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[操作系统]【原】Android热更新开源项目Tinker源码解析系列之二:资源文件热更新

上一篇文章介绍了Dex文件的热更新流程,本文将会分析Tinker中对资源文件的热更新流程。

同Dex,资源文件的热更新同样包括三个部分:资源补丁生成,资源补丁合成及资源补丁加载。

 

本系列将从以下三个方面对Tinker进行源码解析:

  1. Android热更新开源项目Tinker源码解析系列之一:Dex热更新
  2. Android热更新开源项目Tinker源码解析系列之二:资源热更新
  3. Android热更新开源项目Tinker源码解析系类之三:so热更新

 

转载请标明本文来源:http://www.cnblogs.com/yyangblog/p/6252490.html
更多内容欢迎star作者的github:https://github.com/LaurenceYang/article
如果发现本文有什么问题和任何建议,也随时欢迎交流~

 

一、资源补丁生成

ResDiffDecoder.patch(File oldFile, File newFile)主要负责资源文件补丁的生成。

如果是新增的资源,直接将资源文件拷贝到目标目录。

如果是修改的资源文件则使用dealWithModeFile函数处理。

 1 // 如果是新增的资源,直接将资源文件拷贝到目标目录. 2 if (oldFile == null || !oldFile.exists()) { 3   if (Utils.checkFileInPattern(config.mResIgnoreChangePattern, name)) { 4     Logger.e("found add resource: " + name + " ,but it match ignore change pattern, just ignore!"); 5     return false; 6   } 7   FileOperation.copyFileUsingStream(newFile, outputFile); 8   addedSet.add(name); 9   writeResLog(newFile, oldFile, TypedValue.ADD);10   return true;11 }12 ...13 // 新旧资源文件的md5一样,表示没有修改.14 if (oldMd5 != null && oldMd5.equals(newMd5)) {15   return false;16 }17 ...18 // 修改的资源文件使用dealWithModeFile函数处理.19 dealWithModeFile(name, newMd5, oldFile, newFile, outputFile);

dealWithModeFile会对文件大小进行判断,如果大于设定值(默认100Kb),采用bsdiff算法对新旧文件比较生成补丁包,从而降低补丁包的大小。

如果小于设定值,则直接将该文件加入修改列表,并直接将该文件拷贝到目标目录。

 1 if (checkLargeModFile(newFile)) { //大文件采用bsdiff算法 2   if (!outputFile.getParentFile().exists()) { 3     outputFile.getParentFile().mkdirs(); 4   } 5   BSDiff.bsdiff(oldFile, newFile, outputFile); 6   //treat it as normal modify 7   // 对生成的diff文件大小和newFile进行比较,只有在达到我们的压缩效果后才使用diff文件 8   if (Utils.checkBsDiffFileSize(outputFile, newFile)) { 9     LargeModeInfo largeModeInfo = new LargeModeInfo();10     largeModeInfo.path = newFile;11     largeModeInfo.crc = FileOperation.getFileCrc32(newFile);12     largeModeInfo.md5 = newMd5;13     largeModifiedSet.add(name);14     largeModifiedMap.put(name, largeModeInfo);15     writeResLog(newFile, oldFile, TypedValue.LARGE_MOD);16     return true;17   }18 }19 modifiedSet.add(name); // 加入修改列表20 FileOperation.copyFileUsingStream(newFile, outputFile);21 writeResLog(newFile, oldFile, TypedValue.MOD);22 return false;

BsDiff属于二进制比较,其具体实现大家可以自行百度。

ResDiffDecoder.onAllPatchesEnd()中会加入一个测试用的资源文件,放在assets目录下,用于在加载补丁时判断其是否加在成功。

这一步同时会向res_meta.txt文件中写入资源更改的信息。

 1 //加入一个测试用的资源文件 2 addAssetsFileForTestResource(); 3 ... 4 //first, write resource meta first 5 //use resources.arsc's base crc to identify base.apk 6 String arscBaseCrc = FileOperation.getZipEntryCrc(config.mOldApkFile, TypedValue.RES_ARSC); 7 String arscMd5 = FileOperation.getZipEntryMd5(extractToZip, TypedValue.RES_ARSC); 8 if (arscBaseCrc == null || arscMd5 == null) { 9   throw new TinkerPatchException("can't find resources.arsc's base crc or md5");10 }11 12 String resourceMeta = Utils.getResourceMeta(arscBaseCrc, arscMd5);13 writeMetaFile(resourceMeta);14 15 //pattern16 String patternMeta = TypedValue.PATTERN_TITLE;17 HashSet<String> patterns = new HashSet<>(config.mResRawPattern);18 //we will process them separate19 patterns.remove(TypedValue.RES_MANIFEST);20 21 writeMetaFile(patternMeta + patterns.size());22 //write pattern23 for (String item : patterns) {24   writeMetaFile(item);25 }26 //write meta file, write large modify first27 writeMetaFile(largeModifiedSet, TypedValue.LARGE_MOD);28 writeMetaFile(modifiedSet, TypedValue.MOD);29 writeMetaFile(addedSet, TypedValue.ADD);30 writeMetaFile(deletedSet, TypedValue.DEL);

最后的res_meta.txt文件的格式范例如下:

resources_out.zip,4019114434,6148149bd5ed4e0c2f5357c6e2c577d6pattern:4resources.arscr/*res/*assets/*modify:1r/g/ag.

到此,资源文件的补丁打包流程结束。

 

二、补丁下发成功后资源补丁的合成

ResDiffPatchInternal.tryRecoverResourceFiles会调用extractResourceDiffInternals进行补丁的合成。

合成过程比较简单,没有使用bsdiff生成的文件直接写入到resources.apk文件;

使用bsdiff生成的文件则采用bspatch算法合成资源文件,然后将合成文件写入resouces.apk文件。

最后,生成的resouces.apk文件会存放到/data/data/${package_name}/tinker/res对应的目录下。

 1 / 首先读取res_meta.txt的数据 2 ShareResPatchInfo.parseAllResPatchInfo(meta, resPatchInfo); 3 // 验证resPatchInfo的MD5是否合法 4 if (!SharePatchFileUtil.checkIfMd5Valid(resPatchInfo.resArscMd5)) { 5 ... 6 // resources.apk 7 File resOutput = new File(directory, ShareConstants.RES_NAME); 8  9 // 该函数里面会对largeMod的文件进行合成,合成的算法也是采用bsdiff10 if (!checkAndExtractResourceLargeFile(context, apkPath, directory, patchFile, resPatchInfo, type, isUpgradePatch)) {11 12 // 基于oldapk,合并补丁后将这些资源文件写入resources.apk文件中13 while (entries.hasMoreElements()) {14   TinkerZipEntry zipEntry = entries.nextElement();15   if (zipEntry == null) {16     throw new TinkerRuntimeException("zipEntry is null when get from oldApk");17   }18   String name = zipEntry.getName();19   if (ShareResPatchInfo.checkFileInPattern(resPatchInfo.patterns, name)) {20     //won't contain in add set.21     if (!resPatchInfo.deleteRes.contains(name)22       && !resPatchInfo.modRes.contains(name)23       && !resPatchInfo.largeModRes.contains(name)24       && !name.equals(ShareConstants.RES_MANIFEST)) {25       ResUtil.extractTinkerEntry(oldApk, zipEntry, out);26       totalEntryCount++;27     }28   }29 }30 31 //process manifest32 TinkerZipEntry manifestZipEntry = oldApk.getEntry(ShareConstants.RES_MANIFEST);33 if (manifestZipEntry == null) {34   TinkerLog.w(TAG, "manifest patch entry is null. path:" + ShareConstants.RES_MANIFEST);35   manager.getPatchReporter().onPatchTypeExtractFail(patchFile, resOutput, ShareConstants.RES_MANIFEST, type, isUpgradePatch);36   return false;37 }38 ResUtil.extractTinkerEntry(oldApk, manifestZipEntry, out);39 totalEntryCount++;40 41 for (String name : resPatchInfo.largeModRes) {42   TinkerZipEntry largeZipEntry = oldApk.getEntry(name);43   if (largeZipEntry == null) {44     TinkerLog.w(TAG, "large patch entry is null. path:" + name);45     manager.getPatchReporter().onPatchTypeExtractFail(patchFile, resOutput, name, type, isUpgradePatch);46     return false;47   }48   ShareResPatchInfo.LargeModeInfo largeModeInfo = resPatchInfo.largeModMap.get(name);49   ResUtil.extractLargeModifyFile(largeZipEntry, largeModeInfo.file, largeModeInfo.crc, out);50   totalEntryCount++;51 }52 53 for (String name : resPatchInfo.addRes) {54   TinkerZipEntry addZipEntry = newApk.getEntry(name);55   if (addZipEntry == null) {56     TinkerLog.w(TAG, "add patch entry is null. path:" + name);57     manager.getPatchReporter().onPatchTypeExtractFail(patchFile, resOutput, name, type, isUpgradePatch);58     return false;59   }60   ResUtil.extractTinkerEntry(newApk, addZipEntry, out);61   totalEntryCount++;62 }63 64 for (String name : resPatchInfo.modRes) {65   TinkerZipEntry modZipEntry = newApk.getEntry(name);66   if (modZipEntry == null) {67     TinkerLog.w(TAG, "mod patch entry is null. path:" + name);68     manager.getPatchReporter().onPatchTypeExtractFail(patchFile, resOutput, name, type, isUpgradePatch);69     return false;70   }71   ResUtil.extractTinkerEntry(newApk, modZipEntry, out);72   totalEntryCount++;73 }74 75 //最后对resouces.apk文件进行MD5检查,判断是否与resPatchInfo中的MD5一致76 boolean result = SharePatchFileUtil.checkResourceArscMd5(resOutput, resPatchInfo.resArscMd5);

到此,resources.apk文件生成完毕。

 

三、资源补丁加载

合成好的资源补丁存放在/data/data/${PackageName}/tinker/res/中,名为reosuces.apk。

资源补丁的加载的操作主要放在TinkerResourceLoader.loadTinkerResources函数中,同dex的加载时机一样,在app启动时会被调用。直接上源码,loadTinkerResources会调用monkeyPatchExistingResources执行实际的补丁加载。

 1 public static boolean loadTinkerResources(Context context, boolean tinkerLoadVerifyFlag, String directory, Intent intentResult) { 2   if (resPatchInfo == null || resPatchInfo.resArscMd5 == null) { 3     return true; 4   } 5   String resourceString = directory + "/" + RESOURCE_PATH + "/" + RESOURCE_FILE; 6   File resourceFile = new File(resourceString); 7   long start = System.currentTimeMillis(); 8  9   if (tinkerLoadVerifyFlag) {10     if (!SharePatchFileUtil.checkResourceArscMd5(resourceFile, resPatchInfo.resArscMd5)) {11       Log.e(TAG, "Failed to load resource file, path: " + resourceFile.getPath() + ", expect md5: " + resPatchInfo.resArscMd5);12       ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_VERSION_RESOURCE_MD5_MISMATCH);13       return false;14     }15     Log.i(TAG, "verify resource file:" + resourceFile.getPath() + " md5, use time: " + (System.currentTimeMillis() - start));16   }17   try {18     TinkerResourcePatcher.monkeyPatchExistingResources(context, resourceString);19     Log.i(TAG, "monkeyPatchExistingResources resource file:" + resourceString + ", use time: " + (System.currentTimeMillis() - start));20   } catch (Throwable e) {21     Log.e(TAG, "install resources failed");22     //remove patch dex if resource is installed failed23     try {24       SystemClassLoaderAdder.uninstallPatchDex(context.getClassLoader());25     } catch (Throwable throwable) {26       Log.e(TAG, "uninstallPatchDex failed", e);27     }28     intentResult.putExtra(ShareIntentUtil.INTENT_PATCH_EXCEPTION, e);29     ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_VERSION_RESOURCE_LOAD_EXCEPTION);30     return false;31   }32 33   return true;34 }

monkeyPatchExistingResources中实现了对外部资源的加载。

 1 public static void monkeyPatchExistingResources(Context context, String externalResourceFile) throws Throwable { 2   if (externalResourceFile == null) { 3     return; 4   } 5   // Find the ActivityThread instance for the current thread 6   Class<?> activityThread = Class.forName("android.app.ActivityThread"); 7   Object currentActivityThread = getActivityThread(context, activityThread); 8  9   for (Field field : new Field[]{packagesFiled, resourcePackagesFiled}) {10     Object value = field.get(currentActivityThread);11 12     for (Map.Entry<String, WeakReference<?>> entry13       : ((Map<String, WeakReference<?>>) value).entrySet()) {14       Object loadedApk = entry.getValue().get();15       if (loadedApk == null) {16         continue;17       }18       if (externalResourceFile != null) {19         resDir.set(loadedApk, externalResourceFile);20       }21     }22   }23   // Create a new AssetManager instance and point it to the resources installed under24   // /sdcard25   // 通过反射调用AssetManager的addAssetPath添加资源路径26   if (((Integer) addAssetPathMethod.invoke(newAssetManager, externalResourceFile)) == 0) {27     throw new IllegalStateException("Could not create new AssetManager");28   }29 30   // Kitkat needs this method call, Lollipop doesn't. However, it doesn't seem to cause any harm31   // in L, so we do it unconditionally.32   ensureStringBlocksMethod.invoke(newAssetManager);33 34   for (WeakReference<Resources> wr : references) {35     Resources resources = wr.get();36     //pre-N37     if (resources != null) {38       // Set the AssetManager of the Resources instance to our brand new one39       try {40         assetsFiled.set(resources, newAssetManager);41       } catch (Throwable ignore) {42         // N43         Object resourceImpl = resourcesImplFiled.get(resources);44         // for Huawei HwResourcesImpl45         Field implAssets = ShareReflectUtil.findField(resourceImpl, "mAssets");46         implAssets.setAccessible(true);47         implAssets.set(resourceImpl, newAssetManager);48       }49 50       resources.updateConfiguration(resources.getConfiguration(), resources.getDisplayMetrics());51     }52   }53 54   // 使用我们的测试资源文件测试是否更新成功55   if (!checkResUpdate(context)) {56     throw new TinkerRuntimeException(ShareConstants.CHECK_RES_INSTALL_FAIL);57   }58 }

主要原理还是依靠反射,通过AssertManager的addAssetPath函数,加入外部的资源路径,然后将Resources的mAssets的字段设为前面的AssertManager,这样在通过getResources去获取资源的时候就可以获取到我们外部的资源了。更多具体资源动态替换的原理,可以参考文档。

 

转载请标明本文来源:http://www.cnblogs.com/yyangblog/p/6252490.html
更多内容欢迎star作者的github:https://github.com/LaurenceYang/article
如果发现本文有什么问题和任何建议,也随时欢迎交流~