andriod用RecyclerView打造微信朋友圈效果（第一讲）

andriod用RecyclerView打造微信朋友圈效果（第一讲）

先看效果图

关于RecyclerView 

RecyclerView 是 ListView 的升级版 ，RecyclerView 将 ViewHolder 标准化，我们不再需要面向 view ，而是直接面向 ViewHolder 编写实现我们需要的 Adapter，这样一来，逻辑结构就变得非常清晰。

RecyclerView 的优缺点：
优点：新控件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 ListView，GirdView，瀑布流等效果。
缺点： Item的点击、长按事件，需要自己写。

开发步骤

新建一个activity

MainActivity的布局文件改为

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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"
    tools:context=".MainActivity">

    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <androidx.appcompat.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

    </com.google.android.material.appbar.AppBarLayout>
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/id_recyclerview_horizontal"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_centerVertical="false"
        android:background="#ffffff"
        android:scrollbars="none" />
    <!--<include layout="@layout/content_main" />-->

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        app:srcCompat="@android:drawable/ic_dialog_email" />

</androidx.coordinatorlayout.widget.CoordinatorLayout>

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

    <ImageView
        android:id="@+id/id_index_gallery_item_image"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="false"
        android:layout_centerHorizontal="false"

        android:layout_margin="5dp"

        android:scaleType="centerCrop" />

    <TextView
        android:id="@+id/id_index_gallery_item_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/id_index_gallery_item_image"
        android:layout_centerHorizontal="false"
        android:layout_marginBottom="5dp"
        android:layout_marginTop="5dp"
        android:textColor="#2596cc"
        android:textAlignment="center"
        android:text="漂亮的星空美丽的步伐"
        android:textSize="14dp" />

</RelativeLayout>

package wiki.bfw.weixin;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.view.View.OnClickListener;

import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

public class FriendsAdapter extends
        RecyclerView.Adapter<FriendsAdapter.ViewHolder>{
    private LayoutInflater mInflater;
    private List<Integer> mDatas;

    /**
     * ItemClick的回调接口
     * @author zhy
     *
     */
    public interface OnItemClickLitener
    {
        void onItemClick(View view, int position);
    }

    private OnItemClickLitener mOnItemClickLitener;

    public void setOnItemClickLitener(OnItemClickLitener mOnItemClickLitener)
    {
        this.mOnItemClickLitener = mOnItemClickLitener;
    }

    public FriendsAdapter(Context context, List<Integer> datats)
    {
        mInflater = LayoutInflater.from(context);
        mDatas = datats;
    }

    public static class ViewHolder extends RecyclerView.ViewHolder
    {
        public ViewHolder(View arg0)
        {
            super(arg0);
        }

        ImageView mImg;
        TextView mTxt;
    }

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

    /**
     * 创建ViewHolder
     */
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i)
    {
        View view = mInflater.inflate(R.layout.friendtopic_item,
                viewGroup, false);
        ViewHolder viewHolder = new ViewHolder(view);

        viewHolder.mImg = (ImageView) view
                .findViewById(R.id.id_index_gallery_item_image);
        return viewHolder;
    }

    /**
     * 设置值
     */
    @Override
    public void onBindViewHolder(final ViewHolder viewHolder, final int i)
    {
        viewHolder.mImg.setImageResource(mDatas.get(i));
        if (mOnItemClickLitener != null)
        {
            viewHolder.itemView.setOnClickListener(new OnClickListener()
            {
                @Override
                public void onClick(View v)
                {
                    mOnItemClickLitener.onItemClick(viewHolder.itemView, i);
                }
            });

        }
    }

}

将activity改成如下

package wiki.bfw.weixin;

import android.os.Bundle;
import androidx.recyclerview.widget.RecyclerView;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.view.Window;
import android.widget.Toast;

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

public class MainActivity extends AppCompatActivity {
    private RecyclerView mRecyclerView;
    private FriendsAdapter mAdapter;
    private List<Integer> mDatas;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        initDatas();
        //得到控件
        mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerview_horizontal);
        //设置布局管理器
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        mRecyclerView.setLayoutManager(linearLayoutManager);
        //设置适配器
        mAdapter = new FriendsAdapter(this, mDatas);
        mAdapter.setOnItemClickLitener(new FriendsAdapter.OnItemClickLitener()
        {
            @Override
            public void onItemClick(View view, int position)
            {
                Toast.makeText(MainActivity.this, position+"", Toast.LENGTH_SHORT)
                        .show();
            }
        });
        mRecyclerView.setAdapter(mAdapter);


        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }
    private void initDatas()
    {
        mDatas = new ArrayList<Integer>(Arrays.asList(R.mipmap.demo, R.mipmap.demo,R.mipmap.demo,R.mipmap.demo,R.mipmap.demo,R.mipmap.demo,R.mipmap.demo,R.mipmap.demo,R.mipmap.demo,R.mipmap.demo,R.mipmap.demo,R.mipmap.demo));
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}