2.2 Java 非阻塞io(NIO)
阿新 • • 發佈:2018-12-12
Java 非阻塞io(NIO)
執行流程
1.Server
-
開啟通道選擇器Selector
-
建立ServerSocketChannel通道 並繫結介面
-
ServerSocketChannel 通道註冊到selector serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT)並指定SelectionKey(通道型別)
-
呼叫selector.select()方法檢查IO就緒事件
-
如果就緒 1.)serverSocketChannel.accept()開始處理
2.Client
- SocketChannel.open()開啟channel
- bind繫結IP和埠
- 開始讀寫
程式碼展示
Server
SelectionKey.OP_READ 對應 00000001,通道中有資料可以進行讀取 SelectionKey.OP_WRITE 對應 00000100,可以往通道中寫入資料 SelectionKey.OP_CONNECT 對應 00001000,成功建立 TCP 連線 SelectionKey.OP_ACCEPT 對應 00010000,接受 TCP 連線
// 建立通道選擇器。
Selector selector = Selector.open();
// 建立通道
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.socket().bind(new InetSocketAddress(8081));
// 將通道註冊到selector上
// 如果為 true,則此通道將被置於阻塞模式;如果為 false,則此通道將被置於非阻塞模式
serverSocketChannel.configureBlocking(false);
// 可以使用陣列組合
serverSocketChannel. register(selector, SelectionKey.OP_ACCEPT);
while (true) {
// 獲取通道數目
int readyChannels = selector.select();
if(readyChannels == 0){
continue;
}
// 獲取SelectionKey既對通道的操作
Set<SelectionKey> readyKey = selector.selectedKeys();
// 遍歷
Iterator<SelectionKey> iterator = readyKey.iterator();
while(iterator.hasNext()){
SelectionKey key = iterator.next();
iterator.remove();
// if(key.isAcceptable()) {
// // a connection was accepted by a ServerSocketChannel.
// } else if (key.isConnectable()) {
// // a connection was established with a remote server.
// } else if (key.isReadable()) {
// // a channel is ready for reading
// } else if (key.isWritable()) {
// // a channel is ready for writing
// }
if (key.isAcceptable()) {
// 有已經接受的新的到服務端的連線
SocketChannel socketChannel = serverSocketChannel.accept();
// 有新的連線並不代表這個通道就有資料,
// 這裡將這個新的 SocketChannel 註冊到 Selector,監聽 OP_READ 事件,等待資料
socketChannel.configureBlocking(false);
socketChannel.register(selector, SelectionKey.OP_READ);
} else if (key.isReadable()) {
// 有資料可讀
// 上面一個 if 分支中註冊了監聽 OP_READ 事件的 SocketChannel
SocketChannel socketChannel = (SocketChannel) key.channel();
// 建立快取空間
ByteBuffer readBuffer = ByteBuffer.allocate(1024);
int num = socketChannel.read(readBuffer);
if (num > 0) {
// 處理進來的資料...
System.out.println("收到資料:" + new String(readBuffer.array()).trim());
ByteBuffer buffer = ByteBuffer.wrap("返回給客戶端的資料...".getBytes());
socketChannel.write(buffer);
} else if (num == -1) {
// -1 代表連線已經關閉
socketChannel.close();
}
}
}
}
}catch(IOException e){
// key.cancel();
// channel.socket().close();
// channel.close();
return;
}
}
}
client
public class Client {
public static void main(String[] args) {
try {
SocketChannel socketChannel = SocketChannel.open();
socketChannel.connect(new InetSocketAddress("localhost",8081));
// 傳送請求
ByteBuffer buffer = ByteBuffer.wrap("你好嗎".getBytes());
socketChannel.write(buffer);
// 獲取server響應
ByteBuffer readBuffer = ByteBuffer.allocate(1024);
int num ;
if((num = socketChannel.read(readBuffer))> 0 ){
readBuffer.flip();
byte[] result = new byte[num];
readBuffer.get(result);
String demo = new String(result,"UTF-8");
System.out.println("返回值:"+demo);
}
}catch (Exception e){
e.printStackTrace();
}
}
}
結果和分析
server client