一：windows操作系统，在网站根目录下，新建web.config这个文件
1：不带www跳转到www代码示例
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <rewrite>
      <rules>
        <rule name="to www" stopProcessing="true">
          <match url=".*" />
          <conditions>
              <add input="{HTTP_HOST}" pattern="^sznest\.net$" />
          </conditions>
          <action type="Redirect" url="http://www.sznest.net/{R:0}" />
        </rule>
        <rule name="http to https" stopProcessing="true">
          <match url="(.*)" />
          <conditions>
          <add input="{HTTPS}" pattern="off" ignoreCase="true" />
          </conditions>
          <action type="Redirect" redirectType="Found" url="https://{HTTP_HOST}/{R:1}" />
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

2：http跳转到https代码示例
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <rewrite>
      <rules>
        <rule name="http to https" stopProcessing="true">
          <match url="(.*)" />
          <conditions>
          <add input="{HTTPS}" pattern="off" ignoreCase="true" />
          </conditions>
          <action type="Redirect" redirectType="Found" url="https://{HTTP_HOST}/{R:1}" />
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

也可以用下面的
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <rewrite>
      <rules>
        <rule name="http to https" stopProcessing="true">
          <match url="^(.*)$" ignoreCase="false" ></match>
          <conditions logicalGrouping="MatchAll">                       
            <add input="{HTTP_FROM_HTTPS}" pattern="^on$" negate="true" ></add>  
          </conditions>
          <action type="Redirect" url="https://www.顶级域名/{R:1}" redirectType="Permanent" ></action>
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

3：不带www跳转到www，http跳转到https代码示例
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <rewrite>
      <rules>
        <rule name="to www" stopProcessing="true">
          <match url=".*" />
          <conditions>
              <add input="{HTTP_HOST}" pattern="^sznest\.net$" />
          </conditions>
          <action type="Redirect" url="https://www.sznest.net/{R:0}" />
        </rule>
        <rule name="http to https" stopProcessing="true">
          <match url="(.*)" />
          <conditions>
          <add input="{HTTPS}" pattern="off" ignoreCase="true" />
          </conditions>
          <action type="Redirect" redirectType="Found" url="https://{HTTP_HOST}/{R:1}" />
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

二：Linux操作系统，在网站根目录下，新建.htaccess这个文件
1：不带www跳转到www代码示例
<IfModule mod_rewrite.c>
    RewriteEngine on
    RewriteCond %{HTTP_HOST} ^sznest.net [NC]
    RewriteRule ^(.*)$ http://www.sznest.net/$1 [L,R=301]
</IfModule>

2：http跳转到https代码示例
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteBase /
RewriteCond %{SERVER_PORT} !^443$
RewriteRule (.*) https://%{SERVER_NAME}/$1 [R=301,L]
</IfModule>

3：不带www跳转到www，http跳转到https代码示例
<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteCond %{HTTP_HOST} ^sznest.net [NC]
    RewriteRule ^(.*)$ https://www.sznest.net/$1 [L,R=301]
    RewriteCond %{SERVER_PORT} 80
    RewriteRule ^(.*)$ https://www.sznest.net/$1 [L,R=301]
</IfModule>