即使在添加用户权限后，我也会收到 mailjava.io.FileNotFoundException

Question

我正在创建一个按钮，它将获取数据库，在文档文件夹中创建 .xls 文件并将其作为电子邮件或 whatsapp 的附件发送。但是，即使在向清单文件添加权限后，我也会收到 mailjava.io.FileNotFoundException 错误。我知道我缺少一些小东西，但无法弄清楚。

1. 我尝试在内部缓存目录中创建文件，该文件已成功创建，但无法作为电子邮件或 whatsapp 的附件获取。
2. 我没有任何问题应该保存文件，因为我在作为附件发送后无论如何都要删除它。

3. 在 Email Intent 中，我使用 Uri 作为 Uri.parse("content://", file.getAbsolutePath()) file.toUri(); Uri uri = Uri.fromFile(file);都有相同的结果显示此错误。父类有所有定义的变量

       imbtnMail.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View v) {
             try {
   
               Cursor cursor = dbManager.fetch(DatabaseHelper.TICKET_TABLE);
   
               String filename = "Report-" + DateUtil.timeMilisToString(System.currentTimeMillis(), "ddMMyy");
               String xlsfile = filename + ".xlx";
               file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS), xlsfile);
               Log.i("File written at:",file.getAbsolutePath());
   
               //file path
               WorkbookSettings wbSettings = new WorkbookSettings();
               wbSettings.setLocale(new Locale("en", "EN"));
               WritableWorkbook workbook;
               workbook = Workbook.createWorkbook(file, wbSettings);
               //Excel sheet name. 0 represents first sheet
               WritableSheet sheet = workbook.createSheet("Daily Report", 0);
   
               // column and row
               sheet.addCell(new Label(0, 0, "Pass Report"));
               sheet.addCell(new Label(1, 0, "User"));
   
               if (cursor.moveToFirst()) {
                   do {
                       String Rno = cursor.getString(cursor.getColumnIndex(DatabaseHelper.TICKET_RECEIPT));
                       String vno = cursor.getString(cursor.getColumnIndex(DatabaseHelper.TICKET_V_NO));
                       String vtype = cursor.getString(cursor.getColumnIndex(DatabaseHelper.TICKET_V_TYPE));
                       String vin = cursor.getString(cursor.getColumnIndex(DatabaseHelper.TICKET_V_IN_TIME));
                       String vout = cursor.getString(cursor.getColumnIndex(DatabaseHelper.TICKET_V_OUT_TIME));
                       int i = cursor.getPosition() + 1;
                       sheet.addCell(new Label(0, i, Rno));
                       sheet.addCell(new Label(1, i, vno));
                       sheet.addCell(new Label(2, i, vtype));
                       sheet.addCell(new Label(3, i, vin));
                       sheet.addCell(new Label(4, i, vout));
                   } while (cursor.moveToNext());
               }
   
               //closing cursor
               cursor.close();
               workbook.write();
               workbook.close();
   
               Intent intent = new Intent(Intent.ACTION_SEND);
               intent.setType("*/*");
               intent.putExtra(Intent.EXTRA_EMAIL, new String[]{"email@example.com"});
               intent.putExtra(Intent.EXTRA_SUBJECT, "subject here");
               intent.putExtra(Intent.EXTRA_TEXT, "body text");
               if (!file.exists() || !file.canRead()) {
                   Toast.makeText(ViewLog.this, "Attachment Error", Toast.LENGTH_SHORT).show();
                   return;
               }
               Uri uri = Uri.fromFile(file);
   
               intent.putExtra(Intent.EXTRA_STREAM, uri);
               startActivityForResult(Intent.createChooser(intent, "Send email..."),ViewLog.REQUEST_WRITE_STORAGE);
           } catch (Exception e) {
               System.out.println("is exception raises during sending mail" + e);
           }
       }
   });
   

这是我点击此按钮后遇到的错误

I/System.out：发送期间是否引发异常 mailjava.io.FileNotFoundException： /storage/emulated/0/Documents/Report-020219.xlx（没有这样的文件或 目录）

Manifest.xml

    <?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="mypackagename">
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <uses-permission android:name="android.permission.GET_ACCOUNTS" />
    <uses-permission android:name="android.permission.READ_PROFILE" />
    <uses-permission android:name="android.permission.READ_CONTACTS" />
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.INTERNET" />
<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme"
    tools:ignore="GoogleAppIndexingWarning">
    <activity android:name=".VehicleSetup"></activity>
    <activity android:name=".About" />
    <activity android:name=".Parked" />
    <activity android:name=".AppSetup" />
    <activity android:name=".ViewLog" />
    <activity android:name=".LoginActivity" />
    <activity android:name=".Main" />
    <activity android:name=".Splashscreen">
      <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

我希望将此文件写入任何位置，但应作为附件在任何电子邮件客户端或 whatsapp 中使用

Answer 1

我刚刚发现了导致 mailjava.io.FileNotFoundException 的错误，因为只创建了实例而不是实际文件。

基本上，有两个错误是造成这种情况的原因。

1. 我在类本身中声明了 File 实例（文件）（而不是在 onClick 方法中）。由于它是在类变量中声明的，因此它会抛出 FileUriExposedException，这确实暴露了在 catch 块中捕获的 URI。
2. 我试图从内部缓存目录中获取该文件，根据this issue，这在 GMail 5.0 中是不允许的

解决方案

1. 在 onClick 方法本身中声明文件实例，以便不暴露 URI。
2. 在 ExternalSD 中创建文件，因为 GMail 5.0 可以访问并接受它

imbtnMail.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                try {
                    Cursor cursor = dbManager.fetch(DatabaseHelper.TICKET_TABLE);
                    File file = new File(Environment.getExternalStorageDirectory(),"Report-"+DateUtil.timeMilisToString(System.currentTimeMillis(),"hh-MM-yy")+".xls");
                    Toast.makeText(getApplicationContext(),"File saved",Toast.LENGTH_LONG).show();

                    WorkbookSettings wbSettings = new WorkbookSettings();
                    wbSettings.setLocale(new Locale("en", "EN"));
                    WritableWorkbook workbook;
                    workbook = Workbook.createWorkbook(file, wbSettings);
                    WritableSheet sheet = workbook.createSheet("Daily Report", 0);

                    // column and row
                    sheet.addCell(new Label(0, 0, "Pass Report"));
                    sheet.addCell(new Label(1, 0, "User"));

                    if (cursor.moveToFirst()) {
                        do {
                            String Rno = cursor.getString(cursor.getColumnIndex(DatabaseHelper.TICKET_RECEIPT));
                            String vno = cursor.getString(cursor.getColumnIndex(DatabaseHelper.TICKET_V_NO));
                            String vtype = cursor.getString(cursor.getColumnIndex(DatabaseHelper.TICKET_V_TYPE));
                            String vin = cursor.getString(cursor.getColumnIndex(DatabaseHelper.TICKET_V_IN_TIME));
                            String vout = cursor.getString(cursor.getColumnIndex(DatabaseHelper.TICKET_V_OUT_TIME));
                            int i = cursor.getPosition() + 1;
                            sheet.addCell(new Label(0, i, Rno));
                            sheet.addCell(new Label(1, i, vno));
                            sheet.addCell(new Label(2, i, vtype));
                            sheet.addCell(new Label(3, i, vin));
                            sheet.addCell(new Label(4, i, vout));
                        } while (cursor.moveToNext());
                    }

                    //closing cursor
                    cursor.close();
                    workbook.write();
                    workbook.close();

                    Intent intent = new Intent(Intent.ACTION_SEND);
                    intent.setType("text/plain");
                    intent.putExtra(Intent.EXTRA_EMAIL, new String[] {"email@example.com"});
                    intent.putExtra(Intent.EXTRA_SUBJECT, "subject here");
                    intent.putExtra(Intent.EXTRA_TEXT, "body text");
                    if (!file.exists() || !file.canRead()) {
                        Toast.makeText(getApplicationContext(), "Attachment Error", Toast.LENGTH_SHORT).show();
                        return;
                    }
                    Uri uri = Uri.fromFile(file);
                    intent.putExtra(Intent.EXTRA_STREAM, uri);
                    startActivity(Intent.createChooser(intent, "Send email..."));
                }
                catch (Exception e){e.printStackTrace();}
            }
        });