短信主界面：src/com/android/mms/ui/ConversationList.java
res/layout/conversation_list_screen.xml
短信主界面 listView Item 界面：res/layout/conversation_list_item.xml

发送界面 res/layout/compose_message_activity.xml
发送Activity : src/com/android/mms/ui/ComposeMessageActivity.java

发送按钮id：send_button_sms

发送代码的方法 ：一下都是关联的
confirmSendMessageIfNeeded
sendMsimMessage(boolean bCheckEcmMode, int subscription)
sendMsimMessage(boolean bCheckEcmMode)
sendMessage(boolean bCheckEcmMode)
createGroupChatOrSendGroupChatMessage(String recipient)
RcsApiManager.getGroupChatApi().create(subject, users);

删除相关的信息：
ConversationList.java下：

Cursor cursor = mListAdapter.getCursor();
    if (cursor != null && cursor.getPosition() >= 0) {
        Conversation conv = Conversation.from(ConversationList.this, cursor);
        long threadId = conv.getThreadId();
        switch (item.getItemId()) {
        case MENU_DELETE: {
            confirmDeleteThread(threadId, mQueryHandler);
            break;
        }
        case MENU_VIEW: {
            openThread(threadId);
            break;
        }
MessageListItem.java 短信内容（是否是文字短信）
 private void updateBodyTextView() {
 if (mMessageItem.isMms() && mMessageItem.mLayoutType == LayoutModel.LAYOUT_TOP_TEXT) {
 mBodyTextView = mBodyTopTextView;
 } else {
 mBodyTextView = mBodyButtomTextView;
 }
 if (!isRcsMessage() || mMessageItem.mRcsType == RcsUtils.RCS_MSG_TYPE_MAP) {
 mBodyTextView.setVisibility(View.VISIBLE);
 }
 }public void saveDraft(final boolean isStopping) 这个方法是判断是否保存草稿箱
private void LaunchMsimDialog(final boolean bCheckEcmMode) 这个是判断选择哪一张卡