在存儲中保存文本的權限 android 不起作用

Question

我已經為用戶構建了示例應用程序來編寫一些文本並將其保存在內部存儲中。

格式為 TXT 或 pdf。 我已經嘗試過 android Kitkat sdk 19 並且它工作正常但是當我嘗試使用最新的 android 9 時我被拒絕無法將文本保存在內部存儲中

編輯：我想知道是否必須手動創建我的文件文件夾

我錯過了什么？

安卓清單

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

主要活動

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

       mSaveTextBtn.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v) {
            mText = mResultEt.getText().toString().trim();
            if(mText.isEmpty()){
                Toast.makeText(MainActivity.this, "write text First...", Toast.LENGTH_SHORT).show();
            }
            else{
                if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M){
                    if(checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE)
                    == PackageManager.PERMISSION_GRANTED){
                        String[] permissions = {Manifest.permission.WRITE_EXTERNAL_STORAGE};
                        requestPermissions(permissions,WRITE_EXTERNAL_STORAGE_CODE);
                    }else {
                        saveToTxtFile(mText);
                    }
                }else {
                    saveToTxtFile(mText);
                }
            }

        }
    }); 

}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    switch (requestCode){
        case WRITE_EXTERNAL_STORAGE_CODE: {
            if (grantResults.length > 0 && grantResults[0]
                    == PackageManager.PERMISSION_GRANTED) {
                //permission granted save data
                saveToTxtFile(mText);
            } else {
                //permission denied
                Toast.makeText(this, "Storage Permission required to store", Toast.LENGTH_SHORT).show();
            }
        }
        break;
    }
}

private void saveToTxtFile(String mText){
    //get current time for file name
    String timestamp = new SimpleDateFormat("yyyyMMdd_HHmmss",
            Locale.getDefault()).format(System.currentTimeMillis());
    try{
        //path tp storage
        File path = Environment.getExternalStorageDirectory();
        //create folder named "My file"
        File dir = new File( path + "/My Files/");
        dir.mkdirs();
        //file name
        String fileName = "MyFile_" + timestamp + ".txt";

        File file = new File (dir, fileName);

        //used to store characater in file
        FileWriter fw = new FileWriter(file.getAbsoluteFile());
        BufferedWriter bw = new BufferedWriter(fw);
        bw.write(mText);
        bw.close();

        //show file name and path where file saved
        Toast.makeText(this, fileName+"is saved to\n" +dir, Toast.LENGTH_SHORT).show();

    }catch (Exception e){
        //if anything goes wrong
        Toast.makeText(this, e.getMessage(), Toast.LENGTH_SHORT).show();
    }
}

Answer 1

正如Shashanth和kashyap所建議的那樣。

這只是一種解決方法，但它有效。

我已經添加了

android:requestLegacyExternalStorage="true"

到我的AndroidManifest.xml文件中的<application>元素。

並改變了線路

File path = Environment.getExternalStorageDirectory();

到

File path = new File(getExternalFilesDir(null).getAbsolutePath());

Answer 2

在您的MainActivity您應該檢查是否授予權限，然后使用!=運算符。

if(checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE)
                        == PackageManager.PERMISSION_GRANTED) {}

這一行應該是——

if(checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE)
                    != PackageManager.PERMISSION_GRANTED){}