Resolve context path issue when deploying to servlet container

Prior to this update, when deploying to a servlet container:
- the style.css does not resolve
- the favicon.ico does not resolve
- the "Linked Data Fragments" image does not resolve
- the contexts of datasource do not resolve

Resolves: LinkedDataFragments#52

src/main/java/org/linkeddatafragments/servlet/LinkedDataFragmentServlet.java

@@ -4,6 +4,7 @@
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
+import java.io.InputStream;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -15,10 +16,10 @@
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import org.apache.commons.io.IOUtils;
 import org.apache.http.HttpHeaders;
 import org.apache.jena.query.ARQ;
 import org.apache.jena.riot.Lang;
-import org.apache.jena.sys.JenaSystem;
 import org.linkeddatafragments.config.ConfigReader;
 import org.linkeddatafragments.datasource.DataSourceFactory;
 import org.linkeddatafragments.datasource.DataSourceTypesRegistry;
@@ -30,6 +31,7 @@
 import org.linkeddatafragments.fragments.ILinkedDataFragment;
 import org.linkeddatafragments.fragments.ILinkedDataFragmentRequest;
 import org.linkeddatafragments.util.MIMEParse;
+import org.linkeddatafragments.views.HtmlTriplePatternFragmentWriterImpl;
 import org.linkeddatafragments.views.ILinkedDataFragmentWriter;
 import org.linkeddatafragments.views.LinkedDataFragmentWriterFactory;
 
@@ -106,6 +108,8 @@ public void init(ServletConfig servletConfig) throws ServletException {
             MIMEParse.register(Lang.NTRIPLES.getHeaderString());
             MIMEParse.register(Lang.JSONLD.getHeaderString());
             MIMEParse.register(Lang.TTL.getHeaderString());
+
+            HtmlTriplePatternFragmentWriterImpl.setContextPath(servletConfig.getServletContext().getContextPath());
         } catch (Exception e) {
             throw new ServletException(e);
         }
@@ -163,6 +167,22 @@ private IDataSource getDataSource(HttpServletRequest request) throws DataSourceN
      */
     @Override
     public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException {
+
+        // Ensure that 'assets' (favicon, css) resolve
+        int fileNamePos = request.getRequestURI().toLowerCase().lastIndexOf("assets/");
+        if (fileNamePos > 0) {
+            try {
+                String fileName = request.getRequestURI().substring(fileNamePos - 1);
+                InputStream in = LinkedDataFragmentServlet.class.getResourceAsStream(fileName);
+                if (in != null) {
+                    IOUtils.copy(in, response.getOutputStream());
+                }
+                return;
+            } catch (IOException ioe) {
+                log("Should never happen", ioe);
+            }
+        }
+
         ILinkedDataFragment fragment = null;
         try {
             // do conneg

src/main/java/org/linkeddatafragments/views/HtmlTriplePatternFragmentWriterImpl.java

@@ -36,7 +36,16 @@ public class HtmlTriplePatternFragmentWriterImpl extends TriplePatternFragmentWr
     private final Template notfoundTemplate;
     private final Template errorTemplate;
 
-    private final String HYDRA = "http://www.w3.org/ns/hydra/core#"; 
+    private final String HYDRA = "http://www.w3.org/ns/hydra/core#";
+
+    private static String contextPath;
+
+    public static void setContextPath(String path) {
+        contextPath = path;
+        if (!contextPath.endsWith("/")) {
+            contextPath += "/";
+        }
+    }
 
     /**
      *
@@ -72,6 +81,7 @@ public void writeFragment(ServletOutputStream outputStream, IDataSource datasour
         Map data = new HashMap();
 
         // base.ftl.html
+        data.put("homePath", (contextPath != null ? contextPath : ""));
         data.put("assetsPath", "assets/");
         data.put("header", datasource.getTitle());
         data.put("date", new Date());
@@ -124,6 +134,7 @@ public void writeFragment(ServletOutputStream outputStream, IDataSource datasour
     @Override
     public void writeNotFound(ServletOutputStream outputStream, HttpServletRequest request) throws Exception {
         Map data = new HashMap();
+        data.put("homePath", (contextPath != null ? contextPath : ""));
         data.put("assetsPath", "assets/");
         data.put("datasources", getDatasources());
         data.put("date", new Date());
@@ -135,6 +146,7 @@ public void writeNotFound(ServletOutputStream outputStream, HttpServletRequest r
     @Override
     public void writeError(ServletOutputStream outputStream, Exception ex)  throws Exception {
         Map data = new HashMap();
+        data.put("homePath", (contextPath != null ? contextPath : ""));
         data.put("assetsPath", "assets/");
         data.put("date", new Date());
         data.put("error", ex);

src/main/resources/views/base.ftl.html

@@ -5,16 +5,16 @@
 <head>
   <meta charset="utf-8">
   <title>${ title!header!"Linked Data Fragments Server" }</title>
-  <link rel="shortcut icon" href="assets/favicon.ico">
+  <link rel="shortcut icon" href="${ assetsPath }favicon.ico">
   <link rel="stylesheet" href="${ assetsPath }style.css" />
   <link rel="stylesheet" href="//fonts.googleapis.com/css?family=Open+Sans:700italic,400,700|Droid+Sans+Mono" type="text/css" />
   <meta name="viewport" content="width=device-width,minimum-scale=1,maximum-scale=1">
 </head>
 <body>
   <header>
-    <h1><a href="/">${header!"Linked Data Fragments Server"}</a></h1>
+    <h1><a href="${homePath}">Linked Data Fragments Server</a></h1>
     <figure class="logo">
-      <a href="http://linkeddatafragments.org/"><img src="${ assetsPath }logo.svg" alt="Linked Data Fragments" /></a>
+      <a href="http://linkeddatafragments.org/"><img src="https://linkeddatafragments.org/images/logo.svg" alt="Linked Data Fragments" /></a>
     </figure>
   </header>
   <main>

src/main/resources/views/index.ftl.html

@@ -7,7 +7,7 @@ <h2>Available datasets</h2>
   <dl class="datasets">
       <#if datasources??>
     <#list datasources?keys as datasourceName>
-        <dt><a href="${datasourceName}">${datasources[datasourceName].getTitle() }</a></dt>
+        <dt><a href="${homePath}${datasourceName}">${datasources[datasourceName].getTitle() }</a></dt>
         <dd>${ datasources[datasourceName].getDescription()!"" }</dd>
     </#list>
     </#if>