Start on lower memory POIFS implementation - data source to provide common access to array of bytes and files

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1050607 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 48 insertions, 0 deletions

diff --git a/src/java/org/apache/poi/poifs/nio/FileBackedDataSource.java b/src/java/org/apache/poi/poifs/nio/FileBackedDataSource.java
new file mode 100644
index 0000000000..7f5e8e6354
--- /dev/null
+++ b/src/java/org/apache/poi/poifs/nio/FileBackedDataSource.java
@@ -0,0 +1,48 @@
+/* ====================================================================
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You under the Apache License, Version 2.0
+   (the "License"); you may not use this file except in compliance with
+   the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+==================================================================== */
+
+package org.apache.poi.poifs.nio;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+
+/**
+ * A POIFS {@link DataSource} backed by a File
+ */
+public class FileBackedDataSource extends DataSource {
+   private FileChannel file;
+   public FileBackedDataSource(FileChannel file) {
+      this.file = file;
+   }
+   
+   public void read(ByteBuffer dst, long position) throws IOException {
+      file.read(dst, position);
+   }
+   
+   public void write(ByteBuffer src, long position) throws IOException {
+      file.write(src, position);
+   }
+   
+   public long size() throws IOException {
+      return file.size();
+   }
+   
+   public void close() throws IOException {
+      file.close();
+   }
+}