From 9c632725afb73bbf0966e52ca50c6d66c12d853b Mon Sep 17 00:00:00 2001
From: Szymon Szukalski <szymon.szukalski@gmail.com>
Date: Tue, 2 Oct 2012 21:11:19 +1000
Subject: Re-wrote AsynchronousFileReader.

Various clean-ups.
---
 .../skas/melbjvm/nio2/AsynchronousFileReader.java  | 81 ++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 src/main/java/io/skas/melbjvm/nio2/AsynchronousFileReader.java

(limited to 'src/main/java/io/skas/melbjvm/nio2/AsynchronousFileReader.java')

diff --git a/src/main/java/io/skas/melbjvm/nio2/AsynchronousFileReader.java b/src/main/java/io/skas/melbjvm/nio2/AsynchronousFileReader.java
new file mode 100644
index 0000000..ff7c82b
--- /dev/null
+++ b/src/main/java/io/skas/melbjvm/nio2/AsynchronousFileReader.java
@@ -0,0 +1,81 @@
+package io.skas.melbjvm.nio2;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.AsynchronousFileChannel;
+import java.nio.channels.CompletionHandler;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+
+/**
+ * @author Szymon Szukalski [szymon.szukalski@gmail.com]
+ */
+public class AsynchronousFileReader implements CompletionHandler<Integer, ByteBuffer> {
+
+    public static final Logger LOG = LoggerFactory.getLogger(AsynchronousFileReader.class);
+    public static final int BYTES_IN_MEGABYTE = 1048576;
+
+
+    private Long position;
+    private Path path;
+    private ByteBuffer buffer;
+    private AsynchronousFileChannel asynchronousFileChannel;
+
+    public AsynchronousFileReader(Path path) {
+        this.position = 0L;
+        this.path = path;
+        this.buffer = ByteBuffer.allocate(BYTES_IN_MEGABYTE);
+
+        LOG.info("reading {}...", path);
+
+        this.openChannel();
+        this.readChannel(0);
+    }
+
+    private void openChannel() {
+        try {
+            this.asynchronousFileChannel = AsynchronousFileChannel.open(path, StandardOpenOption.READ);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    private void closeChannel() {
+        try {
+            this.asynchronousFileChannel.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    private void readChannel(long position) {
+        asynchronousFileChannel.read(buffer, position, buffer, this);
+    }
+
+    @Override
+    public void completed(Integer result, ByteBuffer buffer) {
+        if (result < 0) {
+            closeChannel();
+            LOG.debug("read: {} megabytes", position / BYTES_IN_MEGABYTE);
+        } else {
+            position += result;
+            if (buffer.hasRemaining()) {
+                readChannel(position);
+            } else {
+                buffer.flip();
+                // Do something with the content of the buffer
+                buffer.clear();
+                this.readChannel(position);
+            }
+        }
+    }
+
+    @Override
+    public void failed(Throwable exc, ByteBuffer buffer) {
+        LOG.error("read failed: {}", exc.getMessage());
+        exc.printStackTrace();
+    }
+}
-- 
cgit v1.2.3