ListView获取网络数据并展示优化练习

权限：

<uses-permission android:name="android.permission.INTERNET"></uses-permission>

依赖：

compile 'com.google.code.gson:gson:2.8.2'

MainActivity布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.mrzhao.examdemo.MainActivity">

    <Button

android:id="@+id/getData_bt" android:onClick="onClick" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_margin="10dp" android:text="点击获取网络数据" tools:ignore="OnClick" /> <Button android:id="@+id/toSecond_bt" android:onClick="onClick" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_margin="10dp"android:text="跳转到第二个页面" tools:ignore="OnClick" /> </LinearLayout>

MainActivity代码：

public class MainActivity extends AppCompatActivity {

    private String path = "http://www.qubaobei.com/ios/cf/dish_list.php?stage_id=1&limit=20&page=1";
    private FoodEntity foodEntity;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.getData_bt:
                new MyTask().execute();
                break;
            case R.id.toSecond_bt:
                if (foodEntity!=null){
                    Intent intent = new Intent(this,SecondActivity.class);
                    intent.putExtra("food",foodEntity);
                    startActivity(intent);
                }
                break;
        }
    }

    class MyTask extends AsyncTask<String, Void, String> {

        @Override
        protected String doInBackground(String... strings) {
            return getDataFromNet();
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            //判断不是空就去解析
            if (!TextUtils.isEmpty(s)) {
                Gson gson = new Gson();
                foodEntity= gson.fromJson(s, FoodEntity.class);
            }
        }
    }
    /**
     * 网络获取数据
     *
     * @return
*/
private String getDataFromNet() {
        InputStream inputStream = null;
        ByteArrayOutputStream outputStream = null;
        try {
            URL url = new URL(path);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            conn.setConnectTimeout(30 * 1000);
            conn.setReadTimeout(30 * 1000);
            conn.connect();
            if (conn.getResponseCode() == 200) {
                inputStream = conn.getInputStream();
                outputStream = new ByteArrayOutputStream();
                int len = 0;
                byte[] bytes = new byte[1024];
                while ((len = inputStream.read(bytes)) != -1) {
                    outputStream.write(bytes, 0, len);
                }
                return outputStream.toString();
            }
        } catch (MalformedURLException e) {
            e.printStackTrace(www.fengshen157.com);
        } catch (ProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

finally {
    if (inputStream!=null){
        try {
            inputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    if (outputStream!=null){
        try {
            outputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

return null; }}

SecondActivity布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://www.fengshen157.com schemas.android.com/apk/res/android"
    xmlns:app="http://www.huarenyl.cn   schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.mrzhao.examdemo.SecondActivity">

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

SecondActivity代码：

public class SecondActivity extends AppCompatActivity {

    private ListView listView;
    private MyAdapter myAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        //获取传递过来的解析对象
        FoodEntity foodEntity = (FoodEntity) getIntent().getSerializableExtra("food");
        final List<FoodEntity.DataBean> data = foodEntity.getData();

        //实例化视图
        listView = www.006665.cn  (ListView) findViewById(R.id.listView);
        myAdapter = new MyAdapter(data, this);
        listView.setAdapter(myAdapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Toast.makeText(SecondActivity.this, www.huayi157.com/ data.get(position).getTitle(), Toast.LENGTH_SHORT).show();
            }
        });
    }
}

Item条目布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_www.baohuayule.com  width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/title_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:textSize="20sp"www.baohuayule.cn />
</LinearLayout>

适配器：

public class MyAdapter extends BaseAdapter {
    private List<FoodEntity.DataBean> list;
    private Context context;
    private LayoutInflater www.thylgw.cn/ inflater;

    public MyAdapter(List<FoodEntity.DataBean> list, Context context) {
        this.list = list;
        this.context = context;
        inflater = LayoutInflater.from(context);
    }

    @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;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.item_layout, parent, false);
            holder = new ViewHolder();
            holder.titleTv = (TextView) convertView.findViewById(R.id.title_tv);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }
        String title = list.get(position).getTitle();
        holder.titleTv.setText(title);
        return convertView;
    }

    static class ViewHolder {
        TextView titleTv;
    }
}

解析实体类：

public class FoodEntity implements Serializable{

    /**
     * ret : 1
     * data : [{"id":"8289","title":"油焖大虾","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/9/8289.jpg","collect_num":"1659","food_str":"大虾 葱 生姜 植物油 料酒","num":1659},{"id":"2127","title":"四川回锅肉","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/3/2127.jpg","collect_num":"1585","food_str":"猪肉 青蒜 青椒 红椒 姜片","num":1585},{"id":"30630","title":"超简单芒果布丁","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/31/30630.jpg","collect_num":"1529","food_str":"QQ糖 牛奶 芒果","num":1529},{"id":"9073","title":"家常红烧鱼","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/10/9073.jpg","collect_num":"1419","food_str":"鲜鱼 姜 葱 蒜 花椒","num":1419},{"id":"10097","title":"家常煎豆腐","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/11/10097.jpg","collect_num":"1406","food_str":"豆腐 新鲜红椒 青椒 葱花 油","num":1406},{"id":"10509","title":"水煮肉片","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/11/10509.jpg","collect_num":"1336","food_str":"瘦猪肉 生菜 豆瓣酱 干辣椒 花椒","num":1336},{"id":"46968","title":"红糖苹果银耳汤","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/47/46968.jpg","collect_num":"1245","food_str":"银耳 苹果 红糖","num":1245},{"id":"10191","title":"麻婆豆腐","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/11/10191.jpg","collect_num":"1214","food_str":"豆腐 肉末 生抽 白糖 芝麻油","num":1214},{"id":"2372","title":"皮蛋瘦肉粥","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/3/2372.jpg","collect_num":"1147","food_str":"大米 皮蛋 猪肉 油条 香葱","num":1147},{"id":"2166","title":"蚂蚁上树","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/3/2166.jpg","collect_num":"1140","food_str":"红薯粉 肉 姜 蒜 花椒","num":1140},{"id":"2262","title":"糖醋肉","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/3/2262.jpg","collect_num":"1074","food_str":"猪肉 红椒 黄椒 洋葱 蛋清","num":1074},{"id":"9971","title":"鱼香豆腐","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/10/9971.jpg","collect_num":"1004","food_str":"豆腐 木耳 胡萝卜 香葱 番茄酱","num":1004},{"id":"10172","title":"干煸四季豆","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/11/10172.jpg","collect_num":"988","food_str":"四季豆 干辣椒 蒜头 酱油 糖","num":988},{"id":"2685","title":"胡萝卜肉末蒸蛋","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/3/2685.jpg","collect_num":"918","food_str":"胡萝卜 肉 蛋 生抽 盐","num":918},{"id":"9972","title":"虎皮青椒","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/10/9972.jpg","collect_num":"889","food_str":"青辣椒 大蒜 香醋 白糖 生抽","num":889},{"id":"10437","title":"叉烧排骨","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/11/10437.jpg","collect_num":"797","food_str":"排骨 李锦记叉烧酱 植物油 清水 油菜","num":797},{"id":"2892","title":"\u201c五行\u201d彩蔬汤","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/3/2892.jpg","collect_num":"756","food_str":"黑木耳 玉米 牛蒡 胡萝卜 西兰花","num":756},{"id":"33783","title":"美人豆浆","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/34/33783.jpg","collect_num":"753","food_str":"黄豆 红豆 绿豆 黑豆 黑米","num":753},{"id":"2348","title":"麻辣肉丝面","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/3/2348.jpg","collect_num":"753","food_str":"面条 肉丝 淀粉 酱油 辣椒","num":753},{"id":"10044","title":"土豆炖翅根","pic":"http://www.qubaobei.com/ios/cf/uploadfile/132/11/10044.jpg","collect_num":"752","food_str":"土豆 翅根 葱 姜 料酒","num":752}]
     */
private int ret;
    private List<DataBean> data;

    public int getRet() {
        return ret;
    }

    public void setRet(int ret) {
        this.ret = ret;
    }

    public List<DataBean> getData() {
        return data;
    }

    public void setData(List<DataBean> data) {
        this.data = data;
    }

    public static class DataBean implements Serializable{
        /**
         * id : 8289
         * title : 油焖大虾
         * pic : http://www.qubaobei.com/ios/cf/uploadfile/132/9/8289.jpg
         * collect_num : 1659
         * food_str : 大虾 葱 生姜 植物油 料酒
         * num : 1659
         */
private String id;
        private String title;
        private String pic;
        private String collect_num;
        private String food_str;
        private int num;

        public String getId() {
            return id;
        }

        public void setId(String id) {
            this.id = id;
        }

        public String getTitle() {
            return title;
        }

        public void setTitle(String title) {
            this.title = title;
        }

        public String getPic() {
            return pic;
        }

        public void setPic(String pic) {
            this.pic = pic;
        }

        public String getCollect_num() {
            return collect_num;
        }

        public void setCollect_num(String collect_num) {
            this.collect_num = collect_num;
        }

        public String getFood_str() {
            return food_str;
        }

        public void setFood_str(String food_str) {
            this.food_str = food_str;
        }

        public int getNum() {
            return num;
        }

        public void setNum(int num) {
            this.num = num;
        }