常见的contentType

array[0] = "application/ecmascript";
array[1] = "application/javascript";
array[2] = "application/json";
array[3] = "application/pdf";
array[4] = "application/rtf";
array[5] = "application/octect-stream";
array[6] = "audio/3gpp";
array[7] = "audio/3gpp2";
array[8] = "audio/mp4";
array[9] = "audio/mpeg";
array[10] = "audio/ogg";
array[11] = "audio/vorbis";
array[12] = "image/gif";
array[13] = "image/jpeg";
array[14] = "image/png";
array[15] = "image/svg+xml";
array[16] = "image/tiff";
array[17] = "text/plain";
array[18] = "text/html";
array[19] = "text/csv";
array[20] = "text/plain";
array[21] = "text/uri-list";
array[22] = "text/xml";