RecyclerView用法--展示多种类型Item数据

如题，本文主要介绍RecyclerView的基本使用方法，像ListView一样展示多种类型的Item数据。

首先介绍一下实体类：ItemPO，用来表示每个Item代表的数据类型：

package com.example.cxc.fullscreendemo.decoration.po;

import java.io.Serializable;

public class ItemPO implements Serializable {
    private static final long serialVersionUID = 7879752396036182745L;

    private String name;
    private int age;

    public ItemPO(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }
}

其次，介绍一下测试的Activity页面，其布局activity_recycler_view_test.xml及RecyclerViewTestActivity如下：

package com.example.cxc.fullscreendemo.decoration;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

import com.example.cxc.fullscreendemo.R;
import com.example.cxc.fullscreendemo.decoration.adapter.RecyclerViewTestAdapter;
import com.example.cxc.fullscreendemo.decoration.po.ItemPO;

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

public class RecyclerViewTestActivity extends AppCompatActivity {
    private static final String TAG = "RecyclerViewTestActivity";

    private RecyclerView mRecyclerView;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //设置布局
        setContentView(R.layout.activity_recycler_view_test);

        mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);

        //设置LayoutManager
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        mRecyclerView.setLayoutManager(layoutManager);

        //设置Adapter
        RecyclerViewTestAdapter adapter = new RecyclerViewTestAdapter();
        mRecyclerView.setAdapter(adapter);

        //设置数据
        List items = fakeItems();
        adapter.notifyDataSetChanged(items);
    }


    private static final int ITEM_COUNT = 100;

    private static List fakeItems() {
        List items = new ArrayList<>(ITEM_COUNT);

        for (int i = 0; i < ITEM_COUNT; i++) {
            ItemPO tItem = new ItemPO("Name_" + i, i);
            items.add(tItem);
        }

        return items;
    }
}

布局及Activity中的逻辑都很简单明了，构造了100个用户信息Item用来展示。为了UI界面的丰富性，年龄为偶数的Item，名字和年龄分两行展示，年龄为奇数的Item名字和年龄在一行展示。如何构造ItemView并展示数据，需要使用Adapter来完成,即RecyclerViewTestAdapter。

package com.example.cxc.fullscreendemo.decoration.adapter;

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

import com.example.cxc.fullscreendemo.R;
import com.example.cxc.fullscreendemo.decoration.po.ItemPO;

import java.util.List;

public class RecyclerViewTestAdapter extends RecyclerView.Adapter {
    private static final int TYPE_1 = 1;//横向排列名字和年龄
    private static final int TYPE_2 = 2;//竖向排列名字和年龄

    private List items;

    @Override
    public int getItemViewType(int position) {
        ItemPO item = getItem(position);
        //age是奇数时使用TYPE_1,偶数时使用TYPE_2;
        return item != null && item.getAge() % 2 == 0 ? TYPE_2 : TYPE_1;
    }

    @Override
    public TestBaseViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        TestBaseViewHolder holder = null;
        switch (viewType) {
            case TYPE_1:
                View itemView1 = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_type_1_layout, parent, false);
                holder = new TestViewHolder(itemView1);
                break;
            case TYPE_2:
                View itemView2 = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_type_2_layout, parent, false);
                holder = new TestViewHolder(itemView2);
                break;
        }
        return holder;
    }

    @Override
    public void onBindViewHolder(TestBaseViewHolder holder, int position) {
        ItemPO item = getItem(position);
        holder.fillData(item);
    }

    @Override
    public int getItemCount() {
        return items == null ? 0 : items.size();
    }

    public ItemPO getItem(int position) {
        return position >= 0 && position < getItemCount() ? items.get(position) : null;
    }

    public void notifyDataSetChanged(List items) {
        this.items = items;
        notifyDataSetChanged();
    }
}

其中:

public int getItemViewType(int position) :返回position位置的Item的ViewType,以便ItemView回收利用；

public int getItemCount()：DataSet中数据Item的个数；

public TestBaseViewHolder onCreateViewHolder(ViewGroup parent, int viewType)：根据viewType返回相应的ViewHolder,也就是创建不同UI的ItemView;

public void onBindViewHolder(TestBaseViewHolder holder, int position):将DataSet中position位置的数据填充至该ViewHolder中展示；

运行结果如下图如示，其中红色/蓝色各代表一个用户信息，红色：名字和年龄各占一行展示；蓝色：名字和年龄共占一行展示；

可以根据getItemViewType()返回值在onCreateViewHolder()中创建各种各样的Ui样式，然后在onBindViewHolder()中将数据填充展示。

完整示例请参考：

GitHub:https://github.com/cxcbupt/FullscreenDemo