Android课程---优化ListView列表视图（2）

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <ImageView
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:src="@drawable/yuantu"
        android:id="@+id/lv2"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="20dp">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="美食图片"
            android:id="@+id/tv1"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="很好吃啊"
            android:id="@+id/tv2"/>

    </LinearLayout>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/lv_2">

</ListView>

package com.hanqi.test5;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;

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

public class UIActivity5 extends AppCompatActivity
{

    //数据源
    //List<Map<String,Object>> lm;
    List<Food> lf;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_ui5);

        //获取ListView
        ListView lv_2 =(ListView)findViewById(R.id.lv_2);
        //准备数据源
        lf = new ArrayList<Food>();
        lf.add(new Food(R.drawable.yuantu,"内容1","美食1"));
        lf.add(new Food(R.drawable.yuantu,"内容2","美食2"));
        lf.add(new Food(R.drawable.yuantu,"内容3","美食3"));
        lf.add(new Food(R.drawable.yuantu,"内容4","美食4"));
       /* lm =new ArrayList<Map<String,Object>>();
        Map<String,Object> map = new Hashtable<String, Object>();

        map.put("image",R.drawable.yuantu);
        map.put("name","美食图片01");
        map.put("content","很好吃啊01");
        lm.add(map);

        map = new Hashtable<String, Object>();
        map.put("image",R.drawable.yuantu);
        map.put("name","美食图片02");
        map.put("content","很好吃啊02");
        lm.add(map);

        map = new Hashtable<String, Object>();
        map.put("image",R.drawable.yuantu);
        map.put("name","美食图片03");
        map.put("content","很好吃啊03");
        lm.add(map);

        map = new Hashtable<String, Object>();
        map.put("image",R.drawable.yuantu);
        map.put("name","美食图片04");
        map.put("content","很好吃啊04");
        lm.add(map);*/

        lv_2.setAdapter(new MyBaseAdapter());

    }
    class MyBaseAdapter extends BaseAdapter
    {
        //获取要显示的行数
        @Override
        public int getCount()
        {

            return lf.size();
        }

        //获取对应下标的行
        @Override
        public Object getItem(int position)
        {
            return lf.get(position);
        }
        //获取对应行的id
        @Override
        public long getItemId(int position)
        {
            return position;
        }
        //给视图适配数据，返回视图
        //3个参数：1.position(数据的下标)
        //2.convertView(可重复使用的视图)
        //3.parent(父视图)
        @Override
        public View getView(int position, View convertView, ViewGroup parent)
        {
            //如果convertView为空，就加载layout文件
            if (convertView == null)
            {
            Log.e("TAG","position = "+position);

            //1.获取样式文件(layout文件)
            LayoutInflater layoutInflater = getLayoutInflater();
                convertView = layoutInflater.inflate(R.layout.layout_simple, null);
            }
            //2.数据和layout文件的视图组件进行绑定
            //1)从数据源里获取一行数据
            //Map<String,Object> map = lm.get(position);

            Food food = lf.get(position);

            //2)获取layout文件的视图组件
            ImageView iv_2 = (ImageView)convertView.findViewById(R.id.lv2);
            TextView tv1 = (TextView)convertView.findViewById(R.id.tv1);
            TextView tv2 = (TextView)convertView.findViewById(R.id.tv2);

            //3)绑定(数据适配)
//            iv_2.setImageResource((int) map.get("image"));
//            tv1.setText(map.get("name").toString());
//            tv2.setText(map.get("content").toString());

            iv_2.setImageResource((int) food.getImage());
            tv1.setText(food.getName());
            tv2.setText(food.getContent());

            //3.返回视图
            return convertView;
        }
    }
}