Android studio 如何从活动结果API获取请求代码

我对Android Kotlin编程非常陌生。我正在制作一个应用程序，使用Storage Access Framework创建、读取和删除文件。我通过实现不推荐的startActivityForResult意图来执行文件读取、创建和删除任务。我试图使用ActivityResultAPI实现它，但我被困在请求代码中，找不到它。 在新的实现中，有resultCode，但没有requestCode

我的意思如下。如何使用活动结果API实现以下内容

fun createFile()
{
    val filename: String = etFileName.text.toString()
    val intent = Intent(Intent.ACTION_CREATE_DOCUMENT).apply {
        type = "text/*"
        addCategory(Intent.CATEGORY_OPENABLE)
        putExtra(Intent.EXTRA_TITLE, filename)
    }
    startActivityForResult(intent, WRITE_REQUEST_CODE)
}


fun readFile(){
    etFileName.setText("")
    val intent = Intent(Intent.ACTION_OPEN_DOCUMENT).apply {
        addCategory(Intent.CATEGORY_OPENABLE)
        type = "text/*"
    }
    startActivityForResult(intent, READ_REQUEST_CODE)
}

fun deleteFile(uri: Uri){
    val filename = queryName(contentResolver, uri)
    DocumentsContract.deleteDocument(contentResolver, uri)
    Toast.makeText(applicationContext, "Done deleting $filename", Toast.LENGTH_SHORT).show()
}

fun writeText(uri: Uri) : String{
    //var writetext: String = "typing high speed"
    var writeStream = contentResolver.openFileDescriptor(uri, "w")
    val filename: String = queryName(contentResolver, uri)
    etFileName.setText(filename)
    var fileOutputStream = FileOutputStream(writeStream?.fileDescriptor)
    fileOutputStream.write(filename.toByteArray())
    fileOutputStream.close()
    return filename.toString()
}

fun openFileContent(uri: Uri): String{
    val inputStream = contentResolver.openInputStream(uri)
    val reader = BufferedReader(InputStreamReader(inputStream))
    val stringBuilder = StringBuilder()

    val filename = queryName(contentResolver, uri)
    etFileName.setText(filename)
    var currentline = reader.readLine()

    while (currentline != null) {
        stringBuilder.append(currentline + "\n")
        currentline = reader.readLine()
    }
    inputStream?.close()
    val str =  stringBuilder.toString()
    Log.d("Uri Read", ": $str")
    return str
}

private fun queryName(resolver: ContentResolver, uri: Uri): String {
    val returnCursor: Cursor = resolver.query(uri, null, null, null, null)!!
    val nameIndex: Int = returnCursor.getColumnIndex(OpenableColumns.DISPLAY_NAME)
    returnCursor.moveToFirst()
    val name: String = returnCursor.getString(nameIndex)
    returnCursor.close()
    return name
}

override fun onActivityResult(requestCode: Int, resultCode: Int, resultData: Intent?) {
    super.onActivityResult(requestCode, resultCode, resultData)

    if (requestCode == READ_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        val uri =resultData?.data
        Log.d("Uri Read", "$uri")
        if (uri != null) {
            val readfile: String = openFileContent(uri)
            etContent.setText(readfile)
        }
    } else if (requestCode == WRITE_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        resultData?.data?.also { uri ->
            Log.i("Uri Write", "Uri: $uri")   // 1
            val write = writeText(uri)   // 2
            etContent.setText(write)
        }
    } else if (requestCode == DELETE_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        val uri =resultData?.data
        Log.d("Uri Delete", "$uri")
        if (uri != null) {
            deleteFile(uri)
        }
    }
}

如何从活动结果API获取请求代码

fun createFile()
{
    val filename: String = etFileName.text.toString()
    val intent = Intent(Intent.ACTION_CREATE_DOCUMENT).apply {
        type = "text/*"
        addCategory(Intent.CATEGORY_OPENABLE)
        putExtra(Intent.EXTRA_TITLE, filename)
    }
    startActivityForResult(intent, WRITE_REQUEST_CODE)
}


fun readFile(){
    etFileName.setText("")
    val intent = Intent(Intent.ACTION_OPEN_DOCUMENT).apply {
        addCategory(Intent.CATEGORY_OPENABLE)
        type = "text/*"
    }
    startActivityForResult(intent, READ_REQUEST_CODE)
}

fun deleteFile(uri: Uri){
    val filename = queryName(contentResolver, uri)
    DocumentsContract.deleteDocument(contentResolver, uri)
    Toast.makeText(applicationContext, "Done deleting $filename", Toast.LENGTH_SHORT).show()
}

fun writeText(uri: Uri) : String{
    //var writetext: String = "typing high speed"
    var writeStream = contentResolver.openFileDescriptor(uri, "w")
    val filename: String = queryName(contentResolver, uri)
    etFileName.setText(filename)
    var fileOutputStream = FileOutputStream(writeStream?.fileDescriptor)
    fileOutputStream.write(filename.toByteArray())
    fileOutputStream.close()
    return filename.toString()
}

fun openFileContent(uri: Uri): String{
    val inputStream = contentResolver.openInputStream(uri)
    val reader = BufferedReader(InputStreamReader(inputStream))
    val stringBuilder = StringBuilder()

    val filename = queryName(contentResolver, uri)
    etFileName.setText(filename)
    var currentline = reader.readLine()

    while (currentline != null) {
        stringBuilder.append(currentline + "\n")
        currentline = reader.readLine()
    }
    inputStream?.close()
    val str =  stringBuilder.toString()
    Log.d("Uri Read", ": $str")
    return str
}

private fun queryName(resolver: ContentResolver, uri: Uri): String {
    val returnCursor: Cursor = resolver.query(uri, null, null, null, null)!!
    val nameIndex: Int = returnCursor.getColumnIndex(OpenableColumns.DISPLAY_NAME)
    returnCursor.moveToFirst()
    val name: String = returnCursor.getString(nameIndex)
    returnCursor.close()
    return name
}

override fun onActivityResult(requestCode: Int, resultCode: Int, resultData: Intent?) {
    super.onActivityResult(requestCode, resultCode, resultData)

    if (requestCode == READ_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        val uri =resultData?.data
        Log.d("Uri Read", "$uri")
        if (uri != null) {
            val readfile: String = openFileContent(uri)
            etContent.setText(readfile)
        }
    } else if (requestCode == WRITE_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        resultData?.data?.also { uri ->
            Log.i("Uri Write", "Uri: $uri")   // 1
            val write = writeText(uri)   // 2
            etContent.setText(write)
        }
    } else if (requestCode == DELETE_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        val uri =resultData?.data
        Log.d("Uri Delete", "$uri")
        if (uri != null) {
            deleteFile(uri)
        }
    }
}

由于上面的方法已被弃用，我尝试使用Intent launcher来实现它，但是任何地方都没有对requestCode的引用，所以我被困在这里。如下图所示：

val startforFile: ActivityResultLauncher<Intent> = registerForActivityResult(ActivityResultContracts.StartActivityForResult()){
    result: ActivityResult ->

    // could not find reference to requestCode here

    if (requestCode == READ_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        val uri =resultData?.data
        Log.d("Uri Read", "$uri")
        if (uri != null) {
            val readfile: String = openFileContent(uri)
            etContent.setText(readfile)
        }
    } else if (requestCode == WRITE_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        resultData?.data?.also { uri ->
            Log.i("Uri Write", "Uri: $uri")   // 1
            val write = writeText(uri)   // 2
            etContent.setText(write)
        }
    } else if (requestCode == DELETE_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        val uri =resultData?.data
        Log.d("Uri Delete", "$uri")
        if (uri != null) {
            deleteFile(uri)
        }
    }
}

val startforFile:ActivityResultLauncher=registerForActivityResult（ActivityResultContracts.StartActivityForResult（））{
结果：ActivityResult->
//在此处找不到对requestCode的引用
if（requestCode==READ\u REQUEST\u CODE&&resultCode==Activity.RESULT\u OK）{
val uri=resultData？.data
Log.d（“Uri读取”，“$Uri”）
if（uri！=null）{
val readfile:String=openFileContent（uri）
etContent.setText（readfile）
}
}else if（requestCode==WRITE\u REQUEST\u CODE&&resultCode==Activity.RESULT\u OK）{
结果数据？数据？也{uri->
Log.i（“Uri写入”，“Uri:$Uri”）//1
val write=writeText（uri）//2
etContent.setText（写入）
}
}else if（requestCode==DELETE\u REQUEST\u CODE&&resultCode==Activity.RESULT\u OK）{
val uri=resultData？.data
Log.d（“Uri删除”，“$Uri”）
if（uri！=null）{
删除文件（uri）
}
}
}

---

有人能告诉我如何正确执行吗？

使用ActivityResultContracts.StartActivityForResult有两种方法

通过注册多个侦听器发出多个请求：

val startforFileRead:ActivityResultLauncher=registerForActivityResult（ActivityResultContracts.StartActivityForResult（））{
结果：ActivityResult->
if（resultCode==Activity.RESULT\u确定）{
val uri=resultData？.data
Log.d（“Uri读取”，“$Uri”）
if（uri！=null）{
val readfile:String=openFileContent（uri）
etContent.setText（readfile）
}
} 
}
val startforFileWrite:ActivityResultLauncher=registerForActivityResult（ActivityResultContracts.StartActivityForResult（））{
结果：ActivityResult->
if（resultCode==Activity.RESULT\u确定）{
结果数据？数据？也{uri->
Log.i（“Uri写入”，“Uri:$Uri”）//1
val write=writeText（uri）//2
etContent.setText（写入）
}
} 
}
val startforFileDelete:ActivityResultLauncher=registerForActivityResult（ActivityResultContracts.StartActivityForResult（））{
结果：ActivityResult->
if（resultCode==Activity.RESULT\u确定）{
val uri=resultData？.data
Log.d（“Uri删除”，“$Uri”）
if（uri！=null）{
删除文件（uri）
}
} 
}

在其他活动返回的意图中添加额外内容。将其解压缩为您的请求代码

const val REQUEST\u code=“REQUEST\u code”
//...
val startforFile:ActivityResultLauncher=
registerForActivityResult（ActivityResultContracts.StartActivityForResult（））{result->
val requestCode=result.data？.extras？.getInt（请求代码）
if（requestCode==null）{
Log.e（“FileResultLauncher”，“在数据意图中未返回任何请求代码。”）
return@registerForActivityResult
}
val uri=结果.data？.data
if（uri==null | | result.resultCode！=result|u OK）{
Log.i（“FileResultLauncher”，“未返回Uri或结果不正常”。）
return@registerForActivityResult
}
何时（请求代码）{
读取请求代码->运行{
Log.d（“Uri读取”，“$Uri”）
val readfile:String=openFileContent（uri）
etContent.setText（readfile）
}
写入请求代码->运行{
Log.i（“Uri写入”，“Uri:$Uri”）//1
val write=writeText（uri）//2
etContent.setText（写入）
}
删除请求代码->运行{
Log.d（“Uri删除”，“$Uri”）
删除文件（uri）
}
}
}

使用

ActivityResultContracts有两种方法。StartActivityForResult

通过注册多个侦听器发出多个请求：

val startforFileRead:ActivityResultLauncher=registerForActivityResult（ActivityResultContracts.StartActivityForResult（））{
结果：ActivityResult->
if（resultCode==Activity.RESULT\u确定）{
val uri=resultData？.data
Log.d（“Uri读取”，“$Uri”）
if（uri！=null）{
val readfile:String=openFileContent（uri）
etContent.setText（readfile）
}
} 
}
val startforFileWrite:ActivityResultLauncher=registerForActivityResult（ActivityResultContracts.StartActivityForResult（））{
结果：ActivityResult->
if（resultCode==Activity.RESULT\u确定）{
结果数据？数据？也{uri->
Log.i（“Uri写入”，“Uri:$Uri”）//1
val write=writeText（uri）//2
etContent.setText（写入）
}
} 
}
val startforFileDelete:ActivityResultLauncher=registerForActivityResult（ActivityResultContracts.StartActivityForResult（））{
结果：ActivityResult->
if（resultCode==Activity.RESULT\u确定）{
val uri=resultData？.data
Log.d（“Uri删除”，“$Uri”）
if（uri！=null）{
删除文件（uri）
}
} 
}

在其他活动返回的意图中添加额外内容。将其解压缩为您的请求代码

const val REQUEST\u code=“REQUEST\u code”
//...
val startforFile:ActivityResultLauncher=
ActivityResult注册表（ActivityResultContracts.StartActiv
const val REQUEST_CODE = "REQUEST_CODE"
//...

val startforFile: ActivityResultLauncher<Intent> =
    registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
    val requestCode = result.data?.extras?.getInt(REQUEST_CODE)
    if (requestCode == null) {
        Log.e("FileResultLauncher", "No REQUEST_CODE was returned in data intent.")
        return@registerForActivityResult
    }
    val uri = result.data?.data
    if (uri == null || result.resultCode != RESULT_OK) {
        Log.i("FileResultLauncher", "No Uri returned or result wasn't OK.")
        return@registerForActivityResult
    }
    when (requestCode) {
        READ_REQUEST_CODE -> run {
            Log.d("Uri Read", "$uri")
            val readfile: String = openFileContent(uri)
            etContent.setText(readfile)
        }
        WRITE_REQUEST_CODE -> run {
            Log.i("Uri Write", "Uri: $uri")   // 1
            val write = writeText(uri)   // 2
            etContent.setText(write)
        }
        DELETE_REQUEST_CODE -> run {
            Log.d("Uri Delete", "$uri")
            deleteFile(uri)
        }
    }
}