Apktool源码解析——第二篇

上一篇讲到ApkDecoder这个类，大部分调用到还是Androlib类，而且上次发现brutall的代码竟然不是最新的，遂去找iBotP.的代码了。

今天来看Androlib的代码：

 　 private final AndrolibResources mAndRes = new AndrolibResources();

    protected final ResUnknownFiles mResUnknownFiles = new ResUnknownFiles();

    public ApkOptions apkOptions;


　　/**两个构造方法*/

    public Androlib(ApkOptions apkOptions) {

        this.apkOptions = apkOptions;

        mAndRes.apkOptions = apkOptions;

    }



    public Androlib() {//默认ApkOption

        this.apkOptions = new ApkOptions();

        mAndRes.apkOptions = this.apkOptions;

    }



    public ResTable getResTable(ExtFile apkFile)

            throws AndrolibException {

        return mAndRes.getResTable(apkFile, true);//终究还是去AndrolibRecources类里，所以下篇预告就是它了

    }



    public ResTable getResTable(ExtFile apkFile, boolean loadMainPkg)

            throws AndrolibException {

        return mAndRes.getResTable(apkFile, loadMainPkg);

    }

Androlib主要分为两类，一类是decodeXXX解码(反编译)方法，一类是buildXXX构建(回编译)方法。这里暂且不讲build方法，先看decode。

源文件的反编译有三个方法decodeSourceRow()、decodeSourceSmali()、decodeSourceJava()，decodeSourceRow()方法就直接把classes.dex文件拷贝的输出目录，decodeSourceSmali()方法是通过SmaliDecoder类去解码出smali文件，decodeSourceJava()方法就是调用AndrolibJava类解码java文件。

public void decodeSourcesRaw(ExtFile apkFile, File outDir, String filename)

            throws AndrolibException {

        try {

            LOGGER.info("Copying raw classes.dex file...");

            apkFile.getDirectory().copyToDir(outDir, filename);

        } catch (DirectoryException ex) {

            throw new AndrolibException(ex);

        }

    }



    public void decodeSourcesSmali(File apkFile, File outDir, String filename, boolean debug, String debugLinePrefix,

                                   boolean bakdeb, int api) throws AndrolibException {

        try {

            File smaliDir;

            if (filename.equalsIgnoreCase("classes.dex")) {

                smaliDir = new File(outDir, SMALI_DIRNAME);

            } else {

                smaliDir = new File(outDir, SMALI_DIRNAME + "_" + filename.substring(0, filename.indexOf(".")));

            }

            OS.rmdir(smaliDir);

            smaliDir.mkdirs();//创建smali目录

            LOGGER.info("Baksmaling " + filename + "...");

            SmaliDecoder.decode(apkFile, smaliDir, filename, debug, debugLinePrefix, bakdeb, api);//解析出smali

        } catch (BrutException ex) {

            throw new AndrolibException(ex);

        }

    }



    public void decodeSourcesJava(ExtFile apkFile, File outDir, boolean debug)

            throws AndrolibException {

        LOGGER.info("Decoding Java sources...");

        new AndrolibJava().decode(apkFile, outDir);//这个AndrolibJava().decode()方法不多，就一个输入文件和输出目录

}

XXXRow后缀的方法都是不解码直接拷贝，下面是对AndroidManifest.xml的反编译。

  public void decodeManifestRaw(ExtFile apkFile, File outDir)

            throws AndrolibException {

        try {

            Directory apk = apkFile.getDirectory();

            LOGGER.info("Copying raw manifest...");

            apkFile.getDirectory().copyToDir(outDir, APK_MANIFEST_FILENAMES);

        } catch (DirectoryException ex) {

            throw new AndrolibException(ex);

        }

    }



    public void decodeManifestFull(ExtFile apkFile, File outDir, ResTable resTable)

            throws AndrolibException {

        mAndRes.decodeManifest(resTable, apkFile, outDir);//这里有一个ResTable参数

    }

xml文件都是用AndrolibRecources去反编译的，下面看res的解码。

  public void decodeResourcesRaw(ExtFile apkFile, File outDir)

            throws AndrolibException {

        try {

            LOGGER.info("Copying raw resources...");

            apkFile.getDirectory().copyToDir(outDir, APK_RESOURCES_FILENAMES);

        } catch (DirectoryException ex) {

            throw new AndrolibException(ex);

        }

    }



    public void decodeResourcesFull(ExtFile apkFile, File outDir, ResTable resTable)

            throws AndrolibException {

        mAndRes.decode(resTable, apkFile, outDir);//这里发现AndrolibRecources的所有decode方法都要一个ResTable，资源表？

    }

接下来是lib目录和assets目录的反编译，其实这里就是直接拷贝输出。

 public void decodeRawFiles(ExtFile apkFile, File outDir)

            throws AndrolibException {

        LOGGER.info("Copying assets and libs...");

        try {

            Directory in = apkFile.getDirectory();

            if (in.containsDir("assets")) {

                in.copyToDir(outDir, "assets");

            }

            if (in.containsDir("lib")) {

                in.copyToDir(outDir, "lib");

            }

            if (in.containsDir("libs")) {

                in.copyToDir(outDir, "libs");

            }

        } catch (DirectoryException ex) {

            throw new AndrolibException(ex);

        }

    }

还有一个decodeUnknownFiles()方法，就是非apk内常见的文件。这里先列一下哪些是apk标准文件名：

private final static String[] APK_STANDARD_ALL_FILENAMES = new String[] {

            "classes.dex", "AndroidManifest.xml", "resources.arsc", "res", "lib", "libs", "assets", "META-INF" };

其他的都不是apk支持的文件，处理方法就是直接拷贝输出。

   private boolean isAPKFileNames(String file) {//判断apk包内文件是不是以上的常规文件

        for (String apkFile : APK_STANDARD_ALL_FILENAMES) {

            if (apkFile.equals(file) || file.startsWith(apkFile + "/")) {

                return true;

            }

        }

        return false;

    }



    public void decodeUnknownFiles(ExtFile apkFile, File outDir, ResTable resTable)

            throws AndrolibException {

        LOGGER.info("Copying unknown files...");

        File unknownOut = new File(outDir, UNK_DIRNAME);

        ZipEntry invZipFile;



        // have to use container of ZipFile to help identify compression type

        // with regular looping of apkFile for easy copy

        try {

            Directory unk = apkFile.getDirectory();

            ZipExtFile apkZipFile = new ZipExtFile(apkFile.getAbsolutePath());



            // loop all items in container recursively, ignoring any that are pre-defined by aapt

            Set<String> files = unk.getFiles(true);

            for (String file : files) {//取出apk内所有文件名

                if (!isAPKFileNames(file) && !file.endsWith(".dex")) {//不是常规文件也不是.dex文件



                    // copy file out of archive into special "unknown" folder

                    unk.copyToDir(unknownOut, file);//拷贝至unknown目录

                    try {

                        // ignore encryption

                        apkZipFile.getEntry(file).getGeneralPurposeBit().useEncryption(false);

                        invZipFile = apkZipFile.getEntry(file);



                        // lets record the name of the file, and its compression type

                        // so that we may re-include it the same way

                        if (invZipFile != null) {//这里把他们收集起来，如果需要回编译还可以原封不动的塞回去

                            mResUnknownFiles.addUnknownFileInfo(invZipFile.getName(), String.valueOf(invZipFile.getMethod()));

                        }

                    } catch (NullPointerException ignored) { }

                }

            }

            apkZipFile.close();

        } catch (DirectoryException | IOException ex) {

            throw new AndrolibException(ex);

        }

    }

最后一个writeOriginalFiles()方法，相比大家用过apktool的都知道反编译的目录里有个original目录，就是存放原始文件的目录。

 public void writeOriginalFiles(ExtFile apkFile, File outDir)

            throws AndrolibException {

        LOGGER.info("Copying original files...");

        File originalDir = new File(outDir, "original");//创建original目录

        if (!originalDir.exists()) {

            originalDir.mkdirs();

        }



        try {

            Directory in = apkFile.getDirectory();

            if(in.containsFile("AndroidManifest.xml")) {

                in.copyToDir(originalDir, "AndroidManifest.xml");

            }

            if (in.containsDir("META-INF")) {//证书文件是在original目录

                in.copyToDir(originalDir, "META-INF");

            }

        } catch (DirectoryException ex) {

            throw new AndrolibException(ex);

        }

    }

不过还有一个创建apktool.yml描述文件的方法。

 public void writeMetaFile(File mOutDir, Map<String, Object> meta)//键值对信息

            throws AndrolibException {

        DumperOptions options = new DumperOptions();

        options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);

        Yaml yaml = new Yaml(options);



        try (

                Writer writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(

                        new File(mOutDir, "apktool.yml")), "UTF-8"));//输出目录

        ) {

            yaml.dump(meta, writer);

        } catch (IOException ex) {

            throw new AndrolibException(ex);

        }

    }

好了，我们看一眼一个反编译实例的目录。

这下想必大家都了然于胸了，这里有几点要说的。签名证书是在original目录，另外original也有一份AndroidManifest.xml是没有解码的，打开是乱码的，最外层的那个才是解码后的。

还有unknown目录，可以打卡看一看可能会是其他库的rar文件，图片文件，数据文件之类的。最后看一眼apktool.tml:

version: 2.0.0-RC3



apkFileName: Baidu_Lebo_M01.apk



isFrameworkApk: false



usesFramework:

  

ids: - 1



sdkInfo:

  

minSdkVersion: '8'

  

targetSdkVersion: '11'



packageInfo:

  

forced-package-id: '127'



versionInfo:

  

versionCode: '16'

  

versionName: 2.0.1



compressionType: true



unknownFiles://前面都是meta键值对生成

  

com/baidu/music/lebo/logic/api/model/model.rar: '8'

com/handmark/pulltorefresh/library/logo.png: '8'

com/j256/ormlite/android/LICENSE.txt: '8'

com/j256/ormlite/android/README.txt: '8'

com/j256/ormlite/core/LICENSE.txt: '8'

com/j256/ormlite/core/README.txt: '8'

 

再回过头来看一下上篇讲到的ApkDecoder.decode()方法，思路就很清晰了。

1.首先创建输出目录

2.反编译资源文件，这里有几个判断，如果apk有recources.arsc文件就调用AndrolibRecources.decodeResourcesXXX()，如果没有资源文件有AndroidMenifest.xml文件，就直接调用AndrolibRecources.decodeManifestXXX()方法。由此可见，如果recources.arsc和AndroidMenifest.xml都有的话，应该都是在AndrolibRecources.decodeResources里解码的。

3.反编译源文件，这里也有两种情况，新版Android支持MultiDex(原来的有53566方法数限制)了也就意味着一个apk里可能不止classes.dex一个dex文件了，可能叫classes1.dex、classes2.dex(没去实践)。如果是有多个dex就循环调用decodeSourcesSmali、decodeSourcesJava、decodeSourcesRow这三个方法。

4.拷贝libs、assets目录文件和其他文件至输出目录。//mAndrolib.decodeRawFiles(mApkFile, outDir);mAndrolib.decodeUnknownFiles(mApkFile, outDir, mResTable);

5.输出原始文件original目录，这里只看对这两个文件的拷贝AndroidManifest.xml和META-INF目录。//mAndrolib.writeOriginalFiles(mApkFile, outDir);

ApkDecoder.decode()的代码就补贴了，上一篇应该贴过了，这里贴一下几个判断的代码，这样大家更容易明白。

   public boolean hasSources() throws AndrolibException {//判断有没有源文件的依据就是看apk压缩包内有没有classes.dex文件

        try {

            return mApkFile.getDirectory().containsFile("classes.dex");

        } catch (DirectoryException ex) {

            throw new AndrolibException(ex);

        }

    }



    public boolean hasMultipleSources() throws AndrolibException {//看有没有多个.dex文件

        try {

            Set<String> files = mApkFile.getDirectory().getFiles(true);

            for (String file : files) {

                if (file.endsWith(".dex")) {

                    if (! file.equalsIgnoreCase("classes.dex")) {

                        return true;

                    }

                }

            }



            return false;

        } catch (DirectoryException ex) {

            throw new AndrolibException(ex);

        }

    }



    public boolean hasManifest() throws AndrolibException {//有没有AndroidManifest.xml文件，这个必须要有啊

        try {

            return mApkFile.getDirectory().containsFile("AndroidManifest.xml");

        } catch (DirectoryException ex) {

            throw new AndrolibException(ex);

        }

    }



    public boolean hasResources() throws AndrolibException {//判断有没有资源文件resources.arsc

        try {

            return mApkFile.getDirectory().containsFile("resources.arsc");

        } catch (DirectoryException ex) {

            throw new AndrolibException(ex);

        }

    }