<?php

header('Content-type: application/image/pjpeg');//输出的类型
header('Content-Disposition: attachment; filename="downloaded.jpg"'); //下载显示的名字,注意格式
readfile('my.jpg');

// 并将这个文件以前面header发送信息设定的类型输出,从而会弹出一个下载框
// 就是把服务器上的my.jpg下载下来,下载显示和保存的名字默认是downloaded.jpg
?> 

附带文档类型及服务器响应类别

所谓实现文本文件的下载就是说当我们点击一个文本文件的链接的时候不是打开这个文件，而是弹出一个下载对话框让我们下载，这就是今天讨论的主要问 题。PHP帮助文档里面关于PHP通过header触发下载的说明比较简单，而网上关于此方面的文章也少的可怜，有很多文章都无法实现所需要的效果。今天 我也来谈一下这个方面的话题，如果你感觉比网上的某些文章有所改进，那我就很知足了。

如果从准确的角度来说，那PHP文档是最准确的，因为它很简练的列出了实现文本类文件触发下载所需要的三条语句，以PDF为例就是：

// We'll be outputting a PDF
header('Content-type: application/pdf');
// It will be called downloaded.pdf
header('Content-Disposition: attachment; filename="downloaded.pdf"');
// The PDF source is in original.pdf
readfile('original.pdf');

这三句是正确的，但是在真正用的过程中很容易出现一些无法预料的问题，如果你是一个很仔细的人的话，也可以很容易的避免这些问题。而我不是，所以我就遇到了这样的问题，这里就以我的问题来简单说一下。

对于第一句，应该没啥说的，是必须的，只要改一下文档的类型就行，例如是下载txt文件，那就改为header(’Content-type: application/txt’);

第二句也没啥说的，就是为你的下载文档起一个名字，如果是txt文件的话，可以改为 header(’Content-Disposition: attachment; filename=”downloaded.txt”‘);

第三句的问题就比较多了，readfile这个函数的意思就是读取一个文件然后输出，这里文 件的路径需要是真实的文件路径，如果是downloads文件夹下面的一个original.txt文件，可以这样写 readfile(’downloads/original.txt’);，而如果提交的页面会输出文本等字符，那么下载到的文件会是原文件 original.txt和提交的页面输出的文字的混合文件。

我在这里就缺少了仔细的观察，一看下面不对就立即去查代码了，而没发现上面的文本就是我需要 的内容，发现了这部分内容，你可能就很快想到怎么来解决这个问题了，也就是关闭提交到的页面的文本内容的输出。

到这里，我们的问题就解决了，从而也就实现了文本文件链接被点击的时候会触发下载对话框的效果

一共两个版本.

文档类型   和 服务器响应HTTP的类型

上面的这个可以在上传文件的类型中对应上.下面的差了点.(原文下面的是用来写在文件头上的.来确定该文件是什么类型.)
 

    'chm'=>'application/octet-stream',

    'ppt'=>'application/vnd.ms-powerpoint',

    'xls'=>'application/vnd.ms-excel',

    'doc'=>'application/msword',

    'exe'=>'application/octet-stream',

    'rar'=>'application/octet-stream',

    'js'=>"javascrīpt/js",

    'css'=>"text/css",

    'hqx'=>"application/mac-binhex40",

    'bin'=>"application/octet-stream",

    'oda'=>"application/oda",

    'pdf'=>"application/pdf",

    'ai'=>"application/postsrcipt",

    'eps'=>"application/postsrcipt",

    'es'=>"application/postsrcipt",

    'rtf'=>"application/rtf",

    'mif'=>"application/x-mif",

    'csh'=>"application/x-csh",

    'dvi'=>"application/x-dvi",

    'hdf'=>"application/x-hdf",

    'nc'=>"application/x-netcdf",

    'cdf'=>"application/x-netcdf",

    'latex'=>"application/x-latex",

    'ts'=>"application/x-troll-ts",

    'src'=>"application/x-wais-source",

    'zip'=>"application/zip",

    'bcpio'=>"application/x-bcpio",

    'cpio'=>"application/x-cpio",

    'gtar'=>"application/x-gtar",

    'shar'=>"application/x-shar",

    'sv4cpio'=>"application/x-sv4cpio",

    'sv4crc'=>"application/x-sv4crc",

    'tar'=>"application/x-tar",

    'ustar'=>"application/x-ustar",

    'man'=>"application/x-troff-man",

    'sh'=>"application/x-sh",

    'tcl'=>"application/x-tcl",

    'tex'=>"application/x-tex",

    'texi'=>"application/x-texinfo",

    'texinfo'=>"application/x-texinfo",

    't'=>"application/x-troff",

    'tr'=>"application/x-troff",

    'roff'=>"application/x-troff",

    'shar'=>"application/x-shar",

    'me'=>"application/x-troll-me",

    'ts'=>"application/x-troll-ts",

    'gif'=>"image/gif",

    'jpeg'=>"image/pjpeg",

    'jpg'=>"image/pjpeg",

    'jpe'=>"image/pjpeg",

    'ras'=>"image/x-cmu-raster",

    'pbm'=>"image/x-portable-bitmap",

    'ppm'=>"image/x-portable-pixmap",

    'xbm'=>"image/x-xbitmap",

    'xwd'=>"image/x-xwindowdump",

    'ief'=>"image/ief",

    'tif'=>"image/tiff",

    'tiff'=>"image/tiff",

    'pnm'=>"image/x-portable-anymap",

    'pgm'=>"image/x-portable-graymap",

    'rgb'=>"image/x-rgb",

    'xpm'=>"image/x-xpixmap",

    'txt'=>"text/plain",

    'c'=>"text/plain",

    'cc'=>"text/plain",

    'h'=>"text/plain",

    'html'=>"text/html",

    'htm'=>"text/html",

    'htl'=>"text/html",

    'rtx'=>"text/richtext",

    'etx'=>"text/x-setext",

    'tsv'=>"text/tab-separated-values",

    'mpeg'=>"video/mpeg",

    'mpg'=>"video/mpeg",

    'mpe'=>"video/mpeg",

    'avi'=>"video/x-msvideo",

    'qt'=>"video/quicktime",

    'mov'=>"video/quicktime",

    'moov'=>"video/quicktime",

    'movie'=>"video/x-sgi-movie",

    'au'=>"audio/basic",

    'snd'=>"audio/basic",

    'wav'=>"audio/x-wav",

    'aif'=>"audio/x-aiff",

    'aiff'=>"audio/x-aiff",

    'aifc'=>"audio/x-aiff",

    'swf'=>"application/x-shockwave-flash"

    'myz'=>"application/myz"

".*"="application/octet-stream"

".001"="application/x-001"

".301"="application/x-301"

".323"="text/h323"

".906"="application/x-906"

".907"="drawing/907"

".a11"="application/x-a11"

".acp"="audio/x-mei-aac"

".ai"="application/postscript"

".aif"="audio/aiff"

".aifc"="audio/aiff"

".aiff"="audio/aiff"

".anv"="application/x-anv"

".asa"="text/asa"

".asf"="video/x-ms-asf"

".asp"="text/asp"

".asx"="video/x-ms-asf"

".au"="audio/basic"

".avi"="video/avi"

".awf"="application/vnd.adobe.workflow"

".biz"="text/xml"

".bmp"="application/x-bmp"

".bot"="application/x-bot"

".c4t"="application/x-c4t"

".c90"="application/x-c90"

".cal"="application/x-cals"

".cat"="application/vnd.ms-pki.seccat"

".cdf"="application/x-netcdf"

".cdr"="application/x-cdr"

".cel"="application/x-cel"

".cer"="application/x-x509-ca-cert"

".cg4"="application/x-g4"

".cgm"="application/x-cgm"

".cit"="application/x-cit"

".class"="java/*"

".cml"="text/xml"

".cmp"="application/x-cmp"

".cmx"="application/x-cmx"

".cot"="application/x-cot"

".crl"="application/pkix-crl"

".crt"="application/x-x509-ca-cert"

".csi"="application/x-csi"

".css"="text/css"

".cut"="application/x-cut"

".dbf"="application/x-dbf"

".dbm"="application/x-dbm"

".dbx"="application/x-dbx"

".dcd"="text/xml"

".dcx"="application/x-dcx"

".der"="application/x-x509-ca-cert"

".dgn"="application/x-dgn"

".dib"="application/x-dib"

".dll"="application/x-msdownload"

".doc"="application/msword"

".dot"="application/msword"

".drw"="application/x-drw"

".dtd"="text/xml"

".dwf"="Model/vnd.dwf"

".dwf"="application/x-dwf"

".dwg"="application/x-dwg"

".dxb"="application/x-dxb"

".dxf"="application/x-dxf"

".edn"="application/vnd.adobe.edn"

".emf"="application/x-emf"

".eml"="message/rfc822"

".ent"="text/xml"

".epi"="application/x-epi"

".eps"="application/x-ps"

".eps"="application/postscript"

".etd"="application/x-ebx"

".exe"="application/x-msdownload"

".fax"="image/fax"

".fdf"="application/vnd.fdf"

".fif"="application/fractals"

".fo"="text/xml"

".frm"="application/x-frm"

".g4"="application/x-g4"

".gbr"="application/x-gbr"

".gcd"="application/x-gcd"

".gif"="image/gif"

".gl2"="application/x-gl2"

".gp4"="application/x-gp4"

".hgl"="application/x-hgl"

".hmr"="application/x-hmr"

".hpg"="application/x-hpgl"

".hpl"="application/x-hpl"

".hqx"="application/mac-binhex40"

".hrf"="application/x-hrf"

".hta"="application/hta"

".htc"="text/x-component"

".htm"="text/html"

".html"="text/html"

".htt"="text/webviewhtml"

".htx"="text/html"

".icb"="application/x-icb"

".ico"="image/x-icon"

".ico"="application/x-ico"

".iff"="application/x-iff"

".ig4"="application/x-g4"

".igs"="application/x-igs"

".iii"="application/x-iphone"

".img"="application/x-img"

".ins"="application/x-internet-signup"

".isp"="application/x-internet-signup"

".IVF"="video/x-ivf"

".java"="java/*"

".jfif"="image/jpeg"

".jpe"="image/jpeg"

".jpe"="application/x-jpe"

".jpeg"="image/jpeg"

".jpg"="image/jpeg"

".jpg"="application/x-jpg"

".js"="application/x-javascript"

".jsp"="text/html"

".la1"="audio/x-liquid-file"

".lar"="application/x-laplayer-reg"

".latex"="application/x-latex"

".lavs"="audio/x-liquid-secure"

".lbm"="application/x-lbm"

".lmsff"="audio/x-la-lms"

".ls"="application/x-javascript"

".ltr"="application/x-ltr"

".m1v"="video/x-mpeg"

".m2v"="video/x-mpeg"

".m3u"="audio/mpegurl"

".m4e"="video/mpeg4"

".mac"="application/x-mac"

".man"="application/x-troff-man"

".math"="text/xml"

".mdb"="application/msaccess"

".mdb"="application/x-mdb"

".mfp"="application/x-shockwave-flash"

".mht"="message/rfc822"

".mhtml"="message/rfc822"

".mi"="application/x-mi"

".mid"="audio/mid"

".midi"="audio/mid"

".mil"="application/x-mil"

".mml"="text/xml"

".mnd"="audio/x-musicnet-download"

".mns"="audio/x-musicnet-stream"

".mocha"="application/x-javascript"

".movie"="video/x-sgi-movie"

".mp1"="audio/mp1"

".mp2"="audio/mp2"

".mp2v"="video/mpeg"

".mp3"="audio/mp3"

".mp4"="video/mpeg4"

".mpa"="video/x-mpg"

".mpd"="application/vnd.ms-project"

".mpe"="video/x-mpeg"

".mpeg"="video/mpg"

".mpg"="video/mpg"

".mpga"="audio/rn-mpeg"

".mpp"="application/vnd.ms-project"

".mps"="video/x-mpeg"

".mpt"="application/vnd.ms-project"

".mpv"="video/mpg"

".mpv2"="video/mpeg"

".mpw"="application/vnd.ms-project"

".mpx"="application/vnd.ms-project"

".mtx"="text/xml"

".mxp"="application/x-mmxp"

".net"="image/pnetvue"

".nrf"="application/x-nrf"

".nws"="message/rfc822"

".odc"="text/x-ms-odc"

".out"="application/x-out"

".p10"="application/pkcs10"

".p12"="application/x-pkcs12"

".p7b"="application/x-pkcs7-certificates"

".p7c"="application/pkcs7-mime"

".p7m"="application/pkcs7-mime"

".p7r"="application/x-pkcs7-certreqresp"

".p7s"="application/pkcs7-signature"

".pc5"="application/x-pc5"

".pci"="application/x-pci"

".pcl"="application/x-pcl"

".pcx"="application/x-pcx"

".pdf"="application/pdf"

".pdf"="application/pdf"

".pdx"="application/vnd.adobe.pdx"

".pfx"="application/x-pkcs12"

".pgl"="application/x-pgl"

".pic"="application/x-pic"

".pko"="application/vnd.ms-pki.pko"

".pl"="application/x-perl"

".plg"="text/html"

".pls"="audio/scpls"

".plt"="application/x-plt"

".png"="image/png"

".png"="application/x-png"

".pot"="application/vnd.ms-powerpoint"

".ppa"="application/vnd.ms-powerpoint"

".ppm"="application/x-ppm"

".pps"="application/vnd.ms-powerpoint"

".ppt"="application/vnd.ms-powerpoint"

".ppt"="application/x-ppt"

".pr"="application/x-pr"

".prf"="application/pics-rules"

".prn"="application/x-prn"

".prt"="application/x-prt"

".ps"="application/x-ps"

".ps"="application/postscript"

".ptn"="application/x-ptn"

".pwz"="application/vnd.ms-powerpoint"

".r3t"="text/vnd.rn-realtext3d"

".ra"="audio/vnd.rn-realaudio"

".ram"="audio/x-pn-realaudio"

".ras"="application/x-ras"

".rat"="application/rat-file"

".rdf"="text/xml"

".rec"="application/vnd.rn-recording"

".red"="application/x-red"

".rgb"="application/x-rgb"

".rjs"="application/vnd.rn-realsystem-rjs"

".rjt"="application/vnd.rn-realsystem-rjt"

".rlc"="application/x-rlc"

".rle"="application/x-rle"

".rm"="application/vnd.rn-realmedia"

".rmf"="application/vnd.adobe.rmf"

".rmi"="audio/mid"

".rmj"="application/vnd.rn-realsystem-rmj"

".rmm"="audio/x-pn-realaudio"

".rmp"="application/vnd.rn-rn_music_package"

".rms"="application/vnd.rn-realmedia-secure"

".rmvb"="application/vnd.rn-realmedia-vbr"

".rmx"="application/vnd.rn-realsystem-rmx"

".rnx"="application/vnd.rn-realplayer"

".rp"="image/vnd.rn-realpix"

".rpm"="audio/x-pn-realaudio-plugin"

".rsml"="application/vnd.rn-rsml"

".rt"="text/vnd.rn-realtext"

".rtf"="application/msword"

".rtf"="application/x-rtf"

".rv"="video/vnd.rn-realvideo"

".sam"="application/x-sam"

".sat"="application/x-sat"

".sdp"="application/sdp"

".sdw"="application/x-sdw"

".sit"="application/x-stuffit"

".slb"="application/x-slb"

".sld"="application/x-sld"

".slk"="drawing/x-slk"

".smi"="application/smil"

".smil"="application/smil"

".smk"="application/x-smk"

".snd"="audio/basic"

".sol"="text/plain"

".sor"="text/plain"

".spc"="application/x-pkcs7-certificates"

".spl"="application/futuresplash"

".spp"="text/xml"

".ssm"="application/streamingmedia"

".sst"="application/vnd.ms-pki.certstore"

".stl"="application/vnd.ms-pki.stl"

".stm"="text/html"

".sty"="application/x-sty"

".svg"="text/xml"

".swf"="application/x-shockwave-flash"

".tdf"="application/x-tdf"

".tg4"="application/x-tg4"

".tga"="application/x-tga"

".tif"="image/tiff"

".tif"="application/x-tif"

".tiff"="image/tiff"

".tld"="text/xml"

".top"="drawing/x-top"

".torrent"="application/x-bittorrent"

".tsd"="text/xml"

".txt"="text/plain"

".uin"="application/x-icq"

".uls"="text/iuls"

".vcf"="text/x-vcard"

".vda"="application/x-vda"

".vdx"="application/vnd.visio"

".vml"="text/xml"

".vpg"="application/x-vpeg005"

".vsd"="application/vnd.visio"

".vsd"="application/x-vsd"

".vss"="application/vnd.visio"

".vst"="application/vnd.visio"

".vst"="application/x-vst"

".vsw"="application/vnd.visio"

".vsx"="application/vnd.visio"

".vtx"="application/vnd.visio"

".vxml"="text/xml"

".wav"="audio/wav"

".wax"="audio/x-ms-wax"

".wb1"="application/x-wb1"

".wb2"="application/x-wb2"

".wb3"="application/x-wb3"

".wbmp"="image/vnd.wap.wbmp"

".wiz"="application/msword"

".wk3"="application/x-wk3"

".wk4"="application/x-wk4"

".wkq"="application/x-wkq"

".wks"="application/x-wks"

".wm"="video/x-ms-wm"

".wma"="audio/x-ms-wma"

".wmd"="application/x-ms-wmd"

".wmf"="application/x-wmf"

".wml"="text/vnd.wap.wml"

".wmv"="video/x-ms-wmv"

".wmx"="video/x-ms-wmx"

".wmz"="application/x-ms-wmz"

".wp6"="application/x-wp6"

".wpd"="application/x-wpd"

".wpg"="application/x-wpg"

".wpl"="application/vnd.ms-wpl"

".wq1"="application/x-wq1"

".wr1"="application/x-wr1"

".wri"="application/x-wri"

".wrk"="application/x-wrk"

".ws"="application/x-ws"

".ws2"="application/x-ws"

".wsc"="text/scriptlet"

".wsdl"="text/xml"

".wvx"="video/x-ms-wvx"

".xdp"="application/vnd.adobe.xdp"

".xdr"="text/xml"

".xfd"="application/vnd.adobe.xfd"

".xfdf"="application/vnd.adobe.xfdf"

".xhtml"="text/html"

".xls"="application/vnd.ms-excel"

".xls"="application/x-xls"

".xlw"="application/x-xlw"

".xml"="text/xml"

".xpl"="audio/scpls"

".xq"="text/xml"

".xql"="text/xml"

".xquery"="text/xml"

".xsd"="text/xml"

".xsl"="text/xml"

".xslt"="text/xml"

".xwd"="application/x-xwd"

".x_b"="application/x-x_b"

".x_t"="application/x-x_t"

".myz"="application/myz"

header的其他用途请看