RecyclerView的使用(三)多布局

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RecyclerView的使用(三)多布局

在项目中，我们经常用到多布局的情况，跟ListView一样，我们需要通过ViewType来进行区分。
界面效果如图：
这里写图片描述

（一）单布局的Adapter

首先我们看下以前单布局的Adapter是如何去写的：

我们继承了RecyclerView.Adapter，泛型是MyAdapter 中继承的ViewHolder类，这样写后我们的onCreateViewHolder和onBindViewHolder的方法参数都是我们的ViewHolder了，是无法做到区分多布局的。

class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder>{        @Override        public MyAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {            return null;        }        @Override        public void onBindViewHolder(MyAdapter.MyViewHolder holder, int position) {        }        @Override        public int getItemCount() {            return 0;        }        //继承RecyclerView.ViewHolder        class MyViewHolder extends  RecyclerView.ViewHolder{            public MyViewHolder(View itemView) {                super(itemView);            }        }    }

（二）多布局的Adapter

多布局的Adapter我们泛型为RecyclerView.ViewHolder，通过ViewType，我们区分使用不同的ViewHolder。

RecyclerView提供了方法去区分ViewType

 @Override public int getItemViewType(int position) {      return super.getItemViewType(position); }

onCreateViewHolder的第二个参数int viewType就是getItemViewType的返回值

@Overridepublic RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {            return null;}

在onBindViewHolder中，我们的来绑定布局

@Overridepublic void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {}

我们看看如何去实现，我们首先定义两个标志,

public static final int ONE_ITEM = 1;public static final int TWO_ITEM = 2;

代码奉上

import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.support.v7.widget.LinearLayoutManager;import android.support.v7.widget.RecyclerView;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;import java.util.ArrayList;import java.util.List;public class ViewTypeActivity extends AppCompatActivity {    private RecyclerView mRecyclerView;    private List<String> mDatas;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        initData();        setContentView(R.layout.activity_water_full);        mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerview);        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));        mRecyclerView.addItemDecoration(new SpacesItemDecoration(12));        mRecyclerView.setAdapter(new ViewTypeAdapter());    }    private void initData() {        mDatas = new ArrayList<String>();        for (int i = 0; i < 24; i++) {            mDatas.add("位置是" + i);        }    }    class ViewTypeAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>{        public static final int ONE_ITEM = 1;        public static final int TWO_ITEM = 2;        @Override        public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {            LayoutInflater mInflater = LayoutInflater.from(ViewTypeActivity.this);            RecyclerView.ViewHolder holder = null;            if(ONE_ITEM == viewType){                View v = mInflater.inflate(R.layout.item_linear,parent,false);                holder = new OneViewHolder(v);            }else{                View v = mInflater.inflate(R.layout.item_two,parent,false);                holder = new TwoViewHolder(v);            }            return holder;        }        @Override        public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {            if(holder instanceof OneViewHolder){                ((OneViewHolder) holder).tv.setText(mDatas.get(position));            }else {                ((TwoViewHolder) holder).tv1.setText(mDatas.get(position));                ((TwoViewHolder) holder).tv2.setText(mDatas.get(position));            }        }        @Override        public int getItemViewType(int position) {            if(position % 3 == 0){                return TWO_ITEM;            }else{                return ONE_ITEM;            }        }        @Override        public int getItemCount() {            return mDatas.size();        }        class OneViewHolder extends RecyclerView.ViewHolder{            TextView tv;            public OneViewHolder(View itemView) {                super(itemView);                tv = (TextView) itemView.findViewById(R.id.adapter_linear_text);            }        }        class TwoViewHolder extends RecyclerView.ViewHolder{            TextView tv1,tv2;            public TwoViewHolder(View itemView) {                super(itemView);                tv1 = (TextView) itemView.findViewById(R.id.adapter_two_1);                tv2 = (TextView) itemView.findViewById(R.id.adapter_two_2);            }        }    }}

两个XML

<?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="50dp"    android:orientation="horizontal">    <TextView        android:id="@+id/adapter_two_1"        android:layout_width="0dp"        android:layout_height="match_parent"        android:layout_weight="1"        android:layout_marginRight="5dp"        android:background="#3FFF99"        android:gravity="center" />    <TextView        android:id="@+id/adapter_two_2"        android:layout_width="0dp"        android:layout_weight="1"        android:layout_marginLeft="5dp"        android:layout_height="match_parent"        android:background="#3FFF99"        android:gravity="center" /></LinearLayout>

<?xml version="1.0" encoding="utf-8"?><TextView xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/adapter_linear_text"    android:layout_width="match_parent"    android:layout_height="50dp"    android:background="#a9a8ff"    android:gravity="center"/>

间距的设定请看第一篇,效果图如下：

这里写图片描述

通过RecyclerView.Adapter设置多布局是非常方便的，而且大家可以发现当RecyclerView为LinearLayoutManager，我们可以通过viewType给RecyclerView来设置Header和Footer，如

public static final int HEADER = 1;        public static final int FOOTER = 2;        public static final int ITEM = 3;        @Override        public int getItemViewType(int position) {            if(position == 0){                return HEADER;            }else if(position == getItemCount() -1){                return FOOTER;            }else{                return ITEM;            }        }        @Override        public int getItemCount() {            return mDatas.size() + 2;//Header和Footer        }

但是当布局管理器为GridLayoutManager和StaggeredGridLayoutManager时就要不能这样去做了。
如何去加我会放在后面去写。

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