自定义Android资源覆盖rro方案

static void android_content_AssetManager_init(JNIEnv* env, jobject clazz, jboolean isSystem) {if (isSystem) {// Load frameworks-res.apk's overlay through regionalization environmentif (Environment::isSupported()) {Environment* environment = new Environment();if (environment != NULL) {const char* overlay_dir = environment->getOverlayDir();if (overlay_dir != NULL && strcmp(overlay_dir, "") != 0) {ALOGD("Regionalization - getOverlayDir:%s", overlay_dir);verifySystemIdmaps(overlay_dir);}delete environment;}}
//在此处加入我们自己想要定制的overlay目录if (customed) {//判断是否自定义overlay目录char customed_overlay_dir[FILENAME_MAX] = {0};char rro_ui[PROPERTY_VALUE_MAX];//get ui schemes by property valueproperty_get("persist.customed.ui.rro.current", rro_ui, "");//whether rro_ui value is nullif (strlen(rro_ui) > 0) {memset(customed_overlay_dir, 0, FILENAME_MAX);snprintf(customed_overlay_dir, FILENAME_MAX, "/vendor/Customedoverlay/%s", rro_ui);customed_overlay_dir[FILENAME_MAX - 1] = '\0';struct stat info;//check whether customed_overlay_dir is a directoryif(stat(customed_overlay_dir, &info) == 0 && S_ISDIR(info.st_mode))//if the property value equals "overlay", we will user the origin default directory.if(!strcmp("overlay", rro_ui))verifySystemIdmaps(customed_overlay_dir);elseverifySystemIdmaps(AssetManager::OVERLAY_DIR);elseverifySystemIdmaps(AssetManager::OVERLAY_DIR);}} else {verifySystemIdmaps(AssetManager::OVERLAY_DIR);}}AssetManager* am = new AssetManager();if (am == NULL) {jniThrowException(env, "java/lang/OutOfMemoryError", "");return;}am->addDefaultAssets();ALOGV("Created AssetManager %p for Java object %p\n", am, clazz);env->SetLongField(clazz, gAssetManagerOffsets.mObject, reinterpret_cast(am));
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51

由此可见，主要是在jni层的android_content_AssetManager_init函数这里来添加overlay apk的目录，Android默认的目录AssetManager::OVERLAY_DIR是/vendor/overlay，这里我们根据情况

if (customed) {//判断是否自定义overlay目录
1
1

来确定是否需要修改。如果需要修改，这通过我自己定义的属性persist.customed.ui.rro.current来获取自定义目录。这个可以通过adb shell命令来进行set/get操作。 

这样我的overlay目录就是/vendor/Customedoverlay/myUI.

2. App层rro资源覆盖方案

同理，对于自定义App层的RRO资源覆盖目录则是在\framework\base\services\core\Java\com\android\server\pm\PackageManagerService.java 
before：

// Collect vendor overlay packages.
// (Do this before scanning any apps.)
// For security and version matching reason, only consider
// overlay packages if they reside in VENDOR_OVERLAY_DIR.
File vendorOverlayDir = new File(VENDOR_OVERLAY_DIR);
scanDirTracedLI(vendorOverlayDir, mDefParseFlags| PackageParser.PARSE_IS_SYSTEM| PackageParser.PARSE_IS_SYSTEM_DIR| PackageParser.PARSE_TRUSTED_OVERLAY, scanFlags | SCAN_TRUSTED_OVERLAY, 0);
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9

after：

// Collect vendor overlay packages.
// (Do this before scanning any apps.)
// For security and version matching reason, only consider
// overlay packages if they reside in VENDOR_OVERLAY_DIR.
File vendorOverlayDir;
if(customed) {String CUMTOMED_OVERLAY_DIR  = VENDOR_OVERLAY_DIR;String rroUi = SystemProperties.get("persist.customed.ui.rro.current");Slog.d(TAG, "**rroUi**:" + rroUi);if(rroUi != null && !rroUi.equals("")) {try {String tmpOverlay = "/vendor/Customedoverlay/" + rroUi;File tmpFile = new File(tmpOverlay);if(tmpFile.isDirectory() && !rroUi.equals("overlay")) {CUMTOMED_OVERLAY_DIR = tmpOverlay;}} catch (Exception ex) {Slog.e(TAG, "Failed to set CPoverlay dir: " + ex.getMessage());}}vendorOverlayDir = new File(CUMTOMED_OVERLAY_DIR);
} else {vendorOverlayDir = new File(VENDOR_OVERLAY_DIR);
}
scanDirTracedLI(vendorOverlayDir, mDefParseFlags| PackageParser.PARSE_IS_SYSTEM| PackageParser.PARSE_IS_SYSTEM_DIR| PackageParser.PARSE_TRUSTED_OVERLAY, scanFlags | SCAN_TRUSTED_OVERLAY, 0);
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28

在阅读代码寻找线索的过程中，通过查看网上的资料，最初确认的是/system/vendor/overlay这个目录，这里是原生系统中用来存放overlay apk的地方。通过在Linux中使用grep搜索命令来grep -nrs “/system/vendor/overlay”来查找线索。在Environment.cpp中有这个目录的使用，

static const char* OVERLAY_DIR = "/system/vendor/overlay";const char* Environment::getOverlayDir(void)
{if (mPackagesCount != 0 && mStoragePos != NULL && mPackages != NULL) {for (int i = mPackagesCount-1; i >= 0; i--) {memset(mMediaFile, 0, PATH_MAX);strlcpy(mOverlayDir, mStoragePos, PATH_MAX);strlcat(mOverlayDir, "/", PATH_MAX);strlcat(mOverlayDir, mPackages[i], PATH_MAX);strlcat(mOverlayDir, OVERLAY_DIR, PATH_MAX);if (kIsDebug) {ALOGD("Environment::getOverlayDir() = %s\n", mOverlayDir);}// Check if PackageFrameworksRes dir exists.char overlayFile[PATH_MAX];memset(overlayFile, 0, PATH_MAX);strlcpy(overlayFile, mOverlayDir, PATH_MAX);strlcat(overlayFile, "/", PATH_MAX);strlcat(overlayFile, mPackages[i], PATH_MAX);strlcat(overlayFile, "FrameworksRes", PATH_MAX);if (access(overlayFile, R_OK) == 0) {if (kIsDebug) {ALOGD("Environment::getOverlayDir() - overlayFile exists!\n");}return mOverlayDir;}}}return NULL;
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33

一步一步阅读代码才发现，最终也定位到了\framework\base\core\jni\android_util_AssetManager.cpp中，但却是下面这段代码：

if (isSystem) {// Load frameworks-res.apk's overlay through regionalization environmentif (Environment::isSupported()) {Environment* environment = new Environment();if (environment != NULL) {const char* overlay_dir = environment->getOverlayDir();if (overlay_dir != NULL && strcmp(overlay_dir, "") != 0) {ALOGD("Regionalization - getOverlayDir:%s", overlay_dir);verifySystemIdmaps(overlay_dir);}delete environment;}}
1
2
3
4
5
6
7
8
9
10
11
12
13
1
2
3
4
5
6
7
8
9
10
11
12
13

通过修改Environment.cpp中的

static const char* OVERLAY_DIR = "/system/vendor/Customedoverlay";
1
1

但经过验证并没有效果。因此否定之前的设想，在通过查找，得知Android系统在init.rc文件中将/vendor 链接到了system/vendor：

# Link /vendor to /system/vendor for devices without a vendor partition.
symlink /system/vendor /vendor
1
2
1
2

因此也把/vendor/overlay链接到了/system/vendor/overlay。所以后来换成搜索/vendor/overlay来寻找线索，并最终得出以上结论。

本文来自互联网用户投稿，文章观点仅代表作者本人，不代表本站立场，不承担相关法律责任。如若转载，请注明出处。 如若内容造成侵权/违法违规/事实不符，请点击【内容举报】进行投诉反馈！