我使用kotlin扩展，使它非常简单。在你的扩展中添加以下扩展功能。kt文件:

fun AppCompatActivity.startForResult(intent: Intent,
    onResult: (resultCode: Int, data: Intent?) -> Unit
) {
    this.registerForActivityResult(ActivityResultContracts.StartActivityForResult()) {result ->
        onResult(result.resultCode, result.data)
    }.launch(intent)
}

现在，在继承AppCompatActivity的任何活动中，你可以使用下面的简单代码:

val i = Intent(this, TargetActivity::class.java)
startForResult(i) { resultCode, data ->
   //put your code here like:
   if (resultCode == RESULT_OK) {
      //your code here...
      }
   }
}

更新 上述实现可能导致以下异常: java.lang.IllegalStateException: LifecycleOwner xxxx正在尝试注册，而当前状态为恢复。生命周期所有者必须在启动之前调用寄存器。

因此，registerForActivityResult应该提前调用，例如在onCreate之前。这是另一种解决方案。

在你的扩展中添加以下扩展功能。kt文件:

fun AppCompatActivity.registerForResult(onResult: (resultCode: Int, data: Intent?) -> Unit):
        ActivityResultLauncher<Intent> {
    return this.registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
        onResult(result.resultCode, result.data)
    }
}

现在，在继承AppCompatActivity的任何活动中，你可以使用下面的简单代码:

为每个需要结果的操作定义一个类成员变量

private val myActionResult = registerForResult { resultCode, data ->
   //put your code here like:
   if (resultCode == RESULT_OK) {
      //your code here...
      }
   }
}

启动动作

val i = Intent(this, TargetActivity::class.java)
myActionResult.launch(i)

以下是我的解决方案:

在我们的项目中，我们有超过20次的startActivityForResult(和onActivityResult)。

我们希望尽可能少地更改代码(并继续使用请求代码)，同时引入一个优雅的解决方案以供将来使用。

既然我们很多开发人员都使用BaseActivity概念——为什么不利用它呢?

下面是BaseActivity:

abstract class BaseActivity : AppCompatActivity()
{
    private var requestCode: Int = -1
    private var resultHandler: ActivityResultLauncher<Intent>? = null

    override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
        registerForActivityResult()
    }

    private fun registerForActivityResult()
    {
        if (shouldRegisterForActivityResult())
        {
            resultHandler = registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->

                onActivityResult(result.data, requestCode, result.resultCode)
                this.requestCode = -1
            }
        }
    }

   fun startActivityForResult(requestCode: Int, intent: Intent)
   {
       this.requestCode = requestCode
       resultHandler?.launch(intent)
   }

   protected open fun onActivityResult(data: Intent?, requestCode: Int, resultCode: Int)
   {
       // For sub activities
   }

   protected open fun shouldRegisterForActivityResult(): Boolean
   {
      // Sub activities that need the onActivityResult "mechanism", should override this and return true
       return false
   }
}

这是SubActivity:

class SubActivity : BaseActivity()
{
    companion object
    {
        private const val SOME_REQUEST_CODE = 300
    }

    private fun testActivityResult()
    {
        val intent = Intent(this, OtherActivity::class.java)
        startActivityForResult(SOME_REQUEST_CODE, intent)
    }

    override fun shouldRegisterForActivityResult(): Boolean
    {
        return true
    }

    override fun onActivityResult(data: Intent?, requestCode: Int, resultCode: Int)
    {
        if (requestCode == SOME_REQUEST_CODE)
        {
            // Yes!
        }
    }
}

希望它能帮助到别人

对于那些具有多个requestCode的片段，并且如果您不确定如何处理这些requestCode的多个结果，那么您需要了解requestCode在新方法中是无用的。

我想象你以前的编码方式是这样的:

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    if (resultCode == Activity.RESULT_CODE) {
        when (requestCode) {
            REQUEST_TAKE_PHOTO -> {
                // handle photo from camera
            }
            REQUEST_PICK_IMAGE_FROM_GALLERY -> {
                // handle image from gallery
            }
        }
    }
}

在新的API中，你需要在一个单独的ActivityResultContract中实现每个请求的结果:

val takePhotoForResult = registerForActivityResult(StartActivityForResult()) { result: ActivityResult ->
    if (result.resultCode == Activity.RESULT_OK) {
        val intent = result.data
        // handle photo from camera
    }
}

val pickImageFromGalleryForResult = registerForActivityResult(StartActivityForResult()) { result: ActivityResult ->
    if (result.resultCode == Activity.RESULT_OK) {
        val intent = result.data
        // handle image from gallery
    }
}

然后你需要像这样开始这些活动/意图:

private fun startTakePhotoActivity() {
    takePhotoForResult.launch(Intent(requireActivity(), TakePhotoActivity::class.java))
}

private fun pickImageFromGallery() {
    val pickIntent = Intent(Intent.ACTION_PICK)
    pickIntent.setDataAndType(
        MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
        "image/*"
    )
    pickImageFromGalleryForResult.launch(pickIntent)
}

通过这样做，你可以在你的项目中摆脱数百个const val REQUEST_值。

ActivityResultLauncher<Intent> someActivityResultLauncher = registerForActivityResult(
        new ActivityResultContracts.StartActivityForResult(),
        new ActivityResultCallback<ActivityResult>() {
            @Override
            public void onActivityResult(ActivityResult result) {
                if (result.getResultCode() == Activity.RESULT_OK) {

                }
            }
        });

在Java 8中，它可以这样写:

ActivityResultLauncher<Intent> startActivityForResult = registerForActivityResult(
    new ActivityResultContracts.StartActivityForResult(),
    result -> {
        if (result.getResultCode() == AppCompatActivity.RESULT_OK) {
            Intent data = result.getData();
            // ...
        }
    }
);

Intent intent = new Intent( ... );
startActivityForResult.launch(intent);

一个简单的例子:registerForActivityResult和requestmultiplepermission from Activity和Fragment

请求活动以获得活动的结果

registerForActivityResult(
    ActivityResultContracts.StartActivityForResult()
) { activityResult ->
    if (activityResult.resultCode == Activity.RESULT_OK) {
        //...
    }
}

检查ActivityResult

向活动请求许可?

registerForActivityResult(
    ActivityResultContracts.RequestMultiplePermissions()
) {
    //it: Map<String, Boolean>
}

从片段?

使用相同的方法，但确保将这些实现放在初始化中，onAttach()或onCreate()