从Xamarin.Android App添加电子邮件正文文本并发送电子邮件

Question

我正在尝试使用输入到简单Xamarin.Android移动应用程序中的用户提供的信息来创建和发送电子邮件（使用Gmail应用程序）。 我是Xamarin.Android的新手，无法在线找到有关此问题的明确指南。

使用下面的代码，我可以收集文本并创建电子邮件意图，该意图使用用户提供的电子邮件地址和硬编码的主题行。 但是，将正文添加到电子邮件中的代码无法正常工作（Gmail应用已打开，电子邮件地址和主题行正确，但是电子邮件的正文为空）。

[Activity(Label = @"HelloWorld-TestMobileApp", MainLauncher = true, Icon = "@drawable/icon")]
public class MainActivity : Activity
{
    public int ClickCount { get; set; } = 0;
    public string EmailAddress { get; set; }
    public string EmailText { get; set; }

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Main);

        // Get our buttons from the layout resource,
        // and attach a events to them
        Button clickIncrementerButton = FindViewById<Button>(Resource.Id.ClickIncrementer);
        Button sendEmailButton = FindViewById<Button>(Resource.Id.sendEmailButton);
        EditText enterEmailAddressButton = FindViewById<EditText>(Resource.Id.editEmail);
        EditText enterEmailTextButton = FindViewById<EditText>(Resource.Id.emailText);

        clickIncrementerButton.Click += delegate
        {
            ClickCount++;
            clickIncrementerButton.Text = string.Format("{0} clicks!", ClickCount);
        };

        enterEmailAddressButton.TextChanged += delegate
        {
            EmailAddress = enterEmailAddressButton.Text;
        };

        enterEmailTextButton.TextChanged += delegate
        {
            EmailText = enterEmailTextButton.Text;
        };

        sendEmailButton.Click += delegate
        {
            List<string> emailBody = new List<string>
            {
                "Hello from Xamarin.Android!\n",
                "Number of clicks = " + ClickCount + "\n",
                EmailText
            };

            var email = new Intent(Intent.ActionSend);

            email.PutExtra(Intent.ExtraEmail, new string[] {EmailAddress}); // Working 09/24/2016
            email.PutExtra(Intent.ExtraSubject, "Hello World Email");       // Working 09/24/2016
            email.PutStringArrayListExtra(Intent.ExtraText, emailBody);     // NOT Working 09/24/2016

            email.SetType("message/rfc822");

            try
            {
                StartActivity(email);
            }
            catch (Android.Content.ActivityNotFoundException ex)
            {
                Toast.MakeText(this, "There are no email applications installed.", ToastLength.Short).Show();
            }
        };
    }

谁能告诉我如何在不对整个正文文本字符串进行硬编码的情况下，对电子邮件正文进行预格式化并将其包含在Intent中？ （也欢迎其他有关Xamarin.Android应用程序的电子邮件发送评论和指南！）

我希望能够包含用户在应用程序中输入的信息，因此我希望能够在正文中包含变量（我不想对正文进行硬编码）。

谢谢！

Answer 1

问题在于主体也必须是文本。 通过将行更改为将字符串列表组合为一个字符串：

email.PutExtra(Intent.ExtraText, string.Join("", emailBody));

顺便说一句：您不需要注册TextViews的更改。 打开意图时，您可以直接读取它们的值。 我会这样写：

[Activity(Label = @"HelloWorld-TestMobileApp", MainLauncher = true, Icon = "@drawable/icon")]
public class MainActivity2 : Activity
{
    private Button _incrementerButton;
    private Button _emailButton;
    private EditText _addressField;
    private EditText _emailField;
    public int ClickCount { get; set; } = 0;

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Main);

        // Get our buttons from the layout resource,
        // and attach a events to them
        _incrementerButton = FindViewById<Button>(Resource.Id.ClickIncrementer);
        _emailButton = FindViewById<Button>(Resource.Id.sendEmailButton);
        _addressField = FindViewById<EditText>(Resource.Id.editEmail);
        _emailField = FindViewById<EditText>(Resource.Id.emailText);
    }

    protected override void OnStart()
    {
        base.OnStart();
        // register event handlers
        _incrementerButton.Click += IncrementerButtonOnClick;
        _emailButton.Click += SendEmailButtonOnClick;
    }

    protected override void OnStop()
    {
        //deregister event handlers
        _emailButton.Click -= SendEmailButtonOnClick;            
        _incrementerButton.Click -= IncrementerButtonOnClick;
        base.OnStop();
    }

    private void IncrementerButtonOnClick(object sender, EventArgs eventArgs)
    {
        ClickCount++;
        _incrementerButton.Text = string.Format("{0} clicks!", ClickCount);
    }

    private void SendEmailButtonOnClick(object sender, EventArgs eventArgs)
    {
        // build the body
        var emailText = new StringBuilder();
        emailText.AppendLine("Hello from Xamarin.Android!");
        emailText.AppendFormat("Number of clicks = {0}", ClickCount);
        emailText.AppendLine();
        emailText.Append(_emailField.Text);

        // build the intent
        var email = new Intent(Intent.ActionSend);
        email.PutExtra(Intent.ExtraEmail, new string[] { _addressField.Text }); 
        email.PutExtra(Intent.ExtraSubject, "Hello World Email"); 
        email.PutExtra(Intent.ExtraText, emailText.ToString()); 

        email.SetType("message/rfc822");

        try
        {
            StartActivity(email);
        }
        catch (Android.Content.ActivityNotFoundException ex)
        {
            Toast.MakeText(this, "There are no email applications installed.", ToastLength.Short).Show();
        }
    }
}

我正在使用StringBuilder创建电子邮件正文。 并在方法而不是匿名委托中实现事件处理程序。 原因是，我希望能够通过OnStop -=取消注册事件处理程序。 这始终很重要，因为未注销的事件处理程序将导致内存泄漏。