XPosed是与Cydia其名的工具，它能够让Android设备在没有修改源码的情况下修改系统中的API运行结果。我们通常称之为：God Mode（上帝模式）。
之前享大家分享了Xposed的基础，Xposed的作用和最简单的用法。那么，它的原理和它的内部构造是如何构成的？下面，我们从Github上看看，rovo89大神是如何制作的。
rovo89的github地址：https://github.com/rovo89
在主页上我们看到了，xposed其实主要是由三个项目来组成的，如下图所示；
三个分别是：
| 项目 | 说明 |
|---|---|
| Xposed | Xposed框架的native部分（主要是改性app_process二进制文件） |
| XposedInstaller | Xposed框架的Android端本地管理，环境架构搭建，以及第三方module资源下载的工具。 |
| XposedBridge | Xposed向开发者提供的API与相应的工具类库 |
XposedInstaller的构成
Xposed项目使我们最常用的项目，当然，他也是构造Xposed的核心部分。（也许你会说，其实是xposed项目更重要，它主要是替换app_process，ok我们后面再说它）。
如下图所示，是我们在XPosedInstaller apk中见到的，安装xposed框架的界面。
InstallerFragment我们能够在其中找到install方法，其中主要就是针对使用不同方式的将自定义的app_process文件替换掉系统的app_process文件。
<code class="hljs cs 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-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* xposed install
* @return 安装成功返回true，否则false
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> boolean <span class="hljs-title" style="box-sizing: border-box;">install</span>() {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 获取安装的方式，直接写入 or 使用 recovery进行安装</span>
final <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> installMode = getInstallMode();
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 检查获取Root权限</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!startShell())
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
List<String> messages = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> LinkedList<String>();
boolean showAlert = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.sdcard_location, XposedApp.getInstance().getExternalFilesDir(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>)));
messages.add(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>);
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_copying, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Xposed-Disabler-Recovery.zip"</span>));
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 把Xposed-Disabler-Recovery.zip文件 从asset copy到sdcard中</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (AssetUtil.writeAssetToSdcardFile(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Xposed-Disabler-Recovery.zip"</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00644</span>) == <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>) {
messages.add(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>);
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_extract_failed, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Xposed-Disabler-Recovery.zip"</span>));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
}
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 将编译后的app_process二进制文件，从asset文件夹中，copy到/data/data/de.robv.android.xposed.installer/bin/app_process下</span>
File appProcessFile = AssetUtil.writeAssetToFile(APP_PROCESS_NAME, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> File(XposedApp.BASE_DIR + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"bin/app_process"</span>), <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00700</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (appProcessFile == <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>) {
showAlert(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_extract_failed, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"app_process"</span>));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (installMode == INSTALL_MODE_NORMAL) {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 普通安装模式</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 重新挂载/system为rw模式</span>
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_mounting_writable, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/system"</span>));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mRootUtil.executeWithBusybox(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"mount -o remount,rw /system"</span>, messages) != <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_mount_writable_failed, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/system"</span>));
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_trying_to_continue));
}
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 查看原有的app_process文件是否已经备份，如果没有备份，现将原有的app_process文件备份一下</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> File(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/system/bin/app_process.orig"</span>).exists()) {
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_backup_already_exists, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/system/bin/app_process.orig"</span>));
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mRootUtil.executeWithBusybox(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"cp -a /system/bin/app_process /system/bin/app_process.orig"</span>, messages) != <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
messages.add(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>);
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_backup_failed, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/system/bin/app_process"</span>));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_backup_successful, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/system/bin/app_process.orig"</span>));
}
mRootUtil.executeWithBusybox(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"sync"</span>, messages);
}
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 将项目中的自定义app_process文件copy覆盖系统的app_process,修改权限</span>
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_copying, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"app_process"</span>));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mRootUtil.executeWithBusybox(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"cp -a "</span> + appProcessFile.getAbsolutePath() + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">" /system/bin/app_process"</span>, messages) != <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
messages.add(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>);
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_copy_failed, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"app_process"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/system/bin"</span>));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mRootUtil.executeWithBusybox(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"chmod 755 /system/bin/app_process"</span>, messages) != <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
messages.add(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>);
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_set_perms_failed, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/system/bin/app_process"</span>));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mRootUtil.executeWithBusybox(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"chown root:shell /system/bin/app_process"</span>, messages) != <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
messages.add(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>);
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_set_owner_failed, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/system/bin/app_process"</span>));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
}
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (installMode == INSTALL_MODE_RECOVERY_AUTO) {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 自动进入Recovery</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!prepareAutoFlash(messages, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Xposed-Installer-Recovery.zip"</span>))
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (installMode == INSTALL_MODE_RECOVERY_MANUAL) {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 手动进入Recovery</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!prepareManualFlash(messages, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Xposed-Installer-Recovery.zip"</span>))
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
}
File blocker = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> File(XposedApp.BASE_DIR + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"conf/disabled"</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (blocker.exists()) {
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_removing, blocker.getAbsolutePath()));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mRootUtil.executeWithBusybox(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"rm "</span> + blocker.getAbsolutePath(), messages) != <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
messages.add(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>);
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_remove_failed, blocker.getAbsolutePath()));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
}
}
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// copy XposedBridge.jar 到私有目录 XposedBridge.jar是Xposed提供的jar文件，负责在Native层与FrameWork层进行交互</span>
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_copying, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"XposedBridge.jar"</span>));
File jarFile = AssetUtil.writeAssetToFile(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"XposedBridge.jar"</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> File(JAR_PATH_NEWVERSION), <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">00644</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (jarFile == <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>) {
messages.add(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>);
messages.add(getString(R.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">string</span>.file_extract_failed, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"XposedBridge.jar"</span>));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
}
mRootUtil.executeWithBusybox(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"sync"</span>, messages);
showAlert = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
messages.add(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (installMode == INSTALL_MODE_NORMAL) {
offerReboot(messages);
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
offerRebootToRecovery(messages, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Xposed-Installer-Recovery.zip"</span>, installMode);
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">finally</span> {
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 删除busybox 工具库</span>
AssetUtil.removeBusybox();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (showAlert)
showAlert(TextUtils.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">join</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"\n"</span>, messages).trim());
}
}</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><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li><li style="box-sizing: border-box; padding: 0px 5px;">75</li><li style="box-sizing: border-box; padding: 0px 5px;">76</li><li style="box-sizing: border-box; padding: 0px 5px;">77</li><li style="box-sizing: border-box; padding: 0px 5px;">78</li><li style="box-sizing: border-box; padding: 0px 5px;">79</li><li style="box-sizing: border-box; padding: 0px 5px;">80</li><li style="box-sizing: border-box; padding: 0px 5px;">81</li><li style="box-sizing: border-box; padding: 0px 5px;">82</li><li style="box-sizing: border-box; padding: 0px 5px;">83</li><li style="box-sizing: border-box; padding: 0px 5px;">84</li><li style="box-sizing: border-box; padding: 0px 5px;">85</li><li style="box-sizing: border-box; padding: 0px 5px;">86</li><li style="box-sizing: border-box; padding: 0px 5px;">87</li><li style="box-sizing: border-box; padding: 0px 5px;">88</li><li style="box-sizing: border-box; padding: 0px 5px;">89</li><li style="box-sizing: border-box; padding: 0px 5px;">90</li><li style="box-sizing: border-box; padding: 0px 5px;">91</li><li style="box-sizing: border-box; padding: 0px 5px;">92</li><li style="box-sizing: border-box; padding: 0px 5px;">93</li><li style="box-sizing: border-box; padding: 0px 5px;">94</li><li style="box-sizing: border-box; padding: 0px 5px;">95</li><li style="box-sizing: border-box; padding: 0px 5px;">96</li><li style="box-sizing: border-box; padding: 0px 5px;">97</li><li style="box-sizing: border-box; padding: 0px 5px;">98</li><li style="box-sizing: border-box; padding: 0px 5px;">99</li><li style="box-sizing: border-box; padding: 0px 5px;">100</li><li style="box-sizing: border-box; padding: 0px 5px;">101</li><li style="box-sizing: border-box; padding: 0px 5px;">102</li><li style="box-sizing: border-box; padding: 0px 5px;">103</li><li style="box-sizing: border-box; padding: 0px 5px;">104</li><li style="box-sizing: border-box; padding: 0px 5px;">105</li><li style="box-sizing: border-box; padding: 0px 5px;">106</li><li style="box-sizing: border-box; padding: 0px 5px;">107</li><li style="box-sizing: border-box; padding: 0px 5px;">108</li><li style="box-sizing: border-box; padding: 0px 5px;">109</li><li style="box-sizing: border-box; padding: 0px 5px;">110</li><li style="box-sizing: border-box; padding: 0px 5px;">111</li><li style="box-sizing: border-box; padding: 0px 5px;">112</li><li style="box-sizing: border-box; padding: 0px 5px;">113</li><li style="box-sizing: border-box; padding: 0px 5px;">114</li><li style="box-sizing: border-box; padding: 0px 5px;">115</li><li style="box-sizing: border-box; padding: 0px 5px;">116</li><li style="box-sizing: border-box; padding: 0px 5px;">117</li><li style="box-sizing: border-box; padding: 0px 5px;">118</li><li style="box-sizing: border-box; padding: 0px 5px;">119</li><li style="box-sizing: border-box; padding: 0px 5px;">120</li><li style="box-sizing: border-box; padding: 0px 5px;">121</li><li style="box-sizing: border-box; padding: 0px 5px;">122</li><li style="box-sizing: border-box; padding: 0px 5px;">123</li><li style="box-sizing: border-box; padding: 0px 5px;">124</li><li style="box-sizing: border-box; padding: 0px 5px;">125</li><li style="box-sizing: border-box; padding: 0px 5px;">126</li></ul>
ok，我们看完了代码，发现所有的工作都是为了app_process文件的替换。那么，系统中这个app_process是做什么的？为什么我们需要替换？替换成什么样？替换后对于我们么来说有什么帮助呢？
Xposed原理
我们在android的源码中的init.rc文件可以看到
<code class="hljs livecodeserver 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;">service zygote /<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">system</span>/bin/app_process -Xzygote /<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">system</span>/bin –zygote –start-<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">system</span>-server <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">socket</span> zygote stream <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">666</span> onrestart <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">write</span> /sys/android_power/request_state wake onrestart <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">write</span> /sys/power/state <span class="hljs-command" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">on</span></span> onrestart restart media onrestart restart netd</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></ul>
app_process是andriod app的启动程序（具体形式是zygote fork()调用一个 app_process作为Android app的载体）
Xposed的实现方案
针对Hook的不同进程来说又可以分为全局Hook与单个应用程序进程Hook，我们知道在Android系统中，应用程序进程都是由Zygote进程孵化出来的，而Zygote进程是由Init进程启动的。
Zygote进程在启动时会创建一个Dalvik虚拟机实例，每当它孵化一个新的应用程序进程时，都会将这个Dalvik虚拟机实例复制到新的应用程序进程里面去，从而使得每一个应用程序进程都有一个独立的Dalvik虚拟机实例。所以如果选择对Zygote进程Hook，则能够达到针对系统上所有的应用程序进程Hook，即一个全局Hook。如下图所示：
/*