Android開發完整項目案例-首頁底部欄數字和紅點

需求：

底部欄有通知或者未讀消息時顯示紅點或者數字紅點

效果圖：

思路：

其實沒什麼難點，就寫佈局，紅點用ImageView,數字紅點用TextView。
只不過ImageView的src用的是點9圖

關鍵代碼：

就一個xml

<?xml version="1.0" encoding="utf-8"?>

<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".modules.main.activity.MainActivity">

<FrameLayout
    android:id="@+id/fl_content"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintBottom_toTopOf="@id/ll_main_tab"/>

<LinearLayout
    android:id="@+id/ll_main_tab"
    android:layout_width="match_parent"
    android:layout_height="@dimen/d98px"
    android:background="@color/bg_15171a"
    android:gravity="center"
    android:orientation="horizontal"
    app:layout_constraintBottom_toBottomOf="parent">

    <RadioGroup
        android:id="@+id/rg_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:paddingTop="@dimen/d12px">

        <FrameLayout
            android:id="@+id/fl_home"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1">

            <RadioButton
                android:id="@+id/rb_home"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_gravity="center"
                android:button="@null"
                android:checked="true"
                android:drawableTop="@drawable/formal_main_home_button"
                android:gravity="center"
                android:text="首頁"
                android:textColor="@drawable/formal_main_nav_text_color"
                android:textSize="@dimen/s20px" />



            <TextView
                android:id="@+id/tv_home_red"
                android:layout_width="wrap_content"
                android:layout_height="@dimen/d32px"
                android:includeFontPadding="false"
                android:paddingLeft="@dimen/d10px"
                android:paddingRight="@dimen/d10px"
                android:background="@drawable/aliwx_unread_hint"
                android:gravity="center"
                android:layout_gravity="right"
                android:layout_marginRight="@dimen/d32px"
                android:textColor="@android:color/white"
                android:textSize="@dimen/s20px"
                android:visibility="gone"
                tools:visibility="visible"
                android:text="0" />
        </FrameLayout>

        <FrameLayout
            android:id="@+id/fl_discovery"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1">

            <RadioButton
                android:id="@+id/rb_discovery"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:button="@null"
                android:drawableTop="@drawable/formal_main_discovery_button"
                android:gravity="center"
                android:text="@string/discovery"
                android:textColor="@drawable/formal_main_nav_text_color"
                android:textSize="@dimen/s20px" />
        </FrameLayout>

        <FrameLayout
            android:id="@+id/fl_mood"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1">

            <RadioButton
                android:id="@+id/rb_mood"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:button="@null"
                android:drawableTop="@drawable/formal_main_mood_button"
                android:gravity="center"
                android:text="@string/mood"
                android:textColor="@drawable/formal_main_nav_text_color"
                android:textSize="@dimen/s20px" />
            <!--紅點-->
            <ImageView
                android:id="@+id/iv_mood_red"
                android:layout_width="@dimen/d18px"
                android:layout_height="@dimen/d18px"
                android:layout_gravity="right"
                android:layout_marginBottom="@dimen/d10px"
                android:layout_marginRight="20dp"
                android:scaleType="centerCrop"
                android:src="@drawable/aliwx_unread_hint"
                android:visibility="gone" />
        </FrameLayout>

        <FrameLayout
            android:id="@+id/fl_message"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1">

            <RadioButton
                android:id="@+id/rb_message"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:button="@null"
                android:drawableTop="@drawable/formal_main_message_button"
                android:gravity="center"
                android:text="@string/message"
                android:textColor="@drawable/formal_main_nav_text_color"
                android:textSize="@dimen/s20px" />

            

            <!--數字紅點-->
            <TextView
                android:id="@+id/tv_msg_unread_count"
                android:layout_width="wrap_content"
                android:layout_height="@dimen/d32px"
                android:includeFontPadding="false"
                android:paddingLeft="@dimen/d10px"
                android:paddingRight="@dimen/d10px"
                android:background="@drawable/aliwx_unread_hint"
                android:gravity="center"
                android:layout_gravity="right"
                android:layout_marginRight="@dimen/d32px"
                android:textColor="@android:color/white"
                android:textSize="@dimen/s20px"
                android:visibility="gone"
                tools:visibility="visible"
                tools:text="99" />
        </FrameLayout>

        <FrameLayout
            android:id="@+id/fl_me"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1">
            <RadioButton
                android:id="@+id/rb_me"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:button="@null"
                android:drawableTop="@drawable/formal_main_me_button"
                android:gravity="center"
                android:text="@string/me"
                android:textColor="@drawable/formal_main_nav_text_color"
                android:textSize="@dimen/s20px" />

            <ImageView
                android:id="@+id/iv_red_me"
                android:layout_width="@dimen/d18px"
                android:layout_height="@dimen/d18px"
                android:layout_gravity="right"
                android:layout_marginBottom="@dimen/d10px"
                android:layout_marginRight="20dp"
                android:scaleType="centerCrop"
                android:src="@drawable/aliwx_unread_hint"
                android:visibility="gone"/>
        </FrameLayout>
    </RadioGroup>
</LinearLayout>
</android.support.constraint.ConstraintLayout>