二DrawerLayout侧滑 Xlistview 接口获取数据 ImgageLoder

本文介绍了一个基于Android的应用中实现上下拉刷新加载功能的方法。通过XListView组件结合自定义适配器，实现了数据的异步加载及更新，并利用Gson进行JSON解析，展示了完整的实现流程。

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//在清单文件上写的类名   继承 Application     还有权限
public class App extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        //图片
        ImageLoaderConfiguration build = new ImageLoaderConfiguration.Builder(this).build();
        ImageLoader.getInstance().init(build);
    }
}

//上下拉
package com.example.chaixiaokai20170909;
import android.os.AsyncTask;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import com.google.gson.Gson;
import com.nostra13.universalimageloader.core.ImageLoader;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements XListView.IXListViewListener{
    private XListView xlv;
    List<User.NewslistBean> arr=new ArrayList<>();
    private Madapter madapter;
    private Handler handler;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        xlv =(XListView)findViewById(R.id.xlv);
        xlv.setPullLoadEnable(true);//必须加
        xlv.setXListViewListener(this);//接口实现刷新
        new MasatTask().execute("https://api.tianapi.com/wxnew/?key=8d6e3228d25298f13af4fc40ce6c9679&num=10");
        madapter = new Madapter();//创建适配器
        xlv.setAdapter(madapter);
        handler = new Handler();//主线程
    }

    //停止刷新
    public void close(){
        xlv.stopRefresh();
        xlv.stopLoadMore();
        xlv.setRefreshTime("刚刚");
    }
    //刷新
    @Override
    public void onRefresh() {
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {
                  arr.clear();
                  new MasatTask().execute("https://api.tianapi.com/wxnew/?key=8d6e3228d25298f13af4fc40ce6c9679&num=10");
                  close();
            }
        },2000);

    }
     //加载
    @Override
    public void onLoadMore() {
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {
                new MasatTask().execute("https://api.tianapi.com/wxnew/?key=8d6e3228d25298f13af4fc40ce6c9679&num=10");
                close();
            }
        },2000);
    }

    //适配器
    class Madapter extends BaseAdapter{

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

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

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

        //优化
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            User.NewslistBean bean = arr.get(position);
            ViewHolder vh;
            if (convertView==null){
                convertView = View.inflate(MainActivity.this, R.layout.list_item, null);
                vh = new ViewHolder();
                vh.img=(ImageView) convertView.findViewById(R.id.img);
                vh.tv=(TextView) convertView.findViewById(R.id.tv);
                convertView.setTag(vh);
            }else{
                vh=(ViewHolder) convertView.getTag();
            }
            //ImageLoader  获取图片
            ImageLoader.getInstance().displayImage(arr.get(position).getPicUrl(),vh.img);
            vh.tv.setText(arr.get(position).getTitle());
            return convertView;
        }

        class ViewHolder{
            ImageView img;
            TextView tv;
        }

    }

    //异步
    class MasatTask extends AsyncTask<String,Void,String>{
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            Gson gson = new Gson();
            User user = gson.fromJson(s, User.class);
            List<User.NewslistBean> newslist = user.getNewslist();
            arr.addAll(newslist);//添加新数据
            madapter.notifyDataSetChanged();//刷新适配器
        }

        @Override
        protected void onProgressUpdate(Void... values) {
            super.onProgressUpdate(values);
        }

        @Override
        protected String doInBackground(String... params) {
            try {
                URL url = new URL(params[0]);
                HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
                int responseCode = urlConnection.getResponseCode();
                if (responseCode==200){
                    InputStream inputStream = urlConnection.getInputStream();
                    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                    StringBuilder builder = new StringBuilder();
                    String string="";
                    while ((string=bufferedReader.readLine())!=null){
                        builder.append(string);
                    }
                    return builder.toString();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }
    }
}