D:\rnworkspace\Hello>react-native start
Scanning 568 folders for symlinks in D:\rnworkspace\Hello\node_modules (41ms)
┌──────────────────────────────────────
──────────────────────────────────────┐
│ Running packager on port 8081.
│
│
│
│ Keep this packager running while developing on any JS projects. Feel
│
│ free to close this tab and run your own packager instance if you
│
│ prefer.
│
│
│
│ https://github.com/facebook/react-native
│
│
│
└──────────────────────────────────────
──────────────────────────────────────┘
Looking for JS files in
D:\rnworkspace\Hello


ERROR Packager can't listen on port 8081
Most likely another process is already using this port
Run the following command to find out which process:


lsof -n -i4TCP:8081


You can either shut down the other process:


kill -9 <PID>


or run packager on different port.


See http://facebook.github.io/react-native/docs/troubleshooting.html

for common problems and solutions.

解决：

1.修改监听借口 ，命令如react-native start --port=8088

2.找到占用端口的进程，删除 查找命令如下：

netstat -ano

tasklist|findstr "2720" //2720 是PID