Android动态获取权限

Android权限分为普通权限和危险权限两种。普通权限系统会自动授权，而危险权限则需要用户手动授权，否则无法使用相关功能。

以调用相机权限为例

AndroidMenifest.xml

这时候可以在手机的应用详情中看到所申请的权限，如下图所示

在Android6.0之前这个样子就够了，但是6.0之后还需要动态申请权限。

if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED){
	ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.CAMERA}, 1);
}else {
	openCamera();
}

首先通过

ContextCompat.checkSelfPermission()

checkSelfPermission()

PackageManager.PERMISSION_GRANTED

ActivityCompat.requestPermissions()

requestPermissions()

onRequestPermissionsResult()

onRequestPermissionsResult()

onRequestPermissionsResult()

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode){
            case 1:
                if (grantResults.length>0 && grantResults[0]==PackageManager.PERMISSION_GRANTED){
                    openCamera();
                }else {
                    Toast.makeText(MainActivity.this, "相机权限获取失败", Toast.LENGTH_LONG).show();
                }
                break;
            default:
        }
    }

授权的结果已经被授权到grantResults中，在if语句中判断是否正确获取权限，获取权限则打开相机。

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button cameraTest;
        cameraTest = (Button)findViewById(R.id.bt_camera);
        cameraTest.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED){
                    ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.CAMERA}, 1);
                }else {
                    openCamera();
                }
            }
        });
    }
    public void openCamera(){
        try {
            Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            startActivity(intent);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode){
            case 1:
                if (grantResults.length>0 && grantResults[0]==PackageManager.PERMISSION_GRANTED){
                    openCamera();
                }else {
                    Toast.makeText(MainActivity.this, "相机权限获取失败", Toast.LENGTH_LONG).show();
                }
                break;
            default:
        }
    }
}