Java ServerSocketChannel SocketChannel（回调）
我正在努力学习Java。 我想实现一个简单的网络连接4游戏以及聊天function。
我希望我的网络逻辑是非阻塞的，所以经过多次研究后我发现SocketChannel是我在重新考虑我的需求之后。
没有意义的是SocketChannels中缺少CallBack函数。就像在C＃中找到的一样。
我这次的查询是：如何将收到的数据传递给聊天或游戏表单（JFrame）？
一些指导是最受欢迎的。
您需要使用选择器。 首先创建一个Selector来接收事件：
Selector selector = Selector.open() 然后，您需要使用选择器注册ServerSocketChannel：
SelectionKey acceptKey = server.register(selector, SelectionKey.OP_ACCEPT);
然后，您需要使用选择器来处理事件（您可以将其视为流程的“回调”部分：
while(true){ //how many channel keys are available int available = selector.select(); //select is blocking, but should only return if available is >0, this is more of a sanity check if(available == 0) continue; Iterator keys = selector.selectedKeys().iterator(); while(keys.hasNext()){ SelectionKey key = keys.next(); keys.remove(); //someone is trying to connect to the server socket if(key.isAcceptable()) doAccept(key); //someone is sending us data else if(key.isReadable()) doRead(key); //we are trying to (and can) send data else if(key.isWritable()) doWrite(key); }
肉将在doAccept（），doRead（）和doWrite（）中。 对于接受键，选择键将包含用于创建新Socket的信息。
doAccept(SelectionKey key){ //create the new socket SocketChannel socket = ((ServerSocketChannel)key.channel()).accept(); //make it non-blocking as well socket.configureBlocking(false); ... //here you would likely have some code to init your game objects / communication protocol, etc. and generate an identifier object (used below). //and be able to find the socket created above ... //Since it is non blocking it needs a selector as well, and we register for both read and write events SelectionKey socketKey = socket.register(selector, SelectionKey.OP_READ|SelectionKey.OP_WRITE); // so we can identify the events as they come in socketKey.attach(someSocketIndentifier); }
最后一行向键添加了一些对象，以便从选择器接收的事件可以归因于连接（例如，它可能是游戏中的玩家）。 所以现在你可以接受新的连接，你只需要读写。
doRead(SelectionKey key){ //here we retrieve the key we attached earlier, so we now what to do / wheer the data is coming from MyIdentifierType myIdentifier = (MyIdentifierType)key.attachment(); //This is then used to get back to the SocketChannel and Read the Data myIdentifier.readTheData(); }
类似的写作
doWrite(SelectionKey key){ //here we retrieve the key we attached earlier, so we now what to do / wheer the data is coming from MyIdentifierType myIdentifier = (MyIdentifierType)key.attachment(); //This is then used to get back to the SocketChannel and Read the Data myIdentifier.getSocketHandler().writePendingData(); }
读取是相当简单的，您只需创建一个ByteBuffer，然后调用SocketChannels读取（ByteBuffer）（或其中一个变体），以便在通道上准备好数据，直到它为空。
写入有点棘手，因为在收到写入事件之前，通常需要缓冲要写入的数据：
class MyNetworkClass{ ByteBuffer writeBuffer = ByteBuffer.allocate(1024); SocketChannel commchannel; //from the server accept processing ... public void write(byte[] data){ //here the class writeBuffer object is filled with the data //but it isn't actually sent over the socket ... } public void writePendingData(){ //here actually write the data to the socket commchannel.write(writeBuffer); } }
请注意，如果不是缓冲区中的所有数据都写入套接字，则需要适当的代码来管理类中的缓冲区（如果它已满），或者在写入暂挂方法中适当地修改缓冲区，以及在此过程中可能抛出的各种exception。 希望这有助于您入门。