事件:'data'
¥Event: 'data'
收到数据时触发。参数 data 将是 Buffer 或 String。数据编码由 socket.setEncoding() 设置。
¥Emitted when data is received. The argument data will be a Buffer or
String. Encoding of data is set by socket.setEncoding().
如果 Socket 触发 'data' 事件时没有监听器,则数据将丢失。
¥The data will be lost if there is no listener when a Socket
emits a 'data' event.