我正在尝试使用RecyclerView和GridLayoutManager制作一个三列网格，并使用ItemDecoration来制作列间距，现在的问题是第三列中项目的宽度比第一列和第二列中的项目小！请参见下面的屏幕截图。
如果我不将自定义的ItemDecoration添加到RecyclerView中，一切都正常。
以下是我的代码：
MainActivity.java:
如果我不将自定义的ItemDecoration添加到RecyclerView中，一切都正常。
以下是我的代码：
MainActivity.java:
public class MainActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
private MyAdapter mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);
mAdapter = new MyAdapter();
mRecyclerView.setAdapter(mAdapter);
GridLayoutManager gridLayoutManager = new GridLayoutManager(this, 3);
mRecyclerView.setLayoutManager(gridLayoutManager);
int horizontalSpacing = 20;
int verticalSpacing = 10;
SpacingDecoration decoration = new SpacingDecoration(horizontalSpacing, verticalSpacing, true);
mRecyclerView.addItemDecoration(decoration);
}
private static class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private int[] mColors = new int[]{Color.RED, Color.BLUE, Color.MAGENTA};
private static class ItemHolder extends RecyclerView.ViewHolder {
public MyTextView title;
public ItemHolder(View itemView) {
super(itemView);
title = (MyTextView) itemView.findViewById(android.R.id.text1);
title.setTextColor(Color.WHITE);
}
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item, parent, false);
ItemHolder holder = new ItemHolder(itemView);
holder.itemView.setOnClickListener(itemClickListener);
return holder;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder rHolder, int position) {
ItemHolder holder = (ItemHolder) rHolder;
holder.title.setText(String.format("[%d]width:%d", position, holder.itemView.getWidth()));
holder.itemView.setBackgroundColor(mColors[position % mColors.length]);
holder.itemView.setTag(position);
holder.title.setTag(position);
}
@Override
public int getItemCount() {
return 50;
}
private View.OnClickListener itemClickListener = new View.OnClickListener() {
@Override
public void onClick(View v) {
int position = (int) v.getTag();
showText(v.getContext(), String.format("[%d]->width:%d", position, v.getWidth()));
}
};
}
public static class SpacingDecoration extends RecyclerView.ItemDecoration {
private int mHorizontalSpacing = 5;
private int mVerticalSpacing = 5;
private boolean isSetMargin = true;
public SpacingDecoration(int hSpacing, int vSpacing, boolean setMargin) {
isSetMargin = setMargin;
mHorizontalSpacing = hSpacing;
mVerticalSpacing = vSpacing;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
boolean isSetMarginLeftAndRight = this.isSetMargin;
int bottomOffset = mVerticalSpacing;
int leftOffset = 0;
int rightOffset = 0;
RecyclerView.LayoutParams lp = (RecyclerView.LayoutParams) view.getLayoutParams();
if (parent.getLayoutManager() instanceof GridLayoutManager) {
GridLayoutManager lm = (GridLayoutManager) parent.getLayoutManager();
GridLayoutManager.LayoutParams gridLp = (GridLayoutManager.LayoutParams) lp;
if (gridLp.getSpanSize() == lm.getSpanCount()) {
// Current item is occupied the whole row
// We just need to care about margin left and right now
if (isSetMarginLeftAndRight) {
leftOffset = mHorizontalSpacing;
rightOffset = mHorizontalSpacing;
}
} else {
// Current item isn't occupied the whole row
if (gridLp.getSpanIndex() > 0) {
// Set space between items in one row
leftOffset = mHorizontalSpacing;
} else if (gridLp.getSpanIndex() == 0 && isSetMarginLeftAndRight) {
// Set left margin of a row
leftOffset = mHorizontalSpacing;
}
if (gridLp.getSpanIndex() == lm.getSpanCount() - gridLp.getSpanSize() && isSetMarginLeftAndRight) {
// Set right margin of a row
rightOffset = mHorizontalSpacing;
}
}
}
outRect.set(leftOffset, 0, rightOffset, bottomOffset);
}
}
private static Toast sToast;
public static void showText(Context context, String text) {
if (sToast != null) {
sToast.cancel();
}
sToast = Toast.makeText(context, text, Toast.LENGTH_LONG);
sToast.show();
}
}
activity_main.xml
<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/recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</RelativeLayout>
item.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="match_parent"
android:orientation="vertical">
<com.example.liuqing.rvgldemo.MyTextView
android:id="@android:id/text1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="5dp"
android:textColor="#ffffff"
android:textAppearance="?android:attr/textAppearanceMedium"/>
</LinearLayout>
MyTextView.java
public class MyTextView extends TextView {
public MyTextView(Context context) {
super(context);
}
public MyTextView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyTextView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
public void onWindowFocusChanged(boolean hasWindowFocus) {
super.onWindowFocusChanged(hasWindowFocus);
if (hasWindowFocus) {
setText("[" + getTag() + "]width:" + getWidth());
}
}
}
如果有人能解释这个问题，那将会非常感激。
+1实际上不是+1，它应该是+单元格的spanSize。（你可以通过spanSizeLookup或单元格的LayoutParams来检索span大小） - pdegand59