You don’t seem to have a generator with the name webapp installed. You can see available generators with npm search yeoman-generator and then install them with npm install [name].

在使用yeoman的webapp的generator的时候会出现使用命令“yo webapp ****”yeoman会出现类似“You don’t seem to have a generator with the name webapp installed. You can see available generators with npm search yeoman-generator and then install them with npm install [name].”的错误，这个错误有2个原因，
1：是我没有安装generator，使用npm install -g generators-webapp这个命令就可以了；
2：因为generator安装的问题，使用命令“npm install –force -g generator-webapp”就可以了