Firstly I check the port:
$ lsof -i :8080
The results are:
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
WeChat 1527 wonz 241u IPv4 0xbfe135d7b32e86f1 0t0 TCP wonzdembp:63849->116.128.133.101:http-alt (ESTABLISHED)
__debug_b 41009 wonz 4u IPv6 0xbfe135e149b1e659 0t0 TCP *:http-alt (LISTEN)
So I kill PID:
$ kill 41009
Then it works.