[TAP] Add home page configuration in the TAP configuration file. (missing...

[TAP] Add home page configuration in the TAP configuration file. (missing file: tap.resource.HomePage)

src/tap/resource/HomePage.java

+package tap.resource;
+
+/*
+ * This file is part of TAPLibrary.
+ * 
+ * TAPLibrary 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 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * TAPLibrary 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 TAPLibrary.  If not, see <http://www.gnu.org/licenses/>.
+ * 
+ * Copyright 2015 - Astronomisches Rechen Institut (ARI)
+ */
+
+import java.io.BufferedInputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.net.URI;
+
+import javax.servlet.ServletConfig;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import tap.TAPException;
+import uws.service.log.UWSLog.LogLevel;
+
+/**
+ * <p>Write the content of the TAP service's home page.</p>
+ * 
+ * <p><i>Note:
+ * 	This class is using the two following {@link TAP} attributes in order to display the home page:
+ * 	{@link TAP#homePageURI} and {@link TAP#homePageMimeType}. The MIME type is used only for the third case below (local file). 
+ * </i></p>
+ * 
+ * <p>Four cases are taken into account in this class, in function of the {@link TAP#homePageURI} value:</p>
+ * <ol>
+ * 	<li><b>a default content</b> if no custom home page (URI) has been specified using {@link TAP#setHomePageURI(String)}.
+ * 	                             This default home page is hard-coded in this class and displays just an HTML list of
+ * 	                             links. There is one link for each resources of this TAP service (excluding the home page).</li>
+ * 	<li><b>a file inside WebContent</b> if the given URI has no scheme (e.g. "tapIndex.jsp" or "/myFiles/tapIndex.html").
+ * 	                                    The URI is then an absolute (if starting with "/") or a relative path to file inside the WebContent directory.
+ * 	                                    In this case the request is forwarded to this file. It is neither a redirection nor a copy,
+ * 	                                    but a kind of inclusion of the interpreted file into the response.
+ *                                      <i>This method MUST be used if your home page is a JSP.</i></li>
+ * <li><b>a local file</b> if a URI starts with "file:". In this case, the content of the local file is copied in the HTTP response. There is no interpretation. So this method should not be used for JSP.</li>	
+ * <li><b>a distance document</b> in all other cases. Indeed, if there is a scheme different from "file:" the given URI will be considered as a URL.
+ *                                In this case, any request to the TAP home page is redirected to this URL.</li>
+ * </ol>
+ * 
+ * @author Gr&eacute;gory Mantelet (ARI)
+ * @version 2.0 (02/2015)
+ * @since 2.0
+ */
+public class HomePage implements TAPResource {
+
+	/** Name of this TAP resource. */
+	public static final String RESOURCE_NAME = "HOME PAGE";
+
+	/** TAP service owning this resource. */
+	protected final TAP tap;
+
+	public HomePage(final TAP tap){
+		if (tap == null)
+			throw new NullPointerException("Missing TAP object! The HOME PAGE resource can not be initialized without a TAP instance.");
+		this.tap = tap;
+	}
+
+	@Override
+	public void init(final ServletConfig config) throws ServletException{}
+
+	@Override
+	public void destroy(){}
+
+	@Override
+	public void setTAPBaseURL(String baseURL){}
+
+	@Override
+	public final String getName(){
+		return RESOURCE_NAME;
+	}
+
+	@Override
+	public boolean executeResource(final HttpServletRequest request, final HttpServletResponse response) throws IOException, TAPException{
+		PrintWriter writer = response.getWriter();
+		boolean written = false;
+
+		// Display the specified home page, if any is specified:
+		if (tap.homePageURI != null){
+
+			URI uri = null;
+			try{
+				uri = new URI(tap.homePageURI);
+				/* CASE: FILE IN WebContent */
+				if (uri.getScheme() == null){
+					if (request.getServletContext().getResource(tap.homePageURI) != null){
+						request.getRequestDispatcher(tap.homePageURI).forward(request, response);
+						written = true;
+					}else
+						tap.getLogger().logTAP(LogLevel.ERROR, null, "HOME_PAGE", "Can not write the specified home page content (" + tap.homePageURI + "): Web application file not found!", null);
+				}
+				/* CASE: LOCAL FILE */
+				else if (uri.getScheme().equalsIgnoreCase("file")){
+					// Set the content type:
+					response.setContentType(tap.homePageMimeType);
+
+					// Get an input toward the custom home page:
+					BufferedInputStream input = null;
+					try{
+						File f = new File(uri.getPath());
+						if (f.exists() && !f.isDirectory() && f.canRead()){
+							// set the content length:
+							response.setContentLength((int)f.length());
+
+							// get the input stream:
+							input = new BufferedInputStream(new FileInputStream(f));
+
+							// Copy the content of the input into the given writer:
+							byte[] buffer = new byte[2048];
+							int nbReads = 0;
+							while((nbReads = input.read(buffer)) > 0)
+								writer.print(new String(buffer, 0, nbReads));
+
+							// copy successful:
+							written = true;
+						}else
+							tap.getLogger().logTAP(LogLevel.ERROR, null, "HOME_PAGE", "Can not write the specified home page content (" + tap.homePageURI + "): File not found or not readable (" + f.exists() + !f.isDirectory() + f.canRead() + ")!", null);
+
+					}finally{
+						if (input != null)
+							input.close();
+					}
+				}
+				/* CASE: HTTP/HTTPS/FTP/... */
+				else{
+					response.sendRedirect(tap.homePageURI);
+					written = true;
+				}
+
+			}catch(Exception e){
+				tap.getLogger().logTAP(LogLevel.ERROR, null, "HOME_PAGE", "Can not write the specified home page content (" + tap.homePageURI + "): " + e.getMessage(), e);
+			}
+		}
+
+		// DEFAULT: list all available resources:
+		if (!written){
+			// Set the content type: HTML document
+			response.setContentType("text/html");
+
+			// Write the home page:
+			writer.println("<html><head><title>TAP HOME PAGE</title></head><body><h1 style=\"text-align: center\">TAP HOME PAGE</h1><h2>Available resources:</h2><ul>");
+			for(TAPResource res : tap.resources.values())
+				writer.println("<li><a href=\"" + tap.tapBaseURL + "/" + res.getName() + "\">" + res.getName() + "</a></li>");
+			writer.println("</ul></body></html>");
+
+			written = true;
+		}
+
+		return written;
+	}
+
+}