Android RecyclerView(瀑布流)水平/垂直方向分割线

Android RecyclerView不像过去的ListView那样随意的设置水平方向的分割线，如果要实现RecyclerView的水平/垂直分割线，则需要继承自RecyclerView.ItemDecoration重写getItemOffsets方法，从而增加水平/垂直分割线。

写一个例子。

MainActivity.java：

package zhangphil.app;

import android.content.Context;

import android.graphics.Color;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.support.v7.widget.RecyclerView;

import android.support.v7.widget.StaggeredGridLayoutManager;

import android.view.View;

import android.view.ViewGroup;

import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

RecyclerView mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);

// 两列

int spanCount = 2;

// StaggeredGridLayoutManager管理RecyclerView的布局。

StaggeredGridLayoutManager mLayoutManager = new StaggeredGridLayoutManager(spanCount, StaggeredGridLayoutManager.VERTICAL);

mRecyclerView.setLayoutManager(mLayoutManager);

//为RecyclerView增加分割线，水平和垂直方向都有。增加分割线值比如为32。

RecyclerViewItemDecoration decoration = new RecyclerViewItemDecoration(32);

mRecyclerView.addItemDecoration(decoration);

RecyclerViewAdapter mAdapter = new RecyclerViewAdapter(this);

mRecyclerView.setAdapter(mAdapter);

}

private class ItemViewHolder extends RecyclerView.ViewHolder {

private TextView text;

public ItemViewHolder(View itemView) {

super(itemView);

text = (TextView) itemView.findViewById(android.R.id.text1);

text.setTextColor(Color.WHITE);

}

}

public class RecyclerViewAdapter extends RecyclerView.Adapter {

private Context context;

public RecyclerViewAdapter(Context context) {

super();

this.context = context;

}

@Override

public ItemViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {

View view = View.inflate(context, android.R.layout.simple_list_item_1, null);

view.setBackgroundColor(Color.RED);

ItemViewHolder holder = new ItemViewHolder(view);

return holder;

}

@Override

public void onBindViewHolder(ItemViewHolder viewHolder, int pos) {

viewHolder.text.setText(String.valueOf(pos));

}

@Override

public int getItemCount() {

return 15;

}

}

}

布局文件，很简单，就放一个RecyclerView，注意背景颜色的设置：

android:layout_width="match_parent"

android:layout_height="match_parent"

android:background="@android:color/holo_orange_light">

android:id="@+id/recyclerView"

android:layout_width="match_parent"

android:layout_height="match_parent">

最关键的RecyclerViewItemDecoration.java：

package zhangphil.app;

/**

* Created by Phil on 2016/10/8.

*/

import android.graphics.Rect;

import android.support.v7.widget.RecyclerView;

import android.view.View;

/**

* 为RecyclerView增加间距

* 预设2列，如果是3列，则左右值不同

*/

public class RecyclerViewItemDecoration extends RecyclerView.ItemDecoration {

private int space = 0;

private int pos;

public RecyclerViewItemDecoration(int space) {

this.space = space;

}

@Override

public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {

outRect.top = space;

//该View在整个RecyclerView中位置。

pos = parent.getChildAdapterPosition(view);

//取模

//两列的左边一列

if (pos % 2 == 0) {

outRect.left = space;

outRect.right = space / 2;

}

//两列的右边一列

if (pos % 2 == 1) {

outRect.left = space / 2;

outRect.right = space;

}

}

}

代码运行结果：