读写数据的双向通道
常见Channel:
内存缓存区,暂存数据,用来独写数据
常用Buffer:
重要属性:
选择器
配合一个线程来管理多个channel,获取这些channel上发生的事件,这些channel工作在非阻塞模式下。调用selector的select() 会阻塞知道channel发生了独写就绪事件,这些事件方法就会返回这些事件交给trhead来处理。适合流量比较低的场景
网络上有多条数据发送给服务端,数据之间使用 \n 进行分割,但是由于某种原因这些数据在接收时被进行了重新组合。
public static void main(String[] args) throws IOException {
//test1();
//writer();
ByteBuffer encode = StandardCharsets.UTF_8.encode("hello,world\ni am zhangsan\nwe are family");
split(encode);
encode = StandardCharsets.UTF_8.encode(" together . \n 55555");
split(encode);
encode = StandardCharsets.UTF_8.encode(" nonononono . \n");
split(encode);
encode = StandardCharsets.UTF_8.encode(" 222222 . \n");
split(encode);
encode = StandardCharsets.UTF_8.encode(" 33333333333 . \n");
split(encode);
encode = StandardCharsets.UTF_8.encode(" 44444444444444 . \n123456\n");
split(encode);
}
/**
* 粘包/半包,通过使用 /n分割 模拟网络发送的数据包
* 1、查询ThreadLocal中还有没有上一次没有读取完的数据
* 1.1 将上一次未获取完数据跟当前数据进行合并
* 1.2 开启读模式
* 1.3 验证 position的位置 跟limit的位置是否相同,如果不同证明 数据没有取完
* 2、读取数据
*/
private static void split(ByteBuffer byteBuffer){
//切换读模式
Data lastData = dataThreadLocal.get();
if (Objects.nonNull(lastData)) {
ByteBuffer lastDataBuffer = lastData.getData();
ByteBuffer newByteBuffer = ByteBuffer.allocate(byteBuffer.limit() + (lastDataBuffer.limit() - lastDataBuffer.position()));
while (lastDataBuffer.hasRemaining()){
newByteBuffer.put(lastDataBuffer.get());
}
newByteBuffer.put(byteBuffer);
newByteBuffer.flip();
//读取新传入的,将上一次的数据进行合并
for (int i = 0; i < newByteBuffer.limit(); i++) {
byte b = newByteBuffer.get(i);
if ('\n' == b) {
int length = i + 1 - newByteBuffer.position();
ByteBuffer allocate = ByteBuffer.allocate(length);
for (int i1 = 0; i1 < allocate.limit(); i1++) {
allocate.put(newByteBuffer.get());
}
allocate.flip();
System.out.println("后续包数据:"+StandardCharsets.UTF_8.decode(allocate));
}
}
if (newByteBuffer.position() != newByteBuffer.limit()) {
//没有截取完的数据,将后面的数据放入
Data data = new Data(Thread.currentThread().getName(), newByteBuffer);
dataThreadLocal.set(data);
}
}else {
//将数据按照转义符进行分割
for (int i = 0; i < byteBuffer.limit() ; i++) {
//截取数据
byte b = byteBuffer.get(i);
if ('\n' == b) {
int length = i + 1 - byteBuffer.position();
ByteBuffer allocate = ByteBuffer.allocate(length);
for (int i1 = 0; i1 < allocate.limit(); i1++) {
allocate.put(byteBuffer.get());
}
allocate.flip();
System.out.println("打印数据:"+StandardCharsets.UTF_8.decode(allocate));
}
}
if (byteBuffer.position() != byteBuffer.limit()) {
//没有截取完的数据,将后面的数据放入
Data data = new Data(Thread.currentThread().getName(), byteBuffer);
dataThreadLocal.set(data);
}
}
}
public class TimeServer {
public static void main(String[] args) throws InterruptedException {
int port = 8080;
if (args != null && args.length > 0) {
try {
port = Integer.parseInt(args[0]);
} catch (NumberFormatException e) {
//
}
}
new Thread(new MultiplexerTimeServer(port)).start();
Thread.currentThread().join();
}
public static class MultiplexerTimeServer implements Runnable {
//创建多路复用器
private Selector selector;
//简历服务器管道
private ServerSocketChannel serverSocketChannel;
//用来控制服务器是否停止
private volatile boolean stop;
public MultiplexerTimeServer(int port) {
try {
selector = Selector.open();
serverSocketChannel = ServerSocketChannel.open();
//设置为非阻塞模式
serverSocketChannel.configureBlocking(false);
//绑定套接字
serverSocketChannel.socket().bind(new InetSocketAddress(port), 1024);
//注册一个接收的监听位事件
serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
System.out.println("The time server is start int port :" + port);
} catch (IOException e) {
System.exit(1);
}
}
public void stop() {
this.stop = true;
}
@Override
public void run() {
try {
while (!stop) {
//轮询注册在selector上面准备就绪的channel
selector.select(1000);
Set<SelectionKey> selectionKeys = selector.selectedKeys();
Iterator<SelectionKey> keyIterator = selectionKeys.iterator();
SelectionKey key = null;
while (keyIterator.hasNext()) {
key = keyIterator.next();
keyIterator.remove();
this.handleInput(key);
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 处理事件
* @param selectionKey
* @throws IOException
*/
private void handleInput(SelectionKey selectionKey) throws IOException {
if (selectionKey.isValid()) {
//如果是接收事件先处理接收的事件,然后再在管道上面注册一个读的操作位
if (selectionKey.isAcceptable()) {
System.out.println("接收到连接事件。。。。");
ServerSocketChannel channel = (ServerSocketChannel) selectionKey.channel();
SocketChannel sc = channel.accept();
sc.configureBlocking(false);
sc.register(selector, SelectionKey.OP_READ);
}
//如果是读事件
if (selectionKey.isReadable()) {
System.out.println("接收到读事件。。。。");
SocketChannel channel = (SocketChannel) selectionKey.channel();
ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
int read = channel.read(byteBuffer);
byteBuffer.flip();
if (read > 0) {
byte[] bytes = new byte[byteBuffer.remaining()];
byteBuffer.get(bytes);
String body = new String(bytes, StandardCharsets.UTF_8);
System.out.println("The time server receive order :" + body);
//返回客户端时间
String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new Date(System.currentTimeMillis()).toString() : "BAD ORDER";
doWrite(channel, currentTime);
} else if (read < 0) {
selectionKey.cancel();
channel.close();
} else {
; //读取 0 字节 忽略
}
}
}
}
private void doWrite(SocketChannel socketChannel, String response) throws IOException {
if (StringUtils.hasText(response)) {
byte[] bytes = response.getBytes(StandardCharsets.UTF_8);
ByteBuffer wrap = ByteBuffer.allocate(bytes.length);
wrap.put(bytes);
wrap.flip();
socketChannel.write(wrap);
}
}
}
}
public class TimeClient {
public static void main(String[] args) throws InterruptedException {
int port = 8080;
if (args != null && args.length > 0) {
port = Integer.parseInt(args[0]);
}
new Thread(new TimeClientHandle("127.0.0.1", port)).start();
Thread.currentThread().join();
}
public static class TimeClientHandle implements Runnable {
private String host;
private int port;
private Selector selector;
private SocketChannel socketChannel;
private volatile boolean stop;
public TimeClientHandle(String host, int port) {
this.host = host == null ? "127.0.0.1" : host;
this.port = port;
try {
selector = Selector.open();
socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
}
@Override
public void run() {
try {
doConnect();
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
while (!stop) {
try {
selector.select(1000);
Set<SelectionKey> selectionKeys = selector.selectedKeys();
Iterator<SelectionKey> selectionKeyIterator = selectionKeys.iterator();
SelectionKey key = null;
while (selectionKeyIterator.hasNext()) {
key = selectionKeyIterator.next();
selectionKeyIterator.remove();
try {
handleInput(key);
} catch (IOException e) {
e.printStackTrace();
key.cancel();
if (key.channel() != null) {
key.channel().close();
}
}
}
} catch (Exception e) {
e.printStackTrace();
System.exit(1);
}
}
}
/**
* 创建连接
* 1.如果直接连接成功,直接注册读事件到多路复用器上
* 2.没有连接成功的话,注册连接事件到多路复用器上
* @throws IOException
*/
private void doConnect() throws IOException {
if (socketChannel.connect(new InetSocketAddress(host, port))) {
socketChannel.register(selector, SelectionKey.OP_READ);
doWrite(socketChannel);
} else {
socketChannel.register(selector, SelectionKey.OP_CONNECT);
}
}
/**
* 发送请求数据到管道中
*
*
* @param socketChannel
* @throws IOException
*/
private void doWrite(SocketChannel socketChannel) throws IOException {
byte[] bytes = "QUERY TIME ORDER".getBytes(StandardCharsets.UTF_8);
ByteBuffer byteBuffer = ByteBuffer.allocate(bytes.length);
byteBuffer.put(bytes);
byteBuffer.flip();
socketChannel.write(byteBuffer);
if (!byteBuffer.hasRemaining()) {
System.out.println("Send order 2 server succeed .");
}
}
/**
* 先判断key 是否是连接事件,如果连接成功,注册一个读时间发送查询请求
*
* @param selectionKey
* @throws IOException
*/
private void handleInput(SelectionKey selectionKey) throws IOException {
if (selectionKey.isValid()) {
SocketChannel socketChannel = (SocketChannel) selectionKey.channel();
//判断是否连接成功
if (selectionKey.isConnectable()) {
System.out.println("接收到服务器连接事件。。。。");
//完成连接后,注册一个读事件
if (socketChannel.finishConnect()) {
socketChannel.register(selector, SelectionKey.OP_READ);
doWrite(socketChannel);
}
}
//读事件准备就绪
if (selectionKey.isReadable()) {
System.out.println("接收到服务器读事件。。。。");
ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
int read = socketChannel.read(byteBuffer);
if (read > 0) {
byteBuffer.flip();
byte[] bytes = new byte[read];
byteBuffer.get(bytes);
String body = new String(bytes, StandardCharsets.UTF_8);
System.out.println("Now is :" + body);
this.stop = true;
} else if (read < 0) {
selectionKey.cancel();
socketChannel.close();
} else {
; // 读取 0 字节
}
}
}
}
}
}