可以理解为，一台服务器跑了多个网站，既能访问baidu 又能访问qq，就用了一个httpd服务，一个网站多个域名，每个网站都是对应一个虚拟主机。
httpd配置文件里 DocumentRoot "/usr/local/apache2.4/htdocs" 为什么可以在htdocs下访问到1.php，就是只因为这个DocumentRoot这个参数定义了该文件夹
域名为 ServerName 定义的名字
在windows平台修改hosts，在该文件定义域名IP，可以把IP指向某域名，在win的cmd上测试成功
C:\Windows\System32\drivers\etc # Copyright (c) 1993-2009 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 # ::1 localhost 192.168.212.130 www.chyuanliu.com www.chyuanliu1.com
在httpd配置文件中
ServerName www.example.com:80 仅定义了一个域名，为apache的默认主机，也就是说任何一个域名，只要指向这个IP，都会访问到这个站点，这个站点就是默认主机。 这就带来了问题，如果机子上跑多个域名，不希望所有域名都指向到这个站点，所有需要配置一个虚拟主机 在httpd配置文件中 # Virtual hosts #Include conf/extra/httpd-vhosts.conf
打开该注释之后，之前的httpd配置文件中的ServerName和DocumentRoot都会失效
vhosts配置文件中，每一个VirtualHost都是一个虚拟主机，都是一个站点，第一个是默认虚拟主机，即访问IP可以访问到，无论任何域名解析到这个IP上，都会访问第一个，所以一般我们把默认虚拟主机弄成空的。
[root@chy002 htdocs]# vi /usr/local/apache2.4/conf/extra/httpd-vhosts.conf
<VirtualHost *:80>
DocumentRoot "/data/wwwroot/abc.com" #网站根目录
ServerName abc.com #网站域名
ServerAlias www.abc.com www.123.com #网站别名
ErrorLog "logs/abc.com-error_log"
CustomLog "logs/abc.com-access_log" common
</VirtualHost>
<VirtualHost *:80>
DocumentRoot "/data/wwwroot/111.com"
ServerName 111.com
ServerAlias www.example.com
ErrorLog "logs/111.com-error_log"
CustomLog "logs/111.com-access_log" common
</VirtualHost>
[root@chy002 htdocs]# mkdir -p /data/wwwroot/abc.com
[root@chy002 htdocs]# mkdir /data/wwwroot/111.com
[root@chy002 htdocs]# vim /data/wwwroot/abc.com/index.php
[root@chy002 htdocs]# vim /data/wwwroot/111.com/index.php
[root@chy002 htdocs]# vi /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.212.130 111.com abc.com
[root@chy002 htdocs]# ping abc.com
PING 111.com (192.168.212.130) 56(84) bytes of data.
64 bytes from 111.com (192.168.212.130): icmp_seq=1 ttl=64 time=0.070 ms
^C
--- 111.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2000ms
rtt min/avg/max/mdev = 0.051/0.058/0.070/0.008 ms
[root@chy002 htdocs]# curl abc.com
abc.com[root@chy002 htdocs]# curl 111.com
111.com[root@chy002 htdocs]# curl 192.168.212.130
abc.com
#默认abc.com是默认主机
