Changeset 6071

Timestamp:

Jul 30, 2012, 2:03:29 PM (11 years ago)

Author:

Nicklas Nordborg

Message:

Fixes #1705: Add support for pausing and resuming file downloads

File:

• trunk/src/clients/web/net/sf/basedb/clients/web/servlet/Download.java (modified) (5 diffs)

trunk/src/clients/web/net/sf/basedb/clients/web/servlet/Download.java

@@ -69 +69 @@
   private static final Pattern findId = Pattern.compile("/-([0-9a-f]+)-(/.*)$");
 
+  // Find start+end byte in Range header. We support simplified syntax only: bytes=start-(end)
+  private static final Pattern findRange = Pattern.compile("bytes=(\\d+)-(\\d*)");
+  
   private String defaultMimeType = "text/plain";
   private String forceMimeType = null;
@@ -96 +99 @@
     String pathInfo = usePathInfo ? request.getPathInfo() : 
       URLDecoder.decode(request.getRequestURI(), "UTF-8").replace(contextPath+servletPath, "");
+    String range = request.getHeader("Range");
+    String ifRange = request.getHeader("If-Range");
+    
     /*
       The pathInfo is expected to be like:
@@ -126 +132 @@
       return;
     }
+    
+    // Check if a "Range" has been specifed (eg. when resuming a paused download)
+    // We only allow a simplified syntax
+    long startByte = 0;
+    long endByte = 0;
+    if (range != null)
+    {
+      m = findRange.matcher(range);
+      if (m.matches())
+      {
+        startByte = Values.getLong(m.group(1), 0);
+        endByte = Values.getLong(m.group(2), 0);
+      }
+      else
+      {
+        // Ignore range request and serve the full file
+        range = null;
+      }
+    }
+    
+    //System.out.println("Range: " + range + "; startByte=" + startByte + "; endByte="+endByte);
 
     SessionControl sc = null;
@@ -155 +182 @@
       dc = sc.newDbControl();
       f = File.getByPath(dc, path, false);
+      // The ETag is used to support pause/resume when downloading
+      // Seems to work without it in Firefox but not in IE
+      // We use the MD5 checksum if available and the version otherwise
+      String eTag = "\"" + (f.getMd5() == null ? f.getVersion() : f.getMd5()) + "\"";
       String mimeType = forceMimeType != null ? forceMimeType : f.getMimeType();
       if (mimeType == null)
@@ -163 +194 @@
       if (f.getCharacterSet() != null) response.setCharacterEncoding(f.getCharacterSet());
       if (download) response.setHeader("Content-Disposition", "attachment;filename=\""+f.getName() + "\"");
-      long size = f.getSize();
-      if (size >= 0 && size < Integer.MAX_VALUE) response.setContentLength((int)size);
-      in = f.getDownloadStream(0);
+      
+      long fileSize = f.getSize();
+      long contentSize = fileSize;
+      if (range != null && (eTag.equals(ifRange) || ifRange == null))
+      {
+        response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
+        String contentRange = "";
+        if (fileSize >= 0)
+        {
+          // Adjust the range and size if the file size is known
+          if (endByte > fileSize || endByte == 0) endByte = fileSize-1;
+          contentRange = "bytes " + startByte + "-" + endByte + "/" + fileSize;
+          contentSize = endByte - startByte + 1;
+        }
+        else
+        {
+          // Special case for unknown file size
+          contentRange = "bytes " + startByte + "-/*";
+        }
+        response.setHeader("Content-Range", contentRange);
+        //System.out.println("Content-Range: " + contentRange);
+      }
+      if (contentSize >= 0 && contentSize < Integer.MAX_VALUE) response.setContentLength((int)contentSize);
+      response.setHeader("ETag", eTag);
+      
+      in = f.getDownloadStream(startByte);
       dc.close();
       out = response.getOutputStream();