本文共 23264 字,大约阅读时间需要 77 分钟。
热修复是什么
答:
热修复无疑是这2年较火的新技术,是作为安卓工程师必学的技能之一。在热修复出现之前,一个已经上线的app中如果出现了bug,即使是一个非常小的bug,不及时更新的话有可能存在风险,若要及时更新就得将app重新打包发布到应用市场后,让用户再一次下载,这样就大大降低了用户体验,当热修复出现之后,这样的问题就不再是问题了。
目前较火的热修复方案大致分为两派,分别是:
- 阿里系:spohix、andfix:从底层二进制入手(c语言)。
- 腾讯系:tinker:从java加载机制入手。
有接触过tinker吗
答: 有接触过Tinker的 Tinker是一个比较优异修复架构
修复的原理是什么
答: 关于bug的概念自己百度百科吧,我认为的bug一般有2种(可能不太准确):
- 代码功能不符合项目预期,即代码逻辑有问题。
- 程序代码不够健壮导致App运行时崩溃。
这两种情况一般是一个或多个class出现了问题,在一个理想的状态下,我们只需将修复好的这些个class更新到用户手机上的app中就可以修复这些bug了。但说着简单,要怎么才能动态更新这些class呢?其实,不管是哪种热修复方案,肯定是如下几个步骤:
- 下发补丁(内含修复好的class)到用户手机,即让app从服务器上下载(网络传输)
- app通过**"某种方式"**,使补丁中的class被app调用(本地更新)
这里的**"某种方式"**,对本篇而言,就是使用Android的类加载器,通过类加载器加载这些修复好的class,覆盖对应有问题的class,理论上就能修复bug了。所以,下面就先来了解和分析Android中的类加载器吧。
直接从github上clone Tinker的源码进行食用如下:
build.gradle
加入buildscript { dependencies { classpath ('com.tencent.tinker:tinker-patch-gradle-plugin:1.8.1') }}
在app工程中build.gradle
加入
dependencies { //可选,用于生成application类 provided('com.tencent.tinker:tinker-android-anno:1.8.1') //tinker的核心库 compile('com.tencent.tinker:tinker-android-lib:1.8.1') }......//apply tinker插件apply plugin: 'com.tencent.tinker.patch'
这里需要注意tinker编译阶段会判断一个TinkerId
的字段,该字段默认由git提交记录生成HEAD(git rev-parse --short HEAD
)而且是在rootproject中执行的git命令,所以个别工程可能在rootproject目录没有git init过,可以选择在那初始化git或者自定义gradle修改gitSha
方法。
出包还是使用正常的build过程,测试阶段选择assembleDebug
,Tinker产出patch使用gradle tinkerPatchDebug
同样也支持Flavor和Variant,Tiner会在主工程build
目录下创建bakApk,下面会有一个app-yydd-hh-mm-ss
的目录里面对应有Favor子目录里面包含了通过assemble
出的apk包。在build
目录下的outputs
中有tinkerPatch
里面同样也区分了build variant
产物。
需要注意的是在debug出包测试过程中需要修改gradle的参数
ext { //for some reason, you may want to ignore tinkerBuild, such as instant run debug build? tinkerEnabled = true //for normal build //old apk file to build patch apk tinkerOldApkPath = "${bakPath}/app-debug-1018-17-58-54.apk" //proguard mapping file to build patch apk tinkerApplyMappingPath = "${bakPath}/app-debug-1018-17-32-47-mapping.txt" //resource R.txt to build patch apk, must input if there is resource changed tinkerApplyResourcePath = "${bakPath}/app-debug-1018-17-32-47-R.txt" //使用buildvariants修改此处app信息作为基准包 tinkerBuildFlavorDirectory = "${bakPath}/app-1020-11-52-37"}
而release
出包可以直接在gradle命令带上后缀-POLD_APK= -PAPPLY_MAPPING= -PAPPLY_RESOURCE=
Tinker采用了代码框架的方案来解决应用启动加载默认Application导致patch无法修复它。原理就是使用一个ApplicationLike
代理类来完成原Application的功能,把所有原理Application中的代码逻辑移动到ApplicationLike
中,然后删除原来的Application类通过注解让Tinker自动生成默认Application。
@DefaultLifeCycle(application = "com.*.Application", flags = ShareConstants.TINKER_ENABLE_ALL, loadVerifyFlag = false)public class ApplicationLike extends DefaultApplicationLike { @Override public void onBaseContextAttached(Context base) { super.onBaseContextAttached(base); //you must install multiDex whatever tinker is installed! MultiDex.install(base); TinkerManager.setTinkerApplicationLike(this); TinkerManager.initFastCrashProtect(); //should set before tinker is installed TinkerManager.setUpgradeRetryEnable(true); //installTinker after load multiDex //or you can put com.tencent.tinker.** to main dex TinkerManager.installTinker(this); } }
TinkerManager.java
public static void installTinker(ApplicationLike appLike) { if (isInstalled) { TinkerLog.w(TAG, "install tinker, but has installed, ignore"); return; } //or you can just use DefaultLoadReporter LoadReporter loadReporter = new TinkerLoadReporter(appLike.getApplication()); //or you can just use DefaultPatchReporter PatchReporter patchReporter = new TinkerPatchReporter(appLike.getApplication()); //or you can just use DefaultPatchListener PatchListener patchListener = new TinkerPatchListener(appLike.getApplication()); //you can set your own upgrade patch if you need AbstractPatch upgradePatchProcessor = new UpgradePatch(); TinkerInstaller.install(appLike, loadReporter, patchReporter, patchListener, TinkerResultService.class, upgradePatchProcessor); isInstalled = true; }
其中参数application
代表自动生成的application包名路径,flags
代表tinker作用域包括res、so、dex,loadVerifyFlag
代表是否开启加载patch前各个文件进行md5校验,还有一个loaderClass
默认是"com.tencent.tinker.loader.TinkerLoader"
表示加载Tinker的主类名。
在onBaseContextAttached
方法里需要初始化一些Tinker相关回调(在installTinker
方法中)PatchReporter
是对patch进程中合成过程的回调接口实现,LoadReporter
是对主进程加载patch dex补丁过程的回调接口实现。PatchListener
可以对接收到patch补丁后做自定义的check操作比如渠道检查和存储空间检查。
设置AbstractResultService
的实现类TinkerResultService
作为合成补丁完成后的处理重启逻辑的IntentService。
设置AbstractPatch
的实现类UpgradePatch
类作为合成patch方法tryPatch
实现类。
先上github官方首页的图
BaseApk就是我们的基准包,也就是渠道上线的包。
NewApk就是我们的hotfix包,包括修复的代码资源以及so文件。
Tinker做了对应的DexDiff、ResDiff、BsDiff来产出一个patch.apk,里面具体内容也是由lib、res和dex文件组成,assets中还有对应的dex、res和so信息
然后Tinker通过找到基准包data/app/packagename/base.apk通过DexPatch合成新的dex,并且合成一个tinker_classN.apk
(其实就是包含了所有合成dex的zip包)接着在运行时通过反射把这个合成dex文件插入到PathClassLoader
中的dexElements
数组的前面,保证类加载时优先加载补丁dex中的class。
接下来我们就从加载patch和合成patch来弄清Tinker的整个工作流程。
默认情况如果使用了Tinker注解产生Application
可以看到它继承了TinkerApplication
/** * * Generated application for tinker life cycle * */public class Application extends TinkerApplication { public Application() { super(7, "com.jiuyan.infashion.ApplicationLike", "com.tencent.tinker.loader.TinkerLoader", false); }}
跟踪到TinkerApplication
在方法attachBaseContext
中找到最终会调用loadTinker
方法来,最后反射调用了变量loaderClassName
定义类中的tryLoad
方法,默认是com.tencent.tinker.loader.TinkerLoader
这个类中的tryLoad
方法。该方法调用tryLoadPatchFilesInternal
来执行相关代码逻辑。
private void tryLoadPatchFilesInternal(TinkerApplication app, Intent resultIntent) { //..省略一大段校验相关逻辑代码 //now we can load patch jar if (isEnabledForDex) { boolean loadTinkerJars = TinkerDexLoader.loadTinkerJars(app, patchVersionDirectory, oatDex, resultIntent, isSystemOTA); if (isSystemOTA) { // update fingerprint after load success patchInfo.fingerPrint = Build.FINGERPRINT; patchInfo.oatDir = loadTinkerJars ? ShareConstants.INTERPRET_DEX_OPTIMIZE_PATH : ShareConstants.DEFAULT_DEX_OPTIMIZE_PATH; // reset to false oatModeChanged = false; if (!SharePatchInfo.rewritePatchInfoFileWithLock(patchInfoFile, patchInfo, patchInfoLockFile)) { ShareIntentUtil.setIntentReturnCode(resultIntent, ShareConstants.ERROR_LOAD_PATCH_REWRITE_PATCH_INFO_FAIL); Log.w(TAG, "tryLoadPatchFiles:onReWritePatchInfoCorrupted"); return; } // update oat dir resultIntent.putExtra(ShareIntentUtil.INTENT_PATCH_OAT_DIR, patchInfo.oatDir); } if (!loadTinkerJars) { Log.w(TAG, "tryLoadPatchFiles:onPatchLoadDexesFail"); return; } } //now we can load patch resource if (isEnabledForResource) { boolean loadTinkerResources = TinkerResourceLoader.loadTinkerResources(app, patchVersionDirectory, resultIntent); if (!loadTinkerResources) { Log.w(TAG, "tryLoadPatchFiles:onPatchLoadResourcesFail"); return; } } // kill all other process if oat mode change if (oatModeChanged) { ShareTinkerInternals.killAllOtherProcess(app); Log.i(TAG, "tryLoadPatchFiles:oatModeChanged, try to kill all other process"); } //all is ok! ShareIntentUtil.setIntentReturnCode(resultIntent, ShareConstants.ERROR_LOAD_OK); Log.i(TAG, "tryLoadPatchFiles: load end, ok!"); return;}
这里省略了非常多的Tinker校验,一共有包括tinker自身enable属性以及md5和文件存在等相关检查。
先看加载dex部分,TinkerDexLoader.loadTinkerJars
传入四个参数,分别为application,patchVersionDirectory当前patch文件目录,oatDir当前patch的oat文件目录,intent,当前patch是否需要进行oat(由于系统OTA更新需要dex oat重新生成缓存)。
/** * Load tinker JARs and add them to * the Application ClassLoader. * * @param application The application. */@TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)public static boolean loadTinkerJars(final TinkerApplication application, String directory, String oatDir, Intent intentResult, boolean isSystemOTA) { if (loadDexList.isEmpty() && classNDexInfo.isEmpty()) { Log.w(TAG, "there is no dex to load"); return true; } PathClassLoader classLoader = (PathClassLoader) TinkerDexLoader.class.getClassLoader(); if (classLoader != null) { Log.i(TAG, "classloader: " + classLoader.toString()); } else { Log.e(TAG, "classloader is null"); ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_VERSION_DEX_CLASSLOADER_NULL); return false; } String dexPath = directory + "/" + DEX_PATH + "/"; ArrayListlegalFiles = new ArrayList<>(); for (ShareDexDiffPatchInfo info : loadDexList) { //for dalvik, ignore art support dex if (isJustArtSupportDex(info)) { continue; } String path = dexPath + info.realName; File file = new File(path); //...check md5 legalFiles.add(file); } //... verify merge classN.apk File optimizeDir = new File(directory + "/" + oatDir); if (isSystemOTA) { final boolean[] parallelOTAResult = {true}; final Throwable[] parallelOTAThrowable = new Throwable[1]; String targetISA; try { targetISA = ShareTinkerInternals.getCurrentInstructionSet(); } catch (Throwable throwable) { Log.i(TAG, "getCurrentInstructionSet fail:" + throwable);// try {// targetISA = ShareOatUtil.getOatFileInstructionSet(testOptDexFile);// } catch (Throwable throwable) { // don't ota on the front deleteOutOfDateOATFile(directory); intentResult.putExtra(ShareIntentUtil.INTENT_PATCH_INTERPRET_EXCEPTION, throwable); ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_GET_OTA_INSTRUCTION_SET_EXCEPTION); return false;// } } deleteOutOfDateOATFile(directory); Log.w(TAG, "systemOTA, try parallel oat dexes, targetISA:" + targetISA); // change dir optimizeDir = new File(directory + "/" + INTERPRET_DEX_OPTIMIZE_PATH); TinkerDexOptimizer.optimizeAll( legalFiles, optimizeDir, true, targetISA, new TinkerDexOptimizer.ResultCallback() { //... callback } ); if (!parallelOTAResult[0]) { Log.e(TAG, "parallel oat dexes failed"); intentResult.putExtra(ShareIntentUtil.INTENT_PATCH_INTERPRET_EXCEPTION, parallelOTAThrowable[0]); ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_OTA_INTERPRET_ONLY_EXCEPTION); return false; } } try { SystemClassLoaderAdder.installDexes(application, classLoader, optimizeDir, legalFiles); } catch (Throwable e) { Log.e(TAG, "install dexes failed");// e.printStackTrace(); intentResult.putExtra(ShareIntentUtil.INTENT_PATCH_EXCEPTION, e); ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_VERSION_DEX_LOAD_EXCEPTION); return false; } return true;}
省略了几处md5校验代码,首先获取到PathClassLoader
并且通过判断系统是否art过滤出对应legalFiles
,如果发现系统进行过OTA升级则通过ProcessBuilder
命令行执行dex2oat
进行并行的oat优化dex,最后调用installDexes
来安装dex。
@SuppressLint("NewApi")public static void installDexes(Application application, PathClassLoader loader, File dexOptDir, Listfiles) throws Throwable { Log.i(TAG, "installDexes dexOptDir: " + dexOptDir.getAbsolutePath() + ", dex size:" + files.size()); if (!files.isEmpty()) { files = createSortedAdditionalPathEntries(files); ClassLoader classLoader = loader; if (Build.VERSION.SDK_INT >= 24 && !checkIsProtectedApp(files)) { classLoader = AndroidNClassLoader.inject(loader, application); } //because in dalvik, if inner class is not the same classloader with it wrapper class. //it won't fail at dex2opt if (Build.VERSION.SDK_INT >= 23) { V23.install(classLoader, files, dexOptDir); } else if (Build.VERSION.SDK_INT >= 19) { V19.install(classLoader, files, dexOptDir); } else if (Build.VERSION.SDK_INT >= 14) { V14.install(classLoader, files, dexOptDir); } else { V4.install(classLoader, files, dexOptDir); } //install done sPatchDexCount = files.size(); Log.i(TAG, "after loaded classloader: " + classLoader + ", dex size:" + sPatchDexCount); if (!checkDexInstall(classLoader)) { //reset patch dex SystemClassLoaderAdder.uninstallPatchDex(classLoader); throw new TinkerRuntimeException(ShareConstants.CHECK_DEX_INSTALL_FAIL); } }}
针对不同的Android版本需要对DexPathList
中的dexElements
生成方法makeDexElements
进行适配。
主要做的事情就是获取当前app运行时PathClassLoader
的父类BaseDexClassLoader
中的pathList
对象,通过反射它的makePathElements
方法传入对应的path参数构造出Element[]
数组对象,然后拿到pathList
中的Element[]
数组对象dexElements
两者进行合并排序,把patch的相关dex信息放在数组前端,最后合并数组结果赋值给pathList
保证classloader优先到patch中查找加载。
合并代码入口
Tinker.with(context).getPatchListener().onPatchReceived(patchLocation);
传入patch文件所在位置即可,推荐通过服务端下发下载到对应的/data/data/
应用目录下防止被三方软件清理,onPatchReceived
方法在DefaultPatchListener.java
中。
@Overridepublic int onPatchReceived(String path) { File patchFile = new File(path); int returnCode = patchCheck(path, SharePatchFileUtil.getMD5(patchFile)); if (returnCode == ShareConstants.ERROR_PATCH_OK) { TinkerPatchService.runPatchService(context, path); } else { Tinker.with(context).getLoadReporter().onLoadPatchListenerReceiveFail(new File(path), returnCode); } return returnCode;}
先进行tinker的一些初始化配置检查还有patch文件的md5校验。如果check通过returnCode
为0则执行runPatchService
启动一个IntentService
的子类TinkerPatchService
来处理patch的合成。接下来看Service执行任务代码:
@Overrideprotected void onHandleIntent(Intent intent) { final Context context = getApplicationContext(); Tinker tinker = Tinker.with(context); tinker.getPatchReporter().onPatchServiceStart(intent); if (intent == null) { TinkerLog.e(TAG, "TinkerPatchService received a null intent, ignoring."); return; } String path = getPatchPathExtra(intent); if (path == null) { TinkerLog.e(TAG, "TinkerPatchService can't get the path extra, ignoring."); return; } File patchFile = new File(path); long begin = SystemClock.elapsedRealtime(); boolean result; long cost; Throwable e = null; increasingPriority(); PatchResult patchResult = new PatchResult(); try { if (upgradePatchProcessor == null) { throw new TinkerRuntimeException("upgradePatchProcessor is null."); } result = upgradePatchProcessor.tryPatch(context, path, patchResult); } catch (Throwable throwable) { e = throwable; result = false; tinker.getPatchReporter().onPatchException(patchFile, e); } cost = SystemClock.elapsedRealtime() - begin; tinker.getPatchReporter(). onPatchResult(patchFile, result, cost); patchResult.isSuccess = result; patchResult.rawPatchFilePath = path; patchResult.costTime = cost; patchResult.e = e; AbstractResultService.runResultService(context, patchResult, getPatchResultExtra(intent));}
回调PatchReporter
接口的onPatchServiceStart
方法,然后取到patch文件同时调用increasingPriority
启动一个不可见前台Service保活这个TinkerPatchService
,最后开始合成patchupgradePatchProcessor.tryPatch
。同样省略一些常规check代码:
@Overridepublic boolean tryPatch(Context context, String tempPatchPath, PatchResult patchResult) { Tinker manager = Tinker.with(context); final File patchFile = new File(tempPatchPath); //...省略 //check ok, we can real recover a new patch final String patchDirectory = manager.getPatchDirectory().getAbsolutePath(); File patchInfoLockFile = SharePatchFileUtil.getPatchInfoLockFile(patchDirectory); File patchInfoFile = SharePatchFileUtil.getPatchInfoFile(patchDirectory); SharePatchInfo oldInfo = SharePatchInfo.readAndCheckPropertyWithLock(patchInfoFile, patchInfoLockFile); //it is a new patch, so we should not find a exist SharePatchInfo newInfo; //already have patch if (oldInfo != null) { if (oldInfo.oldVersion == null || oldInfo.newVersion == null || oldInfo.oatDir == null) { TinkerLog.e(TAG, "UpgradePatch tryPatch:onPatchInfoCorrupted"); manager.getPatchReporter().onPatchInfoCorrupted(patchFile, oldInfo.oldVersion, oldInfo.newVersion); return false; } if (!SharePatchFileUtil.checkIfMd5Valid(patchMd5)) { TinkerLog.e(TAG, "UpgradePatch tryPatch:onPatchVersionCheckFail md5 %s is valid", patchMd5); manager.getPatchReporter().onPatchVersionCheckFail(patchFile, oldInfo, patchMd5); return false; } // if it is interpret now, use changing flag to wait main process final String finalOatDir = oldInfo.oatDir.equals(ShareConstants.INTERPRET_DEX_OPTIMIZE_PATH) ? ShareConstants.CHANING_DEX_OPTIMIZE_PATH : oldInfo.oatDir; newInfo = new SharePatchInfo(oldInfo.oldVersion, patchMd5, Build.FINGERPRINT, finalOatDir); } else { newInfo = new SharePatchInfo("", patchMd5, Build.FINGERPRINT, ShareConstants.DEFAULT_DEX_OPTIMIZE_PATH); } //it is a new patch, we first delete if there is any files //don't delete dir for faster retry// SharePatchFileUtil.deleteDir(patchVersionDirectory); final String patchName = SharePatchFileUtil.getPatchVersionDirectory(patchMd5); final String patchVersionDirectory = patchDirectory + "/" + patchName; TinkerLog.i(TAG, "UpgradePatch tryPatch:patchVersionDirectory:%s", patchVersionDirectory); //copy file File destPatchFile = new File(patchVersionDirectory + "/" + SharePatchFileUtil.getPatchVersionFile(patchMd5)); //...省略 if (!DexDiffPatchInternal.tryRecoverDexFiles(manager, signatureCheck, context, patchVersionDirectory, destPatchFile)) { TinkerLog.e(TAG, "UpgradePatch tryPatch:new patch recover, try patch dex failed"); return false; } if (!BsDiffPatchInternal.tryRecoverLibraryFiles(manager, signatureCheck, context, patchVersionDirectory, destPatchFile)) { TinkerLog.e(TAG, "UpgradePatch tryPatch:new patch recover, try patch library failed"); return false; } if (!ResDiffPatchInternal.tryRecoverResourceFiles(manager, signatureCheck, context, patchVersionDirectory, destPatchFile)) { TinkerLog.e(TAG, "UpgradePatch tryPatch:new patch recover, try patch resource failed"); return false; } //...省略}
1.检查是否有之前的patch信息oldInfo
,查看旧补丁是否正在执行oat过程,后续会等待主进程oat执行完毕。 2.拷贝new patch到app的data目录的tinker目录下,防止被三方软件删除。 3.分别判断执行tryRecoverDexFiles
合成dex,tryRecoverLibraryFiles
合成so以及tryRecoverResourceFiles
合成资源。
主要看下dex合成过程,这也是我们最关心的地方。
protected static boolean tryRecoverDexFiles(Tinker manager, ShareSecurityCheck checker, Context context, String patchVersionDirectory, File patchFile) { if (!manager.isEnabledForDex()) { TinkerLog.w(TAG, "patch recover, dex is not enabled"); return true; } String dexMeta = checker.getMetaContentMap().get(DEX_META_FILE); if (dexMeta == null) { TinkerLog.w(TAG, "patch recover, dex is not contained"); return true; } long begin = SystemClock.elapsedRealtime(); boolean result = patchDexExtractViaDexDiff(context, patchVersionDirectory, dexMeta, patchFile); long cost = SystemClock.elapsedRealtime() - begin; TinkerLog.i(TAG, "recover dex result:%b, cost:%d", result, cost); return result;}
读取patch包assets/dex_meta.txt
信息转换成String
,进入patchDexExtractViaDexDiff
方法。
private static boolean patchDexExtractViaDexDiff(Context context, String patchVersionDirectory, String meta, final File patchFile) { String dir = patchVersionDirectory + "/" + DEX_PATH + "/"; if (!extractDexDiffInternals(context, dir, meta, patchFile, TYPE_DEX)) { TinkerLog.w(TAG, "patch recover, extractDiffInternals fail"); return false; } File dexFiles = new File(dir); File[] files = dexFiles.listFiles(); ListdexList = files != null ? Arrays.asList(files) : null; final String optimizeDexDirectory = patchVersionDirectory + "/" + DEX_OPTIMIZE_PATH + "/"; return dexOptimizeDexFiles(context, dexList, optimizeDexDirectory, patchFile);}
首先执行方法extractDexDiffInternals
传入了合成后dex
路径,前面读取的dex_meta
信息,patch文件以及type类型dex。为了节约篇幅只提取了主要的代码,详细代码参考github。
private static boolean extractDexDiffInternals(Context context, String dir, String meta, File patchFile, int type) { //parse patchList.clear(); ShareDexDiffPatchInfo.parseDexDiffPatchInfo(meta, patchList); //获取base.apk String apkPath = applicationInfo.sourceDir; apk = new ZipFile(apkPath); patch = new ZipFile(patchFile); for (ShareDexDiffPatchInfo info : patchList) { String patchRealPath; if (infoPath.equals("")) { patchRealPath = info.rawName; } else { patchRealPath = info.path + "/" + info.rawName; } File extractedFile = new File(dir + info.realName); //..省略 ZipEntry patchFileEntry = patch.getEntry(patchRealPath); ZipEntry rawApkFileEntry = apk.getEntry(patchRealPath); patchDexFile(apk, patch, rawApkFileEntry, patchFileEntry, info, extractedFile); } if (!mergeClassNDexFiles(context, patchFile, dir)) { return false; }}
1.解析dex_meta
内容
对应的
ShareDexDiffPatchInfo
信息
final String name = kv[0].trim();final String path = kv[1].trim();final String destMd5InDvm = kv[2].trim();final String destMd5InArt = kv[3].trim();final String dexDiffMd5 = kv[4].trim();final String oldDexCrc = kv[5].trim();final String newDexCrc = kv[6].trim();final String dexMode = kv[7].trim();
2.循环遍历获取到patch中各个classes.dex的crc和md5信息以及一大片校验代码,调用patchDexFile
方法对base.apk和patch中的dex做合并生成新的dex。
3.把合成的dex压缩为一个tinker_classN.apk
接下来看patchDexFile
方法,同样只提取了关键代码。
private static void patchDexFile( ZipFile baseApk, ZipFile patchPkg, ZipEntry oldDexEntry, ZipEntry patchFileEntry, ShareDexDiffPatchInfo patchInfo, File patchedDexFile) throws IOException { InputStream oldDexStream = null; InputStream patchFileStream = null; oldDexStream = new BufferedInputStream(baseApk.getInputStream(oldDexEntry)); patchFileStream = (patchFileEntry != null ? new BufferedInputStream(patchPkg.getInputStream(patchFileEntry)) : null); //...省略判断dex是否是jar类型或者是raw类型,做不同处理 new DexPatchApplier(oldDexStream, patchFileStream).executeAndSaveTo(patchedDexFile); }
下面是github官网上对raw和jar区别的解释
Tinker中的dex配置'raw'与'jar'模式应该如何选择? 它们应该说各有优劣势,大概应该有以下几条原则: 如果你的minSdkVersion小于14, 那你务必要选择'jar'模式; 以一个10M的dex为例,它压缩成jar大约为4M,即'jar'模式能节省6M的ROM空间。 对于'jar'模式,我们需要验证压缩包流中dex的md5,这会更耗时,在小米2S上数据大约为'raw'模式126ms, 'jar'模式为246ms。 因为在合成过程中我们已经校验了各个文件的Md5,并将它们存放在/data/data/..目录中。默认每次加载时我们并不会去校验tinker文件的Md5,但是你也可通过开启loadVerifyFlag强制每次加载时校验,但是这会带来一定的时间损耗。 简单来说,'jar'模式更省空间,但是运行时校验的耗时大约为'raw'模式的两倍。如果你没有打开运行时校验,推荐使用'jar'模式。
最后通过ZipFile拿到base.apk和patch中对应dex文件进行合成为patchedDexFile
。核心部分是如何把差分的dex和基准dex做合成处理产生新的dex,这部分涉及到了dex文件结构、DexDiff和DexPatch算法
扣扣扫码加入粉丝群,领取福利
转载地址:http://scocn.baihongyu.com/