Android---RecyclerView之简单瀑布流实现

1、自定义RecyclerView的xml控件 fruit_item.xml

<?xml version="1.0" encoding="utf-8"?>
<!--瀑布流-->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="5dp">

    <ImageView
        android:id="@+id/fruit_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"/>

    <TextView
        android:id="@+id/fruit_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="left"
        android:layout_marginLeft="10dp" />
</LinearLayout>

2、新建fruit类，管理控件显示的数据

package com.mycompany.waterfallviewtest;

/**
 * Created by sstek_mars on 2017/8/29.
 */

public class Fruit {
    private String name;
    private int imageId;

    public Fruit(String name, int imageId) {
        this.name = name;
        this.imageId = imageId;
    }

    public String getName() {
        return name;
    }

    public int getImageId() {
        return imageId;
    }
}

3、新建适配器

package com.mycompany.waterfallviewtest;

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.List;

/**
 * Created by sstek_mars on 2017/8/29.
 */

public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder> {

    private List<Fruit> mFruitList;

    /**
     * recyclerView适配器理解
     * 1、定义一个内部类ViewHolder，ViewHolder要继承自RecyclerView.ViewHolder。然后ViewHolder的构造函数中要传入一个View参数，这个参数通常就是RecyclerView子项的最外层布局
     * 2、通过findViewById()方法来获取到布局中的ImageView和TextView的实例
     */
    static class ViewHolder extends RecyclerView.ViewHolder {
        ImageView fruitImage;
        TextView fruitName;

        public ViewHolder(View view) {
            super(view);
            fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
            fruitName = (TextView) view.findViewById(R.id.fruit_name);
        }
    }

    /**
     * 这个构造函数方法，用于把要展示的数据源传进来，并赋值给一个全局变量mFruitList。后续的操作都将在这个数据源的基础上进行。
     */
    public FruitAdapter(List<Fruit> fruitList) {
        mFruitList = fruitList;
    }

    /**
     * 由于FruitAdapter是继承于RecyclerView.Adapter的，那么就必须重写onCreateViewHolder()/onBindViewHolder()/getItemCount()
     *
     * onCreateViewHolder():用于创建ViewHolder实例，我们在这个方法化悲愤fruit_item布局加载进行，然后创建一个ViewHolder实例，并把加载出来的布局传入到构造函数中，最后将ViewHolder的实例返回。
     * onBindViewHolder():用于对RecyclerView子项的数据进行赋值的，会在每个子项被滚动到屏幕内的时候执行，position指的是当前Fruit实例的位置，然后再将数据设置到ViewHolder的imageview和textView当中即可。
     * getItemCount():返回数据源长度，用于告诉RecyclerView一共有多少个子项。
     *
     */
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fruit_item, parent, false);
        ViewHolder holder = new ViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Fruit fruit = mFruitList.get(position);
        holder.fruitImage.setImageResource(fruit.getImageId());
        holder.fruitName.setText(fruit.getName());
    }

    @Override
    public int getItemCount() {
        return mFruitList.size();
    }
}

4、MainActivity显示瀑布流页的代码

package com.mycompany.waterfallviewtest;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class MainActivity extends AppCompatActivity {

    private List<Fruit> fruitList = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initFruits();
        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycle_view);

        /**
         * StaggeredGridLayoutManager;
         * 概述：实现瀑布流的函数
         * 第一个参数：用于指定布局的列数，传入几就代表会把布局分为几列
         * 第二个参数：用于指定布局的排列方向
         */
        StaggeredGridLayoutManager layoutManager = new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL);
        recyclerView.setLayoutManager(layoutManager);
        FruitAdapter adapter = new FruitAdapter(fruitList);
        recyclerView.setAdapter(adapter);
    }

    private void initFruits() {
        for (int i = 0;i < 2; i++) {
            Fruit apple = new Fruit(getRandomLengthName("Apple"), R.mipmap.ic_launcher);
            fruitList.add(apple);
            Fruit b = new Fruit(getRandomLengthName("bbbb"), R.mipmap.ic_launcher);
            fruitList.add(b);
            Fruit c = new Fruit(getRandomLengthName("cccc"), R.mipmap.ic_launcher);
            fruitList.add(c);
            Fruit d = new Fruit(getRandomLengthName("dddd"), R.mipmap.ic_launcher);
            fruitList.add(d);
            Fruit e = new Fruit(getRandomLengthName("eeee"), R.mipmap.ic_launcher);
            fruitList.add(e);
            Fruit f = new Fruit(getRandomLengthName("fffff"), R.mipmap.ic_launcher);
            fruitList.add(f);
            Fruit g = new Fruit(getRandomLengthName("gggg"), R.mipmap.ic_launcher);
            fruitList.add(g);
            Fruit h = new Fruit(getRandomLengthName("hhhh"), R.mipmap.ic_launcher);
            fruitList.add(h);
            Fruit l = new Fruit(getRandomLengthName("llll"), R.mipmap.ic_launcher);
            fruitList.add(b);

        }

    }

    private String getRandomLengthName(String name) {
        Random random = new Random();
        int length = random.nextInt(20)+1;
        StringBuilder builder = new StringBuilder();
        for (int i = 0 ;i < length; i++) {
            builder.append(name);
        }
        return builder.toString();
    }
}

5、activity_main.xml中代码

<?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.support.v7.widget.RecyclerView
        android:id="@+id/recycle_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>