一、需求

Android提供了实现网格布局的GridView，还有RecyclerView等，但是在互相嵌套的问题上冲突很多，尤其是GridView焦点状态转移导致体验相当不好。为了能够在RecyclerView上自动实现网格排列，我们提供了如下方案。

​​​​​​​public class AutoFixedHeightGridView extends ViewGroup {    private BaseAdapter mAdapter;    private DataSetObserver mDataSetObserver;    private int columnNums;    private int columnPadding;    private int rowPadding;       Map
    
      rowMaxHeight = new HashMap<>();    public AutoFixedHeightGridView(Context context) {        this(context,null);    }    public AutoFixedHeightGridView(Context context, AttributeSet attrs) {        this(context, attrs,0);    }    public AutoFixedHeightGridView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        final TypedArray a = context.obtainStyledAttributes(                attrs, R.styleable.AutoFixedHeightGridView, defStyleAttr, 0);        columnNums = a.getInt(R.styleable.AutoFixedHeightGridView_numColumns, 1);        int hSpacing = a.getDimensionPixelOffset(                R.styleable.AutoFixedHeightGridView_horizontalSpacing, 0);        columnPadding = hSpacing;        int vSpacing = a.getDimensionPixelOffset(                R.styleable.AutoFixedHeightGridView_verticalSpacing, 0);        rowPadding = vSpacing;        a.recycle();    }    public void setAdapter(BaseAdapter mAdapter) {        if(this.mAdapter!=null &&  mDataSetObserver != null){            this.mAdapter.unregisterDataSetObserver(mDataSetObserver);        }        if(mDataSetObserver==null){            mDataSetObserver = new GridDataSetObserver(this);        }        this.mAdapter = mAdapter;               if(this.mAdapter!=null) {            this.mAdapter.registerDataSetObserver(mDataSetObserver);            this.mAdapter.notifyDataSetChanged();        }else{            datasetChanged();        }    }    public BaseAdapter getAdapter() {        return mAdapter;    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);        int widthMode = MeasureSpec.getMode(widthMeasureSpec);        int heightMode = MeasureSpec.getMode(heightMeasureSpec);        int widthSize = MeasureSpec.getSize(widthMeasureSpec);        int heightSize = MeasureSpec.getSize(heightMeasureSpec);        int rowNums = 0;        if (widthMode == MeasureSpec.UNSPECIFIED) {            widthSize = getPaddingLeft() + getPaddingRight();            if(columnNums>1){                widthSize += (columnNums-1) * columnPadding;            }        }        if (heightMode == MeasureSpec.UNSPECIFIED) {            heightSize = getPaddingBottom() + getPaddingTop();            int contentWidth = widthSize - (getPaddingLeft() + getPaddingRight());            if (columnNums > 1) {                contentWidth = contentWidth - (columnNums - 1) * columnPadding;            }            int columnWidth = contentWidth / columnNums;            int count = this.getAdapter() != null ? this.getAdapter().getCount() : 0;            if (count != getChildCount()) return;            for (int i = 0; i < getChildCount(); i++) {                final View child = getChildAt(i);                LayoutParams params = (LayoutParams) child.getLayoutParams();                params.rightMargin = 0;                params.leftMargin = 0;                int childHeightSpec = getChildMeasureSpec(                        MeasureSpec.makeMeasureSpec(MeasureSpec.getSize(heightMeasureSpec),                                MeasureSpec.UNSPECIFIED), 0, params.height);                int childWidthSpec = getChildMeasureSpec(                        MeasureSpec.makeMeasureSpec(columnWidth, MeasureSpec.EXACTLY), 0, columnWidth);                child.measure(childWidthSpec, childHeightSpec);                int childHeight = child.getMeasuredHeight();                if (i % columnNums == 0 && i > 1) {                    rowNums++;                }                Integer lastMaxHeight = rowMaxHeight.get(rowNums);                if (lastMaxHeight == null) {                    lastMaxHeight = 0;                }                rowMaxHeight.put(rowNums, Math.max(lastMaxHeight, childHeight));            }            int rowCount = (int) Math.ceil(count * 1.0f / columnNums);            for (int i = 0; i < rowCount; i++) {                heightSize += rowMaxHeight.get(i);            }            if (rowCount > 1) {                heightSize += (rowCount - 1) * rowPadding;            }        }else{            int contentWidth = widthSize - (getPaddingLeft() + getPaddingRight());            if (columnNums > 1) {                contentWidth = contentWidth - (columnNums - 1) * columnPadding;            }            int columnWidth = contentWidth / columnNums;            int count = this.getAdapter() != null ? this.getAdapter().getCount() : 0;            if (count != getChildCount()) return;            for (int i = 0; i < getChildCount(); i++) {                final View child = getChildAt(i);                LayoutParams params = (LayoutParams) child.getLayoutParams();                params.rightMargin = 0;                params.leftMargin = 0;                int childHeightSpec = getChildMeasureSpec(                        MeasureSpec.makeMeasureSpec(MeasureSpec.getSize(heightMeasureSpec),                                MeasureSpec.UNSPECIFIED), 0, heightSize);                int childWidthSpec = getChildMeasureSpec(                        MeasureSpec.makeMeasureSpec(columnWidth, MeasureSpec.EXACTLY), 0, columnWidth);                child.measure(childWidthSpec, childHeightSpec);            }        }        setMeasuredDimension(widthSize, heightSize);    }    @Override    protected void onLayout(boolean changed, int l, int t, int r, int b) {        int count = this.getAdapter()!=null?this.getAdapter().getCount():0;        int rowCount = 0;        int nextChildLeft = getPaddingLeft();        int nextChildTop = getPaddingTop();        int contentWidth = getMeasuredWidth() - (getPaddingLeft() + getPaddingRight());        if(columnNums>1){            contentWidth = contentWidth - (columnNums-1) * columnPadding;        }        int columnWidth = contentWidth /columnNums;        if(count!=getChildCount()) return;        for (int i=0;i
     
      0 && i%columnNums==0){                Integer H = rowMaxHeight.get(rowCount);                rowCount++;                nextChildLeft = getPaddingLeft();                if(H==null){                    H = 0;                }                nextChildTop = nextChildTop +H + rowPadding;            }               child.layout(nextChildLeft,nextChildTop,nextChildLeft+columnWidth,nextChildTop+child.getMeasuredHeight());               nextChildLeft = nextChildLeft+child.getMeasuredWidth() + columnPadding ;        }    }    protected void datasetChanged() {        if(this.mAdapter==null){            removeAllViews();            return;        }        final int count = this.mAdapter.getCount();        for (int i=0;i
      
       viewTypeCount) {                throw  new IllegalArgumentException("viewType is correct");            }             View view = null;            if(i
       
        0){                removeViewsInLayout(getChildCount()-delta,delta);          }         rquestLayout();         invalidate();    }   protected void addViewInLayout(View child){        this.addViewInLayout(child,-1);    }    /**     *     * @param child     * @param index 位置，如果是-1，则自动添加到末尾     */    protected void addViewInLayout(View child,int index){        if (child == null) {            throw new IllegalArgumentException("Cannot add a null child view to a ViewGroup");        }        ViewGroup.LayoutParams params = child.getLayoutParams();        if (params == null) {            params = generateDefaultLayoutParams();            if (params == null) {                throw new IllegalArgumentException("generateDefaultLayoutParams() cannot return null");            }        }        super.addViewInLayout(child,index,params);    }    public static  class GridDataSetObserver extends DataSetObserver{        private AutoFixedHeightGridView fixedHeightGridView;        public GridDataSetObserver(FixedHeightGridView fixedHeightGridView) {            this.fixedHeightGridView = fixedHeightGridView;        }        @Override        public void onChanged() {            super.onChanged();            fixedHeightGridView.datasetChanged();        }        @Override        public void onInvalidated() {            super.onInvalidated();            fixedHeightGridView.datasetChanged();        }    }    @Override    protected ViewGroup.LayoutParams generateDefaultLayoutParams() {  //child默认布局参数        return new LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.MATCH_PARENT);    }    @Override    protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {        return new LayoutParams(p);    }    @Override    protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {  //重写该方法，否则        return (p instanceof LayoutParams) ;    }    @Override    public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) {        return new LayoutParams(getContext(), attrs);    }    public static  class LayoutParams extends  ViewGroup.MarginLayoutParams{      private int viewType;      private static final int TYPE_UNDEFINED = 0;      public LayoutParams(Context c, AttributeSet attrs) {          super(c, attrs);          TypedArray a=c.obtainStyledAttributes(attrs, R.styleable.AutoFixedHeightGridView);          this.viewType = a.getInt(R.styleable.AutoFixedHeightGridView_viewType, TYPE_UNDEFINED); //该属性定义给child的          a.recycle();      }      public LayoutParams(int width, int height) {          super(width, height);          this.viewType = TYPE_UNDEFINED;      }      public LayoutParams(MarginLayoutParams source) {          super(source);          if(source instanceOf LayoutParams){               this.viewType = ((LayoutParams)source).viewType;          }else{             this.viewType = TYPE_UNDEFINED;          }      }      public LayoutParams(ViewGroup.LayoutParams source) {          super(source);             if(source instanceOf LayoutParams){               this.viewType = ((LayoutParams)source).viewType;             } else{               this.viewType = TYPE_UNDEFINED;            }      }      public int getViewType(){        return viewType;     }  }}
       
      
     
    

自定义属性部分