在商城第一篇的開篇當中,咱們看到商城的效果圖裏面有一個底部導航欄效果,以下圖所示:java
今天咱們就來實現商城底部導航欄,最終效果圖以下所示:android
那麼這種效果是如何實現,實現的方式有不少種,最多見的就是使用Fragment+RadioButton去實現。下面咱們來寫一個例子緩存
首先咱們先在activity_mian.xml定義佈局,整個佈局的外面是線性佈局,上面是幀佈局切換不一樣的Fragment,底下是RadioGroup嵌套的是RadioButton。代碼以下所示:app
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#ffffff" android:orientation="vertical"> <FrameLayout android:id="@+id/frameLayout" android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1" /> <RadioGroup android:id="@+id/rg_main" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:background="@drawable/home_bottom_parent_bg" android:orientation="horizontal"> <RadioButton android:id="@+id/rb_home" style="@style/MainButtonStyle" android:drawableTop="@drawable/home_button_selector" android:text="首頁" /> <RadioButton android:id="@+id/rb_type" style="@style/MainButtonStyle" android:drawableTop="@drawable/type_button_selector" android:text="分類" /> <RadioButton android:id="@+id/rb_community" style="@style/MainButtonStyle" android:drawableTop="@drawable/community_button_selector" android:paddingTop="10dp" android:text="發現" /> <RadioButton android:id="@+id/rb_cart" style="@style/MainButtonStyle" android:drawableTop="@drawable/cart_button_selector" android:text="購物車" /> <RadioButton android:id="@+id/rb_user" style="@style/MainButtonStyle" android:drawableTop="@drawable/user_button_selector" android:text="我的中心" /> </RadioGroup> </LinearLayout>
注意:上面還有樣式和drawable,下面咱們一個一個的來完善。ide
首先來看樣式,打開【res】—【values】—【styles】,代碼以下所示:佈局
<style name="MainButtonStyle">
<!-- Customize your theme here. -->
<item name="android:layout_width">0dp</item>
<item name="android:layout_height">wrap_content</item>
<item name="android:layout_weight">1</item>
<item name="android:button">@null</item>
<!-- <item name="android:drawablePadding">3dp</item>-->
<item name="android:textColor">@drawable/bottom_button_text_selector</item>
<item name="android:textSize">10sp</item>
<item name="android:gravity">center</item>
</style>
裏面還有一個<item name="android:textColor">@drawable/bottom_button_text_selector</item>,這個是設置圖片和文字的顏色,在drawable的目錄下建bottom_button_text_selector,代碼以下所示:this
<?xml version="1.0" encoding="utf-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:color="#535353" android:state_checked="false"></item> <item android:color="#ff4040" android:state_checked="true"></item> </selector>
接着咱們繼續來完善drawable,有【首頁】【分類】【發現】【購物車】【我的中心】,寫法都是同樣的,這裏用【首頁】來作例子,在drawable目錄下建home_button_selector,代碼以下所示:spa
<?xml version="1.0" encoding="utf-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:drawable="@drawable/main_home" android:state_checked="false"></item> <item android:drawable="@drawable/main_home_press" android:state_checked="true"></item> </selector>
接下來看MainActivity中的代碼,代碼以下:3d
package com.nyl.shoppingmall.app.activity; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentTransaction; import android.widget.FrameLayout; import android.widget.RadioGroup; import com.nyl.shoppingmall.R; import com.nyl.shoppingmall.base.BaseFragment; import com.nyl.shoppingmall.community.fragment.CommunityFragment; import com.nyl.shoppingmall.home.fragment.HomeFragment; import com.nyl.shoppingmall.shoppingcart.fragment.ShoppingCartFragment; import com.nyl.shoppingmall.type.fragment.TypeCartFragment; import com.nyl.shoppingmall.user.fragment.UserCartFragment; import java.util.ArrayList; import butterknife.Bind; import butterknife.ButterKnife; public class MainActivity extends FragmentActivity{ @Bind(R.id.frameLayout) FrameLayout frameLayout; @Bind(R.id.rg_main) RadioGroup rgMain; //裝fragment的實例集合 private ArrayList<BaseFragment> fragments; private int position = 0; //緩存Fragment或上次顯示的Fragment private Fragment tempFragment; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //ButterKnife和當前Activity綁定 ButterKnife.bind(this); //初始化Fragment initFragment(); //設置RadioGroup的監聽 initListener(); } private void initListener() { rgMain.check(R.id.rb_home); rgMain.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() { @Override public void onCheckedChanged(RadioGroup radioGroup, int i) { switch (i){ case R.id.rb_home: //首頁 position = 0; break; case R.id.rb_type: //分類 position = 1; break; case R.id.rb_community: //發現 position = 2; break; case R.id.rb_cart: //購物車 position = 3; break; case R.id.rb_user: //我的中心 position = 4; break; default: position = 0; break; } //根據位置獲得相應的Fragment BaseFragment baseFragment = getFragment(position); /** * 第一個參數: 上次顯示的Fragment * 第二個參數: 當前正要顯示的Fragment */ switchFragment(tempFragment,baseFragment); } }); } /** * 添加的時候按照順序 */ private void initFragment(){ fragments = new ArrayList<>(); fragments.add(new HomeFragment()); fragments.add(new TypeCartFragment()); fragments.add(new CommunityFragment()); fragments.add(new ShoppingCartFragment()); fragments.add(new UserCartFragment()); } /** * 根據位置獲得對應的 Fragment * @param position * @return */ private BaseFragment getFragment(int position){ if(fragments != null && fragments.size()>0){ BaseFragment baseFragment = fragments.get(position); return baseFragment; } return null; } /** * 切換Fragment * @param fragment * @param nextFragment */ private void switchFragment(Fragment fragment,BaseFragment nextFragment){ if (tempFragment != nextFragment){ tempFragment = nextFragment; if (nextFragment != null){ FragmentTransaction transaction = getSupportFragmentManager().beginTransaction(); //判斷nextFragment是否添加成功 if (!nextFragment.isAdded()){ //隱藏當前的Fragment if (fragment != null){ transaction.hide(fragment); } //添加Fragment transaction.add(R.id.frameLayout,nextFragment).commit(); }else { //隱藏當前Fragment if (fragment != null){ transaction.hide(fragment); } transaction.show(nextFragment).commit(); } } } } }
首先使用ButterKnife初始化佈局控件,而後在onCreate方法中初始化Fragment和綁定RadioGroup的選中改變事件,爲了方便初始化Fragment,寫了一個initFragment方法,在方法內部建立HomeFragment,TypeCartFragment,CommunityFragment,ShoppingCartFragment,UserCartFragment四個Fragment實例,而後使用一個fragments集合存儲這四個實例。接下來寫一個switchFragment方法,用於切換顯示指定的Fragmetn,當RadioGroup的選中改變時,首先根據選中的位置獲取到對應的Fragment,而後將獲取到的Fragment傳入到switchFragment方法中進行顯示。因爲每次RadioGroup的選中改變獲取到的Fragment都不同,從而能夠實現根據選中的RadioGroup展現不一樣的Fragment效果,也就是常見的Tab切換效果。code
Activity中用到的HomeFragment,TypeCartFragment,CommunityFragment,ShoppingCartFragment,UserCartFragment這四個Fragment的代碼比較簡單,以HomeFragment爲例,代碼以下:
package com.nyl.shoppingmall.home.fragment; import android.util.Log; import android.view.Gravity; import android.view.View; import android.widget.TextView; import com.nyl.shoppingmall.base.BaseFragment; /** * 首頁Fragment */ public class HomeFragment extends BaseFragment { private final static String TAG = HomeFragment.class.getSimpleName(); private TextView textView; @Override public View initView() { textView = new TextView(mContext); textView.setGravity(Gravity.CENTER); textView.setTextSize(25); Log.e(TAG,"主頁面的Fragment的UI被初始化了"); return textView; } @Override public void initData() { super.initData(); textView.setText("首頁"); Log.e(TAG,"主頁面的Fragment的數據被初始化了"); } }
HomeFragment繼承自BaseFragment,而後重寫父類的initView方法和initData方法,BaseFragment的代碼以下:
package com.nyl.shoppingmall.base; import android.content.Context; import android.os.Bundle; import android.support.annotation.Nullable; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; /** * 基類Fragment * 首頁:HomeFragment * 分類:TypeFragment * 發現:CommunityFragment * 購物車:ShoppingCartFragment * 用戶中心:UserFragment * 等等都要繼承該類 */ public abstract class BaseFragment extends Fragment{ protected Context mContext; /** * 當該類被系統建立的時候回調 * @param savedInstanceState */ @Override public void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); mContext = getActivity(); } @Nullable @Override public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { return initView(); } //抽象類,由孩子實現,實現不一樣的效果 public abstract View initView(); @Override public void onActivityCreated(@Nullable Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); initData(); } /** * 當子類須要聯網請求數據的時候,能夠重寫該方法,該方法中聯網請求 */ public void initData() { } }
其他幾個Fragment的代碼也相似,這裏就再也不細說了,使用Fragment+RadioButton實現底部導航欄的思路和代碼實現就是這樣的。