Android自定义Spinner

项目中用到Spinner，什么都好，就是内含的popup无法限制高度。当我展示的数据较多时，
spinner会自动计算屏高，尽可能多的展示，导致item列表时高时矮，不甚美观。耗费了很多时间和精力
在网上查找解决方法，并仔细看了Spinner源码，发现真的没有提供限制高度这一方法。无奈只能尝试自己写一个类似功能的
MySpinner。
我们知道Spinner有DropdownPopup，DialogPopup两种展示模式，这里只用到DropDown模式，所以MySpinner中只用到了
TextView,PopupWindow和ListView。思路是点击TextView,显示包含ListView的PopupWindow和ListView，
然后设置 一系列点击事件和监听，满足需求。特点就在于可灵活设置PopupWindow宽高和Spinner常见功能。但因为只用到了基本的ArrayAdapter,所以功能有点受限。

代码如下：

public class MySpinner extends AppCompatTextView {    private PopupWindow popupWindow;    private int popupWindowWidth = 50;    private int popupWindowHeight = 50;    private int listviewDividerHeight = 0;    private int selectedItemPosition = 0;    private ListView listView;    private ListAdapter adapter;    private MySpinnerListener listener;//可监听listview Item点击，回调结果    public MySpinner(Context context) {        super(context);        initView(context);        initListener();    }    public MySpinner(Context context, @Nullable AttributeSet attrs) {        super(context, attrs);        initView(context);        initListener();    }    public MySpinner(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        initView(context);        initListener();    }    private void initView(Context context) {        popupWindow = new PopupWindow(this);        listView = new ListView(context);    }    private void initListener() {        setOnItemClickListener();        popupWindowShowAsDropDown(MySpinner.this);    }    public void setPopupWindowParams(int windowWidth,int windowHeight) {        this.popupWindowWidth = windowWidth;        this.popupWindowHeight = windowHeight;    }    public void setPopupWindowWidth(int windowWidth) {        this.popupWindowWidth = windowWidth;    }    public void setPopupWindowHeight(int windowHeight) {        this.popupWindowHeight = windowHeight;    }    public void setListviewDividerHeight(int listviewDividerHeight) {        this.listviewDividerHeight = listviewDividerHeight;    }    public void setAdapter(ListAdapter adapter) {        this.adapter = adapter;    }    //listview 点击事件    private void setOnItemClickListener() {        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {            @Override            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {                selectedItemPosition = position;                String itemselect = (String) parent.getItemAtPosition(position);                MySpinner.this.setText(itemselect);                popupWindow.dismiss();                //回调                if (listener != null)                    listener.onItemSelected(itemselect, position);            }        });    }    //作用同 listview setOnItemSelectedListener    public void setMySpinnerOnItemSelectedListener(MySpinnerListener listener) {        this.listener = listener;    }    public void popupWindowShowAsDropDown(View anchor) {        popupWindowShowAsDropDown(anchor, 0, 0);    }    public void popupWindowShowAsDropDown(View anchor, int xoff, int yoff) {        popupWindowShowAsDropDown(anchor, xoff, yoff, Gravity.TOP | Gravity.START);    }    public void popupWindowShowAsDropDown(final View anchor, final int xoff, final int yoff, final int gravity) {        //popupwindow显示事件        this.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                popupWindow.showAsDropDown(anchor, xoff, yoff, gravity);            }        });    }    public void show() {        listView.setBackgroundResource(R.drawable.shape_bg_test);        listView.setDividerHeight(listviewDividerHeight);        listView.setAdapter(adapter);        popupWindow.setWidth(popupWindowWidth);        popupWindow.setHeight(popupWindowHeight);        popupWindow.setContentView(listView);        popupWindow.setBackgroundDrawable(new ColorDrawable(0x00000000));        popupWindow.setOutsideTouchable(false);        popupWindow.setFocusable(true);        setSelection(0);    }    public void setSelection(int i) {        if (adapter != null && adapter.getCount() > i) {            selectedItemPosition = i;            listView.setSelection(i);            MySpinner.this.setText((String) adapter.getItem(i));        }    }    public String getSelectedItem() {        return (String) listView.getItemAtPosition(selectedItemPosition);    }    public int getSelectedItemPosition() {        return selectedItemPosition;    }}

public interface MySpinnerListener {    public void onItemSelected(String item,int position);}

调用如下：

    myspinner.setPopupWindowParams(dip2px(getActivity(), 70), dip2px(getActivity(), 26*7));    myspinner.setAdapter(new ArrayAdapter<String>(getActivity(), R.layout.simple_spinner_dropdown_item, getDays()));    myspinner.show();