最好的(也是最简单的)方法是使用Intent:

Intent i = new Intent(Intent.ACTION_SEND);
i.setType("message/rfc822");
i.putExtra(Intent.EXTRA_EMAIL  , new String[]{"recipient@example.com"});
i.putExtra(Intent.EXTRA_SUBJECT, "subject of email");
i.putExtra(Intent.EXTRA_TEXT   , "body of email");
try {
    startActivity(Intent.createChooser(i, "Send mail..."));
} catch (android.content.ActivityNotFoundException ex) {
    Toast.makeText(MyActivity.this, "There are no email clients installed.", Toast.LENGTH_SHORT).show();
}

否则你就得自己写客户端了。

Kotlin版本，只显示电子邮件客户端(没有联系人等):

    with(Intent(Intent.ACTION_SEND)) {
        type = "message/rfc822"
        data = Uri.parse("mailto:")
        putExtra(Intent.EXTRA_EMAIL, arrayOf("user@example.com"))
        putExtra(Intent.EXTRA_SUBJECT,"YOUR SUBJECT")
        putExtra(Intent.EXTRA_TEXT, "YOUR BODY")
        try {
            startActivity(Intent.createChooser(this, "Send Email with"))
        } catch (ex: ActivityNotFoundException) {
            // No email clients found, might show Toast here
        }
    }

其他解决方案可以是

Intent emailIntent = new Intent(android.content.Intent.ACTION_SEND);
emailIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
emailIntent.setType("plain/text");
emailIntent.setClassName("com.google.android.gm", "com.google.android.gm.ComposeActivityGmail");
emailIntent.putExtra(android.content.Intent.EXTRA_EMAIL, new String[]{"someone@gmail.com"});
emailIntent.putExtra(android.content.Intent.EXTRA_SUBJECT, "Yo");
emailIntent.putExtra(android.content.Intent.EXTRA_TEXT, "Hi");
startActivity(emailIntent);

假设大多数android设备已经安装了GMail应用程序。

这个函数首先直接意图gmail发送电子邮件，如果gmail没有找到，然后提升意图选择器。我在许多商业应用程序中使用了这个功能，它工作得很好。希望对你有所帮助:

public static void sentEmail(Context mContext, String[] addresses, String subject, String body) {

    try {
        Intent sendIntentGmail = new Intent(Intent.ACTION_VIEW);
        sendIntentGmail.setType("plain/text");
        sendIntentGmail.setData(Uri.parse(TextUtils.join(",", addresses)));
        sendIntentGmail.setClassName("com.google.android.gm", "com.google.android.gm.ComposeActivityGmail");
        sendIntentGmail.putExtra(Intent.EXTRA_EMAIL, addresses);
        if (subject != null) sendIntentGmail.putExtra(Intent.EXTRA_SUBJECT, subject);
        if (body != null) sendIntentGmail.putExtra(Intent.EXTRA_TEXT, body);
        mContext.startActivity(sendIntentGmail);
    } catch (Exception e) {
        //When Gmail App is not installed or disable
        Intent sendIntentIfGmailFail = new Intent(Intent.ACTION_SEND);
        sendIntentIfGmailFail.setType("*/*");
        sendIntentIfGmailFail.putExtra(Intent.EXTRA_EMAIL, addresses);
        if (subject != null) sendIntentIfGmailFail.putExtra(Intent.EXTRA_SUBJECT, subject);
        if (body != null) sendIntentIfGmailFail.putExtra(Intent.EXTRA_TEXT, body);
        if (sendIntentIfGmailFail.resolveActivity(mContext.getPackageManager()) != null) {
            mContext.startActivity(sendIntentIfGmailFail);
        }
    }
}

试试这个:

String mailto = "mailto:bob@example.org" +
    "?cc=" + "alice@example.com" +
    "&subject=" + Uri.encode(subject) +
    "&body=" + Uri.encode(bodyText);

Intent emailIntent = new Intent(Intent.ACTION_SENDTO);
emailIntent.setData(Uri.parse(mailto));

try {
    startActivity(emailIntent);
} catch (ActivityNotFoundException e) {
    //TODO: Handle case where no email app is available
}

上面的代码将打开用户最喜欢的电子邮件客户端预填充的电子邮件准备发送。

源

使用. settype ("message/rfc822")或者选择器会显示所有(许多)支持发送意图的应用程序。