Android 7.1 写入文本文件

Question

Nougat 的新手来自 Jelly bean 尝试将文本文件写入 sdcard 我知道我现在必须请求权限，但找不到任何有效的代码

尝试了以下

        StringBuilder bodyStr=new StringBuilder();
                 bodyStr.append(data1Str.toString()).append(",").append(data2Str.toString()).append(",").append(data3Str.toString()).append(",").append(data4Str.toString()).append(",").append(data5Str.toString()).append(",").append(data22Str.toString()).append(",").append(data23Str.toString()).append(lineSep);; 
             String bodytextStr=bodyStr.toString();

                boolean hasPermission = (ContextCompat.checkSelfPermission(data_entry.this,
                        Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED);
                if (!hasPermission) {
                    ActivityCompat.requestPermissions(data_entry.this,
                            new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                            REQUEST_WRITE_STORAGE);
                }


                try {

                    File myFile = new File(fileName);
                    myFile.createNewFile();
                    FileOutputStream fOut = new FileOutputStream(myFile);
                    OutputStreamWriter myOutWriter =
                            new OutputStreamWriter(fOut);
                    myOutWriter.append(bodytextStr);
                    myOutWriter.close();
                    fOut.close();
                    Toast.makeText(getBaseContext(),
                            "Done writing SD 'mysdfile.txt'",
                            Toast.LENGTH_SHORT).show();
                } catch (Exception e) {
                    Toast.makeText(getBaseContext(), e.getMessage(),
                            Toast.LENGTH_SHORT).show();
                }

回来[权限被拒绝]

在清单中设置了通常的权限

我哪里出错了的任何想法

感谢任何帮助

标记

Answer 1

您要么拥有权限并且可以在写入文件的地方执行 try catch 块，要么您必须在 onRequestPermissionsResult 中执行。

类似：

public void yourMethod(){
    boolean hasPermission = (ContextCompat.checkSelfPermission(data_entry.this,
                    Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED);
    if(hasPermission){
      // write
    }else{
      // ask the permission
      ActivityCompat.requestPermissions(data_entry.this,
                        new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                        REQUEST_WRITE_STORAGE);
      // You have to put nothing here (you can't write here since you don't
      // have the permission yet and requestPermissions is called asynchronously)
   }
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
                                       @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    // The result of the popup opened with the requestPermissions() method
    // is in that method, you need to check that your application comes here
    if (requestCode == REQUEST_WRITE_STORAGE) {
        if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            // write
        }
    }
}

我建议你检查这个链接：https://developer.android.com/training/permissions/requesting.html

Answer 2

这就是你需要的：https://developer.android.com/training/articles/scoped-directory-access.html#accessing

您必须要求用户授予访问权限。