Question

我在获取从手机上保存文件的权限时遇到问题。我明确表示：

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

在我使用onclick的java中，我有保存文件的功能

saveTestButton.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {

                InputStream in = null;
                FileOutputStream fout = null;
                try {
                    in = getResources().openRawResource(R.raw.testsound);
                    String downloadsDirectoryPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath();
                    String filename = "testsound.mp3";
                    fout = new FileOutputStream(new File(downloadsDirectoryPath + filename));

                    final byte data[] = new byte[1024];
                    int count;
                    while ((count = in.read(data, 0, 1024)) != -1) {
                        fout.write(data, 0, count);
                    }
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                } finally {
                    if (in != null) {
                        try {
                            in.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if (fout != null) {
                        try {
                            fout.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
        }

    });

要检查权限：

private static final int REQUEST_EXTERNAL_STORAGE = 1;
    private static String[] PERMISSIONS_STORAGE = {
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE
    };
public static void verifyStoragePermissions(Activity activity) {
    // Check if we have write permission
    int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);

    if (permission != PackageManager.PERMISSION_GRANTED) {
        // We don't have permission so prompt the user
        ActivityCompat.requestPermissions(
                activity,
                PERMISSIONS_STORAGE,
                REQUEST_EXTERNAL_STORAGE
        );
    }
}

当我尝试通过点击应用中的按钮来保存此文件时，我收到错误：

W / System.err：java.io.FileNotFoundException：/storage/emulated/0/Downloadtestsound.mp3：open failed：EACCES（Permission denied）

有什么问题？

Answer 1

我相信这是你的问题：

dataGridView1

使用以下代码：

 private void button5_Click(object sender, EventArgs e)
 {
       conn.Close();

       try
       {
                conn.Open();
                SqlCommand selectCommand = new SqlCommand("Select * from Stocks_Item where Stock_No = @Stocks_no", conn);
                selectCommand.Parameters.Add(new SqlParameter("Stocks_no", txtsearch_stock_no.Text.ToString()));
                SqlDataReader reader = selectCommand.ExecuteReader();
                bool rowFound = reader.HasRows;


                SqlDataAdapter data = new SqlDataAdapter("Select * from Stocks_Item", conn);
                DataTable dt = new DataTable();
                data.Fill(dt);
                dataGridView1.DataSource = dt;

                /* SqlDataAdapter sda;
                 DataTable dt1;
                 sda = new SqlDataAdapter("select * FROM colombo_branch ",conn);
                 dt1 = new DataTable();
                 sda.Fill(dt1);
                 dataGridView.DataSource = dt1;*/
                MessageBox.Show("Search Found", "Form", MessageBoxButtons.OK, MessageBoxIcon.Information);
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }

    conn.Close();
}

您只有fout = new FileOutputStream(new File(downloadsDirectoryPath + filename));而非fout = new FileOutputStream(new File(downloadsDirectoryPath , filename));

的权限

Answer 2

将“/”放在filename和downloadsDirectoryPath之间，这就是为什么它会给出错误。如果您没有获得权限则进行测试然后转到设置并在那里手动授予权限并再次启动。

public void onClick(View v) {

        InputStream in = null;
        FileOutputStream fout = null;
        try {
            in = getResources().openRawResource(R.raw.testsound);
            String downloadsDirectoryPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath();
            String filename = "testsound.mp3";
            fout = new FileOutputStream(new File(downloadsDirectoryPath + "/"+filename));

            final byte data[] = new byte[1024];
            int count;
            while ((count = in.read(data, 0, 1024)) != -1) {
                fout.write(data, 0, count);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fout != null) {
                try {
                    fout.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
}

});

如何获得Android应用程序的权限？

2 个答案: