Closes #172: smart images caching

docs-core/src/main/java/com/sismics/util/HttpUtil.java

@@ -1,14 +1,8 @@
 package com.sismics.util;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import java.io.BufferedReader;
-import java.io.IOException;
-import java.io.InputStreamReader;
-import java.io.OutputStreamWriter;
-import java.net.URL;
-import java.net.URLConnection;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.Locale;
 
 /**
  * HTTP request utilities.
@@ -17,77 +11,17 @@ import java.net.URLConnection;
  */
 public class HttpUtil {
     /**
-     * Logger.
+     * Format of the expires header.
      */
-    private static final Logger log = LoggerFactory.getLogger(HttpUtil.class);
+    private static final SimpleDateFormat EXPIRES_FORMAT = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss Z", Locale.ENGLISH);
 
     /**
-     * Loads the content of an URL into a string.
-     * 
-     * @param url URL to load
-     * @return Contents of the resource
+     * Build an Expires HTTP header.
+     *
+     * @param futureTime Expire interval
+     * @return Formatted header value
      */
-    public static String readUrlIntoString(URL url) {
-        URLConnection connection;
-        BufferedReader in = null;
-        try {
-            connection = url.openConnection();
-            in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
-            StringBuilder sb = new StringBuilder();
-            String inputLine;
-            while ((inputLine = in.readLine()) != null) {
-                sb.append(inputLine);
-            }
-            return sb.toString();
-        } catch (IOException e) {
-            if (log.isErrorEnabled()) {
-                log.error("Error reading URL", e);
-            }
-            return null;
-        } finally {
-            if (in != null) {
-                try {
-                    in.close();
-                } catch (Exception e) {
-                    // NOP
-                }
-            }
-        }
-    }
-    
-    public static String postUrl(URL url, String data) throws IOException {
-        OutputStreamWriter wr = null;
-        BufferedReader rd = null;
-        try {
-            URLConnection conn = url.openConnection();
-            conn.setDoOutput(true);
-            wr = new OutputStreamWriter(conn.getOutputStream());
-            wr.write(data);
-            wr.flush();
-    
-            // Get the response
-            rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
-            StringBuilder sb = new StringBuilder();
-            String line = null;
-            while ((line = rd.readLine()) != null) {
-                sb.append(line).append("\n");
-            }
-            return sb.toString();
-        } finally {
-            if (wr != null) {
-                try {
-                    wr.close();
-                } catch (IOException e) {
-                    // NOP
-                }
-            }
-            if (rd != null) {
-                try {
-                    rd.close();
-                } catch (IOException e) {
-                    // NOP
-                }
-            }
-        }
+    public static String buildExpiresHeader(long futureTime) {
+        return EXPIRES_FORMAT.format(new Date().getTime() + futureTime);
     }
 }