function.header.html

php的帮助文档,涉及到PHP的案例和基本语法,以及实际应用内容

      <tr valign="middle">
       <td colspan="1" rowspan="1" align="left">4.4.2 and 5.1.2</td>
       <td colspan="1" rowspan="1" align="left">
        This function now prevents more than one header to be sent at once as
        a protection against header injection attacks.
       </td>
      </tr>

      <tr valign="middle">
       <td colspan="1" rowspan="1" align="left">4.3.0</td>
       <td colspan="1" rowspan="1" align="left">
        The <i><tt class="parameter">http_response_code</tt></i>
 parameter was added.
       </td>
      </tr>

      <tr valign="middle">
       <td colspan="1" rowspan="1" align="left">4.0.4</td>
       <td colspan="1" rowspan="1" align="left">
        The <i><tt class="parameter">replace</tt></i>
 parameter was added.
       </td>
      </tr>

     </tbody>
    </colgroup>

   </table>
  </p>
 </div>


 <div class="refsect1 examples">
  <h3 class="title">Examples</h3>
  <p class="para">
   <div class="example">
    <p><b>Example #1 Download dialog</b></p>
    <div class="example-contents"><p>
     If you want the user to be prompted to save the data you are
     sending, such as a generated PDF file, you can use the <a href="http://www.faqs.org/rfcs/rfc2183" class="link external">&raquo; Content-Disposition</a> header to
     supply a recommended filename and force the browser to display the
     save dialog.
    </p></div>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #FF8000">//&nbsp;We'll&nbsp;be&nbsp;outputting&nbsp;a&nbsp;PDF<br /></span><span style="color: #0000BB">header</span><span style="color: #007700">(</span><span style="color: #DD0000">'Content-type:&nbsp;application/pdf'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">//&nbsp;It&nbsp;will&nbsp;be&nbsp;called&nbsp;downloaded.pdf<br /></span><span style="color: #0000BB">header</span><span style="color: #007700">(</span><span style="color: #DD0000">'Content-Disposition:&nbsp;attachment;&nbsp;filename="downloaded.pdf"'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">//&nbsp;The&nbsp;PDF&nbsp;source&nbsp;is&nbsp;in&nbsp;original.pdf<br /></span><span style="color: #0000BB">readfile</span><span style="color: #007700">(</span><span style="color: #DD0000">'original.pdf'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

   </div>
  </p>
  <p class="para">
   <div class="example">
    <p><b>Example #2 Caching directives</b></p>
    <div class="example-contents"><p>
     PHP scripts often generate dynamic content that must not be cached
     by the client browser or any proxy caches between the server and the
     client browser. Many proxies and clients can be forced to disable
     caching with:
    </p></div>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />header</span><span style="color: #007700">(</span><span style="color: #DD0000">"Cache-Control:&nbsp;no-cache,&nbsp;must-revalidate"</span><span style="color: #007700">);&nbsp;</span><span style="color: #FF8000">//&nbsp;HTTP/1.1<br /></span><span style="color: #0000BB">header</span><span style="color: #007700">(</span><span style="color: #DD0000">"Expires:&nbsp;Sat,&nbsp;26&nbsp;Jul&nbsp;1997&nbsp;05:00:00&nbsp;GMT"</span><span style="color: #007700">);&nbsp;</span><span style="color: #FF8000">//&nbsp;Date&nbsp;in&nbsp;the&nbsp;past<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>
     <blockquote><p><b class="note">Note</b>: 
      
       You may find that your pages aren&#039;t cached even if you don&#039;t
       output all of the headers above. There are a number of options
       that users may be able to set for their browser that change its
       default caching behavior. By sending the headers above, you should
       override any settings that may otherwise cause the output of your
       script to be cached.
      <br />
      
       Additionally, <a href="function.session-cache-limiter.html" class="function">session_cache_limiter()</a> and
       the <i>session.cache_limiter</i> configuration
       setting can be used to automatically generate the correct
       caching-related headers when sessions are being used.
      <br />
     </p></blockquote>
    </p></div>
   </div>
  </p>
 </div>


 <div class="refsect1 notes">
  <h3 class="title">Notes</h3>
  <blockquote><p><b class="note">Note</b>: 
   
    As of PHP 4, you can use output buffering to get around this problem,
    with the overhead of all of your output to the browser being buffered
    in the server until you send it. You can do this by calling
    <a href="function.ob-start.html" class="function">ob_start()</a> and <a href="function.ob-end-flush.html" class="function">ob_end_flush()</a>
    in your script, or setting the <i>output_buffering</i>
    configuration directive on in your <var class="filename">php.ini</var> or
    server configuration files.
   <br />
  </p></blockquote>
  <blockquote><p><b class="note">Note</b>: 
   
    The HTTP status header line will always be the first sent
    to the client, regardless of the actual <b>header()</b>
    call being the first or not. The status may be overridden
    by calling <b>header()</b> with a new status line
    at any time unless the HTTP headers have already been sent.
   <br />
  </p></blockquote>
  <blockquote><p><b class="note">Note</b>: 
   
    There is a bug in Microsoft Internet Explorer 4.01 that prevents
    this from working. There is no workaround. There is also a bug
    in Microsoft Internet Explorer 5.5 that interferes with this,
    which can be resolved by upgrading to Service Pack 2 or later.
   <br />
  </p></blockquote>
  <blockquote><p><b class="note">Note</b>: 
   <span class="simpara">
    If <a href="features.safe-mode.html#ini.safe-mode" class="link">safe mode</a> is enabled the
    uid of the script is added to the <i>realm</i> part
    of the <i>WWW-Authenticate</i> header if you set
    this header (used for HTTP Authentication).
   </span>
  </p></blockquote>
  <blockquote><p><b class="note">Note</b>: 
   
    HTTP/1.1 requires an absolute <acronym title="Uniform Resource Identifier">URI</acronym> as argument to
    <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.30" class="link external">&raquo; Location:</a>
    including the scheme, hostname and absolute path, but
    some clients accept relative URIs. You can usually use
    <var class="varname"><a href="reserved.variables.server.html" class="classname">$_SERVER['HTTP_HOST']</a></var>,
    <var class="varname"><a href="reserved.variables.server.html" class="classname">$_SERVER['PHP_SELF']</a></var>
    and <a href="function.dirname.html" class="function">dirname()</a> to make an absolute URI from a
    relative one yourself:
    <div class="informalexample">
     <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #FF8000">/*&nbsp;Redirect&nbsp;to&nbsp;a&nbsp;different&nbsp;page&nbsp;in&nbsp;the&nbsp;current&nbsp;directory&nbsp;that&nbsp;was&nbsp;requested&nbsp;*/<br /></span><span style="color: #0000BB">$host&nbsp;&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$_SERVER</span><span style="color: #007700">[</span><span style="color: #DD0000">'HTTP_HOST'</span><span style="color: #007700">];<br /></span><span style="color: #0000BB">$uri&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">rtrim</span><span style="color: #007700">(</span><span style="color: #0000BB">dirname</span><span style="color: #007700">(</span><span style="color: #0000BB">$_SERVER</span><span style="color: #007700">[</span><span style="color: #DD0000">'PHP_SELF'</span><span style="color: #007700">]),&nbsp;</span><span style="color: #DD0000">'/\\'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$extra&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'mypage.php'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">header</span><span style="color: #007700">(</span><span style="color: #DD0000">"Location:&nbsp;http://$host$uri/$extra"</span><span style="color: #007700">);<br />exit;<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
     </div>

    </div>
   <br />
  </p></blockquote>
  <blockquote><p><b class="note">Note</b>: 
   
    Session ID is not passed with Location header even if <a href="session.configuration.html#ini.session.use-trans-sid" class="link">session.use_trans_sid</a> is
    enabled. It must by passed manually using <b><tt>SID</tt></b>
    constant.
   <br />
  </p></blockquote>
 </div>


 <div class="refsect1 seealso">
  <h3 class="title">See Also</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><a href="function.headers-sent.html" class="function" rel="rdfs-seeAlso">headers_sent()</a></li>
    <li class="member"><a href="function.setcookie.html" class="function" rel="rdfs-seeAlso">setcookie()</a></li>
    <li class="member">
     The section on <a href="features.http-auth.html" class="link">HTTP
     authentication</a>
    </li>
   </ul>
  </p>
 </div>


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