Java IO（3）非阻塞式输入输出（NIO）

1 ByteBuffer buffer = ByteBuffer.allocate(1024);
2 byte b = 121;
3 buffer.put(b);
4 buffer.flip();    //读写转换，由“写模式”转换为“读模式”
5 System.out.println((char)buffer.get());    

1 RandomAccessFile file = new RandomAccessFile("/Users/yulinfeng/Documents/Coding/Idea/simplenio/src/main/java/com/demo/test.json", "rw");
2 FileChannel channel = file.getChannel();
3 ByteBuffer buffer = ByteBuffer.allocate(1024);
4 channel.read(buffer);
5 buffer.flip();
6 System.out.println(new String(buffer.array()));

1 InputStream in = new FileInputStream("/Users/yulinfeng/Documents/Coding/Idea/simplenio/src/main/java/com/demo/test.json");
2 byte[] bytes = new byte[1024];
3 in.read(bytes);
4 System.out.println(new String(bytes));

1 RandomAccessFile file = new RandomAccessFile("E:\\IdeaProjects\\simplenio\\src\\main\\java\\com\\demo\\out\\test.json", "rw");
2 FileChannel channel = file.getChannel();
3 ByteBuffer buffer = Charset.forName("utf-8").encode("{\"name\": \"Kevin\"}");    //这里会自动进行读写转换，第1个例子需要手动调用flip方法进行读写模式的转换

1 RandomAccessFile readFile = new RandomAccessFile("E:\\IdeaProjects\\simplenio\\src\\main\\java\\com\\demo\\inout\\from.json", "rw");
2 FileChannel readChannel = readFile.getChannel();
3 ByteBuffer buffer = ByteBuffer.allocate(1024);
4 readChannel.read(buffer);
5 buffer.flip();      //读写转换
6 RandomAccessFile writeFile = new RandomAccessFile("E:\\IdeaProjects\\simplenio\\src\\main\\java\\com\\demo\\inout\\to.json", "rw");
7 FileChannel writeChannel = writeFile.getChannel();
8 writeChannel.write(buffer);

1 RandomAccessFile fromFile = new RandomAccessFile("E:\\IdeaProjects\\simplenio\\src\\main\\java\\com\\demo\\inout\\from.json", "rw");
2 FileChannel fromChannel = fromFile.getChannel();
3 RandomAccessFile toFile = new RandomAccessFile("E:\\IdeaProjects\\simplenio\\src\\main\\java\\com\\demo\\inout\\to.json", "rw");
4 FileChannel toChannel = toFile.getChannel();
5 
6 toChannel.transferFrom(fromChannel, 0, fromChannel.size());

 1 /**
 2  * BIO客户端
 3  * Created by Kevin on 2017/12/18.
 4  */
 5 public class Client {
 6     public static void main(String[] args) throws Exception{
 7         String data = "this is Client.";
 8         DatagramSocket socket = new DatagramSocket();
 9         DatagramPacket packet = new DatagramPacket(data.getBytes(), data.getBytes().length, InetAddress.getByName("127.0.0.1"), 8989);
10         socket.send(packet);
11     }
12 }

 1 /**
 2  * 服务器端
 3  * BIO Created by Kevin on 2017/12/18.
 4  */
 5 public class Server {
 6     public static void main(String[] args) throws Exception{
 7         DatagramSocket socket = new DatagramSocket(8989);
 8         byte[] data = new byte[1024];
 9         DatagramPacket packet = new DatagramPacket(data, data.length);
10         socket.receive(packet);    //服务器端在未收到数据时，会在此处被阻塞挂起
11         System.out.println(new String(packet.getData()));
12     }
13 }

 1 /**
 2  * NIO客户端
 3  * Created by Kevin on 2017/12/18.
 4  */
 5 public class Client {
 6     public static void main(String[] args) throws Exception{
 7         DatagramChannel channel = DatagramChannel.open();       //类似读取本地文件，首先都需要建立一个通道
 8         ByteBuffer buffer = Charset.forName("utf-8").encode("this is Client.");     //其次建立一个缓冲区
 9         channel.send(buffer, new InetSocketAddress("127.0.0.1", 8989));
10     }
11 }

 1 /**
 2  *NIO 服务器端
 3  * Created by Kevin on 2017/12/18.
 4  */
 5 public class Server {
 6     public static void main(String[] args) throws Exception{
 7         DatagramChannel channel = DatagramChannel.open();
 8         channel.socket().bind(new InetSocketAddress("127.0.0.1", 8989));
 9         ByteBuffer buffer = ByteBuffer.allocate(1024);
10         channel.receive(buffer);    //服务器端没有收到来自客户端的数据，会在这里和BIO Socket一样被阻塞
11         System.out.println(new String(buffer.array()));
12     }
13 }

 1 /**
 2  * NIO 客户端，此处只有一个客户端连接
 3  * Created by Kevin on 2017/12/24.
 4  */
 5 public class Client {
 6     public static void main(String[] args) throws Exception{
 7         DatagramChannel channel = DatagramChannel.open();
 8         ByteBuffer buffer = Charset.forName("utf-8").encode("this is Client.");
 9         channel.send(buffer, new InetSocketAddress("127.0.0.1", 8989));
10     }
11 }

 1 /**
 2  * NIO 服务器端
 3  * Created by Kevin on 2017/12/23.
 4  */
 5 public class Server {
 6     public static void main(String[] args) throws Exception{
 7         Selector selector = Selector.open();    //Selector选择器
 8         DatagramChannel channel = DatagramChannel.open();   //Channel通道
 9         channel.configureBlocking(false);
10         channel.bind(new InetSocketAddress("127.0.0.1", 8989));
11         channel.register(selector, SelectionKey.OP_READ);   //此通道注册在Selector时关注是否可读
12         while (true) {
13             selector.select();  //如果没有一个注册到此Selector上的通道就绪，则阻塞；反之，只要有一个通道就绪则不会被阻塞。selectNow方法不论是否有通道就绪，都不会阻塞。
14             Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();   //选择就绪的通道
15             while (iterator.hasNext()) {
16                 SelectionKey key = iterator.next();
17                 iterator.remove();
18                 if (key.isReadable()) {     //收到客户端数据
19                     receive(key);
20                 }
21                 if (key.isWritable()) {     //服务器端通道准备好向客户端发送数据
22                     send(key);
23                 }
24             }
25         }
26     }
27 
28     /**
29      * 服务器端收到客户端数据，并做处理
30      * @param key
31      */
32     private static void receive(SelectionKey key) throws Exception{
33         DatagramChannel channel = (DatagramChannel) key.channel();
34         ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
35         channel.receive(byteBuffer);
36         System.out.println(new String(byteBuffer.array()));
37     }
38     /**
39      * 服务器端通道已准备好向客户端发送数据
40      * @param key
41      */
42     private static void send(SelectionKey key) {
43 
44     }
45 }