Android RecyclerView应用

基本使用

配置build.gradle
implementation 'com.android.support:recyclerview-v7:28.0.0'
创建activity_recycleview.xml
<?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="match_parent">

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

</RelativeLayout>
创建RecyclerViewActivity.java
import android.content.Context;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.FragmentActivity;
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 RecyclerViewActivity extends FragmentActivity {

    RecyclerView recyclerView;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_recycleview);

        recyclerView = findViewById(R.id.recycerview);

        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(new MyAdapter(this, getListData()));
    }

    private List<String> getListData() {
        List<String> dataSource = new ArrayList<>();
        for (int index = 0; index < 20; index++) {
            dataSource.add(String.valueOf(index));
        }
        return dataSource;
    }

    class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {

        Context mContext;
        List<String> mDataSource;

        public MyAdapter(Context context, List<String> dataSource) {
            mContext = context;
            mDataSource = dataSource;
        }

        @NonNull
        @Override
        public MyViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
            View itemView = LayoutInflater.from(mContext).inflate(R.layout.item_view, viewGroup, false);
            MyViewHolder myViewHolder = new MyViewHolder(itemView);
            return myViewHolder;
        }

        @Override
        public void onBindViewHolder(@NonNull MyViewHolder myViewHolder, int i) {
            myViewHolder.valueTv.setText(mDataSource.get(i));
        }

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

        class MyViewHolder extends RecyclerView.ViewHolder {

            TextView valueTv;

            public MyViewHolder(@NonNull View itemView) {
                super(itemView);

                valueTv = itemView.findViewById(R.id.tv_item);
            }
        }
    }
}
效果如下
device-2018-11-21-000235.png
设置分割线

分割线的设置可以如上面示例中的一样在item的xml文件中直接设置，也可以如下方式设置

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) {
        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);
        }
    }
}

使用

recyclerView.addItemDecoration(new DividerItemDecoration(RecyclerViewActivity.this, DividerItemDecoration.VERTICAL_LIST));
效果如下
device-2018-11-21-002353.png
实现网格布局

创建DividerGridItemDecoration.java

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;

    public DividerGridItemDecoration(Context context) {
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        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);
        }
    }

    private boolean isLastColum(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;
    }

    private boolean isLastRaw(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 (isLastRaw(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 (isLastColum(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());
        }
    }
}

使用

recyclerView.setLayoutManager(new StaggeredGridLayoutManager(4,StaggeredGridLayoutManager.VERTICAL));
recyclerView.addItemDecoration(new DividerGridItemDecoration(this));
效果如下
device-2018-11-21-003059.png
瀑布流实现

修改item_view.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="wrap_content"
    android:layout_margin="2dp"
    android:background="@android:color/white"
    android:orientation="vertical">

    <TextView
        android:id="@+id/tv_item"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:gravity="center"
        android:text="moon" />
</LinearLayout>

修改RecyclerViewActivity.java

import android.content.Context;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.FragmentActivity;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;

import com.example.liudeshu.androidtest.util.DividerGridItemDecoration;

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

public class RecyclerViewActivity extends FragmentActivity {

    RecyclerView recyclerView;
    
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_recycleview);

        recyclerView = findViewById(R.id.recycerview);

//        recyclerView.setLayoutManager(new LinearLayoutManager(this));
//        recyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST));
        recyclerView.setLayoutManager(new StaggeredGridLayoutManager(4,
                StaggeredGridLayoutManager.VERTICAL));
        recyclerView.addItemDecoration(new DividerGridItemDecoration(this));
        recyclerView.setAdapter(new MyAdapter(this, getListData()));
    }

    private List<String> getListData() {
        List<String> dataSource = new ArrayList<>();
        for (int index = 0; index < 20; index++) {
            dataSource.add(String.valueOf(index));
        }
        return dataSource;
    }

    class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {

        Context mContext;
        List<String> mDataSource;
        List<Integer> mHeightSource;

        public MyAdapter(Context context, List<String> dataSource) {
            mContext = context;
            mDataSource = dataSource;
            mHeightSource = getItemDataHeight();
        }

        private List<Integer> getItemDataHeight() {
            List<Integer> heightSource = new ArrayList<Integer>();
            for (int i = 0; i < mDataSource.size(); i++) {
                heightSource.add((int) (100 + Math.random() * 300));
            }
            return heightSource;
        }

        @NonNull
        @Override
        public MyViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
            View itemView = LayoutInflater.from(mContext).inflate(R.layout.item_view, viewGroup, false);
            MyViewHolder myViewHolder = new MyViewHolder(itemView);
            return myViewHolder;
        }

        @Override
        public void onBindViewHolder(@NonNull MyViewHolder myViewHolder, final int i) {
            LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) myViewHolder.valueTv.getLayoutParams();
            lp.height = mHeightSource.get(i);
            myViewHolder.valueTv.setLayoutParams(lp);

            myViewHolder.valueTv.setText(mDataSource.get(i));
            myViewHolder.valueTv.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Toast.makeText(mContext, "这是第" + i + "项", Toast.LENGTH_SHORT).show();
                }
            });
        }

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

        class MyViewHolder extends RecyclerView.ViewHolder {

            TextView valueTv;

            public MyViewHolder(@NonNull View itemView) {
                super(itemView);

                valueTv = itemView.findViewById(R.id.tv_item);
            }
        }
    }
}
效果如下
device-2018-11-21-004032.png
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