src/Pure/System/download.scala

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Pure/System/download.scala	Wed May 05 22:23:45 2010 +0200
@@ -0,0 +1,53 @@
+/*  Title:      Pure/System/download.scala
+    Author:     Makarius
+
+Download URLs -- with progress monitor.
+*/
+
+package isabelle
+
+
+import java.io.{BufferedInputStream, BufferedOutputStream, FileOutputStream,
+  File, InterruptedIOException}
+import java.net.{URL, URLConnection}
+import java.awt.{Component, HeadlessException}
+import javax.swing.ProgressMonitorInputStream
+
+
+object Download
+{
+  def stream(parent: Component, url: URL): (URLConnection, BufferedInputStream) =
+  {
+    val connection = url.openConnection
+
+    val stream = new ProgressMonitorInputStream(null, "Downloading", connection.getInputStream)
+    val monitor = stream.getProgressMonitor
+    monitor.setNote(connection.getURL.toString)
+
+    val length = connection.getContentLength
+    if (length != -1) monitor.setMaximum(length)
+
+    (connection, new BufferedInputStream(stream))
+  }
+
+  def file(parent: Component, url: URL, file: File)
+  {
+    val (connection, instream) = stream(parent, url)
+    val mod_time = connection.getLastModified
+
+    def read() =
+      try { instream.read }
+      catch { case _ : InterruptedIOException => error("Download canceled!") }
+    try {
+      val outstream = new BufferedOutputStream(new FileOutputStream(file))
+      try {
+        var c: Int = 0
+        while ({ c = read(); c != -1}) outstream.write(c)
+      }
+      finally { outstream.close }
+      if (mod_time > 0) file.setLastModified(mod_time)
+    }
+    finally { instream.close }
+  }
+}
+