Android下拉列表选项框及指示箭头动画

android原生的spinner提供了下拉列表选项框，但在一些流行的app中，原生的spinner似乎不太受待见，而通常会有下图所示的下拉列表选项框：

初始化状态：

点击弹出下拉选择选项框：

选中后：

注意那个指示箭头，如果把这个控件写的比较精细的话，在下拉-选择-复位过程中箭头是应该有动画旋转效果的。

这种样式的选择框实现方案很多，并且常见、常用，我自己写了一个，我写的这个例子的代码运行结果就是上图所示。

首先是mainactivity.java：

package zhangphil.app;

import android.content.context;
import android.graphics.color;
import android.support.v7.app.appcompatactivity;
import android.os.bundle;
import android.support.v7.widget.listpopupwindow;
import android.view.layoutinflater;
import android.view.view;
import android.view.viewgroup;
import android.widget.adapterview;
import android.widget.arrayadapter;
import android.widget.imageview;
import android.widget.linearlayout;
import android.widget.popupwindow;
import android.widget.textview;
import android.widget.toast;


public class mainactivity extends appcompatactivity {

  private listpopupwindow listpopupwindow = null;

  private imageview arrowimageview;
  private textview choosetext;
  private linearlayout linearlayout;
  private sortaadapter adapter = null;

  @override
  protected void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.activity_main);

    linearlayout= (linearlayout) findviewbyid(r.id.linearlayout);

    arrowimageview = (imageview)findviewbyid(r.id.arrow);
    choosetext= (textview) findviewbyid(r.id.choosetext);

    linearlayout.setonclicklistener(new view.onclicklistener() {
      @override
      public void onclick(view view) {
        showlistpopupwindow(linearlayout);
      }
    });
  }

  private class sortaadapter extends arrayadapter {

    private string[] strs = {"最新", "推荐", "全部", "最热"};
    private layoutinflater inflater;
    private int res;

    public sortaadapter(context context, int resource) {
      super(context, resource);
      inflater = layoutinflater.from(context);
      res = resource;
    }

    @override
    public view getview(int position, view convertview, viewgroup parent) {
      if (convertview == null)
        convertview = inflater.inflate(res, null);

      textview text = (textview) convertview.findviewbyid(android.r.id.text1);
      text.settext(getitem(position));
      text.settextcolor(color.white);
      text.settextsize(10);

      convertview.setbackgroundcolor(color.red);

      return convertview;
    }

    @override
    public string getitem(int position) {
      return strs[position];
    }

    @override
    public int getcount() {
      return strs.length;
    }
  }


  public void showlistpopupwindow(view view) {
    if (listpopupwindow == null)
      listpopupwindow = new listpopupwindow(this);

    if (adapter == null) {
      adapter = new sortaadapter(this, android.r.layout.simple_list_item_1);

      // listview适配器
      listpopupwindow.setadapter(adapter);

      // 选择item的监听事件
      listpopupwindow.setonitemclicklistener(new adapterview.onitemclicklistener() {
        @override
        public void onitemclick(adapterview<?> parent, view view, int pos, long id) {
          toast.maketext(getapplicationcontext(), adapter.getitem(pos), toast.length_short).show();
          choosetext.settext(adapter.getitem(pos));

          listpopupwindow.dismiss();
        }
      });

      listpopupwindow.setondismisslistener(new popupwindow.ondismisslistener() {
        @override
        public void ondismiss() {
          //旋转0度是复位imageview
          arrowimageview.animate().setduration(500).rotation(0).start();
        }
      });
    }


    // listpopupwindow的锚,弹出框的位置是相对当前view的位置
    listpopupwindow.setanchorview(view);

    listpopupwindow.setverticaloffset(dip2px(this,5));

    // 对话框的宽高
    listpopupwindow.setwidth(view.getwidth());

    listpopupwindow.setmodal(true);

    listpopupwindow.show();
    arrowimageview.animate().setduration(500).rotation(180).start();
  }


  public static int dip2px(context context, float dipvalue) {
    float sdensity = context.getresources().getdisplaymetrics().density;
    final float scale = sdensity;
    return (int) (dipvalue * scale + 0.5f);
  }
}

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent">

  <linearlayout
    android:id="@+id/linearlayout"
    android:layout_width="wrap_content"
    android:layout_height="24dp"
    android:background="@drawable/round_corner_line_radius_3dp"
    android:orientation="horizontal"
    android:paddingleft="8dp"
    android:paddingright="8dp"
    android:layout_centerinparent="true">

    <textview
      android:id="@+id/choosetext"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_gravity="center_vertical"
      android:text="分类"
      android:textcolor="@android:color/holo_orange_dark"
      android:textsize="12dp" />

    <imageview
      android:id="@+id/arrow"
      android:layout_width="14dp"
      android:layout_height="14dp"
      android:layout_gravity="center_vertical"
      android:layout_marginleft="8dp"
      android:src="@drawable/icon" />

  </linearlayout>

</relativelayout>

linearlayout的背景需要一个圆角背景res/drawable/round_corner_line_radius_3dp.xml：

<?xml version="1.0" encoding="utf-8"?> 
<shape
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:shape= "rectangle">

  <stroke android:color="@android:color/holo_orange_dark"
    android:width="2px"/>

  <solid android:color="@android:color/transparent"/>
  <corners android:radius="3dp" />

</shape> 

箭头icon.png：

附：android第三方开源下拉框nicespinner

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。