[add] add SelectorDemo for NIO

java-io/src/main/java/com/brianway/learning/java/nio/tutorial/SelectorDemo.java

@@ -0,0 +1,64 @@
+package com.brianway.learning.java.nio.tutorial;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.nio.channels.SelectionKey;
+import java.nio.channels.Selector;
+import java.nio.channels.ServerSocketChannel;
+import java.util.Iterator;
+import java.util.Set;
+
+/**
+ * Full Selector Example
+ * 启动后，浏览器输入 localhost:9999
+ *
+ * @auther brian
+ * @since 2019/6/24 22:29
+ */
+public class SelectorDemo {
+
+    public static void main(String[] args) throws IOException {
+        Selector selector = Selector.open();
+        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
+        serverSocketChannel.socket().bind(new InetSocketAddress(9999));
+        serverSocketChannel.configureBlocking(false);
+
+        // SelectionKey key =
+        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
+
+        while (true) {
+
+            int readyChannels = selector.selectNow();
+
+            if (readyChannels == 0) {
+                // System.out.println("readyChannels == 0");
+                continue;
+            }
+
+            Set<SelectionKey> selectedKeys = selector.selectedKeys();
+
+            Iterator<SelectionKey> keyIterator = selectedKeys.iterator();
+
+            while (keyIterator.hasNext()) {
+
+                SelectionKey key = keyIterator.next();
+
+                if (key.isAcceptable()) {
+                    // a connection was accepted by a ServerSocketChannel.
+                    System.out.println("accepted");
+                } else if (key.isConnectable()) {
+                    // a connection was established with a remote server.
+                    System.out.println("connectable");
+                } else if (key.isReadable()) {
+                    // a channel is ready for reading
+                    System.out.println("ready");
+                } else if (key.isWritable()) {
+                    // a channel is ready for writing
+                    System.out.println("writable");
+                }
+
+                keyIterator.remove();
+            }
+        }
+    }
+}