android 适配器模式（二）添加适配器

1.搭建适配器 继承 BaseAdapter

public class CircleMenuAdapter extends BaseAdapter {
    private List<Menu> list;
    public CircleMenuAdapter(List<Menu> list) {
        this.list = list;
    }
    @Override
    public int getCount() {
        return list.size();
    }
    @Override
    public Object getItem(int position) {
        return position;
    }
    @Override
    public long getItemId(int position) {
        return position;
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        View view = inflater.inflate(R.layout.circle_menu_item,parent,false);
        initMenuItem(view,position);
        return view;
    }
    private void initMenuItem(View v,int p) {
        Menu menu = list.get(p);
        TextView textView = v.findViewById(R.id.circle_menu_text);
        ImageView img = v.findViewById(R.id.circle_menu_img);
        textView.setText(menu.text);
        Log.d("text",menu.text);
        img.setImageResource(menu.imgId);
    }
}

2.向viewgroup添加适配器

public class CircleMenuLayout extends ViewGroup {
    private int mRadius;
    //子布局默认的尺寸
    private static final float RADIUS_CHILD_ITEM = 1/4f;
    private static final float RADIUS_PADDING = 1/12f;
    private float padding;
    private double startAngle;
    private CircleMenuAdapter adapter;
    public void setCircleAdapter(CircleMenuAdapter adapter){
        this.adapter = adapter;
    }
    public CircleMenuLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        setPadding(0,0,0,0);
    }

    @Override
    protected void onAttachedToWindow() {
        if (adapter != null){
            buildMenuItem();
        }
        super.onAttachedToWindow();
    }
    private void buildMenuItem(){
        for (int i=0;i<adapter.getCount();++i){
            View itemView = adapter.getView(i,null,this);
            addView(itemView);
        }
    }
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        measureSelf(widthMeasureSpec,heightMeasureSpec);
        measureChildItem();
    }
    private void measureSelf(int widthMeasureSpec, int heightMeasureSpec){
        int resWidth;
        int resHeight;
        int width = MeasureSpec.getSize(widthMeasureSpec);
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int height = MeasureSpec.getSize(heightMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        if (widthMode == MeasureSpec.EXACTLY || heightMode == MeasureSpec.EXACTLY){
            resWidth = getSuggestedMinimumWidth();
            resWidth = resWidth == 0 ? getWidth() : resWidth;
            resHeight = getSuggestedMinimumHeight();
            resHeight = resHeight == 0 ? getHeight() : resHeight;
        }else {
            resWidth = resHeight = Math.min(width,height);
        }
        setMeasuredDimension(resWidth,resHeight);
    }
    private void measureChildItem(){
        mRadius = Math.max(getMeasuredWidth(),getMeasuredHeight());
        int childSize = (int) (mRadius * RADIUS_CHILD_ITEM);
        int childMode = MeasureSpec.EXACTLY;
        for (int i=0;i<adapter.getCount();++i){
            View childView = getChildAt(i);
            int measureChild = -1;
            measureChild = MeasureSpec.makeMeasureSpec(childSize,childMode);
            childView.measure(measureChild,measureChild);
        }
        padding = mRadius * RADIUS_PADDING;
    }
    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int childCount = adapter.getCount();
        int left,top;
        int angleDelay = 360/childCount;
        int itemWidth = (int) (mRadius*RADIUS_CHILD_ITEM);
        for (int i=0;i<adapter.getCount();++i){
            View childView = getChildAt(i);
            startAngle %= 360;
            //到中心点的距离
            int distanceFromCenter = (int) (mRadius/2 - itemWidth/2 - padding);
            left = mRadius/2 + (int) (Math.round(distanceFromCenter*Math.cos(Math.toRadians(startAngle)))-1/2f*itemWidth);
            top = mRadius/2 + (int)(Math.round(distanceFromCenter*Math.sin(Math.toRadians(startAngle)))-1/2f*itemWidth);
            childView.layout(left,top,left+itemWidth,top+itemWidth);
            startAngle+=angleDelay;
        }
    }
}

效果图

其实（一）（二）的效果是一样的，这里就不做详细介绍了。