Android RecyclerView的使用

原创

shineflowers 2022-12-06 01:30:16 博主文章分类：Android ©著作权

文章标签 RecyclerView android ide java 文章分类 运维

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RecyclerView是一种新的视图组，目标是为任何给予适配器的视图提供相似的渲染方式，被作为ListView和GridView的继承者更加强大，大家可以通过导入support-v7对其进行使用。

如果使用RecyclerView，你需要了解以下三个元素：

LayoutManager 控制显示方式（布局管理器）
ItemDecoration 控制Item间距
ItemAnimator 控制Item增删动画

还有一点：点击和长按事件，需要自己实现

使用方法如下：

content_main.xml

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

content_item.xml

<TextView
        android:id="@+id/letter"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="1" />

MainActivity.java

package com.jackie.recyclerview;

import android.content.Context;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.Toast;

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

public class MainActivity extends AppCompatActivity {

    private Context mContext;
    private List<String> mList;
    private RecyclerView mRecyclerView;
    private RecyclerViewAdapter mAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) 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();
            }
        });

        mContext = this;

        initData();
        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerview);
        //1.设置布局管理器
//        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));  //线性管理器，支持横向、纵向

        //纵向的GridView，可以纵向滑动
//        mRecyclerView.setLayoutManager(new GridLayoutManager(this, 4)); //网格布局管理器，第二个参数为列
        //横向的GridView，可以横向滑动
//        mRecyclerView.setLayoutManager(new GridLayoutManager(this, 4, GridLayoutManager.HORIZONTAL, false)); //网格布局管理器，第二个参数为行

        /**
         * StaggeredGridLayoutManager构造的第二个参数传一个orientation，
         * 如果传入的是StaggeredGridLayoutManager.VERTICAL代表有多少列，可以纵向滑动
         * 那么传入的如果是StaggeredGridLayoutManager.HORIZONTAL就代表有多少行，可以横向滑动
         */
        mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(4, StaggeredGridLayoutManager.VERTICAL)); // 瀑布式布局管理器
        //2.设置Adapter
        mAdapter = new RecyclerViewAdapter(mContext, mList);
        mRecyclerView.setAdapter(mAdapter);

        mAdapter.setOnItemClickListener(new RecyclerViewAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(View view, int position) {
                Toast.makeText(MainActivity.this, position + " short click", Toast.LENGTH_SHORT).show();
                mAdapter.addItem(position);
            }

            @Override
            public void onItemLongClick(View view, int position) {
                Toast.makeText(MainActivity.this, position + " long click", Toast.LENGTH_SHORT).show();
                mAdapter.removeItem(position);
            }
        });

        //3.添加分割线
//        mRecyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST));
        mRecyclerView.addItemDecoration(new DividerGridItemDecoration(this, 30));
        //4.设置item动画
        mRecyclerView.setItemAnimator(new DefaultItemAnimator());
    }

    private void initData() {
        mList = new ArrayList<String>();
        for (int i = 'A'; i < 'z'; i++) {
            mList.add("" + (char) i);
        }
    }
}

RecyclerViewAdapter.java

package com.jackie.recyclerview;

import android.content.Context;
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.List;
import java.util.Random;

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.RecycleViewHolder> {
    private Context mContext;
    private List<String> mList;

    public RecyclerViewAdapter(Context context, List<String> list) {
        this.mContext = context;
        this.mList = list;
    }

    public interface OnItemClickListener {
        void onItemClick(View view, int position);
        void onItemLongClick(View view , int position);
    }

    private OnItemClickListener onItemClickListener;

    public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
        this.onItemClickListener = onItemClickListener;
    }

    @Override
    public RecyclerViewAdapter.RecycleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        RecycleViewHolder holder = new RecycleViewHolder(LayoutInflater.from(mContext).inflate(R.layout.content_item, parent, false));
        return holder;
    }

    @Override
    public void onBindViewHolder(final RecyclerViewAdapter.RecycleViewHolder holder, int position) {

        // 如果设置了回调，则设置点击事件
        if (onItemClickListener != null) {
            holder.tv.setOnClickListener(new View.OnClickListener()  {
                @Override
                public void onClick(View v) {
                    onItemClickListener.onItemClick(holder.itemView, holder.getLayoutPosition());
                }
            });

            holder.tv.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                    onItemClickListener.onItemLongClick(holder.itemView, holder.getLayoutPosition());
                    return false;
                }
            });
        }

        holder.tv.setWidth(new Random().nextInt(400) + 100);  //随机产生100到500的随机整数
        holder.tv.setHeight(new Random().nextInt(400) + 100);
        holder.tv.setText(mList.get(position));
    }

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

    public class RecycleViewHolder extends RecyclerView.ViewHolder {
        TextView tv;

        public RecycleViewHolder(View itemView) {
            super(itemView);
            tv = (TextView) itemView.findViewById(R.id.letter);
        }
    }

    /**
     * 注意，这里更新数据集不是用adapter.notifyDataSetChanged()而是
     notifyItemInserted(position)与notifyItemRemoved(position)
     * @param position
     */
    public void addItem(int position) {
        mList.add(position, "Insert");
        notifyItemInserted(position);
    }

    public void removeItem(int position) {
        mList.remove(position);
        notifyItemRemoved(position);
    }
}

DividerItemDecoration.java

package com.jackie.recyclerview;

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * limitations under the License.
 */

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;

/**
 * This class is from the v7 samples of the Android SDK. It's not by me!
 * <p/>
 * See the license above for details.
 */
public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    private static final int[] ATTRS = new int[]{
            android.R.attr.listDivider
    };

    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;

    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;

    private Drawable mDivider;

    private int mOrientation;

    public DividerItemDecoration(Context context, int orientation) {
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        a.recycle();
        setOrientation(orientation);
    }

    public void setOrientation(int orientation) {
        if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
            throw new IllegalArgumentException("invalid orientation");
        }
        mOrientation = orientation;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent) {
        Log.v("recyclerview - itemdecoration", "onDraw()");

        if (mOrientation == VERTICAL_LIST) {
            drawVertical(c, parent);
        } else {
            drawHorizontal(c, parent);
        }
    }

    public void drawVertical(Canvas c, RecyclerView parent) {
        final int left = parent.getPaddingLeft();
        final int right = parent.getWidth() - parent.getPaddingRight();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            android.support.v7.widget.RecyclerView v = new android.support.v7.widget.RecyclerView(parent.getContext());
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int top = child.getBottom() + params.bottomMargin;
            final int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    public void drawHorizontal(Canvas c, RecyclerView parent) {
        final int top = parent.getPaddingTop();
        final int bottom = parent.getHeight() - parent.getPaddingBottom();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int left = child.getRight() + params.rightMargin;
            final int right = left + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
        if (mOrientation == VERTICAL_LIST) {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        }
    }
}

DividerGridItemDecoration.java

package com.jackie.recyclerview;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.RecyclerView.LayoutManager;
import android.support.v7.widget.RecyclerView.State;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.View;

public class DividerGridItemDecoration extends RecyclerView.ItemDecoration {

    private static final int[] ATTRS = new int[]{android.R.attr.listDivider};
    private Drawable mDivider;
    private int mSpace;

    public DividerGridItemDecoration(Context context, int space) {
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        mSpace = space;
        a.recycle();
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, State state) {

        drawHorizontal(c, parent);
        drawVertical(c, parent);

    }

    private int getSpanCount(RecyclerView parent) {
        // 列数
        int spanCount = -1;
        LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {

            spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            spanCount = ((StaggeredGridLayoutManager) layoutManager).getSpanCount();
        }
        return spanCount;
    }

    public void drawHorizontal(Canvas c, RecyclerView parent) {
        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int left = child.getLeft() - params.leftMargin;
            final int right = child.getRight() + params.rightMargin + mDivider.getIntrinsicWidth();
            final int top = child.getBottom() + params.bottomMargin;
            final int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    public void drawVertical(Canvas c, RecyclerView parent) {
        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);

            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int top = child.getTop() - params.topMargin;
            final int bottom = child.getBottom() + params.bottomMargin;
            final int left = child.getRight() + params.rightMargin;
            final int right = left + mDivider.getIntrinsicWidth();

            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    //判断是否是最后一列
    private boolean isLastColumn(RecyclerView parent, int pos, int spanCount, int childCount) {
        LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            if ((pos + 1) % spanCount == 0) { // 如果是最后一列，则不需要绘制右边
                return true;
            }
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            int orientation = ((StaggeredGridLayoutManager) layoutManager).getOrientation();
            if (orientation == StaggeredGridLayoutManager.VERTICAL) {
                if ((pos + 1) % spanCount == 0) { // 如果是最后一列，则不需要绘制右边
                    return true;
                }
            } else {
                childCount = childCount - childCount % spanCount;
                if (pos >= childCount)// 如果是最后一列，则不需要绘制右边
                    return true;
            }
        }
        return false;
    }

    //判断是否是最后一行
    private boolean isLastRow(RecyclerView parent, int pos, int spanCount, int childCount) {
        LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            childCount = childCount - childCount % spanCount;
            if (pos >= childCount)// 如果是最后一行，则不需要绘制底部
                return true;
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            int orientation = ((StaggeredGridLayoutManager) layoutManager).getOrientation();
            // StaggeredGridLayoutManager 且纵向滚动
            if (orientation == StaggeredGridLayoutManager.VERTICAL) {
                childCount = childCount - childCount % spanCount;
                // 如果是最后一行，则不需要绘制底部
                if (pos >= childCount)
                    return true;
            } else {
                // StaggeredGridLayoutManager 且横向滚动
                // 如果是最后一行，则不需要绘制底部
                if ((pos + 1) % spanCount == 0) {
                    return true;
                }
            }
        }
        return false;
    }

    @Override
    public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
        int spanCount = getSpanCount(parent);
        int childCount = parent.getAdapter().getItemCount();
        if (isLastRow(parent, itemPosition, spanCount, childCount)) { // 如果是最后一行，则不需要绘制底部
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        } else if (isLastColumn(parent, itemPosition, spanCount, childCount)) { // 如果是最后一列，则不需要绘制右边
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), mDivider.getIntrinsicHeight());
        }

        //设置间距
        outRect.left = outRect.right = outRect.bottom = mSpace;
    }
}