来自Android开发者文档:

public void composeEmail(String[] addresses, String subject) {
    Intent intent = new Intent(Intent.ACTION_SENDTO);
    intent.setData(Uri.parse("mailto:")); // only email apps should handle this
    intent.putExtra(Intent.EXTRA_EMAIL, addresses);
    intent.putExtra(Intent.EXTRA_SUBJECT, subject);
    if (intent.resolveActivity(getPackageManager()) != null) {
        startActivity(intent);
    }
}

Intent emailIntent = new Intent(Intent.ACTION_SENDTO, Uri.fromParts("mailto", email, null));
if (emailIntent.resolveActivity(context.getPackageManager()) != null) {
    context.startActivity(Intent.createChooser(emailIntent, "Send Email..."));
} else {
    Toast.makeText(context, "No apps can perform this action.", Toast.LENGTH_SHORT).show();
}

这些答案大多只适用于不发送附件的简单情况。在我的情况下，我有时需要发送附件(ACTION_SEND)或两个附件(ACTION_SEND_MULTIPLE)。

所以我从这条线索中选择了最好的方法并将它们结合起来。它使用支持库的ShareCompat。但是我只展示了匹配ACTION_SENDTO和"mailto:" uri的应用程序。这样我得到的只有附件支持的电子邮件应用程序列表:

fun Activity.sendEmail(recipients: List<String>, subject: String, file: Uri, text: String? = null, secondFile: Uri? = null) {
    val originalIntent = createEmailShareIntent(recipients, subject, file, text, secondFile)
    val emailFilterIntent = Intent(Intent.ACTION_SENDTO, Uri.parse("mailto:"))
    val originalIntentResults = packageManager.queryIntentActivities(originalIntent, 0)
    val emailFilterIntentResults = packageManager.queryIntentActivities(emailFilterIntent, 0)
    val targetedIntents = originalIntentResults
            .filter { originalResult -> emailFilterIntentResults.any { originalResult.activityInfo.packageName == it.activityInfo.packageName } }
            .map {
                createEmailShareIntent(recipients, subject, file, text, secondFile).apply { `package` = it.activityInfo.packageName }
            }
            .toMutableList()
    val finalIntent = Intent.createChooser(targetedIntents.removeAt(0), R.string.choose_email_app.toText())
    finalIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, targetedIntents.toTypedArray())
    startActivity(finalIntent)
}

private fun Activity.createEmailShareIntent(recipients: List<String>, subject: String, file: Uri, text: String? = null, secondFile: Uri? = null): Intent {
    val builder = ShareCompat.IntentBuilder.from(this)
            .setType("message/rfc822")
            .setEmailTo(recipients.toTypedArray())
            .setStream(file)
            .setSubject(subject)
    if (secondFile != null) {
        builder.addStream(secondFile)
    }
    if (text != null) {
        builder.setText(text)
    }
    return builder.intent
}

根据Android开发者官方文档，这是发送电子邮件意图的正确方式

添加以下代码行到你的应用程序:

Intent intent = new Intent(Intent.ACTION_SEND);//common intent 
intent.setData(Uri.parse("mailto:")); // only email apps should handle this

可选:添加主体和主题，就像这样

intent.putExtra(Intent.EXTRA_SUBJECT, "Your Subject Here");
intent.putExtra(Intent.EXTRA_TEXT, "E-mail body" );

你的问题里已经加了这句话

intent.putExtra(Intent.EXTRA_EMAIL, new String[]{"hello@example.com"});

这将是收件人的地址，这意味着用户将向您(开发人员)发送电子邮件。

来自Android开发者文档:

public void composeEmail(String[] addresses, String subject) {
    Intent intent = new Intent(Intent.ACTION_SENDTO);
    intent.setData(Uri.parse("mailto:")); // only email apps should handle this
    intent.putExtra(Intent.EXTRA_EMAIL, addresses);
    intent.putExtra(Intent.EXTRA_SUBJECT, subject);
    if (intent.resolveActivity(getPackageManager()) != null) {
        startActivity(intent);
    }
}

这就是我使用的方法，对我来说很有效:

//variables
String subject = "Whatever subject you want";
String body = "Whatever text you want to put in the body";
String intentType = "text/html";
String mailToParse = "mailto:";

//start Intent
Intent variableName = new Intent(Intent.ACTION_SENDTO);
variableName.setType(intentType);
variableName.setData(Uri.parse(mailToParse));
variableName.putExtra(Intent.EXTRA_SUBJECT, subject);
variableName.putExtra(Intent.EXTRA_TEXT, body);

startActivity(variableName);

这也可以让用户选择他们喜欢的电子邮件应用程序。唯一不允许你做的是设置收件人的电子邮件地址。