Android中的dex分包

原文：http://blog.csdn.net/hp910315/article/details/51685180

一、为什么要拆包 
当 Android 系统安装一个应用的时候，有一步是对 Dex 进行优化，这个过程有一个专门的工具来处理，叫 DexOpt。DexOpt 是在第一次加载 Dex 文件的时候执行的。这个过程会生成一个 ODEX 文件，即 Optimised Dex。执行 ODEX 的效率会比直接执行 Dex 文件的效率要高很多。

但是在早期的 Android 系统中，DexOpt 有两个问题。 
（一）：DexOpt 会把每一个类的方法 id 检索起来，存在一个链表结构里面，但是这个链表的长度是用一个 short 类型来保存的，导致了方法 id 的数目不能够超过65536个。当一个项目足够大的时候，显然这个方法数的上限是不够的。 
（二）：Dexopt 使用 LinearAlloc 来存储应用的方法信息。Dalvik LinearAlloc 是一个固定大小的缓冲区。在Android 版本的历史上，LinearAlloc 分别经历了4M/5M/8M/16M限制。Android 2.2和2.3的缓冲区只有5MB，Android 4.x提高到了8MB 或16MB。当方法数量过多导致超出缓冲区大小时，也会造成dexopt崩溃。

二、使用dx进行拆包 

从上图看到，java文件通过javac编译成class文件，然后通过dx打包成dex文件，所以如果我们需要将class文件打包多个dex文件，我们也可以通过dx命令完成。

在我们的sdk目录的build-tools/目录下，选择一个版本目录，我们可以看到dx命令。在apk打包的过程中，从class文件到dex文件就是通过这个命令完成的。

参数说明：

<code class="hljs lasso has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">--</span>multi<span class="hljs-attribute" style="box-sizing: border-box;">-dex</span>:表示可以产生多个dex文件<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">--</span>main<span class="hljs-attribute" style="box-sizing: border-box;">-dex</span><span class="hljs-attribute" style="box-sizing: border-box;">-list</span><span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">=<</span>file<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">></span>:file文件中指定的类放到第一个主dex文件中<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">--</span><span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">minimal</span><span class="hljs-attribute" style="box-sizing: border-box;">-main</span><span class="hljs-attribute" style="box-sizing: border-box;">-dex</span>:只有在<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">--</span>main<span class="hljs-attribute" style="box-sizing: border-box;">-dex</span><span class="hljs-attribute" style="box-sizing: border-box;">-list</span><span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">=<</span>file<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">></span>中指定的类才能打包到第一个主dex中，其他的会放到另外一个单独的dex中。</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

三、Google 官方方案

针对 Gradle 进行配置的

<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">android {compileSdkVersion <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">21</span>buildToolsVersion <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"21.1.0"</span>defaultConfig {<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>minSdkVersion <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">14</span>targetSdkVersion <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">21</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>// Enabling multidex support.multiDexEnabled true}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>} afterEvaluate {        tasks.matching {            it.name.startsWith(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'dex'</span>)        }.each { dx ->            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (dx.additionalParameters == null) {                dx.additionalParameters = []            }            dx.additionalParameters += <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'--multi-dex'</span>            // 设置multidex.keep文件中class为第一个dex文件中包含的class，如果没有下一项设置此项无作用            dx.additionalParameters += <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"--main-dex-list=$projectDir/multidex.keep"</span>.toString()            //此项添加后第一个classes.dex文件只能包含-main-dex-list列表中class              dx.additionalParameters += <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'--minimal-main-dex'</span>        }    }dependencies {  compile <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'com.android.support:multidex:1.0.0'</span>}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li></ul>

主要是三点： 
1、multiDexEnabled置为true 
2、引入compile ‘com.android.support:multidex:1.0.0’，这个主要是为了加载dex使用，因为应用默认只会加载主dex，所以其他的dex需要我们自己来加载。 
3、分包

另外分包之后，应用只会加载主dex文件，其他dex需要我们自己加载，具体可以看看文章： MultiDex与热修复实现原理 ，其实用的就是com.android.support:multidex:1.0.0这个包。

dex拆分步骤分为：

1）自动扫描整个工程代码得到main-dex-list； 
2）根据main-dex-list对整个工程编译后的所有class进行拆分，将主、从dex的class文件分开； 
3）用dx工具对主、从dex的class文件分别打包成 .dex文件，并放在apk的合适目录。

怎么得到 main-dex-list？

Android SDK 从 build tools 21 开始提供了 mainDexClasses 脚本来生成主 dex 的文件列表。

<code class="hljs xml has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">mainDexClasses [--output <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">output</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">file</span>></span>] <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">application</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">path</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

1）调用 proguard 的 shrink 操作来生成一个临时 jar 包； 
2）将生成的临时 jar 包和输入的文件集合作为参数，然后调用com.android.multidex.MainDexListBuilder 来生成主 dex 文件列表。

在 shrink 这一步，proguard 会根据 mainDexClasses.rules 规则保留需要的类和类成员，并丢弃不需要的类和类成员。也就是说，上面 shrink 步骤生成的临时 jar 包里面保留了符合 mainDexClasses.rules 规则的类，这些类是需要放在主 dex 中的入口类。

mainDexClasses.rules如下，它也在 build tools 21 目录下：

<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">  -keep <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">android</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">app</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Instrumentation</span> {</span>    <init>();  }  -keep <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">android</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">app</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Application</span> {</span>    <init>();    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> attachBaseContext(android.content.Context);  }  -keep <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">android</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">app</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Activity</span> {</span>    <init>();  }  -keep <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">android</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">app</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Service</span> {</span>    <init>();  }  -keep <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">android</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">content</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">ContentProvider</span> {</span>   <init>();  }  -keep <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">android</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">content</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">BroadcastReceiver</span> {</span>   <init>();  }  -keep <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">android</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">app</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">backup</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">BackupAgent</span> {</span>   <init>();  }   -keep <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> * <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">java</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">lang</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">annotation</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Annotation</span> {</span>   *;  } </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li></ul>

但是仅有这些入口类放在主 dex 还不够，还要找出入口类直接引用的其他类，不然仍然会在启动时出现 NoClassDefFoundError。

参考文章： 
dex分包变形记

美团Android DEX自动拆包及动态加载简介

Android拆分与加载Dex的多种方案对比

Android分包原理

Android关于Dex拆分(MultiDex)技术详解