Android 下拉列表也是一个比较常用的控件，但是Android自带的下拉框样式效果较差，没办法，只好自己来自定义一个。其实主要是利用弹窗来实现的，看一下效果图先~~
我这边仅仅是实现简单的自定义控件，简单易懂，布局上有需要其他效果如边框、虚线等可自行加上。下拉列表是List，所以item也是可以根据需要进行内容上的丰富，修改适配器便可以。
好了，进入正题。首先，我们先创建一个标题及箭头布局，目的是用于点击后弹出下拉菜单。
，代码如下所示：
接下来，创建下拉列表ListView布局，代码如下：
package com.newland.myspinerdemo;
import android.content.Context;
import android.graphics.Color;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.WindowManager;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;
import java.util.List;
/**
* 封装好的下拉列表，包括头部
*/
public class MySpinerView extends LinearLayout implements View.OnClickListener, MySpinerAdapter.IOnItemSelectListener {
private String mExampleString = "";
private int mExampleColor = Color.RED;
private float mExampleDimension = 0;
private Context context;
private RelativeLayout spiner;
private TextView tvSpiner;
private ImageView ivSpiner;
private List
nameList;
private MySpinerPopWindow mSpinerPopWindow;
public MySpinerView(Context context, AttributeSet attrs) {
super(context, attrs);
this.context = context;
LayoutInflater.from(context).inflate(R.layout.sample_my_spiner_view, this);
init(attrs, 0);
spiner = (RelativeLayout) this.findViewById(R.id.spiner);
spiner.setOnClickListener(this);
tvSpiner = (TextView) this.findViewById(R.id.tv_spiner);
ivSpiner = (ImageView) this.findViewById(R.id.iv_spiner);
}
/**
* 设置弹出下拉表单的数据，在Activity那边得到控件后记得调用否则抛异常
* @param nameList
*/
public void setData(List
nameList) {
this.nameList = nameList;
mSpinerPopWindow = new MySpinerPopWindow(context);
mSpinerPopWindow.refreshData(nameList, 0);
mSpinerPopWindow.setItemListener(this); // 设置下拉列表item点击的监听，响应onItemClick回调函数
}
/**
* 头部点击事件
* @param v
*/
@Override
public void onClick(View v) {
switch (v.getId()){
case R.id.spiner:
showSpinWindow();
break;
}
}
/**
* 弹出下拉列表
*/
public void showSpinWindow() {
/**这里还有一步要做，就是让右边箭头向上。自己替换掉ivSpiner图片**/
mSpinerPopWindow.setWidth(((WindowManager) context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay().getWidth());
mSpinerPopWindow.showAsDropDown(tvSpiner);
}
/**
* 下拉列表项点击事件，把选中的值显示在界面上
* @param pos
*/
@Override
public void onItemClick(int pos) {
/**这里还有一步要做，就是让右边箭头还原向下。自己替换掉ivSpiner图片**/
if (pos >= 0 && pos <= nameList.size()) { // pos为-1就是弹窗消失，不管他
String value = nameList.get(pos);
tvSpiner.setText(value);
}
}
/**
* 初始化顶部显示数据
* @param txt
*/
public void initText(String txt){
tvSpiner.setText(txt);
}
}
下拉列表实际上是一个PopWindow，里面有一个ListView，所以我们新建一个自定义弹窗PopWindow。代码如下：
package com.newland.myspinerdemo;
import java.util.List;
import android.content.Context;
import android.graphics.drawable.ColorDrawable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.PopupWindow;
/**
* 下拉列表弹窗
*/
public class MySpinerPopWindow extends PopupWindow implements OnItemClickListener {
private Context mContext;
private ListView mListView;
private MySpinerAdapter mAdapter;
private MySpinerAdapter.IOnItemSelectListener mItemSelectListener;
public MySpinerPopWindow(Context context) {
super(context);
mContext = context;
init();
}
/**
* 为MySpinnerView提供一个item点击事件的监听器，MySpinnerView实例调用此方法设置监听
* @param listener
*/
public void setItemListener(MySpinerAdapter.IOnItemSelectListener listener) {
mItemSelectListener = listener;
}
/**
* 初始化弹窗布局
*/
private void init() {
View view = LayoutInflater.from(mContext).inflate(R.layout.spiner_window_layout, null);
setContentView(view);
setWidth(LayoutParams.WRAP_CONTENT);
setHeight(LayoutParams.WRAP_CONTENT);
setFocusable(true);
ColorDrawable dw = new ColorDrawable(0x00);
setBackgroundDrawable(dw);
mListView = (ListView) view.findViewById(R.id.listview);
mAdapter = new MySpinerAdapter(mContext);
mListView.setAdapter(mAdapter);
mListView.setOnItemClickListener(this);
this.setOnDismissListener(new OnDismissListener() { // 弹窗消失的监听
@Override
public void onDismiss() {
if (mItemSelectListener != null) {
mItemSelectListener.onItemClick(-1); // 弹窗消失，要让布局那边的箭头还原向下，所以那边还得判断一下，>=0的数据在显示，-1就忽略掉，箭头还原
}
}
});
}
/**
* 刷新下拉列表的数据
* @param list
* @param selIndex
*/
public void refreshData(List
list, int selIndex) {
if (list != null && selIndex != -1) {
mAdapter.refreshData(list, selIndex);
}
}
/**
* 下拉列表ListView的点击事件。
* @param arg0
* @param view
* @param pos
* @param arg3
*/
@Override
public void onItemClick(AdapterView
arg0, View view, int pos, long arg3) {
dismiss();
if (mItemSelectListener != null) {
mItemSelectListener.onItemClick(pos); //点击后调用此方法，则MySpinerView会监听到（因为mItemSelectListener是MySpinerView那边设置的监听器）
}
}
}
既然是ListView，那么马上想到的就是适配器，那么我们接下来设置弹窗里面的ListView适配器，代码如下：
package com.newland.myspinerdemo;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
public class MySpinerAdapter
extends BaseAdapter {
private Context mContext;
private List
mObjects = new ArrayList
();
private LayoutInflater mInflater;
public MySpinerAdapter(Context context) {
mContext = context;
mInflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
/**
* 刷新数据
* @param objects
* @param selIndex
*/
public void refreshData(List
objects, int selIndex) {
mObjects = objects;
if (selIndex < 0) {
selIndex = 0;
}
if (selIndex >= mObjects.size()) {
selIndex = mObjects.size() - 1;
}
}
@Override
public int getCount() {
return mObjects.size();
}
@Override
public Object getItem(int pos) {
return mObjects.get(pos).toString();
}
@Override
public long getItemId(int pos) {
return pos;
}
@Override
public View getView(int pos, View convertView, ViewGroup arg2) {
ViewHolder viewHolder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.spiner_item_layout, null);
viewHolder = new ViewHolder();
viewHolder.mTextView = (TextView) convertView.findViewById(R.id.textView);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
String item = (String) getItem(pos);
viewHolder.mTextView.setText(item);
return convertView;
}
public static class ViewHolder {
public TextView mTextView;
}
/**
* 提供一个设置点击事件监听的接口回调
*/
public interface IOnItemSelectListener {
void onItemClick(int pos);
}
}
主页面布局由4个自定义控件（MySpinerView）组成，代码如下：
package com.newland.myspinerdemo;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
public class MainActivity extends Activity{
/**
* 四个下拉列表头部数据
*/
private String name1 = "课程类型";
private String name2 = "教练";
private String name3 = "卡路里";
private String name4 = "时间";
/**
* 四个下拉列表数据
*/
private List
nameList1 = new ArrayList
();
private List
nameList2 = new ArrayList
();
private List
nameList3 = new ArrayList
(); private List
nameList4 = new ArrayList
(); /** * 四个自定义下拉列表 */ private MySpinerView mySpinerView1; private MySpinerView mySpinerView2; private MySpinerView mySpinerView3; private MySpinerView mySpinerView4; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); setupViews(); } /** * 初始化四个下拉列表 */ private void setupViews() { mySpinerView1 = (MySpinerView)findViewById(R.id.mysv1); mySpinerView1.initText(name1); String[] names1 = { "高级课程", "中级课程", "所有课程" }; for (int i = 0; i < names1.length; i++) { nameList1.add(names1[i]); } mySpinerView1.setData(nameList1); mySpinerView2 = (MySpinerView)findViewById(R.id.mysv2); mySpinerView2.initText(name2); String[] names2 = {"小鱼","布拉特", "杰克逊", "菲尔顿", "希伯特"}; for (int i = 0; i < names2.length; i++) { nameList2.add(names2[i]); } mySpinerView2.setData(nameList2); mySpinerView3 = (MySpinerView)findViewById(R.id.mysv3); mySpinerView3.initText(name3); String[] names3 = {"10.0","20.0", "30.0", "40.0", "50.0"}; for (int i = 0; i < names3.length; i++) { nameList3.add(names3[i]); } mySpinerView3.setData(nameList3); mySpinerView4 = (MySpinerView)findViewById(R.id.mysv4); mySpinerView4.initText(name4); String[] names4 = {"1min","1hour", "1day", "1year", "forever"}; for (int i = 0; i < names4.length; i++) { nameList4.add(names4[i]); } mySpinerView4.setData(nameList4); } }
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