聊天室高频率、低延时完全符合websocket的特点，所以聊天室使用websocket再适合不过了。
聊天室的功能并没有比上一节代码多多少，主要在握手阶段对用户的session做处理，对用户的消息进行分发和处理。
握手阶段HandshakeInterceptor需要做的处理
public class HandshakeInterceptor extends HttpSessionHandshakeInterceptor {
.........
@Override
public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object> attributes)throws Exception {
System.out.println("Before Handshake");
if (request instanceof ServletServerHttpRequest) {
ServletServerHttpRequest servletRequest = (ServletServerHttpRequest) request;
HttpSession session = servletRequest.getServletRequest().getSession(false);
String username = (String) session.getAttribute("username");
if(username != null && "".equals(""))
attributes.put("username", username);
}
return super.beforeHandshake(request, response, wsHandler, attributes);
}
MessageHandler需要对消息进行分发
public class MessageHandler extends TextWebSocketHandler {
//保存用户的websocket连接
private Map<String,WebSocketSession> users = new HashMap<String,WebSocketSession>();
protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
if(!"".equals(message.getPayload()))
session.sendMessage(message);
}
public void afterConnectionEstablished(WebSocketSession session)throws Exception {
//连接建立后，保存用户信息，并向全部在线用户发登陆信息
users.put(session.getId(), session);
String username = (String) session.getAttributes().get("username");
if(users != null){
for(WebSocketSession wssession : users.values()){
handleMessage(wssession, new TextMessage(username + " joined!!"));
}
}
}
@Override
public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
//退出后，需要移除用户信息
users.remove(session.getId());
String username = (String) session.getAttributes().get("username");
if(users != null){
for(WebSocketSession wssession : users.values()){
handleMessage(wssession, new TextMessage(username + " left!!"));
}
}
}
//群发信息
public void sendMsgToUsers(TextMessage message) throws Exception{
if(users != null){
for(WebSocketSession wssession : users.values()){
handleMessage(wssession, message);
}
}
}
}
核心代码就是HandshakeInterceptor和MessageHandler，效果图如下：
