Xamarin Android，使用带有选择和选择参数的 CursorLoader 获取联系人手机号码

Question

我正在尝试使用 Intent 获取用户从 Android 中的联系人列表中选择的联系人的详细联系信息，代码如下：

Intent Intent = new Intent(Intent.ActionPick, ContactsContract.Contacts.ContentUri);            
        Intent.SetType(ContactsContract.Contacts.ContentType);
        StartActivityForResult(Intent, 3);

现在在 Intent 结果上，我运行以下代码来获取特定的联系信息：

public override void OnActivityResult(int requestCode, int resultCode, Intent data)
    {           
        if (requestCode == 3 && resultCode == -1 && data != null) //result code -1 means OK 0 Means cancelled Result.Ok
        {
            var ContactData = data.Data;
            string ID = "";
            string name = "";
            string address = "";
            byte[] picture = new byte[0];
            List<string> numbers = new List<string>();
            List<string> emails = new List<string>();
            string mobile = "";
            string email = "";
            string selectionString  = "id = ?";



            string[] columnsNames = new string[] {
                ContactsContract.Contacts.InterfaceConsts.Id,
                ContactsContract.Contacts.InterfaceConsts.DisplayName,
                ContactsContract.Contacts.InterfaceConsts.PhotoUri
            };

            var loader = new CursorLoader(Statics.mainActivity, ContactData, null, null, null, null);                
            var cursor = (ICursor)loader.LoadInBackground();


            if (cursor.MoveToFirst())
            {
                ID = cursor.GetString(cursor.GetColumnIndex(columnsNames[0]));
                name = cursor.GetString(cursor.GetColumnIndex(columnsNames[1]));
                picture = cursor.GetBlob(cursor.GetColumnIndex(columnsNames[2]));                  
            }

            //Store Contact ID
            string[] selectionStringArgs = new string[] { ID };

            //Phone Numbers
            string[] columnsNames2 = new string[] {
                ContactsContract.CommonDataKinds.Phone.Number                 
            };

            var loader2 = new CursorLoader(Statics.mainActivity, ContactsContract.CommonDataKinds.Phone.ContentUri, columnsNames2, selectionString, selectionStringArgs, null);
            var cursor2 = (ICursor)loader2.LoadInBackground();

            while (cursor2.MoveToNext())
            {
                numbers.Add(cursor2.GetString(cursor2.GetColumnIndex(columnsNames2[0])));
            }

            //Email Address
            string[] columnsNames3 = new string[] {
                ContactsContract.CommonDataKinds.Email.Address
            };


            var loader3 = new CursorLoader(Statics.mainActivity, ContactsContract.CommonDataKinds.Email.ContentUri, columnsNames3, selectionString, selectionStringArgs, null);
            var cursor3 = (ICursor)loader3.LoadInBackground();

            while (cursor3.MoveToNext())
            {
                emails.Add(cursor3.GetString(cursor3.GetColumnIndex(columnsNames3[0])));
            }



            int TempRecepitntID = 0;
            EmployeesViewModel tempRecipent = new EmployeesViewModel();
            TempRecepitntID = Statics.mainActivity.currentViewModel.SelectedChat.ReceiverEmployee;

            foreach (EmployeesViewModel evm in Statics.mainActivity.currentViewModel.Employees)
            {
                if (evm.ID == TempRecepitntID)
                    tempRecipent = evm;
            }

            new Android.Support.V7.App.AlertDialog.Builder(Statics.mainActivity)
                   .SetPositiveButton("Yes", (sender1, args) =>
                   {
                       Statics.mainActivity.currentViewModel.AddMessage(picture, tempRecipent, Statics.mainActivity.currentViewModel.SelectedChat.ID, "contact", 0, "", name, numbers[0], mobile, email, address);
                   })
                   .SetNegativeButton("No", (sender1, args) =>
                   {
                        // cancel
                    })
                   .SetMessage("Are you shure you want to send?")
                   .SetTitle("System Message")
                   .Show();                
        }
    }

问题是我只想检索用户选择的联系人的信息，但我得到的是所有其他联系人数据都被检索所以我尝试通过设置字符串 selectionString = "id 来使用 CursorLoader 的 selection 和 selectionargs 参数= ?”;和 selectionArgs 到 string[] selectionStringArgs = new string[] { ID }; ID 值是从以下代码中检索的：

            if (cursor.MoveToFirst())
            {
                ID = cursor.GetString(cursor.GetColumnIndex(columnsNames[0]));
                name = cursor.GetString(cursor.GetColumnIndex(columnsNames[1]));
                picture = cursor.GetBlob(cursor.GetColumnIndex(columnsNames[2]));                  
            }

            //Store Contact ID
            string[] selectionStringArgs = new string[] { ID };

            //Phone Numbers
            string[] columnsNames2 = new string[] {
                ContactsContract.CommonDataKinds.Phone.Number                 
            };

但现在它返回 0 个结果，我在互联网上找不到任何适用于 Xamarin android 的内容，请帮助。

谢谢，

Answer 1

终于找到了解决办法，我在cursorloader方法的选择参数中使用了如下字符串：

string selectionString = ContactsContract.CommonDataKinds.Phone.InterfaceConsts.ContactId + "=" + ID;

现在只检索选定的联系人号码。

我希望这对其他人有帮助。

Answer 2

在@TMSL的附加信息中，我在这个块之后添加了代码

if (cursor.MoveToFirst())
                    {
                        ID = cursor.GetString(cursor.GetColumnIndex(columnsNames[0]));
                        name = cursor.GetString(cursor.GetColumnIndex(columnsNames[1]));
                        picture = cursor.GetBlob(cursor.GetColumnIndex(columnsNames[2]));

                    }

这里

            selectionString = ContactsContract.CommonDataKinds.Phone.InterfaceConsts.ContactId + "=" + ID;

然后我把变量Loader2定义中用到的参数改了，把selectionStringArgs转换成null。

var loader2 = new CursorLoader(this.Activity, ContactsContract.CommonDataKinds.Phone.ContentUri, columnsNames2, selectionString, null,null);
                    var cursor2 = (ICursor)loader2.LoadInBackground();

我从 xamarin 指南中找到了 this 文档

• Uri – ContentProvider 的完全限定名称。
• 投影 - 指定为光标选择哪些列。
• 选择 – 类似于 SQL WHERE 子句。
• SelectionArgs – 要在选择中替换的参数。
• SortOrder – 排序依据的列。

所以，@TMSAL 代码中使用的变量selectionStringArgs 不能使用“contact_id = 2700”之类的值，因为 CursorLoader 的参数SelectionArgs 不是过滤器而不是“选择中要替换的参数"

我希望这对其他人也有帮助。