英语翻译Along with the HTTP response code,Tomcat also sent back

英语翻译
Along with the HTTP response code,Tomcat also sent back a few lines of
information before the contents of主ndex .html,as shown in Figure 2-4.
All of these lines are HTTP headers.HTTP uses headers to send meta-
information with a request or response.A header is a colon一delimited
name:value pair-that is,it contains the header's name,delimited by a colon
followed by the header's value.肠pical response headers include content-type
descriptions,content length,a time-stamp,server information,and the date the
content was last changed.This information helps a client figure out what is
being sent,how big it is,and if the data are newer than a previously seen
response.An HTTP request will always contain a few headers8.Common
request headers consist of the user-agent details and preferred formats,lan-
guages,and content encoding to receive.These headers help tell a server what
the client is and how they would prefer to get back information.Understanding
HTTP headers is important,but for now put the concept on hold until you
learn a little more about Servlets.HTTP headers provide some very helpful
functionality,but it is better to explain them further with some HttpserVlet
examples.
8.There are no mandatory headers in HTTP 1.0; in HTTP 1.1 the only mandatory header is the
Host header.