Android RecyclerView的使用（三）——瀑布流的实现

素颜马尾好姑娘i 2022-06-03 02:53 268阅读 0赞

## Android RecyclerView的使用（三）——瀑布流的实现 ##

**前言：** RecyclerView提供了一种插拔式的体验，高度的解耦，异常的灵活，通过设置它提供的不同LayoutManager，ItemDecoration , ItemAnimator实现绚丽的效果。

*  通过布局管理器LayoutManager，可以控制其显示的方式；
 *  通过ItemDecoration，可以控制Item间的间隔（可定制）；
 *  通过ItemAnimator，可以控制Item增删的动画；
 *  至于点击、长按事件，RecyclerView并没有给我们提供相应的方法接口，需要我们自己实现。

上一节我们了解了如何为RecyclerView 添加分割线本节我们将学习如何实现瀑布流。

**效果图：**

![这里写图片描述][SouthEast]

**1、 布局文件。**

<?xml version="1.0" encoding="utf-8"?>
    <android.support.constraint.ConstraintLayout 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.support.v7.widget.RecyclerView
            android:id="@+id/myRecyclerView"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>
    
    </android.support.constraint.ConstraintLayout>

**2、定义item的样式，item\_single\_imgview.xml**

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:background="#442F2F2F"
        android:layout_margin="3dp"
        android:layout_height="wrap_content">
    
        <ImageView
            android:id="@+id/imgView"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    
    </LinearLayout>

**3、自定义Adapter适配器**

public class StaggeredAdapter extends RecyclerView.Adapter<StaggeredAdapter.MyViewHolder> {
        
    
        private LayoutInflater mInflater;
        private Context mContext;
        private int[] imgIds;
        private List<Integer> heights;
    
        public StaggeredAdapter(Context context, int[] imgIds) {
            this.mContext = context;
            this.imgIds = imgIds;
            mInflater = LayoutInflater.from(context);
            this.heights = new ArrayList<>();
            for (int i = 0; i < datas.size(); i++) {
                this.heights.add((int) (300 + Math.random()*300));
            }
        }
    
        @Override
        public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View view = mInflater.inflate(R.layout.item_single_imgview, parent, false);
            MyViewHolder viewHolder = new MyViewHolder(view);
            return viewHolder;
        }
    
        @Override
        public void onBindViewHolder(MyViewHolder holder, int position) {
            ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();
            lp.height = heights.get(position);
            holder.itemView.setLayoutParams(lp);
            holder.imageView.setBackgroundResource(imgIds[ position % imgIds.length]);
        }
    
        @Override
        public int getItemCount() {
            return mDatas.size();
        }
    
        class MyViewHolder extends RecyclerView.ViewHolder {
        
    
            ImageView imageView;
    
            public MyViewHolder(View itemView) {
                super(itemView);
                imageView = itemView.findViewById(R.id.imgView);
            }
        }
    }

**4、StaggeredActivity.java**

public class StaggeredActivity extends AppCompatActivity {
        
    
        private RecyclerView recyclerView;
    
        private int[] imgIds;
        private StaggeredAdapter mAdapter;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_staggered);
    
            initDatas();
    
            recyclerView = (RecyclerView) findViewById(R.id.myRecyclerView);
            mAdapter = new StaggeredAdapter(this, imgIds);
            recyclerView.setAdapter(mAdapter);
    
            recyclerView.setLayoutManager(new StaggeredGridLayoutManager(3,
                    StaggeredGridLayoutManager.VERTICAL));
        }
    
        private void initDatas() {
            imgIds = new int[]{R.mipmap.img01, R.mipmap.img02, R.mipmap.img03, R.mipmap.img04,
                    R.mipmap.img05, R.mipmap.img06, R.mipmap.img07};
        }
    }

就这样，我们实现了瀑布流，图片的高度是随机生成的。

[SouthEast]: /images/20220603/97d69f5a0cd34c78a56a4394f7fbe443.png