为了让电子邮件应用程序来解决你的意图，你需要指定ACTION_SENDTO作为动作和mailto作为数据。

private void sendEmail(){

    Intent emailIntent = new Intent(Intent.ACTION_SENDTO);
    emailIntent.setData(Uri.parse("mailto:" + "recipient@example.com")); // You can use "mailto:" if you don't know the address beforehand.
    emailIntent.putExtra(Intent.EXTRA_SUBJECT, "My email's subject");
    emailIntent.putExtra(Intent.EXTRA_TEXT, "My email's body");
    
    try {
        startActivity(Intent.createChooser(emailIntent, "Send email using..."));
    } catch (android.content.ActivityNotFoundException ex) {
        Toast.makeText(Activity.this, "No email clients installed.", Toast.LENGTH_SHORT).show();
    }

}

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。

/**
 * Will start the chosen Email app
 *
 * @param context    current component context.
 * @param emails     Emails you would like to send to.
 * @param subject    The subject that will be used in the Email app.
 * @param forceGmail True - if you want to open Gmail app, False otherwise. If the Gmail
 *                   app is not installed on this device a chooser will be shown.
 */
public static void sendEmail(Context context, String[] emails, String subject, boolean forceGmail) {

    Intent i = new Intent(Intent.ACTION_SENDTO);
    i.setData(Uri.parse("mailto:"));
    i.putExtra(Intent.EXTRA_EMAIL, emails);
    i.putExtra(Intent.EXTRA_SUBJECT, subject);
    if (forceGmail && isPackageInstalled(context, "com.google.android.gm")) {
        i.setPackage("com.google.android.gm");
        i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(i);
    } else {
        try {
            context.startActivity(Intent.createChooser(i, "Send mail..."));
        } catch (ActivityNotFoundException e) {
            Toast.makeText(context, "No email app is installed on your device...", Toast.LENGTH_SHORT).show();
        }
    }
}

/**
 * Check if the given app is installed on this devuice.
 *
 * @param context     current component context.
 * @param packageName The package name you would like to check.
 * @return True if this package exist, otherwise False.
 */
public static boolean isPackageInstalled(@NonNull Context context, @NonNull String packageName) {
    PackageManager pm = context.getPackageManager();
    if (pm != null) {
        try {
            pm.getPackageInfo(packageName, 0);
            return true;
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }
    }
    return false;
}

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

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。

我在我的应用程序中使用下面的代码。这显示准确的电子邮件客户端应用程序，如Gmail。

    Intent contactIntent = new Intent(Intent.ACTION_SENDTO, Uri.fromParts("mailto", getString(R.string.email_to), null));
    contactIntent.putExtra(Intent.EXTRA_SUBJECT, getString(R.string.email_subject));
    startActivity(Intent.createChooser(contactIntent, getString(R.string.email_chooser)));