Java tutorial
/** * The contents of this file are subject to the license and copyright * detailed in the LICENSE and NOTICE files at the root of the source * tree and available online at * * http://www.dspace.org/license/ */ package org.purl.sword.client; import java.io.*; import java.net.MalformedURLException; import java.net.URL; import java.security.NoSuchAlgorithmException; import java.util.Properties; import org.apache.commons.httpclient.Header; import org.apache.commons.httpclient.HttpClient; import org.apache.commons.httpclient.HttpException; import org.apache.commons.httpclient.HttpStatus; import org.apache.commons.httpclient.UsernamePasswordCredentials; import org.apache.commons.httpclient.auth.AuthScope; import org.apache.commons.httpclient.methods.FileRequestEntity; import org.apache.commons.httpclient.methods.GetMethod; import org.apache.commons.httpclient.methods.PostMethod; import org.apache.log4j.Logger; import org.purl.sword.base.ChecksumUtils; import org.purl.sword.base.DepositResponse; import org.purl.sword.base.HttpHeaders; import org.purl.sword.base.ServiceDocument; import org.purl.sword.base.SwordValidationInfo; import org.purl.sword.base.UnmarshallException; /** * This is an example Client implementation to demonstrate how to connect to a * SWORD server. The client supports BASIC HTTP Authentication. This can be * initialised by setting a username and password. * * @author Neil Taylor */ public class Client implements SWORDClient { /** * The status field for the response code from the recent network access. */ private Status status; /** * The name of the server to contact. */ private String server; /** * The port number for the server. */ private int port; /** * Specifies if the network access should use HTTP authentication. */ private boolean doAuthentication; /** * The username to use for Basic Authentication. */ private String username; /** * User password that is to be used. */ private String password; /** * The userAgent to identify this application. */ private String userAgent; /** * The client that is used to send data to the specified server. */ private HttpClient client; /** * The default connection timeout. This can be modified by using the * setSocketTimeout method. */ public static final int DEFAULT_TIMEOUT = 20000; /** * Logger. */ private static Logger log = Logger.getLogger(Client.class); /** * Create a new Client. The client will not use authentication by default. */ public Client() { client = new HttpClient(); client.getParams().setParameter("http.socket.timeout", Integer.valueOf(DEFAULT_TIMEOUT)); log.debug("proxy host: " + client.getHostConfiguration().getProxyHost()); log.debug("proxy port: " + client.getHostConfiguration().getProxyPort()); doAuthentication = false; } /** * Initialise the server that will be used to send the network access. * * @param server * @param port */ public void setServer(String server, int port) { this.server = server; this.port = port; } /** * Set the user credentials that will be used when making the access to the * server. * * @param username * The username. * @param password * The password. */ public void setCredentials(String username, String password) { this.username = username; this.password = password; doAuthentication = true; } /** * Set the basic credentials. You must have previously set the server and * port using setServer. * * @param username * @param password */ private void setBasicCredentials(String username, String password) { log.debug("server: " + server + " port: " + port + " u: '" + username + "' p '" + password + "'"); client.getState().setCredentials(new AuthScope(server, port), new UsernamePasswordCredentials(username, password)); } /** * Set a proxy that should be used by the client when trying to access the * server. If this is not set, the client will attempt to make a direct * direct connection to the server. The port is set to 80. * * @param host * The hostname. */ public void setProxy(String host) { setProxy(host, 80); } /** * Set a proxy that should be used by the client when trying to access the * server. If this is not set, the client will attempt to make a direct * direct connection to the server. * * @param host * The name of the host. * @param port * The port. */ public void setProxy(String host, int port) { client.getHostConfiguration().setProxy(host, port); } /** * Clear the proxy setting. */ public void clearProxy() { client.getHostConfiguration().setProxyHost(null); } /** * Clear any user credentials that have been set for this client. */ public void clearCredentials() { client.getState().clearProxyCredentials(); doAuthentication = false; } public void setUserAgent(String userAgent) { this.userAgent = userAgent; } /** * Set the connection timeout for the socket. * * @param milliseconds * The time, expressed as a number of milliseconds. */ public void setSocketTimeout(int milliseconds) { client.getParams().setParameter("http.socket.timeout", Integer.valueOf(milliseconds)); } /** * Retrieve the service document. The service document is located at the * specified URL. This calls getServiceDocument(url,onBehalfOf). * * @param url * The location of the service document. * @return The ServiceDocument, or <code>null</code> if there was a * problem accessing the document. e.g. invalid access. * * @throws SWORDClientException * If there is an error accessing the resource. */ public ServiceDocument getServiceDocument(String url) throws SWORDClientException { return getServiceDocument(url, null); } /** * Retrieve the service document. The service document is located at the * specified URL. This calls getServiceDocument(url,onBehalfOf). * * @param url * The location of the service document. * @return The ServiceDocument, or <code>null</code> if there was a * problem accessing the document. e.g. invalid access. * * @throws SWORDClientException * If there is an error accessing the resource. */ public ServiceDocument getServiceDocument(String url, String onBehalfOf) throws SWORDClientException { URL serviceDocURL = null; try { serviceDocURL = new URL(url); } catch (MalformedURLException e) { // Try relative URL URL baseURL = null; try { baseURL = new URL("http", server, Integer.valueOf(port), "/"); serviceDocURL = new URL(baseURL, (url == null) ? "" : url); } catch (MalformedURLException e1) { // No dice, can't even form base URL... throw new SWORDClientException(url + " is not a valid URL (" + e1.getMessage() + "), and could not form a relative one from: " + baseURL + " / " + url, e1); } } GetMethod httpget = new GetMethod(serviceDocURL.toExternalForm()); if (doAuthentication) { // this does not perform any check on the username password. It // relies on the server to determine if the values are correct. setBasicCredentials(username, password); httpget.setDoAuthentication(true); } Properties properties = new Properties(); if (containsValue(onBehalfOf)) { log.debug("Setting on-behalf-of: " + onBehalfOf); httpget.addRequestHeader(new Header(HttpHeaders.X_ON_BEHALF_OF, onBehalfOf)); properties.put(HttpHeaders.X_ON_BEHALF_OF, onBehalfOf); } if (containsValue(userAgent)) { log.debug("Setting userAgent: " + userAgent); httpget.addRequestHeader(new Header(HttpHeaders.USER_AGENT, userAgent)); properties.put(HttpHeaders.USER_AGENT, userAgent); } ServiceDocument doc = null; try { client.executeMethod(httpget); // store the status code status = new Status(httpget.getStatusCode(), httpget.getStatusText()); if (status.getCode() == HttpStatus.SC_OK) { String message = readResponse(httpget.getResponseBodyAsStream()); log.debug("returned message is: " + message); doc = new ServiceDocument(); lastUnmarshallInfo = doc.unmarshall(message, properties); } else { throw new SWORDClientException("Received error from service document request: " + status); } } catch (HttpException ex) { throw new SWORDClientException(ex.getMessage(), ex); } catch (IOException ioex) { throw new SWORDClientException(ioex.getMessage(), ioex); } catch (UnmarshallException uex) { throw new SWORDClientException(uex.getMessage(), uex); } finally { httpget.releaseConnection(); } return doc; } private SwordValidationInfo lastUnmarshallInfo; /** * */ public SwordValidationInfo getLastUnmarshallInfo() { return lastUnmarshallInfo; } /** * Post a file to the server. The different elements of the post are encoded * in the specified message. * * @param message * The message that contains the post information. * * @throws SWORDClientException * if there is an error during the post operation. */ public DepositResponse postFile(PostMessage message) throws SWORDClientException { if (message == null) { throw new SWORDClientException("Message cannot be null."); } PostMethod httppost = new PostMethod(message.getDestination()); if (doAuthentication) { setBasicCredentials(username, password); httppost.setDoAuthentication(true); } DepositResponse response = null; String messageBody = ""; try { if (message.isUseMD5()) { String md5 = ChecksumUtils.generateMD5(message.getFilepath()); if (message.getChecksumError()) { md5 = "1234567890"; } log.debug("checksum error is: " + md5); if (md5 != null) { httppost.addRequestHeader(new Header(HttpHeaders.CONTENT_MD5, md5)); } } String filename = message.getFilename(); if (!"".equals(filename)) { httppost.addRequestHeader(new Header(HttpHeaders.CONTENT_DISPOSITION, " filename=" + filename)); } if (containsValue(message.getSlug())) { httppost.addRequestHeader(new Header(HttpHeaders.SLUG, message.getSlug())); } if (message.getCorruptRequest()) { // insert a header with an invalid boolean value httppost.addRequestHeader(new Header(HttpHeaders.X_NO_OP, "Wibble")); } else { httppost.addRequestHeader(new Header(HttpHeaders.X_NO_OP, Boolean.toString(message.isNoOp()))); } httppost.addRequestHeader(new Header(HttpHeaders.X_VERBOSE, Boolean.toString(message.isVerbose()))); String packaging = message.getPackaging(); if (packaging != null && packaging.length() > 0) { httppost.addRequestHeader(new Header(HttpHeaders.X_PACKAGING, packaging)); } String onBehalfOf = message.getOnBehalfOf(); if (containsValue(onBehalfOf)) { httppost.addRequestHeader(new Header(HttpHeaders.X_ON_BEHALF_OF, onBehalfOf)); } String userAgent = message.getUserAgent(); if (containsValue(userAgent)) { httppost.addRequestHeader(new Header(HttpHeaders.USER_AGENT, userAgent)); } FileRequestEntity requestEntity = new FileRequestEntity(new File(message.getFilepath()), message.getFiletype()); httppost.setRequestEntity(requestEntity); client.executeMethod(httppost); status = new Status(httppost.getStatusCode(), httppost.getStatusText()); log.info("Checking the status code: " + status.getCode()); if (status.getCode() == HttpStatus.SC_ACCEPTED || status.getCode() == HttpStatus.SC_CREATED) { messageBody = readResponse(httppost.getResponseBodyAsStream()); response = new DepositResponse(status.getCode()); response.setLocation(httppost.getResponseHeader("Location").getValue()); // added call for the status code. lastUnmarshallInfo = response.unmarshall(messageBody, new Properties()); } else { messageBody = readResponse(httppost.getResponseBodyAsStream()); response = new DepositResponse(status.getCode()); response.unmarshallErrorDocument(messageBody); } return response; } catch (NoSuchAlgorithmException nex) { throw new SWORDClientException("Unable to use MD5. " + nex.getMessage(), nex); } catch (HttpException ex) { throw new SWORDClientException(ex.getMessage(), ex); } catch (IOException ioex) { throw new SWORDClientException(ioex.getMessage(), ioex); } catch (UnmarshallException uex) { throw new SWORDClientException(uex.getMessage() + "(<pre>" + messageBody + "</pre>)", uex); } finally { httppost.releaseConnection(); } } /** * Read a response from the stream and return it as a string. * * @param stream * The stream that contains the response. * @return The string extracted from the screen. * * @throws UnsupportedEncodingException * @throws IOException */ private String readResponse(InputStream stream) throws UnsupportedEncodingException, IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(stream, "UTF-8")); String line = null; StringBuffer buffer = new StringBuffer(); while ((line = reader.readLine()) != null) { buffer.append(line); buffer.append("\n"); } return buffer.toString(); } /** * Return the status information that was returned from the most recent * request sent to the server. * * @return The status code returned from the most recent access. */ public Status getStatus() { return status; } /** * Check to see if the specified item contains a non-empty string. * * @param item * The string to check. * @return True if the string is not null and has a length greater than 0 * after any whitespace is trimmed from the start and end. * Otherwise, false. */ private boolean containsValue(String item) { return ((item != null) && (item.trim().length() > 0)); } }