Android_listView_BaseAdapter_downLoadImg

<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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <ListView 
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        ></ListView>
</RelativeLayout>

<?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="match_parent"
    android:orientation="horizontal" >
   <ImageView 
       android:id="@+id/image"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:src="@drawable/ic_launcher"
       />
   <TextView 
       android:id="@+id/text"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text=""/>

</LinearLayout>

package com.example.parserJson;

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

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

import com.example.android_listview_baseadapter_downloadimg.Result;

public class ParserJson {
    public static List<Result> parserJson(String path){
        try {
            JSONObject jsonObject = new JSONObject(path);
            JSONArray jsonArray = jsonObject.getJSONArray("results");
            List<Result> list = new ArrayList<Result>();
            Result result;
            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject jsonObject2 = jsonArray.getJSONObject(i);
                 result= new Result();
                 result.setNamecn(jsonObject2.getString("namecn"));
                 result.setTitleimg(jsonObject2.getString("titleimg"));
                 list.add(result);
            }
            return list;
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
}

package com.example.HttpUtils;

import java.io.IOException;
import java.io.StringReader;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;

public class HttpUtils {
    //从网络下载json数据
    public static String getJsonDataByIntetnet(String path){
        byte[] buffer= getByteArrayByIntetnet(path);
        if(buffer != null && buffer.length != 0){
            return new String(buffer);
        }
        return path;
        
    }
    //从网络获取字节数组
    public static byte[] getByteArrayByIntetnet(String path){
        try {
            DefaultHttpClient client = new  DefaultHttpClient();
            HttpGet httpGet = new HttpGet(path);
            HttpResponse httpResponse = client.execute(httpGet);
            if(200 == httpResponse.getStatusLine().getStatusCode()){
                HttpEntity entity = httpResponse.getEntity();
                return EntityUtils.toByteArray(entity);
            }
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }return null;

    }
    //从网络上获取Bitmap对象
    public static Bitmap getBitmapByIntetnet(byte[] byteArray){
        if(byteArray != null && byteArray.length != 0){
          return BitmapFactory.decodeByteArray(byteArray, 0, byteArray.length);
        }
        return null;
        
    }
}

package com.example.android_listview_baseadapter_downloadimg;

import java.util.List;



interface UpdateNewVIew {
    public abstract void updataNewView(List<Result>list);
}

package com.example.android_listview_baseadapter_downloadimg;

import android.graphics.Bitmap;

public interface UpdateImgView {
    public void updateImgView(Bitmap bitmap);
}

package com.example.android_listview_baseadapter_downloadimg;

public class Result {
    private String namecn;
    private String titleimg;
    public String getNamecn() {
        return namecn;
    }
    public void setNamecn(String namecn) {
        this.namecn = namecn;
    }
    public String getTitleimg() {
        return titleimg;
    }
    public void setTitleimg(String titleimg) {
        this.titleimg = titleimg;
    }
    
}

package com.example.android_listview_baseadapter_downloadimg;

import java.util.List;

import com.example.HttpUtils.HttpUtils;
import com.example.parserJson.ParserJson;

import android.os.AsyncTask;
import android.util.Log;
import android.widget.Toast;

public class MyAsyncTask extends AsyncTask<String, Integer, List<Result>>{
    private UpdateNewVIew updateNewVIew;
    
    public MyAsyncTask(UpdateNewVIew updateNewVIew) {
        super();
        this.updateNewVIew = updateNewVIew;
    }
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }
    @Override
    protected List<Result> doInBackground(String... params) {
        String json = HttpUtils.getJsonDataByIntetnet(params[0]);
        List<Result> dataList = ParserJson.parserJson(json);
        return dataList;
    }
    @Override
    protected void onPostExecute(List<Result> result) {
        super.onPostExecute(result);
        if(result != null && result.size() != 0){
            updateNewVIew.updataNewView(result);
        }else{
            Log.i("MainActivity-MyAsyncTask", "网络错误");
        }
        
    }
}

package com.example.android_listview_baseadapter_downloadimg;

import com.example.HttpUtils.HttpUtils;

import android.content.Context;
import android.graphics.Bitmap;
import android.os.AsyncTask;

public class MyAsyncTask1 extends AsyncTask<String, Integer, Bitmap>{
    private UpdateImgView updateImgView;
    private Context context;
    
    public MyAsyncTask1(Context context,UpdateImgView updateImgView) {
        super();
        this.updateImgView = updateImgView;
        this.context = context;
    }
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }
    //子线程下载图片
    @Override
    protected Bitmap doInBackground(String... params) {
        //将传过来的图片下载存到字节数组中
        byte[] byteArray = HttpUtils.getByteArrayByIntetnet(params[0]);
        //将字节数组转为Bitmap 类型,并传回给主线程
        return HttpUtils.getBitmapByIntetnet(byteArray);
    }
    //主线程更新UI
    @Override
    protected void onPostExecute(Bitmap result) {
        super.onPostExecute(result);
        if(result != null ){
            //将参数回传给接口的实例化方法
            updateImgView.updateImgView(result);
        }
    }
}

package com.example.android_listview_baseadapter_downloadimg;

import java.util.List;

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
/*异步为listView的每个view下载图片--
 * --网络请求json数据,将名字与图片显示在listview控件上
 * 1.初始化控件
 * 2.准备数据
 *         2.1下载json数据
 *             1)创建一个异步任务类下载(MyAsyncTask)
 *             2)解析json数据,将解析后的数据存到list(doInBackground())
 *              3)将结果给主线程,然后显示(通过接口回调)(onPostExecute())    
 *              1)需实现baseAdapter的getView方法(MyAdapter)
 *              2)填充基本的数据类型
 *                 3)填充图片
 *                     1)创建一个异步任务通过图片地址从网络下载图片    (MyAsyncTask1)    
 *                     2)将下载后的图片以Bitmap对象形式存储(doInBackGround)
 *                     3)将Bitmap数据返回给主线程(通过接口回调)(onPostExecute)
 *                     4)image通过setBitmap()设置要显示的图片
 * 3.在接口实现类的实现方法中创建适配器对象(UpdateNewView)
 * 4.设置适配器
 * 
 * */

public class MainActivity extends Activity {

    private ListView listView;
    private static final String path="http://openapi.db.39.net/app/GetDrugCompany?sign=9DFAAD5404FCB6168EA6840DCDFF39E5&app_key=app";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //初始化控件
        listView = (ListView) findViewById(R.id.listView);
        //准备数据
//           2.1下载json数据
//             1)创建一个异步任务类下载
        new MyAsyncTask(new UpdateNewVIew() {
            
            @Override
            public void updataNewView(List<Result> list) {
                //创建适配器
                MyAdapter myAdapter = new MyAdapter(list,MainActivity.this);
                //设置适配器
                listView.setAdapter(myAdapter);
            }
        }).execute(path);
        
    
        
    }
    //自定义适配器
    class MyAdapter extends BaseAdapter{
        private List<Result>list;
        private Context context;
    
        public MyAdapter(List<Result> list,Context context) {
            super();
            this.list = list;
            this.context = context;
        }
        /**
         * 通常返回数据源的长度,当返回0时没有显示
         * 必须实现
         */
        @Override
        public int getCount() {
            return list.size();
        }
        /**
         * position表示的是item对应的索引
         * 通常根据索引来获得对应的数据,并返回
         * 不是必须实现
         */
        
        @Override
        public Object getItem(int position) {
            return list.get(position);
        }
        /**
         * position表示的是item对应的索引
         * 通常直接返回position作为item的id
         * 不是必须实现
         */
        @Override
        public long getItemId(int position) {
            return position;
        }
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View view = convertView;
            final ViewHolder viewHolder;
            if(view == null){
                view = View.inflate(context, R.layout.listview_item, null);
                viewHolder = new ViewHolder();
                viewHolder.text = (TextView) view.findViewById(R.id.text);
                viewHolder.image = (ImageView) view.findViewById(R.id.image);
                view.setTag(viewHolder);
            }else{
                viewHolder = (ViewHolder) view.getTag();
            }
            
            Result result = list.get(position);
            //设置文本资源
            viewHolder.text.setText(result.getNamecn());
            //设置图片资源
            //创建异步任务,下载图片
            String picPath = result.getTitleimg();
            new MyAsyncTask1(MainActivity.this,new UpdateImgView() {
                //设置图片资源
                @Override
                public void updateImgView(Bitmap bitmap) {
                    viewHolder.image.setImageBitmap(bitmap);
                }
            }).execute(picPath);
            return view;
        }
        class ViewHolder{
            private TextView text;
            private ImageView image;
        }
        
    }
    


}