Xposed的新打开方式--Xpatch工作流程分析

1. Xpatch概述

Xpatch是一款利用重打包的方式，使得被处理的Apk启动时自动加载Xposed模块，来实现应用内Hook的工具。

项目地址：https://github.com/WindySha/Xpatch

2. Xpatch处理apk分析

Xpatch修改apk，主要有三个步骤，代码在MainCommand类的doCommandLine方法：

protected void doCommandLine() {
    ......
    if (!disableCrackSignature) {
        // save the apk original signature info, to support crach signature.
        new SaveApkSignatureTask(apkPath, unzipApkFilePath).run();
    }
    FileUtils.decompressZip(apkPath, unzipApkFilePath);
    ......
    // 1. modify the apk dex file to make xposed can run in it
    mXpatchTasks.add(new ApkModifyTask(showAllLogs, keepBuildFiles, unzipApkFilePath, applicationName,
            dexFileCount));

    // 2. copy xposed so and dex files into the unzipped apk
    mXpatchTasks.add(new SoAndDexCopyTask(dexFileCount, unzipApkFilePath, getXposedModules(xposedModules)));

    // 3. compress all files into an apk and then sign it.
    mXpatchTasks.add(new BuildAndSignApkTask(keepBuildFiles, unzipApkFilePath, output));
    ......
    for (Runnable executor : mXpatchTasks) {
        executor.run();
    }
    ......
}

(1) 第一步

在Xpatch的源码中，第一步对应的是ApkModifyTask类，实现的是Runnable接口，它的任务是修改Dex文件，使得被处理的apk在启动时能够执行指定的代码。

如果反编译被Xpatch处理过的Apk,查看App中Application的子类，会发现其中多了以下的代码：

static {
    XposedModuleEntry.init();
}

我们大胆的猜测，这就是Xpatch给注入进去的入口代码。我们回到Xpatch的源码，来看看它是如何注入的。查看ApkModifyTask类，一步步进行跟踪：

ApkModifyTask类的run方法，在任务被启动时调用,它的代码：

public void run() {
    ......
    String targetDexFileName = dumpJarFile(dexFileCount, unzipApkFilePath, jarOutputPath, applicationName);
    ......
}

dumpJarFile方法：

private String dumpJarFile(int dexFileCount, String dexFilePath, String jarOutputPath, String applicationName) {
    ......
    boolean isApplicationClassFound = dex2JarCmd(filePath, jarOutputPath, applicationName);
    ......
}

继续跟踪到dex2JarCmd方法：

private boolean dex2JarCmd(String dexPath, String jarOutputPath, String applicationName) {
    Dex2jarCmd cmd = new Dex2jarCmd();
    String[] args = new String[]{
            dexPath,
            "-o",
            jarOutputPath,
            "-app",
            applicationName,
            "--force"
    };
    cmd.doMain(args);

    boolean isApplicationClassFounded = cmd.isApplicationClassFounded();
    if (showAllLogs) {
        System.out.println("isApplicationClassFounded ->  " + isApplicationClassFounded + "the dexPath is  " +
                dexPath);
    }
    return isApplicationClassFounded;
}

看到了它创建了一个com.googlecode.dex2jar.tools.Dex2jarCmd类实例，这个类在名为dex-tools的外部库里，并调用了Dex2jarCmd的doMain方法，给他传进去一些类似于命令行参数的东西，令我们比较提得起精神的是-app参数，它传进去一个applicationName，这个applicationName的值来自MainCommand类的doCommandLine方法，逻辑是从解压的apk中读取AndroidManifest.xml,并读取application节点下的name属性的值，最后将值赋予applicatioName

protected void doCommandLine() {
    ......
    ManifestParser.Pair pair = ManifestParser.parseManifestFile(manifestFilePath);
    String applicationName;
    if (pair != null && pair.applicationName != null) {
        applicationName = pair.applicationName;
    } else {
        System.out.println(" Application name not found error !!!!!! ");
        applicationName = DEFAULT_APPLICATION_NAME;
    }
    ......
}

exm?就这样？并没有发现任何注入的代码啊，不急，继续跟踪，看到applicationName传进去了，一定能跟踪到有用的信息。接下来就是进入dex-tools外部库了，代码都是反编译出来的

com.googlecode.dex2jar.tools.BaseCmd的doMain方法：

public void doMain(String... args) {
    try {
        this.initOptions();
        this.parseSetArgs(args);
        this.doCommandLine();
    } catch (BaseCmd.HelpException var4) {
        String msg = var4.getMessage();
        if (msg != null && msg.length() > 0) {
            System.err.println("ERROR: " + msg);
        }
        this.usage();
    } catch (Exception var5) {
        var5.printStackTrace(System.err);
    }
}

主要看doCommandLine方法，doCommandLine是个抽象方法，它的真正实现是在Dex2jarCmd类里

protected void doCommandLine() throws Exception {
    ......
    for(var4 = 0; var4 < var3; ++var4) {
        ......
        BaseDexFileReader reader = MultiDexFileReader.open(Files.readAllBytes((new File(fileName)).toPath()));
        BaksmaliBaseDexExceptionHandler handler = this.notHandleException ? null : new BaksmaliBaseDexExceptionHandler();
        this.dex2jar = Dex2jar.from(reader);
        this.dex2jar.withExceptionHandler(handler)
        .reUseReg(this.reuseReg)
        .topoLogicalSort()
        .skipDebug(!this.debugInfo)
        .optimizeSynchronized(this.optmizeSynchronized)
        .printIR(this.printIR)
        .noCode(this.noCode)
        .skipExceptions(this.skipExceptions)
        .setApplicationName(this.applicationName)
        .to(file);
        ......
    }
}

跳转到com.googlecode.d2j.dex.Dex2jar类的to方法

public void to(Path file) throws IOException {
    if (Files.exists(file, new LinkOption[0]) && Files.isDirectory(file, new LinkOption[0])) {
        this.doTranslate(file);
    } else {
        FileSystem fs = createZip(file);
        Throwable var3 = null;

        try {
            this.doTranslate(fs.getPath("/"));
        } catch (Throwable var12) {
            var3 = var12;
            throw var12;
        } finally {
            if (fs != null) {
                if (var3 != null) {
                    try {
                        fs.close();
                    } catch (Throwable var11) {
                        var3.addSuppressed(var11);
                    }
                } else {
                    fs.close();
                }
            }

        }
    }

}

to方法调用doTranslate方法

private void doTranslate(final Path dist) throws IOException {

        ......
        (new ExDex2Asm(this.exceptionHandler) {
            public void convertCode(DexMethodNode methodNode, MethodVisitor mv) {
                if (methodNode.method.getOwner().equals(Dex2jar.this.applicationName) && methodNode.method.getName().equals("<clinit>")) {
                    Dex2jar.this.isApplicationClassFounded = true;
                    mv.visitMethodInsn(184, "com/wind/xposed/entry/XposedModuleEntry", "init", "()V", false);
                }

                if ((Dex2jar.this.readerConfig & 4) == 0 || !methodNode.method.getName().equals("<clinit>")) {
                    super.convertCode(methodNode, mv);
                }
            }

            public void addMethod(DexClassNode classNode, ClassVisitor cv) {
                if (classNode.className.equals(Dex2jar.this.applicationName)) {
                    Dex2jar.this.isApplicationClassFounded = true;
                    boolean hasFoundClinitMethod = false;
                    if (classNode.methods != null) {
                        Iterator var4 = classNode.methods.iterator();

                        while(var4.hasNext()) {
                            DexMethodNode methodNode = (DexMethodNode)var4.next();
                            if (methodNode.method.getName().equals("<clinit>")) {
                                hasFoundClinitMethod = true;
                                break;
                            }
                        }
                    }

                    if (!hasFoundClinitMethod) {
                        MethodVisitor mv = cv.visitMethod(8, "<clinit>", "()V", (String)null, (String[])null);
                        mv.visitCode();
                        mv.visitMethodInsn(184, "com/wind/xposed/entry/XposedModuleEntry", "init", "()V", false);
                        mv.visitInsn(177);
                        mv.visitMaxs(0, 0);
                        mv.visitEnd();
                    }
                }

            }

            ......
        }).convertDex(fileNode, cvf);
    }

doTranslate方法很长,但是我们很容易就能看到了很敏感的字符串：com/wind/xposed/entry/XposedModuleEntry，这就是Xpatch插入自己初始化的代码的地方。visitMethodInsn方法用于在函数内插入一条指令，看到两处调用visitMethodInsn来插入调用 com.wind.xposed.entry.XposedModuleEntry类的init方法的指令。

• convertCode函数中的visitMethodInsn，逻辑是如果要处理的Application类中存在clinit方法，即存在静态代码段，就直接插入调用 com.wind.xposed.entry.XposedModuleEntry类的init方法的指令
• addMethod函数中的visitMethodInsn，如果要处理的Application类中不存在clinit方法，即不存在静态代码段，就创建一个静态代码段，并在其中插入调用 com.wind.xposed.entry.XposedModuleEntry类的init方法的指令，最后返回void

注：上面的操作码，184代表invoke-static，177代表return-void。这些操作码定义在org.objectweb.asm.Opcodes类中。

到这里，第一步我们已经搞清楚了。

(2) 第二步

对应的是SoAndDexCopyTask类，从名字可以看出它的任务是复制so和dex的，具体是怎样的，我们看代码。

SoAndDexCopyTask类，它也实现了Runnable接口，run方法在任务被启动时调用：

@Override
public void run() {
    copySoFile();
    copyDexFile(dexFileCount);
    deleteMetaInfo();
}

这个类主要就做这三个动作：复制so文件，复制dex文件，删除Meta信息。

我们先看copySoFile代码：

private void copySoFile() {
    for (String libPath : APK_LIB_PATH_ARRAY) {
        String apkSoFullPath = fullLibPath(libPath);
        if(new File(apkSoFullPath).exists()) {
            copyLibFile(apkSoFullPath, SO_FILE_PATH_MAP.get(libPath));
        }
    }
    // copy xposed modules into the lib path
    if (xposedModuleArray != null && xposedModuleArray.length > 0) {
        int index = 0;
        for (String modulePath : xposedModuleArray) {
            modulePath = modulePath.trim();
            if (modulePath == null || modulePath.length() == 0) {
                continue;
            }
            File moduleFile = new File(modulePath);
            if (!moduleFile.exists()) {
                continue;
            }
            for (String libPath : APK_LIB_PATH_ARRAY) {
                String apkSoFullPath = fullLibPath(libPath);
                String outputModuleName= XPOSED_MODULE_FILE_NAME_PREFIX + index + SO_FILE_SUFFIX;
                if(new File(apkSoFullPath).exists()) {
                    File outputModuleSoFile = new File(apkSoFullPath, outputModuleName);
                    FileUtils.copyFile(moduleFile, outputModuleSoFile);
                }

            }
            index++;
        }
    }
}

看代码可以知道它的任务是把Xpatch.jar中assets目录下的libxpatch_wl.so复制到apk解压目录的lib/<架构文件夹>下。这个libxpatch_wl.so是whale框架提供so文件，为Hook提供可能。

除了复制so，如果我们在用Xpatch时使用-xm参数来将Xposed模块集成到apk中，那么模块会被就会被重命名成：以libxpatch_xp_module_为前缀，后面接着模块序号，最后再以so为后缀。最终这个模块被复制到apk的lib目录下。

copyDexFile方法：

private void copyDexFile(int dexFileCount) {
    String copiedDexFileName = "classes" + (dexFileCount + 1) + ".dex";
    FileUtils.copyFileFromJar("assets/classes.dex", unzipApkFilePath + copiedDexFileName);
}

逻辑也很明了，把assets下的classes.dex复制到apk解压目录下，根据原来apk中的dex个数来给复制进去的dex重命名。

deleteMetaInfo方法：

private void deleteMetaInfo() {
    String metaInfoFilePath = "META-INF";
    File metaInfoFileRoot = new File(unzipApkFilePath + metaInfoFilePath);
    if (!metaInfoFileRoot.exists()) {
        return;
    }
    File[] childFileList = metaInfoFileRoot.listFiles();
    if (childFileList == null || childFileList.length == 0) {
        return;
    }
    for (File file : childFileList) {
        String fileName = file.getName().toUpperCase();
        if (fileName.endsWith(".MF") || fileName.endsWith(".RAS") || fileName.endsWith(".SF")) {
            file.delete();
        }
    }
}

没什么好说的，就是删除<apk解压目录>/META-INF下的指定文件。

(3) 第三步

对应的是BuildAndSignApkTask类，从名字可以看出它的任务是构建和对apk签名的。

这个BuildAndSignApkTask类也是实现Runnable接口，我们来看run方法：

public void run() {
    ......
    FileUtils.compressToZip(unzipApkFilePath, unsignedApkPath);
    ......
    signApk(unsignedApkPath, keyStoreFilePath, signedApkPath, false);
    ......
}

这个方法做了两件重要的事，把apk解压目录给压缩成zip，并给压缩成的文件签名，这里就不细讲了。

3. 被集成进apk中的dex分析

我们在上面提到过，Xpatch把assets目录下的classes.dex文件复制进了目标apk里，这个dex是不开源的，那么这个dex里面究竟有什么呢，我们把dex解压出来，拖进jadx中反编译。

既然Xpatch将初始化代码注入到应用的Application类，初始化代码调用com.wind.xposed.entry.XposedModuleEntry类的init方法，那么我们从init方法开始看起。

public static void init() {
    if (b.compareAndSet(false, true)) {
        Context createAppContext = XpatchUtils.createAppContext();//1
        if (createAppContext == null) {
            Log.e(a, "try to init XposedModuleEntry, but create app context failed !!!!");
            return;
        }
        d = createAppContext;
        if (VERSION.SDK_INT > 21 && !FileUtils.isFilePermissionGranted(createAppContext)) {
            Log.e(a, "File permission is not granted, can not control xposed module by file ->xposed_config/modules.list");
        }
        XposedHelper.initSeLinux(createAppContext.getApplicationInfo().processName);
        SharedPrefUtils.init(createAppContext);
        ClassLoader classLoader = createAppContext.getClassLoader();
        b.a(createAppContext.getApplicationInfo(), classLoader);//2
        List<String> arrayList = new ArrayList();
        List<String> a = a(createAppContext);//3
        a(createAppContext, (List) arrayList);//4
        if (a.size() > 0) {
            String a2;
            String a3;
            List list = null;
            for (String a32 : arrayList) {
                if (list == null) {
                    list = new ArrayList();
                }
                a2 = a(createAppContext, a32);
                String str = a;
                StringBuilder stringBuilder = new StringBuilder("Current packed module path ----> ");
                stringBuilder.append(a32);
                stringBuilder.append(" packageName = ");
                stringBuilder.append(a2);
                XLog.d(str, stringBuilder.toString());
                list.add(a2);
            }
            if (list == null || list.size() == 0) {
                arrayList.addAll(a);
            } else {
                for (String str2 : a) {
                    a32 = a(createAppContext, str2);
                    a2 = a;
                    StringBuilder stringBuilder2 = new StringBuilder("Current installed module path ----> ");
                    stringBuilder2.append(str2);
                    stringBuilder2.append(" packageName = ");
                    stringBuilder2.append(a32);
                    XLog.d(a2, stringBuilder2.toString());
                    if (!list.contains(a32)) {
                        arrayList.add(str2);
                    }
                }
            }
        }
        for (String str3 : arrayList) {
            String absolutePath = createAppContext.getDir("xposed_plugin_dex", 0).getAbsolutePath();
            if (!TextUtils.isEmpty(str3)) {
                Log.d(a, "Current truely loaded module path ----> ".concat(String.valueOf(str3)));
                b.a(str3, absolutePath, createAppContext.getApplicationInfo(), classLoader);//5
            }
        }
    }
}

init方法代码比较多，上面标注释的地方是比较值得关注的，根据这些地方展开

注释1： 这里主要通过反射来创建Context,作为这么早执行的代码，作者也通过很巧妙的方式创建了Context，有了Context后，很多事就好办多了，XpatchUtils.createAppContext()的代码如下：

public static Context createAppContext() {
    try {
        Class cls = Class.forName("android.app.ActivityThread");
        Method declaredMethod = cls.getDeclaredMethod("currentActivityThread", new Class[0]);
        declaredMethod.setAccessible(true);
        Object invoke = declaredMethod.invoke(null, new Object[0]);
        Field declaredField = cls.getDeclaredField("mBoundApplication");
        declaredField.setAccessible(true);
        Object obj = declaredField.get(invoke);
        Field declaredField2 = obj.getClass().getDeclaredField("info");
        declaredField2.setAccessible(true);
        obj = declaredField2.get(obj);
        Method declaredMethod2 = Class.forName("android.app.ContextImpl").getDeclaredMethod("createAppContext", new Class[]{cls, obj.getClass()});
        declaredMethod2.setAccessible(true);
        Object invoke2 = declaredMethod2.invoke(null, new Object[]{invoke, obj});
        if (invoke2 instanceof Context) {
            return (Context) invoke2;
        }
    } catch (ClassNotFoundException | IllegalAccessException | NoSuchFieldException | NoSuchMethodException | InvocationTargetException e) {
        e.printStackTrace();
    }
    return null;
}

注释2：调用com.wind.xposed.entry.b类的a方法，并将当前App的ApplicationInfo和ClassLoader传过去，从这里开始就开始碰到XposedBridge的代码了

public static void a(ApplicationInfo applicationInfo, ClassLoader classLoader) {
    Wrapper wrapper = new Wrapper(a.a());
    CopyOnWriteSortedSet copyOnWriteSortedSet = new CopyOnWriteSortedSet();
    copyOnWriteSortedSet.add(wrapper);
    LoadPackageParam loadPackageParam = new LoadPackageParam(copyOnWriteSortedSet);
    loadPackageParam.packageName = applicationInfo.packageName;
    loadPackageParam.processName = applicationInfo.processName;
    loadPackageParam.classLoader = classLoader;
    loadPackageParam.appInfo = applicationInfo;
    loadPackageParam.isFirstApplication = true;
    XCallback.callAll(loadPackageParam);
}

方法第一行把a.a()传给了Wrapper的构造函数，a类完整类名是com.wind.xposed.entry.a，该类实现IXposedHookLoadPackage接口，a静态方法返回a类实例，那么Wrapper的构造函数得到的就是IXposedHookLoadPackage接口的类实例。接着Wrapper类实例被添加到一个CopyOnWriteSortedSet中，这个CopyOnWriteSortedSet类是一个操作Object数组的类，CopyOnWriteSortedSet被传到LoadPackageParam类的构造函数中，调用这个构造函数就是在给它父类（Param类）中的callbacks字段赋值。

public static abstract class Param {
    public final Object[] callbacks;
    ......
    protected Param(CopyOnWriteSortedSet<? extends XCallback> copyOnWriteSortedSet) {
        this.callbacks = copyOnWriteSortedSet.getSnapshot();
    }
    ......
}

接下来就是给LoadPackageParam的字段赋值，这些字段存储着当前应用包名，进程名，ApplicationInfo,ClassLoader等等信息。

在com.wind.xposed.entry.b.a(ApplicationInfo applicationInfo, ClassLoader classLoader)方法的最后，调用XCallback类的callAll方法

public static void callAll(Param param) {
    if (param.callbacks != null) {
        int i = 0;
        while (true) {
            Object[] objArr = param.callbacks;
            if (i < objArr.length) {
                try {
                    ((XCallback) objArr[i]).call(param);
                } catch (Throwable th) {
                    XposedBridge.log(th);
                }
                i++;
            } else {
                return;
            }
        }
    }
    ......
}

callAll方法遍历Param类中的所有callback，调用它们的call方法

public void call(Param param) {
    if (param instanceof LoadPackageParam) {
        handleLoadPackage((LoadPackageParam) param);
    }
}

饶了半天，就是调用传进Wrapper类构造函数的类的handleLoadPackage方法，那就是调用com.wind.xposed.entry.a类的handleLoadPackage方法，而com.wind.xposed.entry.a类的handleLoadPackage方法又去调用com.wind.xposed.entry.a.a类的handleLoadPackage方法，那我们去看com.wind.xposed.entry.a.a类的handleLoadPackage的实现

public final void handleLoadPackage(LoadPackageParam loadPackageParam) {
    Context a = XposedModuleEntry.a();
    String readTextFromAssets = FileUtils.readTextFromAssets(a, "xpatch_asset/original_signature_info.ini");
    Log.d("PackageSignatureHooker", "Get the original signature --> ".concat(String.valueOf(readTextFromAssets)));
    if (!(readTextFromAssets == null || readTextFromAssets.isEmpty())) {
        try {
            WhaleRuntime.reserved2();
            Class cls = Class.forName("android.app.ActivityThread");
            Object invoke = cls.getDeclaredMethod("currentActivityThread", new Class[0]).invoke(null, new Object[0]);
            Method declaredMethod = cls.getDeclaredMethod("getPackageManager", new Class[0]);
            declaredMethod.setAccessible(true);
            Object invoke2 = declaredMethod.invoke(invoke, new Object[0]);
            Object newProxyInstance = Proxy.newProxyInstance(Class.forName("android.content.pm.IPackageManager").getClassLoader(), new Class[]{r7}, new a(invoke2, loadPackageParam.packageName, readTextFromAssets));
            Field declaredField = cls.getDeclaredField("sPackageManager");
            declaredField.setAccessible(true);
            declaredField.set(invoke, newProxyInstance);
            PackageManager packageManager = a.getPackageManager();
            declaredField = packageManager.getClass().getDeclaredField("mPM");
            declaredField.setAccessible(true);
            declaredField.set(packageManager, newProxyInstance);
        } catch (Exception e) {
            Log.e("PackageSignatureHooker", " hookSignatureByProxy failed !!", e);
        }
    }
}

这个方法的作用是Hook相关的函数，将被处理的apk的签名替换成原来的，防止某些App检测到自己的Apk被修改。apk在被Xpatch处理之前，签名的信息的被保存了下来，对应的任务类是SaveApkSignatureTask，上文没有讲到，感兴趣可以去看一下。

注释3：调用本类中的a方法，这个方法的参数只有一个参数Context

private static List<String> a(Context context) {
    PackageManager packageManager = context.getPackageManager();
    ArrayList arrayList = new ArrayList();
    List a = a(true);
    final ArrayList arrayList2 = new ArrayList();
    boolean exists = new File(c, "xposed_config/modules.list").exists();
    for (PackageInfo packageInfo : packageManager.getInstalledPackages(128)) {
        ApplicationInfo applicationInfo = packageInfo.applicationInfo;
        if (applicationInfo.enabled) {
            Bundle bundle = applicationInfo.metaData;
            if (bundle != null && bundle.containsKey("xposedmodule")) {
                CharSequence charSequence = packageInfo.applicationInfo.publicSourceDir;
                String charSequence2 = context.getPackageManager().getApplicationLabel(packageInfo.applicationInfo).toString();
                if (TextUtils.isEmpty(charSequence)) {
                    charSequence = packageInfo.applicationInfo.sourceDir;
                }
                if (!TextUtils.isEmpty(charSequence) && (!exists || a == null || a.contains(applicationInfo.packageName))) {
                    XLog.d(a, " query installed module path -> ".concat(String.valueOf(charSequence)));
                    arrayList.add(charSequence);
                }
                arrayList2.add(Pair.create(packageInfo.applicationInfo.packageName, charSequence2));
            }
        }
    }
    new Thread(new Runnable() {
        public final void run() {
            List b = XposedModuleEntry.a(false);
            if (b == null) {
                b = new ArrayList();
            }
            List arrayList = new ArrayList();
            for (Pair pair : arrayList2) {
                if (!b.contains(pair.first)) {
                    XLog.d(XposedModuleEntry.a, " addPackageList packgagePair -> ".concat(String.valueOf(pair)));
                    arrayList.add(pair);
                }
            }
            XposedModuleEntry.a(arrayList);
        }
    }).start();
    return arrayList;
}

这个函数是读取设备中已安装的Apk,根据meta信息判断它们是否属于Xposed模块，如果是并且外部存储不存在xposed_config/modules.list把它们的安装位置添加到列表中。并且开启一个线程，如果xposed_config/modules.list存在则读取，xposed_config/modules.list文件记录着模块加载规则，具体可以去查看Xpatch项目的README。最后，将读取到的Xposed模块安装位置列表返回

注释4：调用本类中的a方法，这个方法的参数是一个Context和List

private static void a(Context context, List<String> list) {
    String str = context.getApplicationInfo().nativeLibraryDir;
    XLog.d(a, "Current loaded module libPath ----> ".concat(String.valueOf(str)));
    File file = new File(str);
    if (file.exists()) {
        File[] listFiles = file.listFiles();
        if (listFiles != null && listFiles.length > 0) {
            for (File file2 : listFiles) {
                if (file2.getName().startsWith("libxpatch_xp_module_")) {
                    XLog.d(a, "add xposed modules from libPath, this lib path is --> ".concat(String.valueOf(file2)));
                    list.add(file2.getAbsolutePath());
                }
            }
        }
    }
}

这个方法的目的是获取所有打包进apk中的Xposed模块的路径添加到传进来的List中

注释5：调用com.wind.xposed.entry.b类的a(String str, String str2, ApplicationInfo applicationInfo, ClassLoader classLoader)方法

public static int a(String str, String str2, ApplicationInfo applicationInfo, ClassLoader classLoader) {
        XLog.i("XposedModuleLoader", "Loading modules from ".concat(String.valueOf(str)));
        if (new File(str).exists()) {
            DexClassLoader dexClassLoader = new DexClassLoader(str, str2, null, classLoader);
            InputStream resourceAsStream = dexClassLoader.getResourceAsStream("assets/xposed_init");
            if (resourceAsStream == null) {
                Log.i("XposedModuleLoader", "assets/xposed_init not found in the APK");
                return 4;
            }
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(resourceAsStream));
            while (true) {
                try {
                    String readLine = bufferedReader.readLine();
                    if (readLine != null) {
                        readLine = readLine.trim();
                        if (!(readLine.isEmpty() || readLine.startsWith("#"))) {
                            try {
                                String str3;
                                XLog.i("XposedModuleLoader", "  Loading class ".concat(String.valueOf(readLine)));
                                Class loadClass = dexClassLoader.loadClass(readLine);
                                if (!XposedHelper.isIXposedMod(loadClass)) {
                                    readLine = "XposedModuleLoader";
                                    str3 = "    This class doesn't implement any sub-interface of IXposedMod, skipping it";
                                } else if (IXposedHookInitPackageResources.class.isAssignableFrom(loadClass)) {
                                    readLine = "XposedModuleLoader";
                                    str3 = "    This class requires resource-related hooks (which are disabled), skipping it.";
                                } else {
                                    Object newInstance = loadClass.newInstance();
                                    if (newInstance instanceof IXposedHookZygoteInit) {
                                        XposedHelper.callInitZygote(str, newInstance);
                                    }
                                    if (newInstance instanceof IXposedHookLoadPackage) {
                                        Wrapper wrapper = new Wrapper((IXposedHookLoadPackage) newInstance);
                                        CopyOnWriteSortedSet copyOnWriteSortedSet = new CopyOnWriteSortedSet();
                                        copyOnWriteSortedSet.add(wrapper);
                                        LoadPackageParam loadPackageParam = new LoadPackageParam(copyOnWriteSortedSet);
                                        loadPackageParam.packageName = applicationInfo.packageName;
                                        loadPackageParam.processName = applicationInfo.processName;
                                        loadPackageParam.classLoader = classLoader;
                                        loadPackageParam.appInfo = applicationInfo;
                                        loadPackageParam.isFirstApplication = true;
                                        XCallback.callAll(loadPackageParam);
                                    }
                                    try {
                                        resourceAsStream.close();
                                    } catch (IOException unused) {
                                    }
                                    return 8;
                                }
                                Log.i(readLine, str3);
                            } catch (Throwable th) {
                                Log.e("XposedModuleLoader", " error ", th);
                            }
                        }
                    }
                } catch (IOException e) {
                    Log.e("XposedModuleLoader", " error ", e);
                } catch (Throwable th2) {
                    try {
                        resourceAsStream.close();
                    } catch (IOException unused2) {
                    }
                }
                try {
                    resourceAsStream.close();
                } catch (IOException unused3) {
                }
                return 16;
            }
        }
        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append(str);
        stringBuilder.append(" does not exist");
        Log.e("XposedModuleLoader", stringBuilder.toString());
        return 2;
    }

这个函数读取传进来的Xposed模块的信息，获取DexClassLoader，读取模块assets下的xposed_init文件，得到其中的类名并根据实例类型（IXposedHookZygoteInit或者IXposedHookLoadPackage）分别实例化它，是IXposedHookZygoteInit实例就callInitZygote，是IXposedHookLoadPackage实例就像上面的注释2所讲的一样调用模块的handleLoadPackage方法。

讲到这里好像并没有涉及到whale框架，我们编写模块的时候，Hook的代码都是写在handleLoadPackage方法中，比如我们在handleLoadPackage方法内，写个findAndHookMethod，最终就会调用WhaleRuntime.hookMethodNative本地方法，来实现应用内的Hook

4. 总结

Xpatch思路很好，不需要ROOT，不用担心Xposed在某些设备上的兼容性，不用每次调试Xposed模块都重启手机，很方便的就可以使用Xposed模块，实现应用内的Hook。但是在使用的过程中也发现了一个小问题，要处理的Apk如果没有手动继承Application类并在AndroidManifest.xml中指定，那么Xpatch就注入不了代码，也就无法正常使用。本文也只讲了Xpatch的基本流程，具体whale是怎么Hook的，能力有限，没能展开。