windows上安装好服务器后，打开本地目录 C:\Windows\System32\drivers\etc\ ，会看到有个hosts文件，打开后里面的代码为：
# Copyright (c) - Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host # localhost name resolution is handled within DNS itself.
# 127.0.0.1 localhost
# :: localhost
这时我们在最底下添加
127.0.0.1 www.dev.com
注意，此时前面不能有分号，这样，当我们访问www.dev.com的时候，其实打开的就是localhost了，即使线上已经有www.dev.com这个域名，打开的也是主机上127.0.0.1这个主机了。