在存储器 android 中保存文本的权限无效

Question

我已经构建了示例应用程序供用户编写一些文本并将其保存在内部存储中。

格式为 TXT 或 pdf。我试过 android Kitkat sdk 19 并且它工作正常但是当我尝试最新的 android 9 我被拒绝无法将文本保存在内部存储中

编辑：我想知道是否必须手动创建我的文件夹

我错过了什么？

AndroidManifest

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

MainActivity

    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

在您的 MainActivity 中，您应该检查是否授予权限，然后使用 != 运算符。

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

这一行应该是-

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

Answer 2

按照 and 两个答案的建议。

这只是一种解决方法，但它确实有效。

我已经添加了

android:requestLegacyExternalStorage="true"

到 AndroidManifest.xml 文件中我的 <application> 元素。

并改行

File path = Environment.getExternalStorageDirectory();

到

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

在存储器 android 中保存文本的权限无效

Permission to save text in storage android not working

java

android

storage

android-permissions