这是之前在ListView类中使用divider和dividerHeight参数实现的一个例子:
<ListView
android:id="@+id/activity_home_list_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:divider="@android:color/transparent"
android:dividerHeight="8dp"/>
然而，在RecyclerView类中我没有看到这样的可能性。
<android.support.v7.widget.RecyclerView
android:id="@+id/activity_home_recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical"/>
在这种情况下，是否可以定义边距和/或直接添加自定义分隔符视图到列表项的布局中，或者是否有更好的方法来实现我的目标?
从谷歌搜索，添加这个ItemDecoration到你的RecyclerView:
public class DividerItemDecoration extends RecyclerView.ItemDecoration {
private Drawable mDivider;
private boolean mShowFirstDivider = false;
private boolean mShowLastDivider = false;
public DividerItemDecoration(Context context, AttributeSet attrs) {
final TypedArray a = context
.obtainStyledAttributes(attrs, new int[]{android.R.attr.listDivider});
mDivider = a.getDrawable(0);
a.recycle();
}
public DividerItemDecoration(Context context, AttributeSet attrs, boolean showFirstDivider,
boolean showLastDivider) {
this(context, attrs);
mShowFirstDivider = showFirstDivider;
mShowLastDivider = showLastDivider;
}
public DividerItemDecoration(Drawable divider) {
mDivider = divider;
}
public DividerItemDecoration(Drawable divider, boolean showFirstDivider,
boolean showLastDivider) {
this(divider);
mShowFirstDivider = showFirstDivider;
mShowLastDivider = showLastDivider;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent,
RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
if (mDivider == null) {
return;
}
if (parent.getChildPosition(view) < 1) {
return;
}
if (getOrientation(parent) == LinearLayoutManager.VERTICAL) {
outRect.top = mDivider.getIntrinsicHeight();
} else {
outRect.left = mDivider.getIntrinsicWidth();
}
}
@Override
public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
if (mDivider == null) {
super.onDrawOver(c, parent, state);
return;
}
// Initialization needed to avoid compiler warning
int left = 0, right = 0, top = 0, bottom = 0, size;
int orientation = getOrientation(parent);
int childCount = parent.getChildCount();
if (orientation == LinearLayoutManager.VERTICAL) {
size = mDivider.getIntrinsicHeight();
left = parent.getPaddingLeft();
right = parent.getWidth() - parent.getPaddingRight();
} else { // Horizontal
size = mDivider.getIntrinsicWidth();
top = parent.getPaddingTop();
bottom = parent.getHeight() - parent.getPaddingBottom();
}
for (int i = mShowFirstDivider ? 0 : 1; i < childCount; i++) {
View child = parent.getChildAt(i);
RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
if (orientation == LinearLayoutManager.VERTICAL) {
top = child.getTop() - params.topMargin;
bottom = top + size;
} else { // Horizontal
left = child.getLeft() - params.leftMargin;
right = left + size;
}
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
// Show the last divider
if (mShowLastDivider && childCount > 0) {
View child = parent.getChildAt(childCount - 1);
RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
if (orientation == LinearLayoutManager.VERTICAL) {
top = child.getBottom() + params.bottomMargin;
bottom = top + size;
} else { // hHorizontal
left = child.getRight() + params.rightMargin;
right = left + size;
}
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
private int getOrientation(RecyclerView parent) {
if (parent.getLayoutManager() instanceof LinearLayoutManager) {
LinearLayoutManager layoutManager = (LinearLayoutManager) parent.getLayoutManager();
return layoutManager.getOrientation();
} else {
throw new IllegalStateException(
"DividerItemDecoration can only be used with a LinearLayoutManager.");
}
}
}
如果有人想为spaceBetween, paddingLeft, paddingTop, paddingRight和paddingBottom设置不同的值。
class ItemPaddingDecoration(
private val spaceBetween: Int,
private val paddingLeft: Int = spaceBetween,
private val paddingTop: Int = spaceBetween,
private val paddingRight: Int = spaceBetween,
private val paddingBottom: Int = spaceBetween
) : RecyclerView.ItemDecoration() {
override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
val position = parent.getChildAdapterPosition(view)
val orientation = when (val layoutManager = parent.layoutManager) {
is LinearLayoutManager -> {
layoutManager.orientation
}
is GridLayoutManager -> {
layoutManager.orientation
}
else -> {
RecyclerView.HORIZONTAL
}
}
if (orientation == RecyclerView.HORIZONTAL) {
when {
position == 0 -> {
outRect.set(paddingLeft, paddingTop, spaceBetween, paddingBottom)
}
position < parent.adapter!!.itemCount - 1 -> {
outRect.set(0, paddingTop, spaceBetween, paddingBottom)
}
else -> {
outRect.set(0, paddingTop, paddingRight, paddingBottom)
}
}
} else {
when {
position == 0 -> {
outRect.set(paddingLeft, paddingTop, paddingRight, paddingBottom)
}
position < parent.adapter!!.itemCount - 1 -> {
outRect.set(paddingLeft, 0, paddingRight, spaceBetween)
}
else -> {
outRect.set(paddingLeft, 0, paddingRight, paddingBottom)
}
}
}
}
}
public class CommonItemSpaceDecoration extends RecyclerView.ItemDecoration {
private int mSpace = 0;
private boolean mVerticalOrientation = true;
public CommonItemSpaceDecoration(int space) {
this.mSpace = space;
}
public CommonItemSpaceDecoration(int space, boolean verticalOrientation) {
this.mSpace = space;
this.mVerticalOrientation = verticalOrientation;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
outRect.top = SizeUtils.dp2px(view.getContext(), mSpace);
if (mVerticalOrientation) {
if (parent.getChildAdapterPosition(view) == 0) {
outRect.set(0, SizeUtils.dp2px(view.getContext(), mSpace), 0, SizeUtils.dp2px(view.getContext(), mSpace));
} else {
outRect.set(0, 0, 0, SizeUtils.dp2px(view.getContext(), mSpace));
}
} else {
if (parent.getChildAdapterPosition(view) == 0) {
outRect.set(SizeUtils.dp2px(view.getContext(), mSpace), 0, 0, 0);
} else {
outRect.set(SizeUtils.dp2px(view.getContext(), mSpace), 0, SizeUtils.dp2px(view.getContext(), mSpace), 0);
}
}
}
}
这将增加每个项目的顶部和底部(或左右)的空间。然后你可以将它设置为你的recyclerView。
recyclerView.addItemDecoration(new CommonItemSpaceDecoration(16));
文件SizeUtils.java
public class SizeUtils {
public static int dp2px(Context context, float dpValue) {
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (dpValue * scale + 0.5f);
}
}
实现它自己的RecyclerView版本。ItemDecoration
public class SpacingItemDecoration extends RecyclerView.ItemDecoration {
private int spacingPx;
private boolean addStartSpacing;
private boolean addEndSpacing;
public SpacingItemDecoration(int spacingPx) {
this(spacingPx, false, false);
}
public SpacingItemDecoration(int spacingPx, boolean addStartSpacing, boolean addEndSpacing) {
this.spacingPx = spacingPx;
this.addStartSpacing = addStartSpacing;
this.addEndSpacing = addEndSpacing;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
if (spacingPx <= 0) {
return;
}
if (addStartSpacing && parent.getChildLayoutPosition(view) < 1 || parent.getChildLayoutPosition(view) >= 1) {
if (getOrientation(parent) == LinearLayoutManager.VERTICAL) {
outRect.top = spacingPx;
} else {
outRect.left = spacingPx;
}
}
if (addEndSpacing && parent.getChildAdapterPosition(view) == getTotalItemCount(parent) - 1) {
if (getOrientation(parent) == LinearLayoutManager.VERTICAL) {
outRect.bottom = spacingPx;
} else {
outRect.right = spacingPx;
}
}
}
private int getTotalItemCount(RecyclerView parent) {
return parent.getAdapter().getItemCount();
}
private int getOrientation(RecyclerView parent) {
if (parent.getLayoutManager() instanceof LinearLayoutManager) {
return ((LinearLayoutManager) parent.getLayoutManager()).getOrientation();
} else {
throw new IllegalStateException("SpacingItemDecoration can only be used with a LinearLayoutManager.");
}
}
}
