iis修改请求内容长度

web.config配置如下：

<?xml version="1.0" encoding="UTF-8"?>
  <configuration>
    <system.webServer>
      <security>
       <requestFiltering>
        <requestLimits maxAllowedContentLength="500000000"></requestLimits>
       </requestFiltering>
      </security>
    </system.webServer>
  </configuration>