包管理之隐藏apk

在\frameworks\base\services\java\com\android\server\pm目录下的Settings.java中，提供了隐藏apk的方法。

被隐藏的apk存储在mDisabledSysPackages中：

    // List of replaced system applications
    private final HashMap<String, PackageSetting> mDisabledSysPackages =
        new HashMap<String, PackageSetting>();

disableSystemPackageLPw方法可以隐藏apk，它会根据packagename去隐藏对应的apk：
    boolean disableSystemPackageLPw(String name) {
		//一定能在mPackages中找到需要隐藏的apk对应的PackageSetting
        final PackageSetting p = mPackages.get(name);
        if(p == null) {
            Log.w(PackageManagerService.TAG, "Package:"+name+" is not an installed package");
            return false;
        }
		//在mDisabledSysPackages中不能找到这个apk的信息
        final PackageSetting dp = mDisabledSysPackages.get(name);
        // always make sure the system package code and resource paths dont change
        if (dp == null) {
            //设置标志位FLAG_UPDATED_SYSTEM_APP
            if((p.pkg != null) && (p.pkg.applicationInfo != null) &&
                    ((p.pkgFlags & ApplicationInfo.FLAG_UNINSTALL_APP) != 0)) {
                p.pkg.applicationInfo.flags |= ApplicationInfo.FLAG_UPDATED_SYSTEM_APP;
            }
			//添加到mDisabledSysPackages中
            mDisabledSysPackages.put(name, p);

            // a little trick...  when we install the new package, we don't
            // want to modify the existing PackageSetting for the built-in
            // version.  so at this point we need a new PackageSetting that
            // is okay to muck with.
            PackageSetting newp = new PackageSetting(p);
            replacePackageLPw(name, newp);
            return true;
        }
        return false;
    }

    PackageSetting enableSystemPackageLPw(String name) {
		//在mDisabledSysPackages中查找，必须能查找到
        PackageSetting p = mDisabledSysPackages.get(name);
        if(p == null) {
            Log.w(PackageManagerService.TAG, "Package:"+name+" is not disabled");
            return null;
        }
        // 清除标志位FLAG_UPDATED_SYSTEM_APP
        if((p.pkg != null) && (p.pkg.applicationInfo != null)) {
            p.pkg.applicationInfo.flags &= ~ApplicationInfo.FLAG_UPDATED_SYSTEM_APP;
        }
		//add package
        PackageSetting ret = addPackageLPw(name, p.realName, p.codePath, p.resourcePath,
                p.nativeLibraryPathString, p.appId, p.versionCode, p.pkgFlags);
		//从mDisabledSysPackages中删除改apk
        mDisabledSysPackages.remove(name);
        return ret;
    }

    boolean isDisabledSystemPackageLPr(String name) {
        return mDisabledSysPackages.containsKey(name);
    }

    void removeDisabledSystemPackageLPw(String name) {
        mDisabledSysPackages.remove(name);
    }



writeDisabledSysPackageLPr方法会把mDisabledSysPackages写入到packages.xml文件中，以updated-package开始和结束，标记这是被隐藏的apk。

for (final PackageSetting pkg : mDisabledSysPackages.values()) {
     writeDisabledSysPackageLPr(serializer, pkg);
｝

    void writeDisabledSysPackageLPr(XmlSerializer serializer, final PackageSetting pkg)
            throws java.io.IOException {
        serializer.startTag(null, "updated-package");
        serializer.attribute(null, ATTR_NAME, pkg.name);
        if (pkg.realName != null) {
            serializer.attribute(null, "realName", pkg.realName);
        }
        serializer.attribute(null, "codePath", pkg.codePathString);
        serializer.attribute(null, "ft", Long.toHexString(pkg.timeStamp));
        serializer.attribute(null, "it", Long.toHexString(pkg.firstInstallTime));
        serializer.attribute(null, "ut", Long.toHexString(pkg.lastUpdateTime));
        serializer.attribute(null, "version", String.valueOf(pkg.versionCode));
        /// M: [Vendor] Add package flags recording in disabled pacakge element
        serializer.attribute(null, "flags", String.valueOf(pkg.pkgFlags));
        if (!pkg.resourcePathString.equals(pkg.codePathString)) {
            serializer.attribute(null, "resourcePath", pkg.resourcePathString);
        }
        if (pkg.nativeLibraryPathString != null) {
            serializer.attribute(null, "nativeLibraryPath", pkg.nativeLibraryPathString);
        }
        if (pkg.sharedUser == null) {
            serializer.attribute(null, "userId", Integer.toString(pkg.appId));
        } else {
            serializer.attribute(null, "sharedUserId", Integer.toString(pkg.appId));
        }
        serializer.startTag(null, "perms");
        if (pkg.sharedUser == null) {
            // If this is a shared user, the permissions will
            // be written there. We still need to write an
            // empty permissions list so permissionsFixed will
            // be set.
            for (final String name : pkg.grantedPermissions) {
                BasePermission bp = mPermissions.get(name);
                if (bp != null) {
                    // We only need to write signature or system permissions but
                    // this wont
                    // match the semantics of grantedPermissions. So write all
                    // permissions.
                    serializer.startTag(null, TAG_ITEM);
                    serializer.attribute(null, ATTR_NAME, name);
                    serializer.endTag(null, TAG_ITEM);
                }
            }
        }
        serializer.endTag(null, "perms");
        serializer.endTag(null, "updated-package");
    }