相机请求代码在Android中意味着什么

Question

有人可以解释相机请求代码是什么？

我们为什么用它？

我正在尝试Android的练习,我看到了代码.

这是我练习的代码;

public class imageActivity extends AppCompatActivity {

    Button image;
    private static final int CAMERA_REQUEST = 1888;
    private ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_resim);

        imageView = (ImageView)this.findViewById(R.id.imageView1);
        image = (Button) findViewById(R.id.capture);

        image.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
                startActivityForResult(cameraIntent, CAMERA_REQUEST);
            }
        });


    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == CAMERA_REQUEST && resultCode == RESULT_OK) {
            Bitmap photo = (Bitmap) data.getExtras().get("data");
            imageView.setImageBitmap(photo);
        }
    }
}

Answer 1

您可以在一个Activity中进行多次调用startActivityForResult(),允许不同的Intents执行不同的操作.使用请求代码来标识Intent您要从哪个返回.

例如:

您可以为结果启动两个活动:

private static final int CAMERA_REQUEST = 1888;
private static final int GALLERY_REQUEST = 1889;
startActivityForResult(cameraIntent, CAMERA_REQUEST);
startActivityForResult(cameraIntent, GALLERY_REQUEST);

在你的 onActivityForResult()

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == CAMERA_REQUEST && resultCode == RESULT_OK) {
        //Do stuff with the camara data result
    }
    else if (requestCode == GALLERY_REQUEST && resultCode == RESULT_OK) {
        //Do stuff with the gallery data result
    }
}

请注意,private static final ints完全是任意的.