readfile.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<!-- EN-Revision: ea62fb83196997032641b50fe44420305466195e Maintainer: daijie Status: ready -->
<!-- CREDITS: mowangjuanzi -->
<refentry xml:id="function.readfile" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>readfile</refname>
  <refpurpose>输出文件</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type class="union"><type>int</type><type>false</type></type><methodname>readfile</methodname>
   <methodparam><type>string</type><parameter>filename</parameter></methodparam>
   <methodparam choice="opt"><type>bool</type><parameter>use_include_path</parameter><initializer>&false;</initializer></methodparam>
   <methodparam choice="opt"><type class="union"><type>resource</type><type>null</type></type><parameter>context</parameter><initializer>&null;</initializer></methodparam>
  </methodsynopsis>
  <para>
   读取文件并写入到输出缓冲。
  </para>
 </refsect1>
 
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>filename</parameter></term>
     <listitem>
      <para>
       要读取的文件名。
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>use_include_path</parameter></term>
     <listitem>
      <para>
       想要在 <link linkend="ini.include-path">include_path</link>
       中搜索文件，可使用这个可选的第二个参数，设为 &true;。
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>context</parameter></term>
     <listitem>
       &note.context-support;
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   成功时返回从文件中读入的字节数，&return.falseforfailure;
  </para>
 </refsect1>

 <refsect1 role="errors">
  &reftitle.errors;
  &fs.emits.warning.on.failure;
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>使用 <function>readfile</function> 强制下载</title>
    <programlisting role="php">
<![CDATA[
<?php
$file = 'monkey.gif';

if (file_exists($file)) {
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename="'.basename($file).'"');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Length: ' . filesize($file));
    readfile($file);
    exit;
}
?>
]]>
    </programlisting>
    &example.outputs.similar;
    <mediaobject>
     <alt>打开 / 保存对话框</alt>
     <imageobject>
      <imagedata fileref="en/reference/filesystem/figures/readfile.png"/>
     </imageobject>
    </mediaobject>
   </example>
  </para>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;

 <note>
   <para>
    <function>readfile</function> 自身不会导致任何内存问题。
    如果出现内存不足的错误，使用 <function>ob_get_level</function> 确保输出缓存已经关闭。
   </para>
  </note>
  
  &tip.fopen-wrapper;
 </refsect1>
 
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>fpassthru</function></member>
    <member><function>file</function></member>
    <member><function>fopen</function></member>
    <member><function>include</function></member>
    <member><function>require</function></member>
    <member><function>virtual</function></member>
    <member><function>file_get_contents</function></member>
    <member><xref linkend="wrappers"/></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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