[add] add buffer demo for Java NIO

brianway · brianway · commit ad3c014ef332 · 2019-06-18T00:38:14.000+08:00
diff --git a/java-io/src/main/java/com/brianway/learning/java/nio/tutorial/BufferDemo.java b/java-io/src/main/java/com/brianway/learning/java/nio/tutorial/BufferDemo.java
@@ -0,0 +1,42 @@
+package com.brianway.learning.java.nio.tutorial;
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+
+/**
+ * 使用Buffer的例子
+ *
+ * @auther brian
+ * @since 2019/6/18 00:26
+ */
+public class BufferDemo {
+    public static void main(String[] args) throws IOException {
+        String path = BufferDemo.class.getResource("/").getPath() + "buffer-demo.txt";
+        RandomAccessFile aFile = new RandomAccessFile(path, "rw");
+        FileChannel inChannel = aFile.getChannel();
+
+        //create buffer with capacity of 48 bytes
+        ByteBuffer buf = ByteBuffer.allocate(48);
+
+        //read into buffer.
+        int bytesRead = inChannel.read(buf);
+        while (bytesRead != -1) {
+
+            //make buffer ready for read
+            buf.flip();
+
+            while (buf.hasRemaining()) {
+                // read 1 byte at a time
+                System.out.print((char) buf.get());
+            }
+
+            //make buffer ready for writing
+            // System.out.println("------");
+            buf.clear();
+            bytesRead = inChannel.read(buf);
+        }
+        aFile.close();
+    }
+}
diff --git a/java-io/src/main/resources/buffer-demo.txt b/java-io/src/main/resources/buffer-demo.txt
@@ -0,0 +1,20 @@
+0123456789
+asdf
+123456789
+asdf
+23456789
+asdf
+3456789
+asdf
+456789
+asdf
+0123456789
+asdf
+123456789
+asdf
+23456789
+asdf
+3456789
+asdf
+456789
+asdf
