Java NIO 阻塞式與非阻塞式

/*
 * 一、使用 NIO 完成網路通訊的三個核心：
 * 
 * 1. 通道（Channel）：負責連線
 *
 *    java.nio.channels.Channel 介面：
 * |--SelectableChannel
 * |--SocketChannel
 * |--ServerSocketChannel
 * |--DatagramChannel
 * 
 * |--Pipe.SinkChannel
 * |--Pipe.SourceChannel
 * 
 * 2. 緩衝區（Buffer）：負責資料的存取
 * 
 * 3. 選擇器（Selector）：是 SelectableChannel 的多路複用器。用於監控 SelectableChannel 的 IO 狀況
 * 

 */

public class TestBlockingNIO {
//客戶端
@Test
public void client() throws IOException{
//1. 獲取通道
SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9898));

FileChannel inChannel = FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);

//2. 分配指定大小的緩衝區
ByteBuffer buf = ByteBuffer.allocate(1024);

//3. 讀取本地檔案，併傳送到服務端
while(inChannel.read(buf) != -1){
buf.flip();
sChannel.write(buf);
buf.clear();
}

//4. 關閉通道
inChannel.close();
sChannel.close();
}

//服務端
@Test
public void server() throws IOException{
//1. 獲取通道
ServerSocketChannel ssChannel = ServerSocketChannel.open();

FileChannel outChannel = FileChannel.open(Paths.get("2.jpg"), StandardOpenOption.WRITE, StandardOpenOption.CREATE);

//2. 繫結連線
ssChannel.bind(new InetSocketAddress(9898));

//3. 獲取客戶端連線的通道
SocketChannel sChannel = ssChannel.accept();

//4. 分配指定大小的緩衝區
ByteBuffer buf = ByteBuffer.allocate(1024);

//5. 接收客戶端的資料，並儲存到本地
while(sChannel.read(buf) != -1){
buf.flip();
outChannel.write(buf);
buf.clear();
}

//6. 關閉通道
sChannel.close();
outChannel.close();
ssChannel.close();

}

}

public class TestBlockingNIO2 {

//客戶端
@Test
public void client() throws IOException{
SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9898));

FileChannel inChannel = FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);

ByteBuffer buf = ByteBuffer.allocate(1024);

while(inChannel.read(buf) != -1){
buf.flip();
sChannel.write(buf);
buf.clear();
}

sChannel.shutdownOutput();

//接收服務端的反饋
int len = 0;
while((len = sChannel.read(buf)) != -1){
buf.flip();
System.out.println(new String(buf.array(), 0, len));
buf.clear();
}

inChannel.close();
sChannel.close();
}

//服務端
@Test
public void server() throws IOException{
ServerSocketChannel ssChannel = ServerSocketChannel.open();

FileChannel outChannel = FileChannel.open(Paths.get("2.jpg"), StandardOpenOption.WRITE, StandardOpenOption.CREATE);

ssChannel.bind(new InetSocketAddress(9898));

SocketChannel sChannel = ssChannel.accept();

ByteBuffer buf = ByteBuffer.allocate(1024);

while(sChannel.read(buf) != -1){
buf.flip();
outChannel.write(buf);
buf.clear();
}

//傳送反饋給客戶端
buf.put("服務端接收資料成功".getBytes());
buf.flip();
sChannel.write(buf);

sChannel.close();
outChannel.close();
ssChannel.close();
}

}

public class TestNonBlockingNIO {

//客戶端
@Test
public void client() throws IOException{
//1. 獲取通道
SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9898));

//2. 切換非阻塞模式
sChannel.configureBlocking(false);

//3. 分配指定大小的緩衝區
ByteBuffer buf = ByteBuffer.allocate(1024);

//4. 傳送資料給服務端
Scanner scan = new Scanner(System.in);

while(scan.hasNext()){
String str = scan.next();
buf.put((new Date().toString() + "\n" + str).getBytes());
buf.flip();
sChannel.write(buf);
buf.clear();
}

//5. 關閉通道
sChannel.close();
}


//服務端
@Test
public void server() throws IOException{
//1. 獲取通道
ServerSocketChannel ssChannel = ServerSocketChannel.open();

//2. 切換非阻塞模式
ssChannel.configureBlocking(false);

//3. 繫結連線
ssChannel.bind(new InetSocketAddress(9898));

//4. 獲取選擇器
Selector selector = Selector.open();

//5. 將通道註冊到選擇器上, 並且指定“監聽接收事件”
ssChannel.register(selector, SelectionKey.OP_ACCEPT);

//6. 輪詢式的獲取選擇器上已經“準備就緒”的事件
while(selector.select() > 0){

//7. 獲取當前選擇器中所有註冊的“選擇鍵(已就緒的監聽事件)”
Iterator<SelectionKey> it = selector.selectedKeys().iterator();

while(it.hasNext()){
//8. 獲取準備“就緒”的是事件
SelectionKey sk = it.next();

//9. 判斷具體是什麼事件準備就緒
if(sk.isAcceptable()){
//10. 若“接收就緒”，獲取客戶端連線
SocketChannel sChannel = ssChannel.accept();

//11. 切換非阻塞模式
sChannel.configureBlocking(false);

//12. 將該通道註冊到選擇器上
sChannel.register(selector, SelectionKey.OP_READ);
}else if(sk.isReadable()){
//13. 獲取當前選擇器上“讀就緒”狀態的通道
SocketChannel sChannel = (SocketChannel) sk.channel();

//14. 讀取資料
ByteBuffer buf = ByteBuffer.allocate(1024);

int len = 0;
while((len = sChannel.read(buf)) > 0 ){
buf.flip();
System.out.println(new String(buf.array(), 0, len));
buf.clear();
}
}

//15. 取消選擇鍵 SelectionKey
it.remove();
}
}
}
}

public class TestNonBlockingNIO2 {

@Test
public void send() throws IOException{
DatagramChannel dc = DatagramChannel.open();

dc.configureBlocking(false);

ByteBuffer buf = ByteBuffer.allocate(1024);

Scanner scan = new Scanner(System.in);

while(scan.hasNext()){
String str = scan.next();
buf.put((new Date().toString() + ":\n" + str).getBytes());
buf.flip();
dc.send(buf, new InetSocketAddress("127.0.0.1", 9898));
buf.clear();
}

dc.close();
}

@Test
public void receive() throws IOException{
DatagramChannel dc = DatagramChannel.open();

dc.configureBlocking(false);

dc.bind(new InetSocketAddress(9898));

Selector selector = Selector.open();

dc.register(selector, SelectionKey.OP_READ);

while(selector.select() > 0){
Iterator<SelectionKey> it = selector.selectedKeys().iterator();

while(it.hasNext()){
SelectionKey sk = it.next();

if(sk.isReadable()){
ByteBuffer buf = ByteBuffer.allocate(1024);

dc.receive(buf);
buf.flip();
System.out.println(new String(buf.array(), 0, buf.limit()));
buf.clear();
}
}

it.remove();
}
}


}