AsynchronousSocketChannel 一次写入/读取所有消息
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【中文标题】AsynchronousSocketChannel 一次写入/读取所有消息【英文标题】:AsynchronousSocketChannel write/read all messages in one 【发布时间】:2014-04-24 13:24:03 【问题描述】:尊重,
我尝试使用新的Java NIO2在客户端和服务器端创建异步SocketChannel并进行通信,但问题是我发送到服务器上的套接字的所有消息,套接字都作为一条消息读取。这是代码:
我创建用于写入和读取数据的处理程序:
读取处理程序:
public class ReadHandler implements CompletionHandler<Integer, Msg>
private AsynchronousSocketChannel _socket;
private SocketHandler _socketHandler;
private ByteBuffer _buffer;
public ReadHandler(SocketHandler socketHandler)
this._socketHandler = socketHandler;
_buffer = ByteBuffer.allocate(100);
this._socket = this._socketHandler.getSocket();
this._socket.read(_buffer, null, this);
@Override
public void completed(Integer result, Msg attachment)
System.out.println("readdddd " + result);
String message = new String(_buffer.array());
System.out.println("mess:" + message);
@Override
public void failed(Throwable exc, Msg attachment)
System.out.println(exc.getMessage());
ClientWriteHandler
public class ClientWriteHandler implements CompletionHandler<Integer, Msg>
private AsynchronousSocketChannel _socket;
private ClientSocket _clientHandler;
private ByteBuffer _buffer;
public ClientWriteHandler(ClientSocket clientHandler)
this._clientHandler = clientHandler;
_buffer = ByteBuffer.allocate(2048);
this._socket = this._clientHandler.getSocket();
@Override
public void completed(Integer result, Msg attachment)
System.out.println("write " + result);
_buffer.clear();
@Override
public void failed(Throwable exc, Msg attachment)
System.out.println(exc.getMessage());
public void write(String data)
_buffer = ByteBuffer.allocate(2048);
this._socket.write(_buffer.wrap(data.getBytes()), new Msg(), this);
然后我调用 write 方法 2 次p>
socket = AsynchronousSocketChannel.open();
socket.connect(new InetSocketAddress("localhost", port)).get();
writeHandler = new ClientWriteHandler(this);
writeHandler.write("hellooo server :)");
writeHandler.write("hellooo server again :)");
我尝试在 ByteBuffer 上使用 clear() 函数,但没有效果。有什么建议吗?
【问题讨论】:
【参考方案1】:WritePendingException 不是因为缓冲区已满而引发的。它被抛出是因为写入未完成但另一个开始写入。
【讨论】:
【参考方案2】:您在第一个 .write() 调用中发送了一些字节,并在第二次调用 .write() 中发送了更多字节。服务器接收它们。 TCP是面向字节的。如果您想要消息之类的内容,则必须将自己发送的消息分开,例如通过特殊的换行符或 XML 标记。
【讨论】:
好的,但是如果我的 ByteBuffer 已满怎么办,我尝试清除 bytebuffer 但随后我收到错误消息 Exception in thread "main" java.nio.channels.WritePendingException【参考方案3】:我在这方面工作,我找到了解决方案及其工作,正如我想象的那样。
在 ClientWrite 处理程序内部,我添加了数据列表并在 try..catch 中设置写入方法以检查 write() 是否已完成,如果仍在写入,我将新字符串添加到数据列表中。当 write 方法完成后,我会检查数据列表中是否有新消息并再次写入消息。
public class ClientWriteHandler implements CompletionHandler<Integer, ByteBuffer>
private AsynchronousSocketChannel _socket;
private ClientSocket _clientHandler;
private ByteBuffer _buffer;
private List<String> datas;
private boolean finished;
public ClientWriteHandler(ClientSocket clientHandler)
this._clientHandler = clientHandler;
_buffer = ByteBuffer.allocate(2048);
this._socket = this._clientHandler.getSocket();
finished = true;
datas = new ArrayList<>();
@Override
public void completed(Integer result, ByteBuffer attachment)
System.out.println("client write complete " + result);
if(datas.size() > 0)
this._socket.write(_buffer.wrap(datas.remove(0).getBytes()), _buffer, this);
else
/////
@Override
public void failed(Throwable exc, ByteBuffer attachment)
System.out.println(exc.getMessage());
public void write(String data)
try
//finished = false;
this._socket.write(_buffer.wrap(data.getBytes()), _buffer, this);
catch(WritePendingException ex)
datas.add(data);
我还在附件中发送缓冲区。 读取完成后在 ReadHandler 内部清除 ByteBuffer 并再次调用 read() 方法,所以下一次读取我得到了新行,现在我不需要设置行分隔符。
public class ReadHandler implements CompletionHandler<Integer, ByteBuffer>
private AsynchronousSocketChannel _socket;
private SocketHandler _socketHandler;
private ByteBuffer _buffer;
public ReadHandler(SocketHandler socketHandler)
this._socketHandler = socketHandler;
_buffer = ByteBuffer.allocate(2048);
this._socket = this._socketHandler.getSocket();
this._socket.read(_buffer, _buffer, this);
@Override
public void completed(Integer result, ByteBuffer attachment)
attachment.flip();
System.out.println("readdddd " + result);
String message = new String(attachment.array());
System.out.println("mess:" + message);
_buffer.clear();
this._socket.read(_buffer, _buffer, this);
@Override
public void failed(Throwable exc, ByteBuffer attachment)
System.out.println(exc.getMessage());
现在这很好用,但是当我继续处理更复杂的东西时,我会检查这段代码的行为。你觉得这个解决方案可以吗?
【讨论】:
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