网络加载数据到ListView

一：

    首先ListView的网络数据加载一直是难题在Android的学习过程中，因为设计到了各种回调方法以及包括Adapter、AsyncTask、网络加载、json数据的解析

二：

    于是可以分析得出需要构建以下几个包及其包含的类：

bean（包）--->Shop（用来封装json数据中的属性的，里面写的是构造函数和Getter和Setter）

utils（工具包）--->HttpUtils（工具类：用来将传入的String类型的网址转换成byte[]然后返回。）

utils（工具包）--->ParserJson（工具类：用来将传入的jsonString字符串转换成list的list集合返回）

AsyncTask（异步任务包）---->DownLoadAsyncTask（用来进行耗时操作的.其中两个方法doInBackground是将传入的

api接口的网址，通过网络解析工具类HttpUtils得到一个bye[]数组，再将byte[]数组通过:

byte[] buff=HttpUils.getHttpResult(params[0]);

String jsOnString=new String（buff,0,buff.length）;

即可以得到：一个json解析后的list集合。再将list回传。在onPostExecute方法中，将list集合进行适配器的适配，所以需要构建一个Adapter了。

adapter(工具包)--->MyBaseAdapter（继承自baseAdapter，在其中有四个方法，最为重要的是getView方法，在这个方法中需要注意的是，首先需要对holder的属性进行实例化，调用方法为LayoutInflater，然后再setTag（holder），再需要进行的是将文字和图片set到item里面，由于需要用将图片下载进行set，所以需要再开启一个异步任务LoadImageAsyncTask，然后返回convertView）

AsyncTask（异步任务包）---->LoadImageAsyncTask（用来将传入的图片的网址转换成图片进行回传到MyBaseAdapter里面，所以需要将数据回传，构建一个CallBack的回调函数，将得到的bitmap图片回传到MyBaseAdapter。）

----然后DownLoadAsyncTask在onPostExecute方法中传入一个listView的实例化对象lv，进行lv.setAdapter(adapter);

----再在主函数中进行最后一步即可，开启DownLoadAsyncTask异步任务。

即有代码：

在MainActivity中：

package com.example.administrator.firstapp;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ListView;

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

import asyncTask.DownloadAsyncTask;
import bean.Shop;

public class MainActivity extends AppCompatActivity {
        private ListView lv;
    private List list=new ArrayList();
    private  String path="http://moblist.baobeigezi.com/v26/m_recommend_product/get_hot_sale_list?page=1&category_id=28&size=15&sign=c06c5b87a9db0a907774f1a094eee819&session_id=&v=2.6.9&c=AppStore&agent=ios&local_cart_id=838618F5-24B3-4356-904D-";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv= (ListView) findViewById(R.id.lv);

        new DownloadAsyncTask(this,list,lv).execute(path);
    }
}

在adapter中：

package adapter;

import android.content.Context;
import android.graphics.Bitmap;
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 com.example.administrator.firstapp.R;

import java.util.List;

import asyncTask.LoadImageAsyncTask;
import bean.Shop;
import utils.HttpUtils;

/**
 * Created by Administrator on 2016/8/22.
 */
public class MyBaseAdapter extends BaseAdapter {
    private Listlist;
    private Context context;
    private  ListView lv;

    public MyBaseAdapter(List list, Context context,ListView lv) {
        this.list = list;
        this.cOntext= context;
        this.lv=lv;
    }

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

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

    @Override
    public long getItemId(int position) {
        return position;
    }
   ViewHolder holder=new ViewHolder();

    public View getView(int position, View convertView, ViewGroup parent) {
        if (cOnvertView==null){

            LayoutInflater layoutInflater=LayoutInflater.from(context);
           cOnvertView=layoutInflater.inflate(R.layout.activity_item_last,null);
            holder.iv= (ImageView) convertView.findViewById(R.id.iv_image_url);
            holder.tv_market_price= (TextView) convertView.findViewById(R.id.tv_market_price);
            holder.tv_store_price= (TextView) convertView.findViewById(R.id.tv_store_price);
            holder.tv_name= (TextView) convertView.findViewById(R.id.tv_name);
            convertView.setTag(holder);
        }
        else {
            holder= (ViewHolder) convertView.getTag();
        }
        holder.tv_name.setText(list.get(position).getName());
        holder.tv_store_price.setText(list.get(position).getMarket_price());
        holder.tv_market_price.setText(list.get(position).getMarket_price());
            new LoadImageAsyncTask(context, new LoadImageAsyncTask.CallBack() {
                @Override
                public void sendImage(Bitmap bm) {
                    holder.iv.setImageBitmap(bm);
                }
            }).execute(list.get(position).getImage_url());

        return convertView;
    }
    static  class  ViewHolder{
        ImageView iv;
        TextView tv_market_price,tv_store_price,tv_name;
    }
}

在 DownLoadAsyncTask中：

package asyncTask;

import android.content.Context;
import android.os.AsyncTask;
import android.widget.ListView;
import android.widget.Toast;

import java.util.List;

import adapter.MyBaseAdapter;
import bean.Shop;
import utils.HttpUtils;
import utils.ParserJson;

/**
 * Created by Administrator on 2016/8/22.
 */
public class DownloadAsyncTask extends AsyncTask> {
    private Context context;
    private  List list;
    private ListView lv;

    public DownloadAsyncTask(Context context, List list, ListView lv) {
        this.cOntext= context;
        this.list = list;
        this.lv = lv;
    }

    @Override
    protected List doInBackground(String... params) {
        if (HttpUtils.isNetWork(context)){
            byte[] buff=HttpUtils.getHttpResult(params[0]);
            String jsOnString= new String(buff,0,buff.length);
            list=ParserJson.parserJsonToList(jsonString);
        }
        return list;
    }

    @Override
    protected void onPostExecute(List result) {
        if (result!=null&&result.size()!=0){
            list.addAll(result);
            MyBaseAdapter adapter=new MyBaseAdapter(list,context,lv);
            lv.setAdapter(adapter);
            }
        else {
            Toast.makeText(context, "下载异常", Toast.LENGTH_SHORT);
        }
    }
}

在 LoadImageAsyncTask中：

package asyncTask;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.util.Log;

import utils.HttpUtils;

/**
 * Created by Administrator on 2016/8/22.
 */
public class LoadImageAsyncTask extends AsyncTask {
    private Context context;
    private  byte[] buff;
    private  CallBack cb;
    private Bitmap bit;

    public LoadImageAsyncTask(Context context,CallBack cb) {
        this.cOntext= context;
        this.cb = cb;

    }

    @Override
    protected byte[] doInBackground(String... params) {
        if (HttpUtils.isNetWork(context)){
            buff =HttpUtils.getHttpResult(params[0]);
            Log.i("TAG",buff.toString());
        }
        return buff;
    }

    @Override
    protected void onPostExecute(byte[] result) {
        if(result!=null&&result.length!=0){
            Bitmap bm =BitmapFactory.decodeByteArray(result,0,result.length);
            cb.sendImage(bm);
        }
    }
    public  interface  CallBack{
        public  void  sendImage(Bitmap bm);
    }
}

在Shop中：

package bean;

/**
 * Created by Administrator on 2016/8/22.
 */
/*{
        "code": 1,
        "msg": "成功！",
        "data": {
        "product_list": [
        {
        "product_id": "29532",
        "market_price": "336.00",
        "store_price": "145.00",
        "name": "【包邮包税】新西兰A2 Platinum酪蛋白婴儿3段奶粉（1-3周岁宝宝）900g 【保质期2018年3月】",

        "image_url": "http://image.baoimg.net/photo/201606/2016061310003240007625.jpg",*/

public class Shop {
  private String market_price;
    private String store_price;
    private  String name;
    private  String image_url;

    public Shop(String market_price, String store_price, String name, String image_url) {
        this.market_price = market_price;
        this.store_price = store_price;
        this.name = name;
        this.image_url = image_url;
    }

    public String getMarket_price() {
        return market_price;
    }

    public void setMarket_price(String market_price) {
        this.market_price = market_price;
    }

    public String getStore_price() {
        return store_price;
    }

    public void setStore_price(String store_price) {
        this.store_price = store_price;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getImage_url() {
        return image_url;
    }

    public void setImage_url(String image_url) {
        this.image_url = image_url;
    }
}

在工具类 HttpUtils中：

package utils;

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

/**
 * Created by Administrator on 2016/8/21.
 */
public class HttpUtils {
    public  static  boolean isNetWork(Context context){
        ConnectivityManager manager= (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo info=manager.getActiveNetworkInfo();
        if (info!=null){
            return info.isConnected();
        }
else {
            return  false;
        }
    }
    public  static  byte[] getHttpResult(String path){
        ByteArrayOutputStream os=new ByteArrayOutputStream();
        try {
            URL url=new URL(path);
            HttpURLConnection cOnn= (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            conn.setDoInput(true);
            conn.connect();
            int respOnseCode=conn.getResponseCode();
            if(respOnseCode==200){
                InputStream in=conn.getInputStream();
                int temp=0;
                byte[] buff=new  byte[1024];
                while ((temp=in.read(buff))!=-1){
                    os.write(buff,0,temp);
                }
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

return  os.toByteArray();
    }
}

在工具类 ParserJson中：

package utils;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

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

import bean.Shop;

/**
 * Created by Administrator on 2016/8/22.
 */
/*{
        "code": 1,
        "msg": "成功！",
        "data": {
        "product_list": [
        {
        "product_id": "29532",
        "market_price": "336.00",
        "store_price": "145.00",
        "name": "【包邮包税】新西兰A2 Platinum酪蛋白婴儿3段奶粉（1-3周岁宝宝）900g 【保质期2018年3月】",

        "image_url": "http://image.baoimg.net/photo/201606/2016061310003240007625.jpg",*/

public class ParserJson {
    public  static List parserJsonToList(String jsonString){
        List list= new ArrayList();
        try {

            JSONObject jsOnObject=new JSONObject(jsonString);
            JSONObject object=jsonObject.getJSONObject("data");
            JSONArray jsOnArray=object.getJSONArray("product_list");
            for (int i=0;i                JSONObject obj=jsonArray.getJSONObject(i);
                String market_price=obj.getString("market_price");
                String store_price=obj.getString("store_price");
                String name=obj.getString("name");
                String image_url=obj.getString("image_url");
                Shop shop=new Shop(market_price,store_price,name,image_url);
                list.add(shop);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return  list;
    }
}