load images from local cache

src/main/java/de/jalin/fedipage/JSONLoader.java

@@ -94,7 +94,12 @@ public class JSONLoader implements Serializable {
     					medium.setDescription(mediumJsonObject.getString("description"));
     				}
     				medium.setMediumUrl(mediumJsonObject.getString("preview_url"));
-    				medium.setMediumImage(mediumJsonObject.getString("url"));
+    				final String imageUrl = mediumJsonObject.getString("url");
+    				if (imageUrl != null && imageUrl.startsWith("https://")) {
+    					medium.setMediumImage(contextUrl  + "cache" + imageUrl.substring(7));
+    				} else {
+    					medium.setMediumImage(imageUrl);
+    				}
     				post.addFediMedium(medium);
     			}
     		}

src/main/java/de/jalin/fedipage/ProxyServlet.java

@@ -0,0 +1,87 @@
+package de.jalin.fedipage;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import jakarta.servlet.ServletConfig;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+
+public class ProxyServlet extends HttpServlet {
+
+	private static final long serialVersionUID = 6847934676281057148L;
+
+	private String cacheDirectory;
+
+	@Override
+	public void init() throws ServletException {
+		final ServletConfig servletConfig = getServletConfig();
+		try {
+			String cache = servletConfig.getInitParameter("cache");
+			if (cache != null) {
+				cacheDirectory = Path.of(cache).toString();
+			} else {
+				cacheDirectory = Files.createTempDirectory("cache").toString();
+			}
+		} catch (IOException e) {
+			throw new ServletException(e);
+		}
+	}
+
+	@Override
+	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+		final String resource = request.getPathInfo();
+		final Path resourcePath = Path.of(cacheDirectory + resource);
+		final File file = resourcePath.toFile();
+		if (file.exists()) {
+	        final BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream(file));
+	        final BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(response.getOutputStream());
+	        final byte[] bytesBuffer = new byte[4096];
+	        int readBytes = bufferedInputStream.read(bytesBuffer);
+	        while (readBytes > 0) {
+	        	bufferedOutputStream.write(bytesBuffer, 0, readBytes);
+	        	readBytes = bufferedInputStream.read(bytesBuffer);
+	        }
+	        bufferedOutputStream.close();
+	        bufferedInputStream.close();
+		} else {
+			try {
+				file.getParentFile().mkdirs();
+				file.createNewFile();	
+				final URI uri = new URI("https:/" + resource);
+		        final URL url = uri.toURL();
+		        final HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+		        connection.setRequestMethod("GET");
+		        final BufferedInputStream bufferedInputStream = new BufferedInputStream(connection.getInputStream());
+		        final BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(response.getOutputStream());
+		        final BufferedOutputStream fileOutputStream = new BufferedOutputStream(new FileOutputStream(file));
+		        final byte[] bytesBuffer = new byte[4096];
+		        int readBytes = bufferedInputStream.read(bytesBuffer);
+		        while (readBytes > 0) {
+		        	bufferedOutputStream.write(bytesBuffer, 0, readBytes);
+		        	fileOutputStream.write(bytesBuffer, 0, readBytes);
+		        	readBytes = bufferedInputStream.read(bytesBuffer);
+		        }
+		        bufferedOutputStream.close();
+		        fileOutputStream.close();
+		        bufferedInputStream.close();
+		        connection.disconnect();
+			} catch (URISyntaxException e) {
+				throw new ServletException(e);
+			}
+		}
+		
+	}
+}

src/main/webapp/WEB-INF/web.xml

@@ -19,11 +19,25 @@
         </init-param>
     </servlet>
     
+    <servlet>
+        <servlet-name>ProxyServlet</servlet-name>
+        <servlet-class>de.jalin.fedipage.ProxyServlet</servlet-class>
+        <init-param>
+        	<param-name>cache</param-name>
+        	<param-value>temp/fedicache</param-value>
+        </init-param>
+    </servlet>
+    
     <servlet-mapping>
         <servlet-name>FediServlet</servlet-name>
         <url-pattern></url-pattern>
     </servlet-mapping>
     
+    <servlet-mapping>
+        <servlet-name>ProxyServlet</servlet-name>
+        <url-pattern>/cache/*</url-pattern>
+    </servlet-mapping>
+    
     <welcome-file-list>
         <welcome-file></welcome-file>
     </welcome-file-list>