android 调用系统前置摄像头 android打开摄像头

第一步 在AndroidManifest.xml中加入权限
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

在你的Activity中设置按钮事件打开摄像头
                intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
                System.out.println("用户点击了拍照按钮"); 

                SimpleDateFormat format = new SimpleDateFormat("yyyyMMdd_HHmmss");
                PhotoFileName =Environment.getExternalStorageDirectory()+File.separator+ format.format(new Date())+"Photo.jpg";

                intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(new File(PhotoFileName)));
                //intent = new Intent(this, com.google.zxing.client.android.CaptureActivity.class);
                startActivityForResult(intent, REQUEST_CAMERA_CODE);

重写onActivityResult方法
    public void onActivityResult(int requestCode, int resultCode, Intent intent) {
        if (resultCode == RESULT_OK){
            switch (requestCode){
  
                case REQUEST_CAMERA_CODE:
                    System.out.println("Get CAMERA  RESULT ");
                  // String LocalPhoto= Environment.getExternalStorageDirectory()+File.separator+PhotoFileName;
                    Bitmap bitmap = getLoacalBitmap(PhotoFileName);
                    PhotoResult.setImageBitmap(bitmap);
                    break;
                    default:
                        break;
            }
        } 
    }

定义常用变量
    private static final int REQUEST_SCAN_BARCODE_CODE = 1;
    private static final int REQUEST_CAMERA_CODE = 2;
    private static  String PhotoFileName="";

    TextView  QRCodeResult;
    ImageView PhotoResult;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_fire_exit_door); 

        QRCodeResult =(TextView)findViewById(R.id.QRCodeResult) ;
        PhotoResult =(ImageView)findViewById(R.id.imageViewPhotoResult);
    }