Android MineType
概述
多用途互联网邮件扩展(MIME,Multipurpose Internet Mail Extensions)是一个互联网标准,它扩展了电子邮件标准,使其能够支持非ASCII字符、二进制格式附件等多种格式的邮件消息。
内容类型(Content-Type),这个头部领域用于指定消息的类型。一般以下面的形式出现:[type]/[subtype]
type有下面的形式:
Text:用于标准化地表示的文本信息,文本消息可以是多种字符集和或者多种格式的;
Multipart:用于连接消息体的多个部分构成一个消息,这些部分可以是不同类型的数据;
Application:用于传输应用程序数据或者二进制数据;
Message:用于包装一个E-mail消息;
Image:用于传输静态图片数据;
Audio:用于传输音频或者音声数据;
Video:用于传输动态影像数据,可以是与音频编辑在一起的视频数据格式。
subtype用于指定type的详细形式。content-type/subtype配对的集合和与此相关的参数,将随着时间而增长。为了确保这些值在一个有序而且公开的状态下开发,MIME使用Internet Assigned Numbers Authority (IANA)作为中心的注册机制来管理这些值。
常用的subtype值如下所示:
text/plain(纯文本)
text/html(HTML文档)
application/xhtml+xml(XHTML文档)
image/gif(GIF图像)
image/jpeg(JPEG图像)【PHP中为:image/pjpeg】
image/png(PNG图像)【PHP中为:image/x-png】
video/mpeg(MPEG动画)
application/octet-stream(任意的二进制数据)
application/pdf(PDF文档)
application/msword(Microsoft Word文件)
message/rfc822(RFC 822形式)
multipart/alternative(HTML邮件的HTML形式和纯文本形式,相同内容使用不同形式表示)
application/x-www-form-urlencoded(使用HTTP的POST方法提交的表单)
multipart/form-data(同上,但主要用于表单提交时伴随文件上传的场合)
Android中MimeType的用途
Intent-Filter中的<data>有一个mimeType . 它的作用是告诉Android系统本Activity可以处理的文件的类型。如设置为 “text/plain”表示可以处理“.txt”文件。
MimeTypeMap类:是专门处理mimeType的类。
package android.webkit; import android.text.TextUtils; import java.util.regex.Pattern; import libcore.net.MimeUtils; public class MimeTypeMap { private static final MimeTypeMap sMimeTypeMap = new MimeTypeMap(); private MimeTypeMap() { } public static String getFileExtensionFromUrl(String url) { if (!TextUtils.isEmpty(url)) { int fragment = url.lastIndexOf('#'); if (fragment > 0) { url = url.substring(0, fragment); } int query = url.lastIndexOf('?'); if (query > 0) { url = url.substring(0, query); } int filenamePos = url.lastIndexOf('/'); String filename = 0 <= filenamePos ? url.substring(filenamePos + 1) : url; if (!filename.isEmpty() && Pattern.matches("[a-zA-Z_0-9\\.\\-\\(\\)\\%]+", filename)) { int dotPos = filename.lastIndexOf('.'); if (0 <= dotPos) { return filename.substring(dotPos + 1); } } } return ""; } public boolean hasMimeType(String mimeType) { return MimeUtils.hasMimeType(mimeType); } public String getMimeTypeFromExtension(String extension) { return MimeUtils.guessMimeTypeFromExtension(extension); } private static String mimeTypeFromExtension(String extension) { return MimeUtils.guessMimeTypeFromExtension(extension); } public boolean hasExtension(String extension) { return MimeUtils.hasExtension(extension); } public String getExtensionFromMimeType(String mimeType) { return MimeUtils.guessExtensionFromMimeType(mimeType); } /* package */ String remapGenericMimeType(String mimeType, String url, String contentDisposition) { if ("text/plain".equals(mimeType) || String filename = null; if (contentDisposition != null) { filename = URLUtil.parseContentDisposition(contentDisposition); } if (filename != null) { url = filename; } String extension = getFileExtensionFromUrl(url); String newMimeType = getMimeTypeFromExtension(extension); if (newMimeType != null) { mimeType = newMimeType; } } else if ("text/vnd.wap.wml".equals(mimeType)) { mimeType = "text/plain"; } else { if ("application/vnd.wap.xhtml+xml".equals(mimeType)) { mimeType = "application/xhtml+xml"; } } return mimeType; } public static MimeTypeMap getSingleton() { return sMimeTypeMap; } }
MimeTypeMap类是单例模式的,既没有公有的构造方法。使用getSinglton()方法获得MimeTypeMap对象:
示例代码一:
MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton(); //MimeTypeMap中是否有txt的MimeType System.out.println(mimeTypeMap.hasExtension("txt")); System.out.println(mimeTypeMap.hasMimeType("text/html")); //获得txt文件类型的MimeType String extension = mimeTypeMap.getMimeTypeFromExtension("txt"); System.out.println(extension);
示例代码二:
private String getMIMEType(File file) { String type = "*"; String end = file.getName().substring(dotIndex, file.getName().length()).toLowerCase(); if (end == "") return type; //在MIME和文件类型的匹配表中找到对应的MIME类型。 for (int i = 0; i < MIME_MapTable.length; i++) { if (end.equals(MIME_MapTable[i][0])) type = MIME_MapTable[i][1]; } return type; } private void openFile(File file) { //Uri uri = Uri.parse("file://"+file.getAbsolutePath()); Intent intent = new Intent(); intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); //设置intent的Action属性 intent.setAction(Intent.ACTION_VIEW); //获取文件file的MIME类型 String type = getMIMEType(file); //设置intent的data和Type属性。 intent.setDataAndType(Uri.fromFile(file), type); //跳转 startActivity(intent); } private final String[][] MIME_MapTable = { //{后缀名, MIME类型} {".3gp", "video/3gpp"}, {".apk", "application/vnd.android.package-archive"}, {".asf", "video/x-ms-asf"}, {".avi", "video/x-msvideo"}, {".bin", "application/octet-stream"}, {".bmp", "image/bmp"}, {".c", "text/plain"}, {".class", "application/octet-stream"}, {".conf", "text/plain"}, {".cpp", "text/plain"}, {".doc", "application/msword"}, {".exe", "application/octet-stream"}, {".gif", "image/gif"}, {".gtar", "application/x-gtar"}, {".gz", "application/x-gzip"}, {".h", "text/plain"}, {".htm", "text/html"}, {".html", "text/html"}, {".jar", "application/java-archive"}, {".java", "text/plain"}, {".jpeg", "image/jpeg"}, {".jpg", "image/jpeg"}, {".js", "application/x-javascript"}, {".log", "text/plain"}, {".m3u", "audio/x-mpegurl"}, {".m4a", "audio/mp4a-latm"}, {".m4b", "audio/mp4a-latm"}, {".m4p", "audio/mp4a-latm"}, {".m4u", "video/vnd.mpegurl"}, {".m4v", "video/x-m4v"}, {".mov", "video/quicktime"}, {".mp2", "audio/x-mpeg"}, {".mp3", "audio/x-mpeg"}, {".mp4", "video/mp4"}, {".mpc", "application/vnd.mpohun.certificate"}, {".mpe", "video/mpeg"}, {".mpeg", "video/mpeg"}, {".mpg", "video/mpeg"}, {".mpg4", "video/mp4"}, {".mpga", "audio/mpeg"}, {".msg", "application/vnd.ms-outlook"}, {".ogg", "audio/ogg"}, {".pdf", "application/pdf"}, {".png", "image/png"}, {".pps", "application/vnd.ms-powerpoint"}, {".ppt", "application/vnd.ms-powerpoint"}, {".prop", "text/plain"}, {".rar", "application/x-rar-compressed"}, {".rc", "text/plain"}, {".rmvb", "audio/x-pn-realaudio"}, {".rtf", "application/rtf"}, {".sh", "text/plain"}, {".tar", "application/x-tar"}, {".tgz", "application/x-compressed"}, {".txt", "text/plain"}, {".wav", "audio/x-wav"}, {".wma", "audio/x-ms-wma"}, {".wmv", "audio/x-ms-wmv"}, {".wps", "application/vnd.ms-works"}, //{".xml", "text/xml"}, {".xml", "text/plain"}, {".z", "application/x-compress"}, {".zip", "application/zip"}, {"", "*/*"} };