自定义控件和试图(部分原生api)下拉菜单

使用android提供的api和自己定义一些布局来做出自己想要的控件显示效果。原生和自定义相结合，这是中级水平。

使用PopupWindow来弹出窗口显示下拉列表

imageView设置为可点击的

android:clickable="true"

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <EditText
        android:id="@+id/input"
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="10dp"
        android:text="@string/hello_world" />

    
    <ImageView 
        android:id="@+id/down_arrow"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/down_arrow"
        android:layout_alignRight="@id/input"
        android:clickable="true"
        android:layout_marginTop="20dp"
        />
</RelativeLayout>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center_vertical"
    android:orientation="horizontal"
    tools:context=".MainActivity" >

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/user" />

    <TextView
        android:id="@+id/tv_list_item"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:gravity="center_horizontal"
        android:text="@string/hello_world" />

    <ImageView
        android:id="@+id/delete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/delete" />

</LinearLayout>

package com.itheima.spinnerdemo28;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.PopupWindow;
import android.widget.TextView;

public class MainActivity extends Activity {

	private EditText input;
	
	private ImageView downArrow;
	
	
	private List<String> msgList;
	
	//弹出的窗口
	private PopupWindow popWin;

	private ListView listView;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		input = (EditText) findViewById(R.id.input);
		downArrow = (ImageView) findViewById(R.id.down_arrow);
		
		msgList = new ArrayList<String>();
	
		//添加下拉列表的内容
		for (int i = 0; i < 20; i++) {
			msgList.add("1000000000"+i);
		}
		
		initListView();
		
		
		downArrow.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				
				System.out.println("=======");
				//定义 popupWindow
				popWin = new PopupWindow(MainActivity.this);
				//获取组件的宽度
				popWin.setWidth(input.getWidth()); //设置宽度
				popWin.setHeight(200);	//设置popWin 高度
				
				popWin.setContentView(listView); //为popWindow填充内容
				//一定要放在showAsDropDown的上面
				popWin.setOutsideTouchable(true); // 点击popWin 以处的区域，自动关闭 popWin
				
				popWin.showAsDropDown(input, 0, 0);//设置 弹出窗口，显示的位置
				
			}
		});
		
		
		
		
	}

	private void initListView() {
		listView = new ListView(this);
		//设置背景后就不会一点击就颜色变了  特别难看
		listView.setBackgroundResource(R.drawable.listview_background); //设置listView 背景
		listView.setDivider(null);	//设置条目之间的分隔线为null
		listView.setVerticalScrollBarEnabled(false); // 关闭数值滑动条  其实就是去掉滚动条
		listView.setAdapter(new MyListAdapter());
	}

	private class MyListAdapter extends BaseAdapter{

		@Override
		public int getCount() {
			return msgList.size();
		}

		@Override
		public Object getItem(int position) {
			return position;
		}

		@Override
		public long getItemId(int position) {
			return position;
		}

		@Override
		public View getView(final int position, View convertView, ViewGroup parent) {
			ViewHolder holder = null;
			if(convertView == null){
				convertView = View.inflate(getApplicationContext(), R.layout.list_item, null);
				holder = new ViewHolder();
				
				holder.delete = (ImageView) convertView.findViewById(R.id.delete);
				holder.tv_msg =(TextView) convertView.findViewById(R.id.tv_list_item);
				convertView.setTag(holder);
			}else{
				holder = (ViewHolder) convertView.getTag();
			}
			
			holder.tv_msg.setText(msgList.get(position));
			
			holder.delete.setOnClickListener(new OnClickListener() {
				
				@Override
				public void onClick(View v) {
				//删除对应的条目
					msgList.remove(position);
					
					//刷新listView
					MyListAdapter.this.notifyDataSetChanged();
				}
			});
			convertView.setOnClickListener(new OnClickListener() {
				
				@Override
				public void onClick(View v) {
					//设置输入框 
					input.setText(msgList.get(position));
					
					popWin.dismiss();
				}
			});
			
			return convertView;
		}
		}

	private class ViewHolder{
		TextView tv_msg;
		ImageView delete;
	}
	
}