[移动开发]registerForActivityResult用法详解（Kotlin）

registerForActivityResult() 是startActivity() 的替换方法，它囊括了更多的功能回调，并且可以赋值给对象，通过 xxx.lunch() 方法重复使用。

1.StartActivityForResult()

回调 it:ActivityResult！

resultCode 有三种?分别为 ：

RESULT_OK,RESULT_ERROR,RESULT_CANCELED

val startActivity= registerForActivityResult(ActivityResultContracts.StartActivityForResult()){
    //首先判断resultCode
    if (it.resultCode== RESULT_OK){
       //后续对data进行操作...
       //data 是 intent 类型的
       it.data.getIntExtra()

    }else{}
}

跳转activity?

startActivity.launch(mIntent)

在第二个activity进行回调传参

setResult(RESULT_OK,intent)

2.权限请求

单个权限请求

val requestCameraPermission =
        registerForActivityResult(ActivityResultContracts.RequestPermission()) { isGranted: Boolean ->
            if (isGranted) {
                //做后续操作
            } else {
                // 权限被拒绝就要提醒
            }
        }

 requestCameraPermission.launch(Manifest.permission.CAMERA)

多权限请求?

注意：多权限请求 返回的是map类型参数，所以需要获取map中所有的value来进行判断是否拿到所有权限

requestMultiplePermission.launch(arrayOf(Manifest.permission.CAMERA,Manifest.permission.READ_EXTERNAL_STORAGE))

val requestMultiplePermission =
        registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions()) { result: Map<String, Boolean> ->
            if (result[Manifest.permission.CAMERA] == true && result[Manifest.permission.READ_EXTERNAL_STORAGE] == true){
                //权限全部获取后的操作
            }else{
                //没有全部获取的操作
            }
        }

3.文件选择

需要在lunch()中写入MIME Type

//获取相册图片
selectFile?.launch("image/*")
//获取视频
selectFile?.launch("video/*")
//获取音频
selectFile?.launch("audio/*")
//txt类型文件
selectFile?.launch("text/plain")
//pdf类型文件
selectFile?.launch("application/pdf")
//Microsoft Word文件
selectFile?.launch("application/msword")

val selectFile = registerForActivityResult(ActivityResultContracts.GetContent()){result:Uri ->
}

4.拍照

拍照有两个方法：

TakePicturePreview() 方法 是直接获取的相机预览界面，返回bitmap

TakePicture() 保存到本地 返回 uri??

启动方法:

lunch(null)

lunch(uri) 照片保存路径

    private val takePhoto =
        registerForActivityResult(ActivityResultContracts.TakePicturePreview()) {
        }

    private val takePhoto  registerForActivityResult(ActivityResultContracts.TakePicture())
{
        }

5.创建文件

返回创建文件的uri

启动：

lunch(“image.jpg”) 文件名+后缀

private val createDocument = registerForActivityResult(ActivityResultContracts.CreateDocument()) {
    }

?6.选择联系人电话

private val pickContact = registerForActivityResult(ActivityResultContracts.PickContact()) { uri ->

        val cursor:Cursor?=mContext.contentResolver.query(uri,null,null,null,null)

        cursor?.let { cursor ->
            while (cursor.moveToNext()){
                //联系人id
                val contactId:String=cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts._ID))
                //联系人姓名
                val contactName=cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME))

                val phones=contentResolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
                    null,
                    ContactsContract.CommonDataKinds.Phone.CONTACT_ID+"="+contactId,
                    null,null
                )
                phones?.let {
                    while (it.moveToNext()){
                        
                        //联系人电话
                        val phoneNumber=it.getString(it.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER))

                    }
                    it.close()
                }

            }
            cursor.close()
        }
        
    }

启动：在请求前需要先请求 Manifest.permission.READ_CONTACTS 权限

val requestPermission =
        registerForActivityResult(ActivityResultContracts.RequestPermission()) { isGranted: Boolean ->
            if (isGranted) {
            pickContact.launch(null)

            } else {
                // 权限被拒绝就要提醒
                //showSettingDialog()
            }
        }