Android Marshmallow及以上版本第三方应用缓存清理实现咨询

Hey there! I see you've got the pre-Marshmallow cache cleaning sorted, but the 6.0+ sandbox changes threw a wrench in things—totally get it. Let's break down why your existing code doesn't work anymore, and how popular cache cleaners handle this problem.

Why Your Old Code Fails on Marshmallow+ #

Starting with Android 6.0 (API 23), Google tightened up app sandboxing and storage permissions:

• Each app's external storage directory (/Android/data/<package-name>/) is isolated—your app can no longer directly read or write to another app's cache folder, even if you have the READ_EXTERNAL_STORAGE or WRITE_EXTERNAL_STORAGE permissions.
• The runtime permission model means even if you request storage permissions, they won't grant access to other apps' private directories.

How Mainstream Cache Cleaners Implement This #

Most popular tools rely on one of these methods, with Accessibility Service being the most common:

1. Accessibility Service (Most Widely Used) #

This is the go-to approach for consumer-facing cache cleaners. Here's the gist:

• Accessibility services let your app observe and interact with the system UI on behalf of the user (with explicit user permission).
• The tool will simulate the manual steps a user would take: navigate to Settings → Apps → Select target app → Storage → Tap "Clear Cache".
• You'll need to:
  • Declare the accessibility service in your AndroidManifest.xml with the appropriate permissions and configuration.
  • Implement logic to detect UI elements (like the "Clear Cache" button) across different device models and Android versions (since OEMs often customize Settings UI).
  • Handle user flows to guide them to enable the accessibility permission (you can't enable it programmatically).

Pros: No root required, works on most consumer devices.
Cons: Requires user setup, needs heavy UI adaptation for different ROMs, and you have to follow Google's accessibility guidelines to avoid being removed from the Play Store.

2. Root Access #

Some tools offer root-only features to directly delete cache files (both internal and external) using file system operations, just like your pre-Marshmallow code. However:

• Rooting is declining in popularity due to security risks, warranty concerns, and modern Android's improved performance.
• You'll need to execute shell commands (like rm -rf) via root access, which can be risky if not handled carefully.

3. Device Owner/Work Profile (Enterprise Use Cases) #

For enterprise apps, using the DevicePolicyManager API with device owner permissions allows managing app storage. But this is rarely used for consumer apps, as it requires the device to be set up as a managed device (not feasible for regular users).

Key Notes for Implementation #

• Permissions Matter: For accessibility services, you can't auto-enable the permission—you need to launch the accessibility settings screen and guide the user to toggle your service on.
• ROM Adaptation: Samsung, Xiaomi, Huawei, etc., all have customized Settings UIs. You'll need to test across multiple devices and use UI element identifiers (like resource IDs or text labels) to reliably find the "Clear Cache" button.
• Compliance: Google strictly prohibits misuse of accessibility services (e.g., background operations without user consent). Make sure your app's use of accessibility is transparent and focused on helping users.

内容的提问来源于stack exchange，提问作者Rahulrr2602