问题与处理策略

问题描述

• 在 Android 项目中，使用相机时，报如下错误

java.lang.RuntimeException: Fail to connect to camera service

# 翻译

无法连接到相机服务

问题原因

1. 通常情况是应用没有获取到相机权限，导致连接相机服务失败

2. Android 系统要求应用在使用相机之前必须获得相应的权限（声明权限 + 动态请求权限）

处理策略

1. 在 AndroidManifest.xml 文件中声明权限

<uses-feature
    android:name="android.hardware.camera"
    android:required="false" />
<uses-permission android:name="android.permission.CAMERA" />

2. Android 6.0 及以上需要动态请求权限

private static final int PERMISSION_REQUEST_CAMERA = 1;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    EdgeToEdge.enable(this);
    setContentView(R.layout.activity_permission_test1);
    ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
        Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
        v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
        return insets;
    });

    if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
            != PackageManager.PERMISSION_GRANTED) {
        Log.i(TAG, "CAMERA - 权限未授予，请求权限");
        ActivityCompat.requestPermissions(this,
                new String[]{Manifest.permission.CAMERA},
                PERMISSION_REQUEST_CAMERA);
    } else {
        Log.i(TAG, "CAMERA - 权限已授予，执行相应操作");
        doCameraOperation();
    }
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    if (requestCode == PERMISSION_REQUEST_CAMERA) {
        if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            Log.i(TAG, "CAMERA - 权限已授予，执行相应操作");
            doCameraOperation();
        } else {
            Log.i(TAG, "CAMERA - 权限被拒绝");
        }
    }
}

private void doCameraOperation() {
}

• Android 6.0 及以上需要动态请求权限（Kotlin 版本）

private val PERMISSION_REQUEST_CAMERA = 1

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    enableEdgeToEdge()
    setContentView(R.layout.activity_permission_test2)
    ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main)) { v, insets ->
        val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
        v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom)
        insets
    }

    if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
        != PackageManager.PERMISSION_GRANTED
    ) {
        Log.i(TAG, "CAMERA - 权限未授予，请求权限");
        ActivityCompat.requestPermissions(
            this,
            arrayOf(Manifest.permission.CAMERA),
            PERMISSION_REQUEST_CAMERA
        )
    } else {
        Log.i(TAG, "CAMERA - 权限已授予，执行相应操作");
        doCameraOperation();
    }
}

override fun onRequestPermissionsResult(
    requestCode: Int,
    permissions: Array<out String>,
    grantResults: IntArray
) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults)

    if (requestCode == PERMISSION_REQUEST_CAMERA) {
        if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            Log.i(TAG, "CAMERA - 权限已授予，执行相应操作");
            doCameraOperation()
        } else {
            Log.i(TAG, "CAMERA - 权限被拒绝")
        }
    }
}

private fun doCameraOperation() {
}