【文件格式探究】EP.1 对ePub文件格式的初探

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这是“文件格式探究”专题的第 1 期——初探 “ePub” 文件格式。这个专题将会给各位读者呈现笔者探索各种文件格式的过程，具体则是文件的内容是如何呈现出来的。原则上我们假定仅对于这些文件格式的用途有所了解，但具体实现的细节并不清楚 (如果提前掌握了部分内容，笔者全当其不存在) 。探究过程中我们会尝试使用各种方法来逐渐初步掌握其概貌。

文件格式简介

根据维基百科大陆简体版本的相关描述：

EPub 是一个自由的开放标准，属于一种可以“自动重新排版”的内容；也就是文字内容可以根据阅读设备的特性，以最适于阅读的方式显示。

之所以后面不截是因为再截就剧透了。简单来说，ePub 就是类似于 PDF 那样的“文档型”文件格式，常用于分发电子读物等。

探究过程

环境

现在笔者手头上有一份用于测试的 ePub 文件，文件路径为 ~/Downloads/咖啡馆推理事件簿系列（全四本）.epub (趁机夹带私货，反正很合我胃口就是了) ，后续所有的探究活动均建立于此文件上。笔者目前的操作系统环境为 Manjaro 21.1.0 on amd64，终端环境为 GNU bash 5.1.8(1)-release 。为了方便，我们先把文件改个名字 (那你还把原来的名字给出来干嘛？！) ：

[littleye233@lymjrolt Downloads]$ cd ~ [littleye233@lymjrolt ~]$ cd Downloads [littleye233@lymjrolt Downloads]$ mv 咖啡馆推理事件簿系列（全四本）.epub test.epub [littleye233@lymjrolt Downloads]$ ll test.epub -rw-r--r-- 1 littleye233 littleye233 1253964 Aug 22 23:24 test.epub

Round I. 文件类型

首先我们先尝试用 Linux 系统的内置命令 file 试试水，看看会输出什么东西。键入 file test.epub后执行：

[littleye233@lymjrolt Downloads]$ file test.epub test.epub: EPUB document EPUB document

哎呀，真可惜！ file 命令几乎什么有效信息都没给我们。 file 命令的 man 页面明确给出此命令可以判断文件格式，但其实它能做到的有很多，例如如果对一个图片文件使用 file ，可能会出现类似下面的结果：

[littleye233@lymjrolt Downloads]$ file ~/.local/share/osu/screenshots/osu_2021-08-21_23-40-03.png /home/littleye233/.local/share/osu/screenshots/osu_2021-08-21_23-40-03.png: PNG image data, 1920 x 961, 8-bit/color RGBA, non-interlaced

这样我们可以通过 file 中提供的相关信息顺藤摸瓜，尝试在文件的二进制编码内容中寻找其蛛丝马迹，进而推测对应“位点”所表达的含义 (因为一些文件格式要求在特定的位置表达某些含义) ，如果能提供类似注释的信息就再好不过了。

Round II. 文件结构

现在我们回到这个 ePub 文件上来。现在我们尝试能否直接获取其内容，目的是通过文件头部的部分可见字符猜测其文件结构。输入 nano test.epub 直接预览，或使用 head --bytes=120 test.epub 查看前面 120 个字节的内容：

[littleye233@lymjrolt Downloads]$ head --bytes=120 test.epub PK!oa�mimetypeapplication/epub+zipPU�N�;�ʯ�META-INF/container.xml]�A �0E�=

果不其然，我们看到了一些有趣的字眼： “mimetypeapplication/epub+zip” ，凭经验猜测，这应该是 ePub 文件格式的文件头，而其中的 “zip” 也说明—— ePub 文件可能本质上就是一个压缩档。

其实很多文件格式 (例如 Word 文档 “*.docx”) 其本质都是在一个压缩档中加入各种资源文件和配置文件，只要有对应的软件进行读取并重新加工，用户即能看到效果。

Round III. 目录树结构

现在我们可以使用解压缩程序解出 ePub 文件中的内容了。在终端中执行 unzip -l test.epub ：

[littleye233@lymjrolt Downloads]$ unzip -l test.epub Archive: test.epub Length Date Time Name --------- ---------- ----- ---- 20 1980-01-01 00:00 mimetype 251 2019-06-27 10:40 META-INF/container.xml 12307 2019-06-27 10:40 OEBPS/content.opf 112368 2019-06-27 10:40 OEBPS/Images/cover00464.jpeg 128680 2019-06-27 10:40 OEBPS/Images/image00456.jpeg 120936 2019-06-27 10:40 OEBPS/Images/image00457.jpeg 1392 2019-06-27 10:40 OEBPS/Images/image00458.jpeg 101948 2019-06-27 10:40 OEBPS/Images/image00459.jpeg 119124 2019-06-27 10:40 OEBPS/Images/image00460.jpeg 1268 2019-06-27 10:40 OEBPS/Images/image00461.jpeg 42944 2019-06-27 10:40 OEBPS/Images/image00462.jpeg 121284 2019-06-27 10:40 OEBPS/Images/image00463.jpeg 2251 2019-06-27 10:40 OEBPS/Styles/style0001.css 9816 2019-06-27 10:40 OEBPS/Styles/style0002.css 2251 2019-06-27 10:40 OEBPS/Styles/style0003.css 9789 2019-06-27 10:40 OEBPS/Styles/style0004.css 2251 2019-06-27 10:40 OEBPS/Styles/style0005.css 29245 2019-06-27 10:40 OEBPS/Styles/style0006.css 2235 2019-06-27 10:40 OEBPS/Styles/style0007.css 29914 2019-06-27 10:40 OEBPS/Styles/style0008.css 2251 2019-06-27 10:40 OEBPS/Styles/style0009.css 624 2019-06-27 10:40 OEBPS/Text/cover_page.xhtml 851 2019-06-27 10:40 OEBPS/Text/part0000.xhtml 561 2019-06-27 10:40 OEBPS/Text/part0001.xhtml 428 2019-06-27 10:40 OEBPS/Text/part0002.xhtml 1518 2019-06-27 10:40 OEBPS/Text/part0003.xhtml 661 2019-06-27 10:40 OEBPS/Text/part0004.xhtml 2311 2019-06-27 10:40 OEBPS/Text/part0005.xhtml 55157 2019-06-27 10:40 OEBPS/Text/part0006.xhtml 58266 2019-06-27 10:40 OEBPS/Text/part0007.xhtml 59953 2019-06-27 10:40 OEBPS/Text/part0008.xhtml 49789 2019-06-27 10:40 OEBPS/Text/part0009.xhtml 66870 2019-06-27 10:40 OEBPS/Text/part0010.xhtml 57342 2019-06-27 10:40 OEBPS/Text/part0011.xhtml 67449 2019-06-27 10:40 OEBPS/Text/part0012.xhtml 16183 2019-06-27 10:40 OEBPS/Text/part0013.xhtml 561 2019-06-27 10:40 OEBPS/Text/part0014.xhtml 428 2019-06-27 10:40 OEBPS/Text/part0015.xhtml 1575 2019-06-27 10:40 OEBPS/Text/part0016.xhtml 496 2019-06-27 10:40 OEBPS/Text/part0017.xhtml 1446 2019-06-27 10:40 OEBPS/Text/part0018.xhtml 52358 2019-06-27 10:40 OEBPS/Text/part0019.xhtml 75746 2019-06-27 10:40 OEBPS/Text/part0020.xhtml 63420 2019-06-27 10:40 OEBPS/Text/part0021.xhtml 57399 2019-06-27 10:40 OEBPS/Text/part0022.xhtml 58590 2019-06-27 10:40 OEBPS/Text/part0023.xhtml 40263 2019-06-27 10:40 OEBPS/Text/part0024.xhtml 66099 2019-06-27 10:40 OEBPS/Text/part0025.xhtml 15143 2019-06-27 10:40 OEBPS/Text/part0026.xhtml 561 2019-06-27 10:40 OEBPS/Text/part0027.xhtml 612 2019-06-27 10:40 OEBPS/Text/part0028.xhtml 1344 2019-06-27 10:40 OEBPS/Text/part0029.xhtml 640 2019-06-27 10:40 OEBPS/Text/part0030.xhtml 6144 2019-06-27 10:40 OEBPS/Text/part0031.xhtml 25197 2019-06-27 10:40 OEBPS/Text/part0032.xhtml 54594 2019-06-27 10:40 OEBPS/Text/part0033.xhtml 87394 2019-06-27 10:40 OEBPS/Text/part0034.xhtml 97557 2019-06-27 10:40 OEBPS/Text/part0035.xhtml 109901 2019-06-27 10:40 OEBPS/Text/part0036.xhtml 17181 2019-06-27 10:40 OEBPS/Text/part0037.xhtml 5238 2019-06-27 10:40 OEBPS/Text/part0038.xhtml 561 2019-06-27 10:40 OEBPS/Text/part0039.xhtml 644 2019-06-27 10:40 OEBPS/Text/part0040.xhtml 1163 2019-06-27 10:40 OEBPS/Text/part0041.xhtml 1473 2019-06-27 10:40 OEBPS/Text/part0042.xhtml 38427 2019-06-27 10:40 OEBPS/Text/part0043.xhtml 90589 2019-06-27 10:40 OEBPS/Text/part0044.xhtml 51278 2019-06-27 10:40 OEBPS/Text/part0045.xhtml 58321 2019-06-27 10:40 OEBPS/Text/part0046.xhtml 29670 2019-06-27 10:40 OEBPS/Text/part0047.xhtml 12903 2019-06-27 10:40 OEBPS/Text/part0048.xhtml 7364 2019-06-27 10:40 OEBPS/toc.ncx --------- ------- 2422768 72 files

同时可以直接解压：

[littleye233@lymjrolt Downloads]$ unzip test.epub -d test_epub Archive: test.epub extracting: test_epub/mimetype inflating: test_epub/META-INF/container.xml inflating: test_epub/OEBPS/content.opf inflating: test_epub/OEBPS/Images/cover00464.jpeg inflating: test_epub/OEBPS/Images/image00456.jpeg inflating: test_epub/OEBPS/Images/image00457.jpeg inflating: test_epub/OEBPS/Images/image00458.jpeg inflating: test_epub/OEBPS/Images/image00459.jpeg inflating: test_epub/OEBPS/Images/image00460.jpeg inflating: test_epub/OEBPS/Images/image00461.jpeg inflating: test_epub/OEBPS/Images/image00462.jpeg inflating: test_epub/OEBPS/Images/image00463.jpeg inflating: test_epub/OEBPS/Styles/style0001.css inflating: test_epub/OEBPS/Styles/style0002.css inflating: test_epub/OEBPS/Styles/style0003.css inflating: test_epub/OEBPS/Styles/style0004.css inflating: test_epub/OEBPS/Styles/style0005.css inflating: test_epub/OEBPS/Styles/style0006.css inflating: test_epub/OEBPS/Styles/style0007.css inflating: test_epub/OEBPS/Styles/style0008.css inflating: test_epub/OEBPS/Styles/style0009.css inflating: test_epub/OEBPS/Text/cover_page.xhtml inflating: test_epub/OEBPS/Text/part0000.xhtml inflating: test_epub/OEBPS/Text/part0001.xhtml inflating: test_epub/OEBPS/Text/part0002.xhtml inflating: test_epub/OEBPS/Text/part0003.xhtml inflating: test_epub/OEBPS/Text/part0004.xhtml inflating: test_epub/OEBPS/Text/part0005.xhtml inflating: test_epub/OEBPS/Text/part0006.xhtml inflating: test_epub/OEBPS/Text/part0007.xhtml inflating: test_epub/OEBPS/Text/part0008.xhtml inflating: test_epub/OEBPS/Text/part0009.xhtml inflating: test_epub/OEBPS/Text/part0010.xhtml inflating: test_epub/OEBPS/Text/part0011.xhtml inflating: test_epub/OEBPS/Text/part0012.xhtml inflating: test_epub/OEBPS/Text/part0013.xhtml inflating: test_epub/OEBPS/Text/part0014.xhtml inflating: test_epub/OEBPS/Text/part0015.xhtml inflating: test_epub/OEBPS/Text/part0016.xhtml inflating: test_epub/OEBPS/Text/part0017.xhtml inflating: test_epub/OEBPS/Text/part0018.xhtml inflating: test_epub/OEBPS/Text/part0019.xhtml inflating: test_epub/OEBPS/Text/part0020.xhtml inflating: test_epub/OEBPS/Text/part0021.xhtml inflating: test_epub/OEBPS/Text/part0022.xhtml inflating: test_epub/OEBPS/Text/part0023.xhtml inflating: test_epub/OEBPS/Text/part0024.xhtml inflating: test_epub/OEBPS/Text/part0025.xhtml inflating: test_epub/OEBPS/Text/part0026.xhtml inflating: test_epub/OEBPS/Text/part0027.xhtml inflating: test_epub/OEBPS/Text/part0028.xhtml inflating: test_epub/OEBPS/Text/part0029.xhtml inflating: test_epub/OEBPS/Text/part0030.xhtml inflating: test_epub/OEBPS/Text/part0031.xhtml inflating: test_epub/OEBPS/Text/part0032.xhtml inflating: test_epub/OEBPS/Text/part0033.xhtml inflating: test_epub/OEBPS/Text/part0034.xhtml inflating: test_epub/OEBPS/Text/part0035.xhtml inflating: test_epub/OEBPS/Text/part0036.xhtml inflating: test_epub/OEBPS/Text/part0037.xhtml inflating: test_epub/OEBPS/Text/part0038.xhtml inflating: test_epub/OEBPS/Text/part0039.xhtml inflating: test_epub/OEBPS/Text/part0040.xhtml inflating: test_epub/OEBPS/Text/part0041.xhtml inflating: test_epub/OEBPS/Text/part0042.xhtml inflating: test_epub/OEBPS/Text/part0043.xhtml inflating: test_epub/OEBPS/Text/part0044.xhtml inflating: test_epub/OEBPS/Text/part0045.xhtml inflating: test_epub/OEBPS/Text/part0046.xhtml inflating: test_epub/OEBPS/Text/part0047.xhtml inflating: test_epub/OEBPS/Text/part0048.xhtml inflating: test_epub/OEBPS/toc.ncx

为了更清楚地显示文件树结构，我们也可以使用 tree 命令 (这个命令在 Windows 中是内置的，在 Linux 中需要安装 tree 这个包，使用软件包管理器或编译安装均可) ：

[littleye233@lymjrolt test_epub]$ tree . ├── META-INF │ └── container.xml ├── mimetype └── OEBPS ├── content.opf ├── Images │ ├── cover00464.jpeg │ ├── image00456.jpeg │ ├── image00457.jpeg │ ├── image00458.jpeg │ ├── image00459.jpeg │ ├── image00460.jpeg │ ├── image00461.jpeg │ ├── image00462.jpeg │ └── image00463.jpeg ├── Styles │ ├── style0001.css │ ├── style0002.css │ ├── style0003.css │ ├── style0004.css │ ├── style0005.css │ ├── style0006.css │ ├── style0007.css │ ├── style0008.css │ └── style0009.css ├── Text │ ├── cover_page.xhtml │ ├── part0000.xhtml │ ├── part0001.xhtml │ ├── part0002.xhtml │ ├── part0003.xhtml │ ├── part0004.xhtml │ ├── part0005.xhtml │ ├── part0006.xhtml │ ├── part0007.xhtml │ ├── part0008.xhtml │ ├── part0009.xhtml │ ├── part0010.xhtml │ ├── part0011.xhtml │ ├── part0012.xhtml │ ├── part0013.xhtml │ ├── part0014.xhtml │ ├── part0015.xhtml │ ├── part0016.xhtml │ ├── part0017.xhtml │ ├── part0018.xhtml │ ├── part0019.xhtml │ ├── part0020.xhtml │ ├── part0021.xhtml │ ├── part0022.xhtml │ ├── part0023.xhtml │ ├── part0024.xhtml │ ├── part0025.xhtml │ ├── part0026.xhtml │ ├── part0027.xhtml │ ├── part0028.xhtml │ ├── part0029.xhtml │ ├── part0030.xhtml │ ├── part0031.xhtml │ ├── part0032.xhtml │ ├── part0033.xhtml │ ├── part0034.xhtml │ ├── part0035.xhtml │ ├── part0036.xhtml │ ├── part0037.xhtml │ ├── part0038.xhtml │ ├── part0039.xhtml │ ├── part0040.xhtml │ ├── part0041.xhtml │ ├── part0042.xhtml │ ├── part0043.xhtml │ ├── part0044.xhtml │ ├── part0045.xhtml │ ├── part0046.xhtml │ ├── part0047.xhtml │ └── part0048.xhtml └── toc.ncx5 directories, 72 files

Round IV. 内部文件

到这里我们大概就能猜出来：

META-INF 文件夹：里面存放的应该是“容器” (也就是这个 ePub 文件) 的相关配置文件；
mimetype 文件：里面定义了这个文件的类型为 “ePub” (其中 “MIME” 是 “Multipurpose Internet Mail Extensions” 的缩写，从字面上也能看出其具有指示 “Extension” 的机能) ；
OEBPS 文件夹：虽暂不知其确切含义，但应存放 ePub 的文字、图片以及其他的界面数据；
- content.opf 文件：里面存放的应该是目录信息——或是定义各种文件的“次序”；
- Images Styles 和 Text 文件夹：明显分别存放图片、层叠样式表和文字数据；
- toc.ncx 文件：可能是真正的目录 (“toc” 是 “table of contents” 的缩写)。

接下来我们将挨个分析。

Round IV.I. 容器

先看 META-INF/container.xml ：

[littleye233@lymjrolt test_epub]$ file META-INF/container.xml META-INF/container.xml: XML 1.0 document, ASCII text

输出其内容：

<?xml version="1.0" encoding="UTF-8"?> <container version="1.0" xmlns="urn:oasis:names:tc:opendocument:xmlns:container"> <rootfiles> <rootfile full-path="OEBPS/content.opf" media-type="application/oebps-package+xml"/> </rootfiles> </container>

显然是一个标准的 XML 文件，其中我们可以注意到 /container/rootfiles/rootfile[@class='full-path']^[1] 中定义了一个我们之前认定的目录文件，但此处可以规范化，故这个文件在大多数 ePub 档中应该是相同的。

Round IV.II. 文件类型定性

接下来看 mimetype 文件：

[littleye233@lymjrolt test_epub]$ cat mimetype application/epub+zip

这也是相当显然的，也不再赘述。

Round IV.III. 目录？

再看 OEBPS/content.opf ：

[littleye233@lymjrolt test_epub]$ file OEBPS/content.opf OEBPS/content.opf: XML 1.0 document, Unicode text, UTF-8 text, with very long lines (504)

这也是一个 XML 文件，令人惊讶的是 file 命令竟能看出这个文件中最长的行有 504 个字符，属实让人害怕。

点此查看 `OEBPS/content.opf` 的全部内容 (已经过格式化)

<?xml version="1.0" encoding="utf-8"?> <package xmlns="http://www.idpf.org/2007/opf" version="2.0" unique-identifier="uid"> <metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf"> <dc:title opf:file-as="kafeiguantuilishijianbuxilie（quansiben）">咖啡馆推理事件簿系列（全四本）</dc:title> <dc:language>zh</dc:language> <dc:identifier id="uid">3899198450</dc:identifier> <dc:creator opf:file-as="（ri）gangqizuomo">（日）冈崎琢磨</dc:creator> <dc:date opf:event="publication">2018-03-15</dc:date>  <meta name="cover" content="x_cover-image"/> <meta name="output encoding" content="utf-8"/> <meta name="primary-writing-mode" content="horizontal-lr"/>  </metadata> <manifest> <item id="x_cover" media-type="application/xhtml+xml" href="Text/cover_page.xhtml"/> <item id="x_TableOfContents" media-type="application/xhtml+xml" href="Text/part0000.xhtml"/> <item id="x_a1cover.html" media-type="application/xhtml+xml" href="Text/part0001.xhtml"/> <item id="x_a1bookname" media-type="application/xhtml+xml" href="Text/part0002.xhtml"/> <item id="x_a1TableOfContents" media-type="application/xhtml+xml" href="Text/part0003.xhtml"/> <item id="x_a1Chapter001" media-type="application/xhtml+xml" href="Text/part0004.xhtml"/> <item id="x_a1Chapter002" media-type="application/xhtml+xml" href="Text/part0005.xhtml"/> <item id="x_a1Chapter003" media-type="application/xhtml+xml" href="Text/part0006.xhtml"/> <item id="x_a1Chapter004" media-type="application/xhtml+xml" href="Text/part0007.xhtml"/> <item id="x_a1Chapter005" media-type="application/xhtml+xml" href="Text/part0008.xhtml"/> <item id="x_a1Chapter006" media-type="application/xhtml+xml" href="Text/part0009.xhtml"/> <item id="x_a1Chapter007" media-type="application/xhtml+xml" href="Text/part0010.xhtml"/> <item id="x_a1Chapter008" media-type="application/xhtml+xml" href="Text/part0011.xhtml"/> <item id="x_a1Chapter009" media-type="application/xhtml+xml" href="Text/part0012.xhtml"/> <item id="x_a1Chapter010" media-type="application/xhtml+xml" href="Text/part0013.xhtml"/> <item id="x_a2cover.html" media-type="application/xhtml+xml" href="Text/part0014.xhtml"/> <item id="x_a2bookname" media-type="application/xhtml+xml" href="Text/part0015.xhtml"/> <item id="x_a2TableOfContents" media-type="application/xhtml+xml" href="Text/part0016.xhtml"/> <item id="x_a2Chapter001" media-type="application/xhtml+xml" href="Text/part0017.xhtml"/> <item id="x_a2Chapter002" media-type="application/xhtml+xml" href="Text/part0018.xhtml"/> <item id="x_a2Chapter003" media-type="application/xhtml+xml" href="Text/part0019.xhtml"/> <item id="x_a2Chapter004" media-type="application/xhtml+xml" href="Text/part0020.xhtml"/> <item id="x_a2Chapter005" media-type="application/xhtml+xml" href="Text/part0021.xhtml"/> <item id="x_a2Chapter006" media-type="application/xhtml+xml" href="Text/part0022.xhtml"/> <item id="x_a2Chapter007" media-type="application/xhtml+xml" href="Text/part0023.xhtml"/> <item id="x_a2Chapter008" media-type="application/xhtml+xml" href="Text/part0024.xhtml"/> <item id="x_a2Chapter009" media-type="application/xhtml+xml" href="Text/part0025.xhtml"/> <item id="x_a2Chapter010" media-type="application/xhtml+xml" href="Text/part0026.xhtml"/> <item id="x_a3cover.html" media-type="application/xhtml+xml" href="Text/part0027.xhtml"/> <item id="x_a3bookname" media-type="application/xhtml+xml" href="Text/part0028.xhtml"/> <item id="x_a3TableOfContents" media-type="application/xhtml+xml" href="Text/part0029.xhtml"/> <item id="x_a3Chapter001" media-type="application/xhtml+xml" href="Text/part0030.xhtml"/> <item id="x_a3Chapter002" media-type="application/xhtml+xml" href="Text/part0031.xhtml"/> <item id="x_a3Chapter003" media-type="application/xhtml+xml" href="Text/part0032.xhtml"/> <item id="x_a3Chapter004" media-type="application/xhtml+xml" href="Text/part0033.xhtml"/> <item id="x_a3Chapter005" media-type="application/xhtml+xml" href="Text/part0034.xhtml"/> <item id="x_a3Chapter006" media-type="application/xhtml+xml" href="Text/part0035.xhtml"/> <item id="x_a3Chapter007" media-type="application/xhtml+xml" href="Text/part0036.xhtml"/> <item id="x_a3Chapter008" media-type="application/xhtml+xml" href="Text/part0037.xhtml"/> <item id="x_a3Chapter009" media-type="application/xhtml+xml" href="Text/part0038.xhtml"/> <item id="x_a4cover.html" media-type="application/xhtml+xml" href="Text/part0039.xhtml"/> <item id="x_a4bookname" media-type="application/xhtml+xml" href="Text/part0040.xhtml"/> <item id="x_a4TableOfContents" media-type="application/xhtml+xml" href="Text/part0041.xhtml"/> <item id="x_a4Chapter001" media-type="application/xhtml+xml" href="Text/part0042.xhtml"/> <item id="x_a4Chapter002" media-type="application/xhtml+xml" href="Text/part0043.xhtml"/> <item id="x_a4Chapter003" media-type="application/xhtml+xml" href="Text/part0044.xhtml"/> <item id="x_a4Chapter004" media-type="application/xhtml+xml" href="Text/part0045.xhtml"/> <item id="x_a4Chapter005" media-type="application/xhtml+xml" href="Text/part0046.xhtml"/> <item id="x_a4Chapter006" media-type="application/xhtml+xml" href="Text/part0047.xhtml"/> <item id="x_a4Chapter007" media-type="application/xhtml+xml" href="Text/part0048.xhtml"/> <item id="item50" media-type="text/css" href="Styles/style0001.css"/> <item id="item51" media-type="text/css" href="Styles/style0002.css"/> <item id="item52" media-type="text/css" href="Styles/style0003.css"/> <item id="item53" media-type="text/css" href="Styles/style0004.css"/> <item id="item54" media-type="text/css" href="Styles/style0005.css"/> <item id="item55" media-type="text/css" href="Styles/style0006.css"/> <item id="item56" media-type="text/css" href="Styles/style0007.css"/> <item id="item57" media-type="text/css" href="Styles/style0008.css"/> <item id="item58" media-type="text/css" href="Styles/style0009.css"/> <item id="item59" media-type="image/jpeg" href="Images/image00456.jpeg"/> <item id="item60" media-type="image/jpeg" href="Images/image00457.jpeg"/> <item id="item61" media-type="image/jpeg" href="Images/image00458.jpeg"/> <item id="item62" media-type="image/jpeg" href="Images/image00459.jpeg"/> <item id="item63" media-type="image/jpeg" href="Images/image00460.jpeg"/> <item id="item64" media-type="image/jpeg" href="Images/image00461.jpeg"/> <item id="item65" media-type="image/jpeg" href="Images/image00462.jpeg"/> <item id="item66" media-type="image/jpeg" href="Images/image00463.jpeg"/> <item id="x_cover-image" media-type="image/jpeg" href="Images/cover00464.jpeg"/> <item id="ncx" media-type="application/x-dtbncx+xml" href="toc.ncx"/> </manifest> <spine toc="ncx"> <itemref idref="x_cover" linear="no"/> <itemref idref="x_TableOfContents" linear="yes"/> <itemref idref="x_a1cover.html" linear="yes"/> <itemref idref="x_a1bookname" linear="yes"/> <itemref idref="x_a1TableOfContents" linear="yes"/> <itemref idref="x_a1Chapter001" linear="yes"/> <itemref idref="x_a1Chapter002" linear="yes"/> <itemref idref="x_a1Chapter003" linear="yes"/> <itemref idref="x_a1Chapter004" linear="yes"/> <itemref idref="x_a1Chapter005" linear="yes"/> <itemref idref="x_a1Chapter006" linear="yes"/> <itemref idref="x_a1Chapter007" linear="yes"/> <itemref idref="x_a1Chapter008" linear="yes"/> <itemref idref="x_a1Chapter009" linear="yes"/> <itemref idref="x_a1Chapter010" linear="yes"/> <itemref idref="x_a2cover.html" linear="yes"/> <itemref idref="x_a2bookname" linear="yes"/> <itemref idref="x_a2TableOfContents" linear="yes"/> <itemref idref="x_a2Chapter001" linear="yes"/> <itemref idref="x_a2Chapter002" linear="yes"/> <itemref idref="x_a2Chapter003" linear="yes"/> <itemref idref="x_a2Chapter004" linear="yes"/> <itemref idref="x_a2Chapter005" linear="yes"/> <itemref idref="x_a2Chapter006" linear="yes"/> <itemref idref="x_a2Chapter007" linear="yes"/> <itemref idref="x_a2Chapter008" linear="yes"/> <itemref idref="x_a2Chapter009" linear="yes"/> <itemref idref="x_a2Chapter010" linear="yes"/> <itemref idref="x_a3cover.html" linear="yes"/> <itemref idref="x_a3bookname" linear="yes"/> <itemref idref="x_a3TableOfContents" linear="yes"/> <itemref idref="x_a3Chapter001" linear="yes"/> <itemref idref="x_a3Chapter002" linear="yes"/> <itemref idref="x_a3Chapter003" linear="yes"/> <itemref idref="x_a3Chapter004" linear="yes"/> <itemref idref="x_a3Chapter005" linear="yes"/> <itemref idref="x_a3Chapter006" linear="yes"/> <itemref idref="x_a3Chapter007" linear="yes"/> <itemref idref="x_a3Chapter008" linear="yes"/> <itemref idref="x_a3Chapter009" linear="yes"/> <itemref idref="x_a4cover.html" linear="yes"/> <itemref idref="x_a4bookname" linear="yes"/> <itemref idref="x_a4TableOfContents" linear="yes"/> <itemref idref="x_a4Chapter001" linear="yes"/> <itemref idref="x_a4Chapter002" linear="yes"/> <itemref idref="x_a4Chapter003" linear="yes"/> <itemref idref="x_a4Chapter004" linear="yes"/> <itemref idref="x_a4Chapter005" linear="yes"/> <itemref idref="x_a4Chapter006" linear="yes"/> <itemref idref="x_a4Chapter007" linear="yes"/> </spine> <tours> </tours> <guide> <reference type="text" title="Start" href="Text/part0004.xhtml"/> <reference type="toc" title="Table of Contents" href="Text/part0000.xhtml"/> <reference type="cover" title="Cover" href="Text/cover_page.xhtml"/> </guide> </package>

说明我之前并没有猜错，这个文件存放的是超越“目录”的东西，而是“次序”——更进一步说。是“索引”。这个文件类似于其他文件格式或目录树中的 index.* ，将 ePub 中的各种数据编上号码，同时这里也定义了标题、语言、作者、出版 (发布) 日期等元信息。至于之前看到的超长行，似乎是一种十六进制的水印 (watermark) ，或许是为了防侵权等。

其中的 /package/manifest/item 定义了所有的索引，以及文件对应的类型； /package/spine/itemref 暂不知进一步的作用，但从中可看出能定义是否“线性” (linear) ； /package/guide/reference 定义了 ePub 的封面等索引，可供文件管理器和 ePub 阅读器使用 (显示预览页) 。

Round IV.IV. 目录！

再看 OEBPS/toc.ncx ：

[littleye233@lymjrolt test_epub]$ file OEBPS/toc.ncx OEBPS/toc.ncx: XML 1.0 document, Unicode text, UTF-8 text

感觉再讨论文件类型已经无关紧要了。再次查看内容：

点此查看 `OEBPS/toc.ncx` 的全部内容 (已经过格式化)

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Black</text> </navLabel> <content src="Text/part0007.xhtml"/> </navPoint> <navPoint id="np_6" playOrder="6"> <navLabel> <text>三隐藏在乳白色中的心</text> </navLabel> <content src="Text/part0008.xhtml"/> </navPoint> <navPoint id="np_7" playOrder="7"> <navLabel> <text>四棋盘上的狩猎</text> </navLabel> <content src="Text/part0009.xhtml"/> </navPoint> <navPoint id="np_8" playOrder="8"> <navLabel> <text>五past，present，f******？</text> </navLabel> <content src="Text/part0010.xhtml"/> </navPoint> <navPoint id="np_9" playOrder="9"> <navLabel> <text>六Animals in the closed room</text> </navLabel> <content src="Text/part0011.xhtml"/> </navPoint> <navPoint id="np_10" playOrder="10"> <navLabel> <text>七下次见面时，请让我品尝你煮的咖啡</text> </navLabel> <content src="Text/part0012.xhtml"/> </navPoint> <navPoint id="np_11" playOrder="11"> <navLabel> <text>终章</text> </navLabel> <content src="Text/part0013.xhtml"/> </navPoint> </navPoint> <navPoint id="np_12" playOrder="12"> <navLabel> <text>咖啡馆推理事件簿2：她梦到了欧蕾咖啡</text> </navLabel> <content src="Text/part0014.xhtml"/> <navPoint id="np_13" playOrder="13"> <navLabel> <text>序曲她的梦</text> </navLabel> <content src="Text/part0018.xhtml"/> </navPoint> <navPoint id="np_14" playOrder="14"> <navLabel> <text>第一章敬启致未来的你</text> </navLabel> <content src="Text/part0019.xhtml"/> </navPoint> <navPoint id="np_15" playOrder="15"> <navLabel> <text>第二章狐狸的迷惑</text> </navLabel> <content src="Text/part0020.xhtml"/> </navPoint> <navPoint id="np_16" playOrder="16"> <navLabel> <text>第三章打碎乳白色的心</text> </navLabel> <content src="Text/part0021.xhtml"/> </navPoint> <navPoint id="np_17" playOrder="17"> <navLabel> <text>第四章咖啡侦探蕾拉事件簿</text> </navLabel> <content src="Text/part0022.xhtml"/> </navPoint> <navPoint id="np_18" playOrder="18"> <navLabel> <text>第五章（She Wanted To Be）WANTED</text> </navLabel> <content src="Text/part0023.xhtml"/> </navPoint> <navPoint id="np_19" playOrder="19"> <navLabel> <text>第六章the Sky Occluded in the Sun</text> </navLabel> <content src="Text/part0024.xhtml"/> </navPoint> <navPoint id="np_20" playOrder="20"> <navLabel> <text>第七章在星空之下同命相连</text> </navLabel> <content src="Text/part0025.xhtml"/> </navPoint> <navPoint id="np_21" playOrder="21"> <navLabel> <text>终章她梦到了欧蕾咖啡</text> </navLabel> <content src="Text/part0026.xhtml"/> </navPoint> </navPoint> <navPoint id="np_22" playOrder="22"> <navLabel> <text>咖啡馆推理事件簿3：扰人心神的咖啡</text> </navLabel> <content src="Text/part0027.xhtml"/> <navPoint id="np_23" playOrder="23"> <navLabel> <text>序曲五年前</text> </navLabel> <content src="Text/part0031.xhtml"/> </navPoint> <navPoint id="np_24" playOrder="24"> <navLabel> <text>第一章参加大赛</text> </navLabel> <content src="Text/part0032.xhtml"/> </navPoint> <navPoint id="np_25" playOrder="25"> <navLabel> <text>第二章前夜</text> </navLabel> <content src="Text/part0033.xhtml"/> </navPoint> <navPoint id="np_26" playOrder="26"> <navLabel> <text>第三章第一天</text> </navLabel> <content src="Text/part0034.xhtml"/> </navPoint> <navPoint id="np_27" playOrder="27"> <navLabel> <text>第四章第二天</text> 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