【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 //pattern
16 String patternMeta = TypedValue.PATTERN_TITLE;
17 HashSet<String> patterns = new HashSet<>(config.mResRawPattern);
18 //we will process them separate
19 patterns.remove(TypedValue.RES_MANIFEST);
20 
21 writeMetaFile(patternMeta + patterns.size());
22 //write pattern
23 for (String item : patterns) {
24     writeMetaFile(item);
25 }
26 //write meta file, write large modify first
27 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,4019114434,6148149bd5ed4e0c2f5357c6e2c577d6
pattern:4
resources.arsc
r/*
res/*
assets/*
modify:1
r/g/ag.xml
add:1
assets/only_use_to_test_tinker_resource.txt

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bsdiff
10 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 manifest
32 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 failed
23         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<?>> entry
13             : ((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 under
24     // /sdcard
25     // 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 harm
31     // 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-N
37         if (resources != null) {
38             // Set the AssetManager of the Resources instance to our brand new one
39             try {
40                 assetsFiled.set(resources, newAssetManager);
41             } catch (Throwable ignore) {
42                 // N
43                 Object resourceImpl = resourcesImplFiled.get(resources);
44                 // for Huawei HwResourcesImpl
45                 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~

posted @ 2017-01-06 09:26 子扬 阅读(...) 评论(...) 编辑 收藏