Java 仅通过一个SocketChannel发送多条消息
在阅读了本教程之后：（关于编写非阻塞服务器和客户端，我阅读了NIO部分，跳过了SSL部分），现在我正试图重写自己的客户端，但在尝试编辑客户端代码时遇到了一个问题 首先，我想让您看到教程的客户端代码，它包括2个文件：Java 仅通过一个SocketChannel发送多条消息,java,nio,socketchannel,Java,Nio,Socketchannel,在阅读了本教程之后：（关于编写非阻塞服务器和客户端，我阅读了NIO部分，跳过了SSL部分），现在我正试图重写自己的客户端，但在尝试编辑客户端代码时遇到了一个问题 首先，我想让您看到教程的客户端代码，它包括2个文件： RspHandler.java： NIOClient.java： 但是我在main函数中编辑了一点NIOClient.java，以解释我的问题，如下所示： import java.io.IOException; import java.net.InetAddress; imp
- RspHandler.java：
- NIOClient.java：
mainimport java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.nio.channels.spi.SelectorProvider;
import java.util.*;
public class NIOClient implements Runnable {
// The host:port combination to connect to
private InetAddress hostAddress;
private int port;
// The selector we'll be monitoring
private Selector selector;
// The buffer into which we'll read data when it's available
private ByteBuffer readBuffer = ByteBuffer.allocate(8192);
// A list of PendingChange instances
private List pendingChanges = new LinkedList();
// Maps a SocketChannel to a list of ByteBuffer instances
private Map pendingData = new HashMap();
// Maps a SocketChannel to a RspHandler
private Map rspHandlers = Collections.synchronizedMap(new HashMap());
public NIOClient(InetAddress hostAddress, int port) throws IOException {
this.hostAddress = hostAddress;
this.port = port;
this.selector = this.initSelector();
}
public void send(byte[] data, RspHandler handler) throws IOException {
// Start a new connection
SocketChannel socket = this.initiateConnection();
// Register the response handler
this.rspHandlers.put(socket, handler);
// And queue the data we want written
synchronized (this.pendingData) {
List queue = (List) this.pendingData.get(socket);
if (queue == null) {
queue = new ArrayList();
this.pendingData.put(socket, queue);
}
queue.add(ByteBuffer.wrap(data));
}
// Finally, wake up our selecting thread so it can make the required changes
this.selector.wakeup();
}
public void run() {
while (true) {
try {
// Process any pending changes
synchronized (this.pendingChanges) {
Iterator changes = this.pendingChanges.iterator();
while (changes.hasNext()) {
ChangeRequest change = (ChangeRequest) changes.next();
switch (change.type) {
case ChangeRequest.CHANGEOPS:
SelectionKey key = change.socket.keyFor(this.selector);
key.interestOps(change.ops);
break;
case ChangeRequest.REGISTER:
change.socket.register(this.selector, change.ops);
break;
}
}
this.pendingChanges.clear();
}
// Wait for an event one of the registered channels
this.selector.select();
// Iterate over the set of keys for which events are available
Iterator selectedKeys = this.selector.selectedKeys().iterator();
while (selectedKeys.hasNext()) {
SelectionKey key = (SelectionKey) selectedKeys.next();
selectedKeys.remove();
if (!key.isValid()) {
continue;
}
// Check what event is available and deal with it
if (key.isConnectable()) {
this.finishConnection(key);
} else if (key.isReadable()) {
this.read(key);
} else if (key.isWritable()) {
this.write(key);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
private void read(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
// Clear out our read buffer so it's ready for new data
this.readBuffer.clear();
// Attempt to read off the channel
int numRead;
try {
numRead = socketChannel.read(this.readBuffer);
} catch (IOException e) {
// The remote forcibly closed the connection, cancel
// the selection key and close the channel.
key.cancel();
socketChannel.close();
return;
}
if (numRead == -1) {
// Remote entity shut the socket down cleanly. Do the
// same from our end and cancel the channel.
key.channel().close();
key.cancel();
return;
}
// Handle the response
this.handleResponse(socketChannel, this.readBuffer.array(), numRead);
}
private void handleResponse(SocketChannel socketChannel, byte[] data, int numRead) throws IOException {
// Make a correctly sized copy of the data before handing it
// to the client
byte[] rspData = new byte[numRead];
System.arraycopy(data, 0, rspData, 0, numRead);
// Look up the handler for this channel
RspHandler handler = (RspHandler) this.rspHandlers.get(socketChannel);
// And pass the response to it
if (handler.handleResponse(rspData)) {
// The handler has seen enough, close the connection
socketChannel.close();
socketChannel.keyFor(this.selector).cancel();
}
}
private void write(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
synchronized (this.pendingData) {
List queue = (List) this.pendingData.get(socketChannel);
// Write until there's not more data ...
while (!queue.isEmpty()) {
ByteBuffer buf = (ByteBuffer) queue.get(0);
socketChannel.write(buf);
if (buf.remaining() > 0) {
// ... or the socket's buffer fills up
break;
}
queue.remove(0);
}
if (queue.isEmpty()) {
// We wrote away all data, so we're no longer interested
// in writing on this socket. Switch back to waiting for
// data.
key.interestOps(SelectionKey.OP_READ);
}
}
}
private void finishConnection(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
// Finish the connection. If the connection operation failed
// this will raise an IOException.
try {
socketChannel.finishConnect();
} catch (IOException e) {
// Cancel the channel's registration with our selector
System.out.println(e);
key.cancel();
return;
}
// Register an interest in writing on this channel
key.interestOps(SelectionKey.OP_WRITE);
}
private SocketChannel initiateConnection() throws IOException {
// Create a non-blocking socket channel
SocketChannel socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
// Kick off connection establishment
socketChannel.connect(new InetSocketAddress(this.hostAddress, this.port));
// Queue a channel registration since the caller is not the
// selecting thread. As part of the registration we'll register
// an interest in connection events. These are raised when a channel
// is ready to complete connection establishment.
synchronized(this.pendingChanges) {
this.pendingChanges.add(new ChangeRequest(socketChannel, ChangeRequest.REGISTER, SelectionKey.OP_CONNECT));
}
return socketChannel;
}
private Selector initSelector() throws IOException {
// Create a new selector
return SelectorProvider.provider().openSelector();
}
public static void main(String[] args) {
try {
NIOClient client = new NIOClient(
InetAddress.getByName("127.0.0.1"), 9090);
Thread t = new Thread(client);
t.setDaemon(true);
t.start();
// 1st
client.send("hehe|||".getBytes());
System.out.println("SEND: " + "hehe|||");
handler.waitForResponse();
System.out.println("------------");
// 2nd
client.send(("hehe|||" + " 2").getBytes());
System.out.println("SEND: " + "hehe|||" + " 2");
handler.waitForResponse();
} catch (Exception e) {
e.printStackTrace();
}
}
}
sendimport java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.nio.channels.spi.SelectorProvider;
import java.util.*;
public class MyClient implements Runnable {
// The host:port combination to connect to
private InetAddress hostAddress;
private int port;
// The selector we'll be monitoring
private Selector selector;
// The buffer into which we'll read data when it's available
private ByteBuffer readBuffer = ByteBuffer.allocate(8);
// A list of PendingChange instances
private List pendingChanges = new LinkedList();
// Maps a SocketChannel to a list of ByteBuffer instances
private Map pendingData = new HashMap();
// Maps a SocketChannel to a RspHandler
private Map rspHandlers = Collections.synchronizedMap(new HashMap());
private SocketChannel socket;
private static MyResponseHandler handler;
public MyClient(InetAddress hostAddress, int port) throws IOException {
this.hostAddress = hostAddress;
this.port = port;
this.selector = this.initSelector();
// Start a new connection
socket = this.initiateConnection();
handler = new MyResponseHandler();
// Register the response handler
this.rspHandlers.put(socket, handler);
}
public void send(byte[] data) throws IOException {
// And queue the data we want written
synchronized (this.pendingData) {
List queue = (List) this.pendingData.get(socket);
if (queue == null) {
queue = new ArrayList();
this.pendingData.put(socket, queue);
}
queue.add(ByteBuffer.wrap(data));
}
// Finally, wake up our selecting thread so it can make the required changes
this.selector.wakeup();
}
public void run() {
while (true) {
try {
// Process any pending changes
synchronized (this.pendingChanges) {
Iterator changes = this.pendingChanges.iterator();
while (changes.hasNext()) {
ChangeRequest change = (ChangeRequest) changes.next();
switch (change.type) {
case ChangeRequest.CHANGEOPS:
SelectionKey key = change.socket.keyFor(this.selector);
key.interestOps(change.ops);
break;
case ChangeRequest.REGISTER:
change.socket.register(this.selector, change.ops);
break;
}
}
this.pendingChanges.clear();
}
// Wait for an event one of the registered channels
this.selector.select();
// Iterate over the set of keys for which events are available
Iterator selectedKeys = this.selector.selectedKeys().iterator();
while (selectedKeys.hasNext()) {
SelectionKey key = (SelectionKey) selectedKeys.next();
selectedKeys.remove();
if (!key.isValid()) {
continue;
}
// Check what event is available and deal with it
if (key.isConnectable()) {
this.finishConnection(key);
} else if (key.isReadable()) {
this.read(key);
} else if (key.isWritable()) {
this.write(key);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
private void read(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
// Clear out our read buffer so it's ready for new data
this.readBuffer.clear();
// Attempt to read off the channel
int numRead;
try {
numRead = socketChannel.read(this.readBuffer);
} catch (IOException e) {
// The remote forcibly closed the connection, cancel
// the selection key and close the channel.
key.cancel();
socketChannel.close();
return;
}
if (numRead == -1) {
// Remote entity shut the socket down cleanly. Do the
// same from our end and cancel the channel.
key.channel().close();
key.cancel();
return;
}
// Handle the response
this.handleResponse(socketChannel, this.readBuffer.array(), numRead);
}
private void handleResponse(SocketChannel socketChannel, byte[] data, int numRead) throws IOException {
// Make a correctly sized copy of the data before handing it
// to the client
byte[] rspData = new byte[numRead];
System.arraycopy(data, 0, rspData, 0, numRead);
// Look up the handler for this channel
MyResponseHandler handler = (MyResponseHandler) this.rspHandlers.get(socketChannel);
// And pass the response to it
if (handler.handleResponse(rspData)) {
// The handler has seen enough, close the connection
socketChannel.close();
socketChannel.keyFor(this.selector).cancel();
}
}
private void write(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
synchronized (this.pendingData) {
List queue = (List) this.pendingData.get(socketChannel);
// Write until there's not more data ...
while (!queue.isEmpty()) {
ByteBuffer buf = (ByteBuffer) queue.remove(0);
socketChannel.write(buf);
//-- DEBUG --
System.out.println("===>>> socketChannel.write: " + new String(buf.array()));
if (buf.remaining() > 0) {
// ... or the socket's buffer fills up
break;
}
}
if (queue.isEmpty()) {
// We wrote away all data, so we're no longer interested
// in writing on this socket. Switch back to waiting for
// data.
key.interestOps(SelectionKey.OP_READ);
}
}
}
private void finishConnection(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
// Finish the connection. If the connection operation failed
// this will raise an IOException.
try {
socketChannel.finishConnect();
} catch (IOException e) {
// Cancel the channel's registration with our selector
System.out.println(e);
key.cancel();
return;
}
// Register an interest in writing on this channel
key.interestOps(SelectionKey.OP_WRITE);
}
private SocketChannel initiateConnection() throws IOException {
// Create a non-blocking socket channel
SocketChannel socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
// Kick off connection establishment
socketChannel.connect(new InetSocketAddress(this.hostAddress, this.port));
// Queue a channel registration since the caller is not the
// selecting thread. As part of the registration we'll register
// an interest in connection events. These are raised when a channel
// is ready to complete connection establishment.
synchronized(this.pendingChanges) {
this.pendingChanges.add(new ChangeRequest(socketChannel, ChangeRequest.REGISTER, SelectionKey.OP_CONNECT));
}
return socketChannel;
}
private Selector initSelector() throws IOException {
// Create a new selector
return SelectorProvider.provider().openSelector();
}
public static void main(String[] args) {
try {
MyClient client = new MyClient(
InetAddress.getByName("127.0.0.1"), 9090);
Thread t = new Thread(client);
t.setDaemon(true);
t.start();
// 1st
client.send("hehe|||".getBytes());
System.out.println("SEND: " + "hehe|||");
handler.waitForResponse();
System.out.println("------------");
// 2nd
client.send(("hehe|||" + " 2").getBytes());
System.out.println("SEND: " + "hehe|||" + " 2");
handler.waitForResponse();
} catch (Exception e) {
e.printStackTrace();
}
}
}
感谢您阅读我的长问题。您从错误的地方开始。那篇文章有许多问题。所有等待更改队列的东西都是一个巨大的、不必要的复杂问题。只要
wakeup（）interesttopsIOExceptionfinishConnection（）OP\u CONNECTclose（）cancel（）如果您在Oracle论坛迁移后仍能找到，我会仔细看看他引用的“驯服NIO马戏团”的帖子，而不是那些相当可疑的混乱。免责声明：我写了一些。您从错误的地方开始。那篇文章有很多问题。所有等待更改队列的内容都是一个巨大的、令人不安的问题必要的复杂性。如果您需要从另一个线程注册/注销，只需
wakeup（），您可以随时以同样的方式以完美的可靠性更改interesttops
，即使他传播的关于不同实现的FUD曾经实现
这篇文章还有其他几个问题表明作者并不真正知道他在说什么。IOException
不一定意味着“远程强制关闭连接”。他的finishConnection（）
方法忽略返回值，如果返回值为false，则表示连接仍处于挂起状态，因此它会过早地在OP\u CONNECT
阶段之外注册通道。关闭通道会取消键，因此所有紧跟在close（）
调用之前或之后的cancel（）
调用都是多余的，可以删除（虽然有一些地方他取消而不关闭，但发生这种情况也是错误的）
进一步：
在刚才介绍的两种方法中，我们没有要求
在套接字通道的选择键上设置OP_CONNECT标志。如果
我们会覆盖OP_CONNECT标志，并且永远不会完成
连接。如果我们把它们结合起来，那么我们就会冒着试图在上面写东西的风险
未连接的通道（或至少必须处理该情况）
这完全是A级胡说八道。设置OP_CONNECT两次，或“合并它们”，无论这意味着什么，都不可能导致你“永远无法完成连接”或“尝试在未连接的通道上写入”。他似乎认为设置两次就可以清除它
数据已经排队（否则我们不会建立
首先是连接）
一种奇怪的、无法解释的假设
如果您在Oracle论坛迁移后仍能找到它，我会仔细看看他引用的“驯服NIO马戏团”帖子，而不是那种令人怀疑的混乱局面。免责声明：我写了一些。我发现了：谢谢您EJPThank you。我也在关注与此帖子相关的文章。我开始怀疑它的复杂性，这是为什么
import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.nio.channels.spi.SelectorProvider;
import java.util.*;
public class MyClient implements Runnable {
// The host:port combination to connect to
private InetAddress hostAddress;
private int port;
// The selector we'll be monitoring
private Selector selector;
// The buffer into which we'll read data when it's available
private ByteBuffer readBuffer = ByteBuffer.allocate(8);
// A list of PendingChange instances
private List pendingChanges = new LinkedList();
// Maps a SocketChannel to a list of ByteBuffer instances
private Map pendingData = new HashMap();
// Maps a SocketChannel to a RspHandler
private Map rspHandlers = Collections.synchronizedMap(new HashMap());
private SocketChannel socket;
private static MyResponseHandler handler;
public MyClient(InetAddress hostAddress, int port) throws IOException {
this.hostAddress = hostAddress;
this.port = port;
this.selector = this.initSelector();
// Start a new connection
socket = this.initiateConnection();
handler = new MyResponseHandler();
// Register the response handler
this.rspHandlers.put(socket, handler);
}
public void send(byte[] data) throws IOException {
// And queue the data we want written
synchronized (this.pendingData) {
List queue = (List) this.pendingData.get(socket);
if (queue == null) {
queue = new ArrayList();
this.pendingData.put(socket, queue);
}
queue.add(ByteBuffer.wrap(data));
}
// Finally, wake up our selecting thread so it can make the required changes
this.selector.wakeup();
}
public void run() {
while (true) {
try {
// Process any pending changes
synchronized (this.pendingChanges) {
Iterator changes = this.pendingChanges.iterator();
while (changes.hasNext()) {
ChangeRequest change = (ChangeRequest) changes.next();
switch (change.type) {
case ChangeRequest.CHANGEOPS:
SelectionKey key = change.socket.keyFor(this.selector);
key.interestOps(change.ops);
break;
case ChangeRequest.REGISTER:
change.socket.register(this.selector, change.ops);
break;
}
}
this.pendingChanges.clear();
}
// Wait for an event one of the registered channels
this.selector.select();
// Iterate over the set of keys for which events are available
Iterator selectedKeys = this.selector.selectedKeys().iterator();
while (selectedKeys.hasNext()) {
SelectionKey key = (SelectionKey) selectedKeys.next();
selectedKeys.remove();
if (!key.isValid()) {
continue;
}
// Check what event is available and deal with it
if (key.isConnectable()) {
this.finishConnection(key);
} else if (key.isReadable()) {
this.read(key);
} else if (key.isWritable()) {
this.write(key);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
private void read(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
// Clear out our read buffer so it's ready for new data
this.readBuffer.clear();
// Attempt to read off the channel
int numRead;
try {
numRead = socketChannel.read(this.readBuffer);
} catch (IOException e) {
// The remote forcibly closed the connection, cancel
// the selection key and close the channel.
key.cancel();
socketChannel.close();
return;
}
if (numRead == -1) {
// Remote entity shut the socket down cleanly. Do the
// same from our end and cancel the channel.
key.channel().close();
key.cancel();
return;
}
// Handle the response
this.handleResponse(socketChannel, this.readBuffer.array(), numRead);
}
private void handleResponse(SocketChannel socketChannel, byte[] data, int numRead) throws IOException {
// Make a correctly sized copy of the data before handing it
// to the client
byte[] rspData = new byte[numRead];
System.arraycopy(data, 0, rspData, 0, numRead);
// Look up the handler for this channel
MyResponseHandler handler = (MyResponseHandler) this.rspHandlers.get(socketChannel);
// And pass the response to it
if (handler.handleResponse(rspData)) {
// The handler has seen enough, close the connection
socketChannel.close();
socketChannel.keyFor(this.selector).cancel();
}
}
private void write(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
synchronized (this.pendingData) {
List queue = (List) this.pendingData.get(socketChannel);
// Write until there's not more data ...
while (!queue.isEmpty()) {
ByteBuffer buf = (ByteBuffer) queue.remove(0);
socketChannel.write(buf);
//-- DEBUG --
System.out.println("===>>> socketChannel.write: " + new String(buf.array()));
if (buf.remaining() > 0) {
// ... or the socket's buffer fills up
break;
}
}
if (queue.isEmpty()) {
// We wrote away all data, so we're no longer interested
// in writing on this socket. Switch back to waiting for
// data.
key.interestOps(SelectionKey.OP_READ);
}
}
}
private void finishConnection(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
// Finish the connection. If the connection operation failed
// this will raise an IOException.
try {
socketChannel.finishConnect();
} catch (IOException e) {
// Cancel the channel's registration with our selector
System.out.println(e);
key.cancel();
return;
}
// Register an interest in writing on this channel
key.interestOps(SelectionKey.OP_WRITE);
}
private SocketChannel initiateConnection() throws IOException {
// Create a non-blocking socket channel
SocketChannel socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
// Kick off connection establishment
socketChannel.connect(new InetSocketAddress(this.hostAddress, this.port));
// Queue a channel registration since the caller is not the
// selecting thread. As part of the registration we'll register
// an interest in connection events. These are raised when a channel
// is ready to complete connection establishment.
synchronized(this.pendingChanges) {
this.pendingChanges.add(new ChangeRequest(socketChannel, ChangeRequest.REGISTER, SelectionKey.OP_CONNECT));
}
return socketChannel;
}
private Selector initSelector() throws IOException {
// Create a new selector
return SelectorProvider.provider().openSelector();
}
public static void main(String[] args) {
try {
MyClient client = new MyClient(
InetAddress.getByName("127.0.0.1"), 9090);
Thread t = new Thread(client);
t.setDaemon(true);
t.start();
// 1st
client.send("hehe|||".getBytes());
System.out.println("SEND: " + "hehe|||");
handler.waitForResponse();
System.out.println("------------");
// 2nd
client.send(("hehe|||" + " 2").getBytes());
System.out.println("SEND: " + "hehe|||" + " 2");
handler.waitForResponse();
} catch (Exception e) {
e.printStackTrace();
}
}
}