
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:app="http://schemas.android.com/apk/res-auto">
 
    <LinearLayout
        android:layout_height="match_parent"
        android:layout_width="match_parent"
        android:orientation="vertical"
        android:gravity="center_horizontal"
        android:padding="5dp">
 
        <ImageView
            android:id="@+id/iv_img"
            android:layout_height="50dp"
            android:layout_width="50dp"
            android:src="@mipmap/laoyou"
            android:scaleType="fitXY"/>
 
        <TextView
            android:id="@+id/tv_title"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="旅游"
            android:layout_marginTop="3dp"/>
 
    </LinearLayout>

2 DrawerLayout 滑动菜单

DrawerLayout 包含两个界面 , 一个主界面和一个隐藏界面。隐藏界面可以通过点击按钮或者滑动屏幕边缘显示出来，一般隐藏界面用来做菜单使用。

代码：


<?xml version="1.0" encoding="utf-8"?> <androidx.drawerlayout.widget.DrawerLayout                 xmlns:android="http://schemas.android.com/apk/res/android"             xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity3"> 
 
    <TextView 
        android:id="@+id/textView" 
        android:layout_width="match_parent" 
        android:layout_height="match_parent" 
        android:text="主界面" /> 
 
    <TextView 
        android:id="@+id/textView2"
        android:layout_gravity="start" 
        android:layout_width="match_parent" 
        android:layout_height="match_parent" 
        android:text="滑出页面" 
        android:background="#fff"/> 
 
</androidx.drawerlayout.widget.DrawerLayout>

3 Fragment

3.1 Fragment的概念

1. Fragment是依赖于 Activity 的，不能独立存在。

2. 一个 Activity 里可以有多个 Fragment 。

3. 一个 Fragment 可以被多个 Activity 重用。

4. Fragment有自己的生命周期，并能接收输入事件。

5. 可以在 Activity 运行时动态地添加或删除 Fragment 。

3.1.1 Fragment生命周期

Activity 加载 Fragment 的时候，依次调用：

onAttach() -> onCreate() -> onCreateView() ->onActivityCreated() -> onStart() ->onResume()

3.2 Fragment的静态加载

1. 定义 Fragment 的布局，就是 fragment 显示内容

fragment_footer.xml


<?xml version="1.0" encoding="utf-8"?> 
<FrameLayout 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" 
tools:context=".fragment.FooterFragment"> 
 
    <TextView 
        android:id="@+id/tv_footer" 
        android:layout_width="match_parent" 
        android:layout_height="80dp" 
        android:background="#83A8C5" 
        android:gravity="center" 
        android:textSize="24dp" 
        android:text="页尾" /> 
 
</FrameLayout>

2. 自定义一个 Fragment 类，需要继承 Fragment 或者它的子类，重写 onCreateView() 方法，在该方法

中调用 inflater.inflate() 方法加载 Fragment 的布局文件，接着返回加载的 view 对象。

FooterFragment.java


public class FooterFragment extends Fragment {
    // TODO: Rename parameter arguments, choose names that match 
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER 
    private static final String ARG_PARAM1 = "param1"; 
    private static final String ARG_PARAM2 = "param2"; 
    // TODO: Rename and change types of parameters 
    private String mParam1; private String mParam2; 
    public FooterFragment() {
         // Required empty public constructor 
    }
    /*** Use this factory method to create a new instance of 
    * this fragment using the provided parameters. 
    ** @param param1 Parameter 1. 
    * @param param2 Parameter 2. 
    * @return A new instance of fragment FooterFragment. 
    */ 
    // TODO: Rename and change types and number of parameters 
    public static FooterFragment newInstance(String param1, String param2) { 
        FooterFragment fragment = new FooterFragment(); 
        Bundle args = new Bundle(); 
        args.putString(ARG_PARAM1, param1); 
        args.putString(ARG_PARAM2, param2); 
        fragment.setArguments(args); 
        return fragment;
    }
    @Override public void onCreate(Bundle savedInstanceState) {                             
        super.onCreate(savedInstanceState); 
        if (getArguments() != null) { 
        mParam1 = getArguments().getString(ARG_PARAM1); 
        mParam2 = getArguments().getString(ARG_PARAM2); 
        } 
    }
    @Override
   publicViewonCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState{ 
        // Inflate the layout for this fragment 
        return inflater.inflate(R.layout.fragment_footer, container, false); 
    } 
}

3. 在需要加载 Fragment 的 Activity 对应的布局文件中添加 fragment 的标签，注意 name 属性是全限定

类名，就是要包含 Fragment 的包名。


<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity4"> 
 
    <fragment 
        android:id="@+id/headerFragment" 
        android:layout_width="match_parent" 
        android:layout_height="80dp" 
        android:layout_alignParentTop="true"
        android:name="com.hopu.cardviewdemo.fragment.HeaderFragment"/> 
    <fragment 
        android:id="@+id/footerFragment" 
        android:layout_width="match_parent" 
        android:layout_height="80dp" 
        android:layout_alignParentBottom="true"
        android:name="com.hopu.cardviewdemo.fragment.FooterFragment"/> 
 
</RelativeLayout>

4. Activity 在 onCreate( ) 方法中调用 setContentView() 加载布局文件。

3.3 Fragment的动态使用(CardView与RecycleView的结合使用)

1. activity_main.xml


<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
 
    <FrameLayout
        android:id="@+id/fl"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
 
    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottom_navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/white"
        android:layout_alignParentBottom="true"
        app:menu="@menu/bottom_navigation_menu" />
 
</RelativeLayout>

2. 子布局CardView文件


<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:app="http://schemas.android.com/apk/res-auto">
 
    <LinearLayout
        android:layout_height="match_parent"
        android:layout_width="match_parent"
        android:orientation="vertical"
        android:gravity="center_horizontal"
        android:padding="5dp">
 
        <ImageView
            android:id="@+id/iv_img"
            android:layout_height="50dp"
            android:layout_width="50dp"
            android:src="@mipmap/laoyou"
            android:scaleType="fitXY"/>
 
        <TextView
            android:id="@+id/tv_title"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="旅游"
            android:layout_marginTop="3dp"/>
 
    </LinearLayout>
 
 
 
</androidx.cardview.widget.CardView>

3. 创建 Fragment


package com.wpw.socialapp.fragment;
 
import android.graphics.Color;
import android.os.Bundle;
 
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.viewpager2.widget.ViewPager2;
 
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
 
import com.wpw.socialapp.R;
import com.wpw.socialapp.adapter.AdsAdpter;
import com.wpw.socialapp.adapter.NaviqationAdapter1;
import com.wpw.socialapp.adapter.NaviqationAdapter2;
import com.wpw.socialapp.adapter.NaviqationAdapter3;
import com.wpw.socialapp.adapter.NaviqationAdapter4;
import com.wpw.socialapp.model.Ads;
import com.wpw.socialapp.model.Naviqation1;
import com.wpw.socialapp.model.Naviqation2;
import com.wpw.socialapp.model.Naviqation3;
import com.wpw.socialapp.model.Naviqation4;
 
import java.util.ArrayList;
import java.util.List;
 
 
public class ShouyeFragment extends Fragment {
 
    private int[] imgs={R.mipmap.g1,R.mipmap.g2};
    private List<Ads> list=new ArrayList<>();
    private ViewPager2 vp_ads;
 
    private int[] imgNavi1={R.mipmap.laoyou,R.mipmap.fuyou,R.mipmap.shangcan,R.mipmap.ziyuan};
    private String[] titles1={"老弱服务","伤残服务","妇幼服务","自愿服务"};
    private List<Naviqation1> listnavi1=new ArrayList<>();
    private RecyclerView rv_navigation1;
 
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view=inflater.inflate(R.layout.fragment_shouye, container, false);
        vp_ads=view.findViewById(R.id.vp_ads);
 
        list.clear();
        listnavi1.clear();
 
        info();
 
        AdsAdpter adsAdpter=new AdsAdpter(list);
        vp_ads.setAdapter(adsAdpter);
 
        rv_navigation1=view.findViewById(R.id.rv_navigation1);
        NaviqationAdapter1 naviqationAdapter1=new NaviqationAdapter1(listnavi1);
        GridLayoutManager layoutManager1=new GridLayoutManager(getActivity(),4);
        rv_navigation1.setLayoutManager(layoutManager1);
        rv_navigation1.setAdapter(naviqationAdapter1);
 
 
        return view;
    }
 
    private void info() {
        for (int i = 0; i < imgs.length; i++) {
            Ads ads=new Ads(imgs[i]);
            list.add(ads);
        }
        for (int i = 0; i < imgNavi1.length; i++) {
            Naviqation1 naviqation1=new Naviqation1(imgNavi1[i],titles1[i]);
            listnavi1.add(naviqation1);
        }
    }
}


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="#F1F0F0"
    tools:context=".fragment.ShouyeFragment">
 
    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/vp_ads"
        android:layout_width="match_parent"
        android:layout_height="170dp"/>
 
    <LinearLayout
        android:layout_below="@+id/vp_ads"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:id="@+id/ll"
        android:background="@color/white">
 
        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/rv_navigation1"
            android:layout_width="match_parent"
            android:layout_height="80dp">
 
        </androidx.recyclerview.widget.RecyclerView>
    </LinearLayout>
 
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_navigation2"
        android:layout_width="match_parent"
        android:background="@color/white"
        android:layout_height="30dp"/>
 
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_navigation3"
        android:layout_marginTop="10dp"
        android:background="@color/white"
        android:layout_width="match_parent"
        android:layout_height="120dp"/>
 
    <ImageView
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_marginTop="10dp"
        android:scaleType="fitXY"
        android:src="@mipmap/tuijian"/>
 
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_navigation4"
        android:background="@color/white"
        android:layout_width="match_parent"
        android:layout_height="200dp"/>
 
 
</LinearLayout>

4. 创建 Fragment2

5. 在活动中，点击按钮后切换 Fragment


package com.wpw.socialapp;
 
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
 
import android.os.Bundle;
import android.view.MenuItem;
 
import com.google.android.material.bottomnavigation.BottomNavigationView;
import com.google.android.material.navigation.NavigationBarView;
import com.wpw.socialapp.fragment.ShouyeFragment;
import com.wpw.socialapp.fragment.WodeFragment;
import com.wpw.socialapp.fragment.XiaoxiFragment;
import com.wpw.socialapp.fragment.ZixunFragment;
 
public class MainActivity extends AppCompatActivity {
 
    private BottomNavigationView bottom_navigation;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        bottom_navigation=findViewById(R.id.bottom_navigation);
 
        ShouyeFragment shouyeFragment=new ShouyeFragment();
        ZixunFragment zixunFragment=new ZixunFragment();
        getSupportFragmentManager().beginTransaction().add(R.id.fl,shouyeFragment).commit();
 
        bottom_navigation.setOnItemSelectedListener(new NavigationBarView.OnItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
 
                if (item.getItemId()==R.id.page_1) {
                    getSupportFragmentManager().beginTransaction().replace(R.id.fl,shouyeFragment).commit();
                }else if (item.getItemId()==R.id.page_2) {
                    getSupportFragmentManager().beginTransaction().replace(R.id.fl,zixunFragment).commit();
                }
 
                return true;
            }
        });
 
    }
}

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