[add] add Channel demo

brianway · brianway · commit 323a55ecaaaf · 2019-06-18T00:05:44.000+08:00
diff --git a/java-io/src/main/java/com/brianway/learning/java/nio/tutorial/ChannelDemo.java b/java-io/src/main/java/com/brianway/learning/java/nio/tutorial/ChannelDemo.java
@@ -0,0 +1,43 @@
+package com.brianway.learning.java.nio.tutorial;
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+
+/**
+ * 基本的 Channel 示例
+ * 一个使用FileChannel读取数据到Buffer中的示例
+ *
+ * @auther brian
+ * @since 2019/6/17 23:41
+ */
+public class ChannelDemo {
+    public static void main(String[] args) {
+        try {
+            String path = ChannelDemo.class.getResource("/").getPath() + "channel-demo.txt";
+            RandomAccessFile aFile = new RandomAccessFile(path, "rw");
+            FileChannel inChannel = aFile.getChannel();
+            // 该值小于文件内容的长度时，结果不同
+            int bufferSize = 48;
+            ByteBuffer buf = ByteBuffer.allocate(bufferSize);
+
+            int bytesRead = inChannel.read(buf);
+            while (bytesRead != -1) {
+
+                System.out.println("Read " + bytesRead);
+                buf.flip();
+
+                while (buf.hasRemaining()) {
+                    System.out.print((char) buf.get());
+                }
+
+                buf.clear();
+                bytesRead = inChannel.read(buf);
+            }
+            aFile.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}
diff --git a/java-io/src/main/resources/channel-demo.txt b/java-io/src/main/resources/channel-demo.txt
@@ -0,0 +1,2 @@
+0123456789
+asdf
