前言

RecyclerView 的使用我就不再多说，接下来的几篇文章主要说一下 RecyclerView 的实用小功能，包括列表宫格的切换，吸顶效果，多布局效果等，今天这篇文章就来实现一下列表宫格的切换，效果如下

一、数据来源

数据来源于知乎日报API，采用 okhttp+retrofit 组合方式请求获取，网络请求没有进行二次封装，只是简单请求数据源，对于有需求的用户自行进行封装修改。

二、使用步骤

1.引入库

  //万能适配器
  implementation 'com.github.CymChad:BaseRecyclerViewAdapterHelper:2.9.50'
  //卡片布局
  implementation 'androidx.cardview:cardview:1.0.0'
  //图片加载
  implementation 'com.github.bumptech.glide:glide:4.9.0'
  //json解析
  implementation 'com.alibaba:fastjson:1.2.61'
  //标题栏
  implementation 'com.github.goweii:ActionBarEx:3.2.2'
  // 只引入ActionBarEx
  implementation 'com.github.goweii.ActionBarEx:actionbarex:3.2.2'
  // 引入ActionBarCommon/Search/Super，依赖于ActionBarEx
  implementation 'com.github.goweii.ActionBarEx:actionbarex-common:3.2.2'

2.获取数据

使用如下 URL 进行数据请求：API 使用的 HTTP Method 均为 GET

https://news-at.zhihu.com/api/3/news/hot

响应实例：

{
    "recent": [
        {
            "news_id": 3748552,
            "thumbnail": "http://p3.zhimg.com/67/6a/676a8337efec71a100eea6130482091b.jpg",
            "title": "长得漂亮能力出众性格单纯的姑娘为什么会没有男朋友？",
            "url": "http://daily.zhihu.com/api/2/news/3748552"
        }
    ]
}

根据实例生成实体类 NewsListBean 实现序列换接口 Serializable

public class NewsListBean implements Serializable {

    private String date;
    private List<Recent> recent;


    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public List<Recent> getRecent() {
        return recent;
    }

    public void setRecent(List<Recent> recent) {
        this.recent = recent;
    }

    public static class Recent implements Serializable {
        private String news_id;
        private String thumbnail;
        private String title;
        private String url;

        public String getNews_id() {
            return news_id;
        }

        public void setNews_id(String news_id) {
            this.news_id = news_id;
        }

        public String getThumbnail() {
            return thumbnail;
        }

        public void setThumbnail(String thumbnail) {
            this.thumbnail = thumbnail;
        }

        public String getTitle() {
            return title;
        }

        public void setTitle(String title) {
            this.title = title;
        }

        public String getUrl() {
            return url;
        }

        public void setUrl(String url) {
            this.url = url;
        }
    }
}

写一个接口类用来管理 API ,可以单独放在一个文件夹下

public interface ApiUrl {

    @GET("/api/4/news/hot")
    Call<NewsListBean> getPic();

}

3.主要代码

1 activity_main.xml

这里使用了三方库 ActionBarEx 实现了沉浸式标题栏，使用了系统的 ProgressBar 实现请求加载框

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <per.goweii.actionbarex.ActionBarEx
        android:id="@+id/abc_main_return"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#14a4fb"
        app:ab_autoImmersion="false"
        app:ab_bottomLineColor="#f3f3f3"
        app:ab_bottomLineHeight="0dp"
        app:ab_statusBarColor="#00000000"
        app:ab_statusBarMode="dark"
        app:ab_statusBarVisible="true"
        app:ab_titleBarHeight="50dp"
        app:ab_titleBarLayout="@layout/top" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/zh_lv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@+id/abc_main_return" />

    <ProgressBar
        android:id="@+id/progressbar"
        style="@style/Base.Widget.AppCompat.ProgressBar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:visibility="gone" />
</RelativeLayout>

2 zh_item_layout.xml

列表子布局 ,采用 CardView 卡片布局

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/zh_card_View"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginLeft="@dimen/dp_10"
    android:layout_marginTop="10dp"
    android:layout_marginRight="@dimen/dp_10"
    android:layout_marginBottom="@dimen/dp_10"
    app:cardBackgroundColor="#ffffff"
    app:cardCornerRadius="10dp"
    app:cardElevation="10dp"
    app:cardPreventCornerOverlap="true"
    app:cardUseCompatPadding="false">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="120dp">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/transparent">

            <ImageView
                android:id="@+id/news_image"
                android:layout_width="70dp"
                android:layout_height="70dp"
                android:layout_centerVertical="true"
                android:layout_margin="10dp"
                android:elevation="2dp"
                android:scaleType="fitXY" />

            <TextView
                android:id="@+id/news_title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerVertical="true"
                android:layout_marginStart="10dp"
                android:layout_marginTop="10dp"
                android:layout_marginEnd="10dp"
                android:layout_toEndOf="@id/news_image"
                android:ellipsize="end"
                android:maxEms="15"
                android:singleLine="true"
                android:textColor="@color/black"
                android:textSize="20sp" />
        </RelativeLayout>
    </RelativeLayout>


</androidx.cardview.widget.CardView>

3 zh_grid__item_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/zh_card_View"
    android:layout_width="match_parent"
    android:layout_height="180dp"
    android:layout_marginLeft="@dimen/dp_10"
    android:layout_marginTop="10dp"
    android:layout_marginRight="@dimen/dp_10"
    android:layout_marginBottom="@dimen/dp_10"
    app:cardBackgroundColor="#ffffff"
    app:cardCornerRadius="10dp"
    app:cardElevation="10dp"
    app:cardPreventCornerOverlap="true"
    app:cardUseCompatPadding="false">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/transparent"
        android:gravity="center"
        android:orientation="vertical"
        android:padding="@dimen/dp_10">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="3">

            <ImageView
                android:id="@+id/news_image"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:scaleType="fitXY" />

        </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:gravity="center">

            <TextView
                android:id="@+id/news_title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:ellipsize="end"
                android:maxEms="8"
                android:singleLine="true"
                android:textColor="@color/black"
                android:textSize="20sp" />

        </LinearLayout>


    </LinearLayout>


</androidx.cardview.widget.CardView>

4 NewsListAdapter 适配器

public class NewsListAdapter extends BaseQuickAdapter<NewsListBean.Recent, BaseViewHolder> {

    public NewsListAdapter(int layoutResId, @Nullable List<NewsListBean.Recent> data) {
        super(layoutResId, data);
    }

    @Override
    protected void convert(@NonNull BaseViewHolder helper, NewsListBean.Recent item) {
        helper.setText(R.id.news_title, item.getTitle());
        String img = item.getThumbnail();
        ImageView newsImage = helper.getView(R.id.news_image);
        Glide.with(mContext).
                asBitmap().
                load(img).
                diskCacheStrategy(DiskCacheStrategy.ALL).
                into(newsImage);
        helper.addOnClickListener(R.id.zh_card_View);
    }


}

5 BaseActivity 基类

public abstract class BaseActivity extends AppCompatActivity {


    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        Window window = getWindow();
        // 5.0以上系统状态栏透明
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
            window.getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                    | View.SYSTEM_UI_FLAG_LAYOUT_STABLE | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);
            window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
            window.setStatusBarColor(Color.TRANSPARENT);
        }
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                // 全屏显示，隐藏状态栏和导航栏，拉出状态栏和导航栏显示一会儿后消失。
                window.getDecorView().setSystemUiVisibility(
                        View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                                // | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                                | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                                // | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                                // | View.SYSTEM_UI_FLAG_FULLSCREEN
                                | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);
            } else {
                // 全屏显示，隐藏状态栏
                window.getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_FULLSCREEN);
            }
        }
        //预防软键盘挡住输入框
        getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN);
        //禁止横屏
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        super.onCreate(savedInstanceState);

    }

  
}

6 MainActivity 主要代码

这里主要通过一个 boolean 值 isGrid 来判断是否切换状态来加载不同的布局，以及布局管理器来达到实际效果

public class MainActivity extends BaseActivity {

    private RecyclerView zhLv;
    private ProgressBar proBar;
    private NewsListAdapter adapter;


    private List<NewsListBean.Recent> mList = new ArrayList<>();


    private static final int REQUEST_EXTERNAL_STORAGE = 1;
    private static String[] PERMISSIONS_STORAGE = {
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE};
    private ImageView menuBtn;
    private LinearLayoutManager layoutManager;
    private ImageView btnImg;
    private LinearLayout backLayoput;

    public static void verifyStoragePermissions(Activity activity) {
        int permission = ActivityCompat.checkSelfPermission(activity,
                Manifest.permission.WRITE_EXTERNAL_STORAGE);
        if (permission != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,
                    REQUEST_EXTERNAL_STORAGE);
        }
    }

    private boolean isGrid = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        verifyStoragePermissions(MainActivity.this);
        initView();
        initData();

        menuBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                switchLayout();
            }
        });
    }


    private void switchLayout() {

        if (isGrid) {
            layoutManager = new LinearLayoutManager(this);
            adapter = new NewsListAdapter(R.layout.zh_item_layout, mList);
            zhLv.setAdapter(adapter);
        } else {
            layoutManager = new GridLayoutManager(this, 2);
            adapter = new NewsListAdapter(R.layout.zh_grid__item_layout, mList);
            zhLv.setAdapter(adapter);
        }
        zhLv.setLayoutManager(layoutManager);
        isGrid = !isGrid;
    }

    private void initView() {
        zhLv = findViewById(R.id.zh_lv);
        proBar = findViewById(R.id.progressbar);
        menuBtn = findViewById(R.id.btn_main_menu);
        btnImg = findViewById(R.id.btn_main_menu);
        backLayoput = findViewById(R.id.btn_back_layout);
        backLayoput.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();
            }
        });
        layoutManager = new LinearLayoutManager(MainActivity.this);
        zhLv.setLayoutManager(layoutManager);
        adapter = new NewsListAdapter(R.layout.zh_item_layout, mList);
        zhLv.setAdapter(adapter);
    }

    private void initData() {
        proBar.setVisibility(View.VISIBLE);
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://news-at.zhihu.com/")
                //设置数据解析器
                .addConverterFactory(GsonConverterFactory.create())
                .build();
        ApiUrl apiUrl = retrofit.create(ApiUrl.class);
        Call<NewsListBean> call = apiUrl.getPic();
        call.enqueue(new Callback<NewsListBean>() {
                         @Override
                         public void onResponse(Call<NewsListBean> call, Response<NewsListBean> response) {

                             List<NewsListBean.Recent> recent = response.body().getRecent();
                             if (response.body() != null && recent.size() > 0) {
                                 try {
                                     mList.addAll(recent);
                                     adapter.setNewData(mList);
                                     proBar.setVisibility(View.GONE);
                                 } catch (Exception e) {
                                     String message = e.getMessage();
                                     e.printStackTrace();
                                 }
                             }
                         }

                         @Override
                         public void onFailure(Call<NewsListBean> call, Throwable t) {
                             Log.e("mmm", "errow " + t.getMessage());
                         }
                     }
        );


    }


}