如何使用Camera2 API检测三星J7 Pro前置闪光灯是否可用？

Great question! Since you're moving from the deprecated Camera API to Camera2, the approach shifts a bit—Camera2 integrates flash control with auto-exposure (AE) modes instead of having a standalone flash mode list. Here's how to replicate your old detection logic for your Samsung J7 Pro with a physical front LED flash:

Step-by-Step Breakdown #

1. Grab the CameraManager: This is the core entry point for accessing camera devices in Camera2.
2. Locate the Front Camera: Iterate through available camera IDs to find the one marked as front-facing.
3. Check for Flash Hardware: Use camera characteristics to confirm if the front camera has flash hardware at all.
4. Map Old Flash Modes to Camera2 AE Modes: The old API's flash modes correspond directly to specific AE modes in Camera2—we'll verify those support.

Code Implementation #

import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraCharacteristics;
import android.hardware.camera2.CameraManager;
import android.hardware.camera2.CaptureRequest;
import android.content.Context;

// Call this method from your activity/fragment (ensure camera permissions are granted first)
public void checkFrontFlashSupport(Context context) {
    CameraManager cameraManager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);
    
    try {
        String[] cameraIds = cameraManager.getCameraIdList();
        
        for (String cameraId : cameraIds) {
            CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId);
            
            // Skip non-front cameras
            Integer lensFacing = characteristics.get(CameraCharacteristics.LENS_FACING);
            if (lensFacing == null || lensFacing != CameraCharacteristics.LENS_FACING_FRONT) {
                continue;
            }
            
            // First: Confirm the front camera has flash hardware
            Boolean hasFlashHardware = characteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE);
            if (hasFlashHardware == null || !hasFlashHardware) {
                // No front flash exists on this device
                return;
            }
            
            // Second: Check which AE modes (flash behaviors) are supported
            int[] availableAEModes = characteristics.get(CameraCharacteristics.CONTROL_AE_AVAILABLE_MODES);
            if (availableAEModes == null) {
                return;
            }
            
            // Map old Camera API flash modes to Camera2 AE modes
            boolean supportsFlashOn = false;
            boolean supportsFlashOff = false;
            boolean supportsFlashAuto = false;
            boolean supportsFlashAlways = false;
            
            for (int aeMode : availableAEModes) {
                switch (aeMode) {
                    case CaptureRequest.CONTROL_AE_MODE_OFF:
                        supportsFlashOff = true;
                        break;
                    case CaptureRequest.CONTROL_AE_MODE_ON:
                        supportsFlashOn = true;
                        break;
                    case CaptureRequest.CONTROL_AE_MODE_AUTO_FLASH:
                        supportsFlashAuto = true;
                        break;
                    case CaptureRequest.CONTROL_AE_MODE_ON_ALWAYS_FLASH:
                        supportsFlashAlways = true;
                        break;
                }
            }
            
            // Replicate your original check: does the equivalent of FLASH_MODE_ON exist?
            boolean isSupportedFlashMode = supportsFlashOn;
            
            // For your Samsung J7 Pro, this should return true, and all four modes should be supported
            boolean allOldModesSupported = supportsFlashOn && supportsFlashOff && supportsFlashAuto && supportsFlashAlways;
            
            // Use these boolean values in your app logic as needed
            break; // Exit loop once we've checked the front camera
        }
    } catch (CameraAccessException e) {
        e.printStackTrace();
        // Handle camera access errors (e.g., permission denied) here
    }
}

Important Notes for Your Samsung J7 Pro #

• Your device's front camera reports four flash modes via the old API, which directly match the four AE modes checked above. This code should detect all of them as supported.
• Unlike the old Camera API, Camera2 doesn't have a direct "supported flash modes" list—flash behavior is tied to auto-exposure settings, so this mapping is the correct approach.
• Make sure to request the CAMERA permission (and dynamic permission on Android 6.0+) before running this code.

内容的提问来源于stack exchange，提问作者nhoxbypass