RecyclerView多布局与Item点击事件

RecyclerView真的是太强大太强大的，没听过这个view 的可以自行google一下；
本文将介绍RecyclerView的多布局；

多布局的实现

布局

多布局是指一个不同的item用不同的layout显示。
我们的主页面里面就放RecyclerView

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

既然是要实现多布局，那么我们就写两个布局吧，一个item_normal,值包含一个 TextView

<?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="?listPreferredItemHeight"
    android:background="?selectableItemBackground"
    android:clickable="true"
    android:gravity="center"
    android:orientation="vertical"
    android:id="@+id/root_view"
    android:padding="10dp">

    <TextView
        android:id="@+id/tv_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="18sp" />
</LinearLayout>

另外一个布局，放一个TextView和一个CheckBox;

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/root_view"
    android:layout_width="match_parent"
    android:layout_height="?listPreferredItemHeight"
    android:background="?selectableItemBackground"
    android:clickable="true"
    android:gravity="center"
    android:orientation="horizontal"
    android:padding="10dp">

    <TextView
        android:id="@+id/tv_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="hunao"
        android:textSize="18sp" />

    <CheckBox
        android:id="@+id/cb"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="true" />

</LinearLayout>

Adapter

布局和item有了，那就要写Adapter了；
自定义Adapter继承RecyclerView.Adapter<RecyclerView.ViewHolder>,复写需要复写的方法，我们来看一个这个方法，传进来的一个int类型的参数viewType,其实这个就相当于不同item的标记吧，我们可以根据这个值，给item选择不同的标记；

 @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
      
    }

那这个标记是从哪里来的呢？这个好办，RecyclerView.Adapter有一个方法getItemViewType(),返回值是int类；这个方法就是返回item布局类型标记的方法。

    private static final int NORMAL_TYPE = 0;
    private static final int CHECK_TYPE = 1;

    @Override
    public int getItemViewType(int position) {
        if (position % 4 == 0) {
            return CHECK_TYPE;
        }
        return NORMAL_TYPE;
    }

如果position%4==0就返回NORMAL_TYPE,否则就返回CHECK_TYPE;然后我们就可以根据比较选择不同的布局了；

 @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (viewType == NORMAL_TYPE) {
            return new NormalHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_normal, parent, false));
        } else
            return new CheckHoldr(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_check, parent, false));
    }

然后我们创建来数据就好了；
给MyAdapter一个构造方法，传进来数据

    private List<String> datas;

    public MyAdapter(List<String> datas) {
        this.datas = datas;
    }

每一个布局都要写一个ViewHolder

 class NormalHolder extends RecyclerView.ViewHolder  {

        TextView tv_name;
        LinearLayout rootView;

        public NormalHolder(View itemView) {
            super(itemView);
            tv_name = (TextView) itemView.findViewById(R.id.tv_name);
            rootView = (LinearLayout) itemView.findViewById(R.id.root_view);
        }

    class CheckHoldr extends NormalHolder {
        public CheckHoldr(View itemView) {
            super(itemView);
        }
    }

这样，就可以给RecyclerView设置Adapter了

 private void initData() {
        datas = new ArrayList<>();
        for (int i = 0; i < 20; i++) {
            datas.add("hunao " + i);
        }
    }

    private void initView() {
        recylerView = (RecyclerView) findViewById(R.id.recylerview);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        recylerView.setLayoutManager(layoutManager);
        MyAdapter adapter = new MyAdapter(datas);
        recylerView.setAdapter(adapter);
    }

Item点击事件

RecyclerView并没有给我们封装item点击事件，那我们就自己动手吧
我们需要在Adapter里面暴露出去一个借口，这样的,定义了一个OnItemClickListener借口，并且给了set方法，然后我们只要处理回调就可以了

   private OnItemClickListener clickListener;

    public void setClickListener(OnItemClickListener clickListener) {
        this.clickListener = clickListener;
    }

    public static interface OnItemClickListener {
        void onClick(View view, int position);
    }

给我们的ViewHolder实现View.OnClickListener,然后重写onClick()方法，当OnItemClickListener监听器不为空的时候，就回调出去

 class NormalHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

        TextView tv_name;
        LinearLayout rootView;

        public NormalHolder(View itemView) {
            super(itemView);
            tv_name = (TextView) itemView.findViewById(R.id.tv_name);
            rootView = (LinearLayout) itemView.findViewById(R.id.root_view);
            rootView.setOnClickListener(this);
        }

        @Override
        public void onClick(View v) {
            if (clickListener != null) {
                clickListener.onClick(itemView, getAdapterPosition());
            }
        }
    }

    class CheckHoldr extends NormalHolder {
        public CheckHoldr(View itemView) {
            super(itemView);
        }
    }

最后只要在Adapter上设置我们的监听器就可以了

 adapter.setClickListener(new MyAdapter.OnItemClickListener() {
            boolean flag = false;
            @Override
            public void onClick(View view, int position) {
                TextView tvName = (TextView) view.findViewById(R.id.tv_name);
                String name = flag ? "hunao" : "china";
                tvName.setText(name + position);
                flag = !flag;
            }
        });

完整代码

Activity

package com.hugo.recylerviewdemo;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.TextView;

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

public class MainActivity extends AppCompatActivity {

    private RecyclerView recylerView;
    private List<String> datas;

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

    private void initData() {
        datas = new ArrayList<>();
        for (int i = 0; i < 20; i++) {
            datas.add("hunao " + i);
        }
    }

    private void initView() {
        recylerView = (RecyclerView) findViewById(R.id.recylerview);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        recylerView.setLayoutManager(layoutManager);
        MyAdapter adapter = new MyAdapter(datas);
        recylerView.setAdapter(adapter);
        adapter.setClickListener(new MyAdapter.OnItemClickListener() {
            boolean flag = false;
            @Override
            public void onClick(View view, int position) {
                TextView tvName = (TextView) view.findViewById(R.id.tv_name);
                String name = flag ? "hunao" : "china";
                tvName.setText(name + position);
                flag = !flag;
            }
        });

    }
}

MyAdapter

package com.hugo.recylerviewdemo;

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

import java.util.List;

/**
 * @auther Hugo
 * Created on 2016/5/12 20:29.
 */
public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private static final int NORMAL_TYPE = 0;
    private static final int CHECK_TYPE = 1;

    @Override
    public int getItemViewType(int position) {
        if (position % 4 == 0) {
            return CHECK_TYPE;
        }
        return NORMAL_TYPE;
    }

    private List<String> datas;

    public MyAdapter(List<String> datas) {
        this.datas = datas;
    }

    private OnItemClickListener clickListener;

    public void setClickListener(OnItemClickListener clickListener) {
        this.clickListener = clickListener;
    }

    public static interface OnItemClickListener {
        void onClick(View view, int position);
    }


    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (viewType == NORMAL_TYPE) {
            return new NormalHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_normal, parent, false));
        } else
            return new CheckHoldr(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_check, parent, false));
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (holder instanceof NormalHolder) {
            ((NormalHolder) holder).tv_name.setText(datas.get(position));
        } else {
            ((CheckHoldr) holder).tv_name.setText(datas.get(position));
        }
    }

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

    class NormalHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

        TextView tv_name;
        LinearLayout rootView;

        public NormalHolder(View itemView) {
            super(itemView);
            tv_name = (TextView) itemView.findViewById(R.id.tv_name);
            rootView = (LinearLayout) itemView.findViewById(R.id.root_view);
            rootView.setOnClickListener(this);
        }

        @Override
        public void onClick(View v) {
            if (clickListener != null) {
                clickListener.onClick(itemView, getAdapterPosition());
            }
        }
    }

    class CheckHoldr extends NormalHolder {
        public CheckHoldr(View itemView) {
            super(itemView);
        }
    }
}