass pid dsid outfile [MMDDYYTHH:MM:SS]");
            }
        } catch (Exception e) {
            e.printStackTrace();
            System.err.println("ERROR: " + e.getMessage());
        }
    }

}