启动helloworld
$ am start -n com.example.helloworld/.MainActivity
关闭helloworld
$ am force-stop com.example.helloworld
列出所有已安装apk的包名
$ pm list packages
强制安装helloworld apk
$ pm install -r /sdcard/helloworld.apk
卸载helloworld apk
$ pm uninstall -k com.example.helloworld