技术标签: Android
这里通过一个实际的例子来说明ContentProvider(内容提供者)是什么,作用是什么
短信应用要访问通讯录应用中的数据,是不能直接访问的,应用通讯录的中的数据是属于通讯录app数据库中的数据,无法直接访问
通讯录应用使用ContentProvider将数据库表数据操作(增删改查)暴露给其他应用(包括本身)访问
其他应用通过ContentResolver来调用ContentProvider方法
ContentResolver和ContentProvider之间是通过URI交流
作用
进程间 进行数据交互 & 共享,即跨进程通信
统一资源标识符,唯一标识 ContentProvider
& 其中的数据,外界进程通过 URI
找到对应的ContentProvider
& 其中的数据,再进行数据操作
以联系人Contacts的Uri为例,其结构如下所示:
注意:
// 设置URI
Uri uri = Uri.parse("content://com.demo.provider/User/1")
// 上述URI指向的资源是:名为 `com.demo.provider`的`ContentProvider` 中表名 为`User` 中的 `id`为1的数据
// 特别注意:URI模式存在匹配通配符* & #
// *:匹配任意长度的任何有效字符的字符串
// 以下的URI 表示 匹配provider的任何内容
content://com.example.app.provider/*
// #:匹配任意长度的数字字符的字符串
// 以下的URI 表示 匹配provider中的table表的所有行
content://com.example.app.provider/table/#
指定某个扩展名的文件用某种应用程序来打开,当该扩展名文件被访问的时候,浏览器会自动使用指定应用程序来打开。多用于指定一些客户端自定义的文件名,以及一些媒体文件打开方式。
如指定.html
文件采用text
应用程序打开、指定.pdf
文件采用flash
应用程序打开
格式前面为后缀名,后面为对应的MIME型
(例如: ".apk", "application/vnd.android.package-archive" 表示。.apk对应的是application/vnd.android.package-archive)
ContentProvider
根据 URI
返回MIME
类型
ContentProvider.geType(uri) ;
3.3MIME
类型组成每种MIME
类型 由2部分组成 = 类型 + 子类型
MIME类型是 一个 包含2部分的字符串
text / html
// 类型 = text、子类型 = html
text/css
text/xml
application/pdf
MIME
类型形式MIME
类型有2种形式:
// 形式1:单条记录
vnd.android.demo.item/自定义
// 形式2:多条记录(集合)
vnd.android.demo.dir/自定义
// 注:
// 1. vnd:表示父类型和子类型具有非标准的、特定的形式。
// 2. 父类型已固定好(即不能更改),只能区别是单条还是多条记录
// 3. 子类型可自定义
实例
<-- 单条记录 -->
// 单个记录的MIME类型
vnd.android.cursor.item/vnd.yourcompanyname.contenttype
// 若一个Uri如下
content://com.example.transportationprovider/trains/122
// 则ContentProvider会通过ContentProvider.geType(url)返回以下MIME类型
vnd.android.cursor.item/vnd.example.rail
<-- 多条记录 -->
// 多个记录的MIME类型
vnd.android.cursor.dir/vnd.yourcompanyname.contenttype
// 若一个Uri如下
content://com.example.transportationprovider/trains
// 则ContentProvider会通过ContentProvider.geType(url)返回以下MIME类型
vnd.android.cursor.dir/vnd.example.rail
import java.io.File;
public class MimeTest {
/**
* MIME全部类型映射
*/
final static String[][] MIME_MapTable = {
{ ".323", "text/h323" },
{ ".3gp", "video/3gpp" },
{ ".aab", "application/x-authoware-bin" },
{ ".aam", "application/x-authoware-map" },
{ ".aas", "application/x-authoware-seg" },
{ ".acx", "application/internet-property-stream" },
{ ".ai", "application/postscript" },
{ ".aif", "audio/x-aiff" },
{ ".aifc", "audio/x-aiff" },
{ ".aiff", "audio/x-aiff" },
{ ".als", "audio/X-Alpha5" },
{ ".amc", "application/x-mpeg" },
{ ".ani", "application/octet-stream" },
{ ".apk", "application/vnd.android.package-archive" },
{ ".asc", "text/plain" },
{ ".asd", "application/astound" },
{ ".asf", "video/x-ms-asf" },
{ ".asn", "application/astound" },
{ ".asp", "application/x-asap" },
{ ".asr", "video/x-ms-asf" },
{ ".asx", "video/x-ms-asf" },
{ ".au", "audio/basic" },
{ ".avb", "application/octet-stream" },
{ ".avi", "video/x-msvideo" },
{ ".awb", "audio/amr-wb" },
{ ".axs", "application/olescript" },
{ ".bas", "text/plain" },
{ ".bcpio", "application/x-bcpio" },
{ ".bin ", "application/octet-stream" },
{ ".bld", "application/bld" },
{ ".bld2", "application/bld2" },
{ ".bmp", "image/bmp" },
{ ".bpk", "application/octet-stream" },
{ ".bz2", "application/x-bzip2" },
{ ".c", "text/plain" },
{ ".cal", "image/x-cals" },
{ ".cat", "application/vnd.ms-pkiseccat" },
{ ".ccn", "application/x-cnc" },
{ ".cco", "application/x-cocoa" },
{ ".cdf", "application/x-cdf" },
{ ".cer", "application/x-x509-ca-cert" },
{ ".cgi", "magnus-internal/cgi" },
{ ".chat", "application/x-chat" },
{ ".class", "application/octet-stream" },
{ ".clp", "application/x-msclip" },
{ ".cmx", "image/x-cmx" },
{ ".co", "application/x-cult3d-object" },
{ ".cod", "image/cis-cod" },
{ ".conf", "text/plain" },
{ ".cpio", "application/x-cpio" },
{ ".cpp", "text/plain" },
{ ".cpt", "application/mac-compactpro" },
{ ".crd", "application/x-mscardfile" },
{ ".crl", "application/pkix-crl" },
{ ".crt", "application/x-x509-ca-cert" },
{ ".csh", "application/x-csh" },
{ ".csm", "chemical/x-csml" },
{ ".csml", "chemical/x-csml" },
{ ".css", "text/css" },
{ ".cur", "application/octet-stream" },
{ ".dcm", "x-lml/x-evm" },
{ ".dcr", "application/x-director" },
{ ".dcx", "image/x-dcx" },
{ ".der", "application/x-x509-ca-cert" },
{ ".dhtml", "text/html" },
{ ".dir", "application/x-director" },
{ ".dll", "application/x-msdownload" },
{ ".dmg", "application/octet-stream" },
{ ".dms", "application/octet-stream" },
{ ".doc", "application/msword" },
{ ".docx",
"application/vnd.openxmlformats-officedocument.wordprocessingml.document" },
{ ".dot", "application/msword" },
{ ".dvi", "application/x-dvi" },
{ ".dwf", "drawing/x-dwf" },
{ ".dwg", "application/x-autocad" },
{ ".dxf", "application/x-autocad" },
{ ".dxr", "application/x-director" },
{ ".ebk", "application/x-expandedbook" },
{ ".emb", "chemical/x-embl-dl-nucleotide" },
{ ".embl", "chemical/x-embl-dl-nucleotide" },
{ ".eps", "application/postscript" },
{ ".epub", "application/epub+zip" },
{ ".eri", "image/x-eri" },
{ ".es", "audio/echospeech" },
{ ".esl", "audio/echospeech" },
{ ".etc", "application/x-earthtime" },
{ ".etx", "text/x-setext" },
{ ".evm", "x-lml/x-evm" },
{ ".evy", "application/envoy" },
{ ".exe", "application/octet-stream" },
{ ".fh4", "image/x-freehand" },
{ ".fh5", "image/x-freehand" },
{ ".fhc", "image/x-freehand" },
{ ".fif", "application/fractals" },
{ ".flr", "x-world/x-vrml" },
{ ".flv", "flv-application/octet-stream" },
{ ".fm", "application/x-maker" },
{ ".fpx", "image/x-fpx" },
{ ".fvi", "video/isivideo" },
{ ".gau", "chemical/x-gaussian-input" },
{ ".gca", "application/x-gca-compressed" },
{ ".gdb", "x-lml/x-gdb" },
{ ".gif", "image/gif" },
{ ".gps", "application/x-gps" },
{ ".gtar", "application/x-gtar" },
{ ".gz", "application/x-gzip" },
{ ".h", "text/plain" },
{ ".hdf", "application/x-hdf" },
{ ".hdm", "text/x-hdml" },
{ ".hdml", "text/x-hdml" },
{ ".hlp", "application/winhlp" },
{ ".hqx", "application/mac-binhex40" },
{ ".hta", "application/hta" },
{ ".htc", "text/x-component" },
{ ".htm", "text/html" },
{ ".html", "text/html" },
{ ".hts", "text/html" },
{ ".htt", "text/webviewhtml" },
{ ".ice", "x-conference/x-cooltalk" },
{ ".ico", "image/x-icon" },
{ ".ief", "image/ief" },
{ ".ifm", "image/gif" },
{ ".ifs", "image/ifs" },
{ ".iii", "application/x-iphone" },
{ ".imy", "audio/melody" },
{ ".ins", "application/x-internet-signup" },
{ ".ips", "application/x-ipscript" },
{ ".ipx", "application/x-ipix" },
{ ".isp", "application/x-internet-signup" },
{ ".it", "audio/x-mod" },
{ ".itz", "audio/x-mod" },
{ ".ivr", "i-world/i-vrml" },
{ ".j2k", "image/j2k" },
{ ".jad", "text/vnd.sun.j2me.app-descriptor" },
{ ".jam", "application/x-jam" },
{ ".jar", "application/java-archive" },
{ ".java", "text/plain" },
{ ".jfif", "image/pipeg" },
{ ".jnlp", "application/x-java-jnlp-file" },
{ ".jpe", "image/jpeg" },
{ ".jpeg", "image/jpeg" },
{ ".jpg", "image/jpeg" },
{ ".jpz", "image/jpeg" },
{ ".js", "application/x-javascript" },
{ ".jwc", "application/jwc" },
{ ".kjx", "application/x-kjx" },
{ ".lak", "x-lml/x-lak" },
{ ".latex", "application/x-latex" },
{ ".lcc", "application/fastman" },
{ ".lcl", "application/x-digitalloca" },
{ ".lcr", "application/x-digitalloca" },
{ ".lgh", "application/lgh" },
{ ".lha", "application/octet-stream" },
{ ".lml", "x-lml/x-lml" },
{ ".lmlpack", "x-lml/x-lmlpack" },
{ ".log", "text/plain" },
{ ".lsf", "video/x-la-asf" },
{ ".lsx", "video/x-la-asf" },
{ ".lzh", "application/octet-stream" },
{ ".m13", "application/x-msmediaview" },
{ ".m14", "application/x-msmediaview" },
{ ".m15", "audio/x-mod" },
{ ".m3u", "audio/x-mpegurl" },
{ ".m3url", "audio/x-mpegurl" },
{ ".m4a", "audio/mp4a-latm" },
{ ".m4b", "audio/mp4a-latm" },
{ ".m4p", "audio/mp4a-latm" },
{ ".m4u", "video/vnd.mpegurl" },
{ ".m4v", "video/x-m4v" },
{ ".ma1", "audio/ma1" },
{ ".ma2", "audio/ma2" },
{ ".ma3", "audio/ma3" },
{ ".ma5", "audio/ma5" },
{ ".man", "application/x-troff-man" },
{ ".map", "magnus-internal/imagemap" },
{ ".mbd", "application/mbedlet" },
{ ".mct", "application/x-mascot" },
{ ".mdb", "application/x-msaccess" },
{ ".mdz", "audio/x-mod" },
{ ".me", "application/x-troff-me" },
{ ".mel", "text/x-vmel" },
{ ".mht", "message/rfc822" },
{ ".mhtml", "message/rfc822" },
{ ".mi", "application/x-mif" },
{ ".mid", "audio/mid" },
{ ".midi", "audio/midi" },
{ ".mif", "application/x-mif" },
{ ".mil", "image/x-cals" },
{ ".mio", "audio/x-mio" },
{ ".mmf", "application/x-skt-lbs" },
{ ".mng", "video/x-mng" },
{ ".mny", "application/x-msmoney" },
{ ".moc", "application/x-mocha" },
{ ".mocha", "application/x-mocha" },
{ ".mod", "audio/x-mod" },
{ ".mof", "application/x-yumekara" },
{ ".mol", "chemical/x-mdl-molfile" },
{ ".mop", "chemical/x-mopac-input" },
{ ".mov", "video/quicktime" },
{ ".movie", "video/x-sgi-movie" },
{ ".mp2", "video/mpeg" },
{ ".mp3", "audio/mpeg" },
{ ".mp4", "video/mp4" },
{ ".mpa", "video/mpeg" },
{ ".mpc", "application/vnd.mpohun.certificate" },
{ ".mpe", "video/mpeg" },
{ ".mpeg", "video/mpeg" },
{ ".mpg", "video/mpeg" },
{ ".mpg4", "video/mp4" },
{ ".mpga", "audio/mpeg" },
{ ".mpn", "application/vnd.mophun.application" },
{ ".mpp", "application/vnd.ms-project" },
{ ".mps", "application/x-mapserver" },
{ ".mpv2", "video/mpeg" },
{ ".mrl", "text/x-mrml" },
{ ".mrm", "application/x-mrm" },
{ ".ms", "application/x-troff-ms" },
{ ".msg", "application/vnd.ms-outlook" },
{ ".mts", "application/metastream" },
{ ".mtx", "application/metastream" },
{ ".mtz", "application/metastream" },
{ ".mvb", "application/x-msmediaview" },
{ ".mzv", "application/metastream" },
{ ".nar", "application/zip" },
{ ".nbmp", "image/nbmp" },
{ ".nc", "application/x-netcdf" },
{ ".ndb", "x-lml/x-ndb" },
{ ".ndwn", "application/ndwn" },
{ ".nif", "application/x-nif" },
{ ".nmz", "application/x-scream" },
{ ".nokia-op-logo", "image/vnd.nok-oplogo-color" },
{ ".npx", "application/x-netfpx" },
{ ".nsnd", "audio/nsnd" },
{ ".nva", "application/x-neva1" },
{ ".nws", "message/rfc822" },
{ ".oda", "application/oda" },
{ ".ogg", "audio/ogg" },
{ ".oom", "application/x-AtlasMate-Plugin" },
{ ".p10", "application/pkcs10" },
{ ".p12", "application/x-pkcs12" },
{ ".p7b", "application/x-pkcs7-certificates" },
{ ".p7c", "application/x-pkcs7-mime" },
{ ".p7m", "application/x-pkcs7-mime" },
{ ".p7r", "application/x-pkcs7-certreqresp" },
{ ".p7s", "application/x-pkcs7-signature" },
{ ".pac", "audio/x-pac" },
{ ".pae", "audio/x-epac" },
{ ".pan", "application/x-pan" },
{ ".pbm", "image/x-portable-bitmap" },
{ ".pcx", "image/x-pcx" },
{ ".pda", "image/x-pda" },
{ ".pdb", "chemical/x-pdb" },
{ ".pdf", "application/pdf" },
{ ".pfr", "application/font-tdpfr" },
{ ".pfx", "application/x-pkcs12" },
{ ".pgm", "image/x-portable-graymap" },
{ ".pict", "image/x-pict" },
{ ".pko", "application/ynd.ms-pkipko" },
{ ".pm", "application/x-perl" },
{ ".pma", "application/x-perfmon" },
{ ".pmc", "application/x-perfmon" },
{ ".pmd", "application/x-pmd" },
{ ".pml", "application/x-perfmon" },
{ ".pmr", "application/x-perfmon" },
{ ".pmw", "application/x-perfmon" },
{ ".png", "image/png" },
{ ".pnm", "image/x-portable-anymap" },
{ ".pnz", "image/png" },
{ ".pot,", "application/vnd.ms-powerpoint" },
{ ".ppm", "image/x-portable-pixmap" },
{ ".pps", "application/vnd.ms-powerpoint" },
{ ".ppt", "application/vnd.ms-powerpoint" },
{ ".pptx",
"application/vnd.openxmlformats-officedocument.presentationml.presentation" },
{ ".pqf", "application/x-cprplayer" },
{ ".pqi", "application/cprplayer" },
{ ".prc", "application/x-prc" },
{ ".prf", "application/pics-rules" },
{ ".prop", "text/plain" },
{ ".proxy", "application/x-ns-proxy-autoconfig" },
{ ".ps", "application/postscript" },
{ ".ptlk", "application/listenup" },
{ ".pub", "application/x-mspublisher" },
{ ".pvx", "video/x-pv-pvx" },
{ ".qcp", "audio/vnd.qcelp" },
{ ".qt", "video/quicktime" },
{ ".qti", "image/x-quicktime" },
{ ".qtif", "image/x-quicktime" },
{ ".r3t", "text/vnd.rn-realtext3d" },
{ ".ra", "audio/x-pn-realaudio" },
{ ".ram", "audio/x-pn-realaudio" },
{ ".rar", "application/octet-stream" },
{ ".ras", "image/x-cmu-raster" },
{ ".rc", "text/plain" },
{ ".rdf", "application/rdf+xml" },
{ ".rf", "image/vnd.rn-realflash" },
{ ".rgb", "image/x-rgb" },
{ ".rlf", "application/x-richlink" },
{ ".rm", "audio/x-pn-realaudio" },
{ ".rmf", "audio/x-rmf" },
{ ".rmi", "audio/mid" },
{ ".rmm", "audio/x-pn-realaudio" },
{ ".rmvb", "audio/x-pn-realaudio" },
{ ".rnx", "application/vnd.rn-realplayer" },
{ ".roff", "application/x-troff" },
{ ".rp", "image/vnd.rn-realpix" },
{ ".rpm", "audio/x-pn-realaudio-plugin" },
{ ".rt", "text/vnd.rn-realtext" },
{ ".rte", "x-lml/x-gps" },
{ ".rtf", "application/rtf" },
{ ".rtg", "application/metastream" },
{ ".rtx", "text/richtext" },
{ ".rv", "video/vnd.rn-realvideo" },
{ ".rwc", "application/x-rogerwilco" },
{ ".s3m", "audio/x-mod" },
{ ".s3z", "audio/x-mod" },
{ ".sca", "application/x-supercard" },
{ ".scd", "application/x-msschedule" },
{ ".sct", "text/scriptlet" },
{ ".sdf", "application/e-score" },
{ ".sea", "application/x-stuffit" },
{ ".setpay", "application/set-payment-initiation" },
{ ".setreg", "application/set-registration-initiation" },
{ ".sgm", "text/x-sgml" },
{ ".sgml", "text/x-sgml" },
{ ".sh", "application/x-sh" },
{ ".shar", "application/x-shar" },
{ ".shtml", "magnus-internal/parsed-html" },
{ ".shw", "application/presentations" },
{ ".si6", "image/si6" },
{ ".si7", "image/vnd.stiwap.sis" },
{ ".si9", "image/vnd.lgtwap.sis" },
{ ".sis", "application/vnd.symbian.install" },
{ ".sit", "application/x-stuffit" },
{ ".skd", "application/x-Koan" },
{ ".skm", "application/x-Koan" },
{ ".skp", "application/x-Koan" },
{ ".skt", "application/x-Koan" },
{ ".slc", "application/x-salsa" },
{ ".smd", "audio/x-smd" },
{ ".smi", "application/smil" },
{ ".smil", "application/smil" },
{ ".smp", "application/studiom" },
{ ".smz", "audio/x-smd" },
{ ".snd", "audio/basic" },
{ ".spc", "application/x-pkcs7-certificates" },
{ ".spl", "application/futuresplash" },
{ ".spr", "application/x-sprite" },
{ ".sprite", "application/x-sprite" },
{ ".sdp", "application/sdp" },
{ ".spt", "application/x-spt" },
{ ".src", "application/x-wais-source" },
{ ".sst", "application/vnd.ms-pkicertstore" },
{ ".stk", "application/hyperstudio" },
{ ".stl", "application/vnd.ms-pkistl" },
{ ".stm", "text/html" },
{ ".svg", "image/svg+xml" },
{ ".sv4cpio", "application/x-sv4cpio" },
{ ".sv4crc", "application/x-sv4crc" },
{ ".svf", "image/vnd" },
{ ".svg", "image/svg+xml" },
{ ".svh", "image/svh" },
{ ".svr", "x-world/x-svr" },
{ ".swf", "application/x-shockwave-flash" },
{ ".swfl", "application/x-shockwave-flash" },
{ ".t", "application/x-troff" },
{ ".tad", "application/octet-stream" },
{ ".talk", "text/x-speech" },
{ ".tar", "application/x-tar" },
{ ".taz", "application/x-tar" },
{ ".tbp", "application/x-timbuktu" },
{ ".tbt", "application/x-timbuktu" },
{ ".tcl", "application/x-tcl" },
{ ".tex", "application/x-tex" },
{ ".texi", "application/x-texinfo" },
{ ".texinfo", "application/x-texinfo" },
{ ".tgz", "application/x-compressed" },
{ ".thm", "application/vnd.eri.thm" },
{ ".tif", "image/tiff" },
{ ".tiff", "image/tiff" },
{ ".tki", "application/x-tkined" },
{ ".tkined", "application/x-tkined" },
{ ".toc", "application/toc" },
{ ".toy", "image/toy" },
{ ".tr", "application/x-troff" },
{ ".trk", "x-lml/x-gps" },
{ ".trm", "application/x-msterminal" },
{ ".tsi", "audio/tsplayer" },
{ ".tsp", "application/dsptype" },
{ ".tsv", "text/tab-separated-values" },
{ ".ttf", "application/octet-stream" },
{ ".ttz", "application/t-time" },
{ ".txt", "text/plain" },
{ ".uls", "text/iuls" },
{ ".ult", "audio/x-mod" },
{ ".ustar", "application/x-ustar" },
{ ".uu", "application/x-uuencode" },
{ ".uue", "application/x-uuencode" },
{ ".vcd", "application/x-cdlink" },
{ ".vcf", "text/x-vcard" },
{ ".vdo", "video/vdo" },
{ ".vib", "audio/vib" },
{ ".viv", "video/vivo" },
{ ".vivo", "video/vivo" },
{ ".vmd", "application/vocaltec-media-desc" },
{ ".vmf", "application/vocaltec-media-file" },
{ ".vmi", "application/x-dreamcast-vms-info" },
{ ".vms", "application/x-dreamcast-vms" },
{ ".vox", "audio/voxware" },
{ ".vqe", "audio/x-twinvq-plugin" },
{ ".vqf", "audio/x-twinvq" },
{ ".vql", "audio/x-twinvq" },
{ ".vre", "x-world/x-vream" },
{ ".vrml", "x-world/x-vrml" },
{ ".vrt", "x-world/x-vrt" },
{ ".vrw", "x-world/x-vream" },
{ ".vts", "workbook/formulaone" },
{ ".wav", "audio/x-wav" },
{ ".wax", "audio/x-ms-wax" },
{ ".wbmp", "image/vnd.wap.wbmp" },
{ ".wcm", "application/vnd.ms-works" },
{ ".wdb", "application/vnd.ms-works" },
{ ".web", "application/vnd.xara" },
{ ".wi", "image/wavelet" },
{ ".wis", "application/x-InstallShield" },
{ ".wks", "application/vnd.ms-works" },
{ ".wm", "video/x-ms-wm" },
{ ".wma", "audio/x-ms-wma" },
{ ".wmd", "application/x-ms-wmd" },
{ ".wmf", "application/x-msmetafile" },
{ ".wml", "text/vnd.wap.wml" },
{ ".wmlc", "application/vnd.wap.wmlc" },
{ ".wmls", "text/vnd.wap.wmlscript" },
{ ".wmlsc", "application/vnd.wap.wmlscriptc" },
{ ".wmlscript", "text/vnd.wap.wmlscript" },
{ ".wmv", "audio/x-ms-wmv" },
{ ".wmx", "video/x-ms-wmx" },
{ ".wmz", "application/x-ms-wmz" },
{ ".wpng", "image/x-up-wpng" },
{ ".wps", "application/vnd.ms-works" },
{ ".wpt", "x-lml/x-gps" },
{ ".wri", "application/x-mswrite" },
{ ".wrl", "x-world/x-vrml" },
{ ".wrz", "x-world/x-vrml" },
{ ".ws", "text/vnd.wap.wmlscript" },
{ ".wsc", "application/vnd.wap.wmlscriptc" },
{ ".wv", "video/wavelet" },
{ ".wvx", "video/x-ms-wvx" },
{ ".wxl", "application/x-wxl" },
{ ".x-gzip", "application/x-gzip" },
{ ".xaf", "x-world/x-vrml" },
{ ".xar", "application/vnd.xara" },
{ ".xbm", "image/x-xbitmap" },
{ ".xdm", "application/x-xdma" },
{ ".xdma", "application/x-xdma" },
{ ".xdw", "application/vnd.fujixerox.docuworks" },
{ ".xht", "application/xhtml+xml" },
{ ".xhtm", "application/xhtml+xml" },
{ ".xhtml", "application/xhtml+xml" },
{ ".xla", "application/vnd.ms-excel" },
{ ".xlc", "application/vnd.ms-excel" },
{ ".xll", "application/x-excel" },
{ ".xlm", "application/vnd.ms-excel" },
{ ".xls", "application/vnd.ms-excel" },
{ ".xlsx",
"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" },
{ ".xlt", "application/vnd.ms-excel" },
{ ".xlw", "application/vnd.ms-excel" }, { ".xm", "audio/x-mod" },
{ ".xml", "text/plain" }, { ".xml", "application/xml" },
{ ".xmz", "audio/x-mod" }, { ".xof", "x-world/x-vrml" },
{ ".xpi", "application/x-xpinstall" },
{ ".xpm", "image/x-xpixmap" }, { ".xsit", "text/xml" },
{ ".xsl", "text/xml" }, { ".xul", "text/xul" },
{ ".xwd", "image/x-xwindowdump" }, { ".xyz", "chemical/x-pdb" },
{ ".yz1", "application/x-yz1" },
{ ".z", "application/x-compress" },
{ ".zac", "application/x-zaurus-zac" },
{ ".zip", "application/zip" }, { ".json", "application/json" } };
/**
* 根据文件后缀名获得对应的MIME类型。
* @param file
*/
public static String getMIMEType(File file) {
String type = "*/*";
String fName = file.getName();
// 获取后缀名前的分隔符"."在fName中的位置。
int dotIndex = fName.lastIndexOf(".");
if (dotIndex < 0) {
return type;
}
/* 获取文件的后缀名 */
String end = fName.substring(dotIndex, fName.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;
}
public static void main(String[] args) {
//下面输出为:application/vnd.android.package-archive
System.out.println(MimeTest.getMIMEType(new File("C:\\oyp.apk")));
}
}
ContentProvider
主要以 表格的形式 组织数据,同时也支持文件数据,只是表格形式用得比较多
每个表格中包含多张表,每张表包含行 & 列,分别对应记录 & 字段
进程间共享数据的本质是:添加、删除、获取 & 修改(更新)数据,所以ContentProvider
的核心方法也主要是上述4个作用
<-- 4个核心方法 -->
public Uri insert(Uri uri, ContentValues values)
// 外部进程向 ContentProvider 中添加数据
public int delete(Uri uri, String selection, String[] selectionArgs)
// 外部进程 删除 ContentProvider 中的数据
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs)
// 外部进程更新 ContentProvider 中的数据
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)
// 外部应用 获取 ContentProvider 中的数据
// 注:
// 1. 上述4个方法由外部进程回调,并运行在ContentProvider进程的Binder线程池中(不是主线程)
// 2. 存在多线程并发访问,需要实现线程同步
// a. 若ContentProvider的数据存储方式是使用SQLite & 一个,则不需要,因为SQLite内部实现好了线程同步,若是多个SQLite则需要,因为SQL对象之间无法进行线程同步
// b. 若ContentProvider的数据存储方式是内存,则需要自己实现线程同步
<-- 2个其他方法 -->
public boolean onCreate()
// ContentProvider创建后 或 打开系统后其它进程第一次访问该ContentProvider时 由系统进行调用
// 注:运行在ContentProvider进程的主线程,故不能做耗时操作
public String getType(Uri uri)
// 得到数据类型,即返回当前 Url 所代表数据的MIME类型
Android
为常见的数据(如通讯录、日程表等)提供了内置了默认的ContentProvider,
本文主要讲解自定义ContentProvider
ContentProvider
,但上述6个方法必须重写ContentProvider
类并不会直接与外部进程交互,而是通过ContentResolver
类统一管理不同 ContentProvider
间的操作,即通过 URI
即可操作 不同的ContentProvider
中的数据
外部进程通过 ContentResolver
类 从而与ContentProvider
类进行交互
为什么要使用通过ContentResolver
类从而与ContentProvider
类进行交互,而不直接访问ContentProvider
类?
答:一般来说,一款应用要使用多个ContentProvider
,若需要了解每个ContentProvider
的不同实现从而再完成数据交互,操作成本高 & 难度大,所以再ContentProvider
类上加多了一个 ContentResolver
类对所有的ContentProvider
进行统一管理。
// 外部进程向 ContentProvider 中添加数据
public Uri insert(Uri uri, ContentValues values)
// 外部进程 删除 ContentProvider 中的数据
public int delete(Uri uri, String selection, String[] selectionArgs)
// 外部进程更新 ContentProvider 中的数据
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs)
// 外部应用 获取 ContentProvider 中的数据
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)
实例
// 使用ContentResolver前,需要先获取ContentResolver
// 可通过在所有继承Context的类中 通过调用getContentResolver()来获得ContentResolver
ContentResolver resolver = getContentResolver();
// 设置ContentProvider的URI
Uri uri = Uri.parse("content://cn.scu.myprovider/user");
// 根据URI 操作 ContentProvider中的数据
// 此处是获取ContentProvider中 user表的所有记录
Cursor cursor = resolver.query(uri, null, null, null, "userid desc");
Android
提供了3个用于辅助ContentProvide
的工具类:
ContentUris
操作 URI
// withAppendedId()作用:向URI追加一个id
Uri uri = Uri.parse("content://cn.scu.myprovider/user")
Uri resultUri = ContentUris.withAppendedId(uri, 7);
// 最终生成后的Uri为:content://cn.scu.myprovider/user/7
// parseId()作用:从URL中获取ID
Uri uri = Uri.parse("content://cn.scu.myprovider/user/7")
long personid = ContentUris.parseId(uri);
//获取的结果为:7
UriMatcher
ContentProvider
中注册URI
URI
匹配 ContentProvider
中对应的数据表// 步骤1:初始化UriMatcher对象
UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);
//常量UriMatcher.NO_MATCH = 不匹配任何路径的返回码
// 即初始化时不匹配任何东西
// 步骤2:在ContentProvider 中注册URI(addURI())
int URI_CODE_a = 1;
int URI_CODE_b = 2;
matcher.addURI("cn.scu.myprovider", "user1", URI_CODE_a);
matcher.addURI("cn.scu.myprovider", "user2", URI_CODE_b);
// 若URI资源路径 = content://cn.scu.myprovider/user1 ,则返回注册码URI_CODE_a
// 若URI资源路径 = content://cn.scu.myprovider/user2 ,则返回注册码URI_CODE_b
// 步骤3:根据URI 匹配 URI_CODE,从而匹配ContentProvider中相应的资源(match())
@Override
public String getType(Uri uri) {
Uri uri = Uri.parse(" content://cn.scu.myprovider/user1");
switch(matcher.match(uri)){
// 根据URI匹配的返回码是URI_CODE_a
// 即matcher.match(uri) == URI_CODE_a
case URI_CODE_a:
return tableNameUser1;
// 如果根据URI匹配的返回码是URI_CODE_a,则返回ContentProvider中的名为tableNameUser1的表
case URI_CODE_b:
return tableNameUser2;
// 如果根据URI匹配的返回码是URI_CODE_b,则返回ContentProvider中的名为tableNameUser2的表
}
}
ContentObserver
内容观察者,观察 Uri
引起 ContentProvider
中的数据变化 & 通知外界(即访问该数据访问者),当ContentProvider
中的数据发生变化(增、删 & 改)时,就会触发该 ContentObserver
类
// 步骤1:注册内容观察者ContentObserver
getContentResolver().registerContentObserver(uri);
// 通过ContentResolver类进行注册,并指定需要观察的URI
// 步骤2:当该URI的ContentProvider数据发生变化时,通知外界(即访问该ContentProvider数据的访问者)
public class UserContentProvider extends ContentProvider {
public Uri insert(Uri uri, ContentValues values) {
db.insert("user", "userid", values);
getContext().getContentResolver().notifyChange(uri, null);
// 通知访问者
}
}
// 步骤3:解除观察者
getContentResolver().unregisterContentObserver(uri);
// 同样需要通过ContentResolver类进行解除
ContentProvider
不仅常用于进程间通信,同时也适用于进程内通信ContentProvider
讲解:
Android
中的SQLite
数据库public class DBHelper extends SQLiteOpenHelper {
// 数据库名
private static final String DATABASE_NAME = "finch.db";
// 表名
public static final String USER_TABLE_NAME = "user";
public static final String JOB_TABLE_NAME = "job";
private static final int DATABASE_VERSION = 1;
//数据库版本号
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
// 创建两个表格:用户表 和职业表
db.execSQL("CREATE TABLE IF NOT EXISTS " + USER_TABLE_NAME + "(_id INTEGER PRIMARY KEY AUTOINCREMENT," + " name TEXT)");
db.execSQL("CREATE TABLE IF NOT EXISTS " + JOB_TABLE_NAME + "(_id INTEGER PRIMARY KEY AUTOINCREMENT," + " job TEXT)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
ContentProvider
类public class MyProvider extends ContentProvider {
private Context mContext;
DBHelper mDbHelper = null;
SQLiteDatabase db = null;
public static final String AUTOHORITY = "cn.scu.myprovider";
// 设置ContentProvider的唯一标识
public static final int User_Code = 1;
public static final int Job_Code = 2;
// UriMatcher类使用:在ContentProvider 中注册URI
private static final UriMatcher mMatcher;
static{
mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
// 初始化
mMatcher.addURI(AUTOHORITY,"user", User_Code);
mMatcher.addURI(AUTOHORITY, "job", Job_Code);
// 若URI资源路径 = content://cn.scu.myprovider/user ,则返回注册码User_Code
// 若URI资源路径 = content://cn.scu.myprovider/job ,则返回注册码Job_Code
}
// 以下是ContentProvider的6个方法
/**
* 初始化ContentProvider
*/
@Override
public boolean onCreate() {
mContext = getContext();
// 在ContentProvider创建时对数据库进行初始化
// 运行在主线程,故不能做耗时操作,此处仅作展示
mDbHelper = new DBHelper(getContext());
db = mDbHelper.getWritableDatabase();
// 初始化两个表的数据(先清空两个表,再各加入一个记录)
db.execSQL("delete from user");
db.execSQL("insert into user values(1,'Carson');");
db.execSQL("insert into user values(2,'Kobe');");
db.execSQL("delete from job");
db.execSQL("insert into job values(1,'Android');");
db.execSQL("insert into job values(2,'iOS');");
return true;
}
/**
* 添加数据
*/
@Override
public Uri insert(Uri uri, ContentValues values) {
// 根据URI匹配 URI_CODE,从而匹配ContentProvider中相应的表名
// 该方法在最下面
String table = getTableName(uri);
// 向该表添加数据
db.insert(table, null, values);
// 当该URI的ContentProvider数据发生变化时,通知外界(即访问该ContentProvider数据的访问者)
mContext.getContentResolver().notifyChange(uri, null);
// // 通过ContentUris类从URL中获取ID
// long personid = ContentUris.parseId(uri);
// System.out.println(personid);
return uri;
}
/**
* 查询数据
*/
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
// 根据URI匹配 URI_CODE,从而匹配ContentProvider中相应的表名
// 该方法在最下面
String table = getTableName(uri);
// // 通过ContentUris类从URL中获取ID
// long personid = ContentUris.parseId(uri);
// System.out.println(personid);
// 查询数据
return db.query(table,projection,selection,selectionArgs,null,null,sortOrder,null);
}
/**
* 更新数据
*/
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
// 由于不展示,此处不作展开
return 0;
}
/**
* 删除数据
*/
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
// 由于不展示,此处不作展开
return 0;
}
@Override
public String getType(Uri uri) {
// 由于不展示,此处不作展开
return null;
}
/**
* 根据URI匹配 URI_CODE,从而匹配ContentProvider中相应的表名
*/
private String getTableName(Uri uri){
String tableName = null;
switch (mMatcher.match(uri)) {
case User_Code:
tableName = DBHelper.USER_TABLE_NAME;
break;
case Job_Code:
tableName = DBHelper.JOB_TABLE_NAME;
break;
}
return tableName;
}
}
ContentProvider
类AndroidManifest.xml
<provider android:name="MyProvider"
android:authorities="cn.scu.myprovider"
/>
ContentProvider
的数据public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/**
* 对user表进行操作
*/
// 设置URI
Uri uri_user = Uri.parse("content://cn.scu.myprovider/user");
// 插入表中数据
ContentValues values = new ContentValues();
values.put("_id", 3);
values.put("name", "Iverson");
// 获取ContentResolver
ContentResolver resolver = getContentResolver();
// 通过ContentResolver 根据URI 向ContentProvider中插入数据
resolver.insert(uri_user,values);
// 通过ContentResolver 向ContentProvider中查询数据
Cursor cursor = resolver.query(uri_user, new String[]{"_id","name"}, null, null, null);
while (cursor.moveToNext()){
System.out.println("query book:" + cursor.getInt(0) +" "+ cursor.getString(1));
// 将表中数据全部输出
}
cursor.close();
// 关闭游标
/**
* 对job表进行操作
*/
// 和上述类似,只是URI需要更改,从而匹配不同的URI CODE,从而找到不同的数据资源
Uri uri_job = Uri.parse("content://cn.scu.myprovider/job");
// 插入表中数据
ContentValues values2 = new ContentValues();
values2.put("_id", 3);
values2.put("job", "NBA Player");
// 获取ContentResolver
ContentResolver resolver2 = getContentResolver();
// 通过ContentResolver 根据URI 向ContentProvider中插入数据
resolver2.insert(uri_job,values2);
// 通过ContentResolver 向ContentProvider中查询数据
Cursor cursor2 = resolver2.query(uri_job, new String[]{"_id","job"}, null, null, null);
while (cursor2.moveToNext()){
System.out.println("query job:" + cursor2.getInt(0) +" "+ cursor2.getString(1));
// 将表中数据全部输出
}
cursor2.close();
// 关闭游标
}
}
本文需要创建2个进程,即创建两个工程,作用如下
进程1:创建ContentProvider+储存数据sqlite
进程2:访问ContentProvider中的储存数据
步骤1:创建数据库类
步骤2:自定义 ContentProvider
类
前2个步骤同上例相同
步骤3:注册 创建的 ContentProvider类
AndroidManifest.xml
<provider
android:name="MyProvider"
android:authorities="scut.carson_ho.myprovider"
// 声明外界进程可访问该Provider的权限(读 & 写)
android:permission="scut.carson_ho.PROVIDER"
// 权限可细分为读 & 写的权限
// 外界需要声明同样的读 & 写的权限才可进行相应操作,否则会报错
// android:readPermisson = "scut.carson_ho.Read"
// android:writePermisson = "scut.carson_ho.Write"
// 设置此provider是否可以被其他进程使用
android:exported="true"
/>
// 声明本应用 可允许通信的权限
<permission android:name="scut.carson_ho.Read" android:protectionLevel="normal"/>
// 细分读 & 写权限如下,但本Demo直接采用全权限
// <permission android:name="scut.carson_ho.Write" android:protectionLevel="normal"/>
// <permission android:name="scut.carson_ho.PROVIDER" android:protectionLevel="normal"/>
步骤1:声明可访问的权限
AndroidManifest.xml
// 声明本应用可允许通信的权限(全权限)
<uses-permission android:name="scut.carson_ho.PROVIDER"/>
// 细分读 & 写权限如下,但本Demo直接采用全权限
// <uses-permission android:name="scut.carson_ho.Read"/>
// <uses-permission android:name="scut.carson_ho.Write"/>
// 注:声明的权限必须与进程1中设置的权限对应
步骤2:访问 ContentProvider的类
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/**
* 对user表进行操作
*/
// 设置URI
Uri uri_user = Uri.parse("content://scut.carson_ho.myprovider/user");
// 插入表中数据
ContentValues values = new ContentValues();
values.put("_id", 4);
values.put("name", "Jordan");
// 获取ContentResolver
ContentResolver resolver = getContentResolver();
// 通过ContentResolver 根据URI 向ContentProvider中插入数据
resolver.insert(uri_user,values);
// 通过ContentResolver 向ContentProvider中查询数据
Cursor cursor = resolver.query(uri_user, new String[]{"_id","name"}, null, null, null);
while (cursor.moveToNext()){
System.out.println("query book:" + cursor.getInt(0) +" "+ cursor.getString(1));
// 将表中数据全部输出
}
cursor.close();
// 关闭游标
/**
* 对job表进行操作
*/
// 和上述类似,只是URI需要更改,从而匹配不同的URI CODE,从而找到不同的数据资源
Uri uri_job = Uri.parse("content://scut.carson_ho.myprovider/job");
// 插入表中数据
ContentValues values2 = new ContentValues();
values2.put("_id", 4);
values2.put("job", "NBA Player");
// 获取ContentResolver
ContentResolver resolver2 = getContentResolver();
// 通过ContentResolver 根据URI 向ContentProvider中插入数据
resolver2.insert(uri_job,values2);
// 通过ContentResolver 向ContentProvider中查询数据
Cursor cursor2 = resolver2.query(uri_job, new String[]{"_id","job"}, null, null, null);
while (cursor2.moveToNext()){
System.out.println("query job:" + cursor2.getInt(0) +" "+ cursor2.getString(1));
// 将表中数据全部输出
}
cursor2.close();
// 关闭游标
}
}
在进程展示时,需要先运行准备数据的进程1,再运行需要访问数据的进程2
在进程1中,我们准备好了一系列数据
在进程2中,我们先向ContentProvider
中插入数据,再查询数据
注意:
SQLite
数据库使用详见
https://www.jianshu.com/p/8e3f294e2828
参考链接
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文章浏览阅读3.8k次,点赞3次,收藏51次。前段时间看到一位发烧友制作的超声波雷达扫描神器,用到了Arduino和Processing,可惜啊,我不会Processing更看不懂人家的程序,咋办呢?嘿嘿,所以我就换了个思路解决,因为我会一点Python啊,那就动手吧!在做这个案例之前先要搞明白一个问题:怎么将Arduino通过超声波检测到的距离反馈到Python端?这个嘛,我首先想到了串行通信接口。没错!就是串口。只要Arduino将数据发送给COM口,然后Python能从COM口读取到这个数据就可以啦!我先写了一个测试程序试了一下,OK!搞定_超声波扫描建模 python库
文章浏览阅读4.2k次。端—端加密指信息由发送端自动加密,并且由TCP/IP进行数据包封装,然后作为不可阅读和不可识别的数据穿过互联网,当这些信息到达目的地,将被自动重组、解密,而成为可读的数据。不可逆加密算法的特征是加密过程中不需要使用密钥,输入明文后由系统直接经过加密算法处理成密文,这种加密后的数据是无法被解密的,只有重新输入明文,并再次经过同样不可逆的加密算法处理,得到相同的加密密文并被系统重新识别后,才能真正解密。2.使用时,加密者查找明文字母表中需要加密的消息中的每一个字母所在位置,并且写下密文字母表中对应的字母。_凯撒加密
文章浏览阅读5.7k次。CIP报文解析常用到的几个字段:普通类型服务类型:[0x00], CIP对象:[0x02 Message Router], ioi segments:[XX]PCCC(带cmd和func)服务类型:[0x00], CIP对象:[0x02 Message Router], cmd:[0x101], fnc:[0x101]..._cip协议embedded_service_error
文章浏览阅读2.4k次,点赞9次,收藏13次。有时候我们在MFC项目开发过程中,需要用到一些微软已经提供的功能,如VC++使用EXCEL功能,这时候我们就能直接通过VS2019到如EXCEL.EXE方式,生成对应的OLE头文件,然后直接使用功能,那么,我们上篇文章中介绍了vs2017及以前的版本如何来添加。但由于微软某些方面考虑,这种方式已被放弃。从上图中可以看出,这一功能,在从vs2017版本15.9开始,后续版本已经删除了此功能。那么我们如果仍需要此功能,我们如何在新版本中添加呢。_vs添加mfc库
文章浏览阅读785次。用ac3编码,执行编码函数时报错入如下:[ac3 @ 0x7fed7800f200] frame_size (1536) was not respected for anon-last frame (avcodec_encode_audio2)用ac3编码时每次送入编码器的音频采样数应该是1536个采样,不然就会报上述错误。这个数字并非刻意固定,而是跟ac3内部的编码算法原理相关。全网找不到,国内音视频之路还有很长的路,音视频人一起加油吧~......_frame_size (1024) was not respected for a non-last frame
文章浏览阅读230次,点赞2次,收藏2次。创建Android应用程序一个项目里面可以有很多模块,而每一个模块就对应了一个应用程序。项目结构介绍_在安卓移动应用开发中要在活动类文件中声迷你一个复选框变量