远程请求json数据，list中显示

Posted 2020-12-24 znsongshu

public class MainActivity extends Activity {

    protected static final int WHAT_REQUEST_SUCCESS = 1;
    protected static final int WHAT_REQUEST_ERROR = 2;
    private ListView lv_main;
    private LinearLayout ll_main_loading;
    private List<ShopInfo> data;
    private ShopInfoAdapter adapter;
    private Handler handler = new Handler(){
        public void handleMessage(android.os.Message msg) {
            switch (msg.what) {
            case WHAT_REQUEST_SUCCESS:
                ll_main_loading.setVisibility(View.GONE);
                //显示列表
                lv_main.setAdapter(adapter);
                break;
            case WHAT_REQUEST_ERROR:
                ll_main_loading.setVisibility(View.GONE);
                Toast.makeText(MainActivity.this, "加载数据失败", Toast.LENGTH_SHORT).show();
                break;

            default:
                break;
            }
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        lv_main = (ListView) findViewById(R.id.lv_main);
        ll_main_loading = (LinearLayout) findViewById(R.id.ll_main_loading);
        adapter = new ShopInfoAdapter();
        
        //1. 主线程, 显示提示视图
        ll_main_loading.setVisibility(View.VISIBLE);
        //2. 分线程, 联网请求
        //启动分线程请求服务器动态加载数据并显示
        new Thread(){
            public void run() {
                //联网请求得到jsonString
                try {
                    String jsonString = requestJson();
                    //解析成List<ShopInfo>
                    data = new Gson().fromJson(jsonString, new TypeToken<List<ShopInfo>>(){}.getType());
                    //3. 主线程, 更新界面
                    handler.sendEmptyMessage(WHAT_REQUEST_SUCCESS);//发请求成功的消息
                } catch (Exception e) {
                    e.printStackTrace();
                    handler.sendEmptyMessage(WHAT_REQUEST_ERROR);//发送请求失败的消息
                }
            }
        }.start();
        
        
    }
    
    /**
     * 联网请求得到jsonString
     * @return
     * @throws Exception 
     */
    private String requestJson() throws Exception {
        String result = null;
        String path = "http://192.168.10.165:8080/L05_Web/ShopInfoListServlet";
        //1. 得到连接对象
        URL url = new URL(path);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        //2. 设置
        connection.setConnectTimeout(5000);
        connection.setReadTimeout(5000);
        //连接
        connection.connect();
        //发请求并读取服务器返回的数据
        int responseCode = connection.getResponseCode();
        if(responseCode==200) {
            InputStream is = connection.getInputStream();
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int len = -1;
            while ((len = is.read(buffer)) != -1) {
                baos.write(buffer, 0, len);
            }
            baos.close();
            is.close();
            connection.disconnect();
            
            result = baos.toString();
        } else {
            //也可以抛出运行时异常
        }
        return result;
    }

    class ShopInfoAdapter extends BaseAdapter {

        private ImageLoader imageLoader;
        
        public ShopInfoAdapter() {
            imageLoader = new ImageLoader(MainActivity.this, R.drawable.loading, R.drawable.error);
        }
        @Override
        public int getCount() {
            return data.size();
        }

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

        @Override
        public long getItemId(int position) {
            return 0;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if(convertView==null) {
                convertView = View.inflate(MainActivity.this, R.layout.item_main, null);
            }
            //得到当前行的数据对象
            ShopInfo shopInfo = data.get(position);
            //得到当前行的子View
            TextView nameTV = (TextView) convertView.findViewById(R.id.tv_item_name);
            TextView priceTV = (TextView) convertView.findViewById(R.id.tv_item_price);
            ImageView imageView = (ImageView) convertView.findViewById(R.id.iv_item_icon);
            //设置数据
            nameTV.setText(shopInfo.getName());
            priceTV.setText(shopInfo.getPrice()+"元");
            String imagePath = shopInfo.getImagePath();
            //根据图片路径启动分线程动态请求服务加载图片并显示
            imageLoader.loadImage(imagePath, imageView);
            return convertView;
        }
        
    }
}

View Code

 

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

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

    <LinearLayout
        android:id="@+id/ll_main_loading"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" 
        android:gravity="center"
        android:visibility="gone">

        <ProgressBar
            style="?android:attr/progressBarStyleLarge"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="正在加载中..." />

    </LinearLayout>

</FrameLayout>

 

<?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="60dp"
    android:orientation="horizontal" >

    <ImageView
        android:id="@+id/iv_item_icon"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:src="@drawable/ic_launcher"/>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" 
        android:gravity="center_vertical"
        android:layout_marginLeft="10dp">

        <TextView
            android:id="@+id/tv_item_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="名称" 
            android:textSize="18sp"/>
        
        <TextView
            android:id="@+id/tv_item_price"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="内容" 
            android:textSize="18sp"/>

    </LinearLayout>
</LinearLayout>