(This set of video tutorials is rich in content, thoroughly explained, from shallow to deep, step by step. Each technical point has practical cases with theoretical explanation and support. The real combination of theory and practice. The tutorial covers: blocking and non blocking IO, channel channel, buffer buffer buffer, selector selector, pipe pipe, filelock file lock, path, files, asynchronous filechannel and charset character coding, etc., and puts all knowledge points of Weilai into practice through the case of multi person chat room.)