XListView实现网络加载图片和下拉刷新

public class MainActivity extends AppCompatActivity { private XListView contents; private int page = 0; private MyBaseAdapter adapter; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  contents = findViewById(R.id.contents);  adapter = new MyBaseAdapter(getLayoutInflater());  contents.setAdapter(adapter);  //是否开启下拉刷新 上拉加载  //contents.setPullRefreshEnable(false);  contents.setPullLoadEnable(true);  contents.setXListViewListener(new XListView.IXListViewListener() {   @Override public void onRefresh() {    page = 0;    loadData(page);    //加载刷新数据   }   @Override public void onLoadMore() {    loadData(page);   }  });  //一进来就去加载第一页数据  loadData(page); } private String url =   "http://apis.juhe.cn/cook/query?key=3ec004200a6a2f4cf4774e480c006375&menu=%E8%A5%BF%E7%BA%A2%E6%9F%BF&rn=10&pn="; private void loadData(int page) {  String requestUrlWithPageNum = url + page;  //加载网络数据  new AsyncTask<String, Void, List<DataItem>>() {   @Override protected List<DataItem> doInBackground(String... strings) {    ResponseBean responseBean = null;    try {     URL url = new URL(strings[0]);     HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();     urlConnection.setRequestMethod("GET");     urlConnection.setConnectTimeout(5000);     urlConnection.setReadTimeout(5000);     int responseCode = urlConnection.getResponseCode();     if (responseCode == 200) {      String str = stream2String(urlConnection.getInputStream());      responseBean = new Gson().fromJson(str, ResponseBean.class);     } else {      //     }     return responseBean == null ? null : responseBean.getResult().getData();    } catch (MalformedURLException e) {     e.printStackTrace();    } catch (IOException e) {     e.printStackTrace();    }    return null;   }   @Override protected void onPostExecute(List<DataItem> dataItems) {    if (dataItems == null) {     Toast.makeText(MainActivity.this, "请求数据错误", Toast.LENGTH_LONG).show();     return;    }    //更新数据    updateData(dataItems);    loadCompleted();   }  }.execute(url); } private String stream2String(InputStream is) throws IOException {  BufferedReader br = new BufferedReader(new InputStreamReader(is));  StringBuilder sb = new StringBuilder();  for (String tmp = br.readLine(); tmp != null; tmp = br.readLine()) {   sb.append(tmp);  }  return sb.toString(); } private void updateData(List<DataItem> datas) {  if (page == 0) {   adapter.setDatas(datas);  } else {   adapter.addDatas(datas);  } } //通过 加载 / 刷新 完成 private void loadCompleted() {  //通过ListView：刷新、加载完成  page++;  contents.stopLoadMore();  contents.stopRefresh(); }}

public class MyBaseAdapter extends BaseAdapter { private List<DataItem> mDatas; protected LayoutInflater mInflater; /**  * 更新数据  */ public void setDatas(List<DataItem> datas) {  mDatas.clear();  if (datas != null) {   mDatas.addAll(datas);  }  notifyDataSetChanged(); } /**  * 追加数据  */ public void addDatas(List<DataItem> datas) {  if (datas != null) {   mDatas.addAll(datas);   notifyDataSetChanged();  } } public MyBaseAdapter(LayoutInflater mInflater) {  this.mInflater = mInflater;  mDatas = new ArrayList<>(); } @Override public int getCount() {  return mDatas.size(); } @Override public DataItem getItem(int position) {  return mDatas.get(position); } @Override public long getItemId(int position) {  return position; } @Override public View getView(int position, View convertView, ViewGroup parent) {  BaseViewHolder viewHolder = null;  if (convertView == null) {   convertView = mInflater.inflate(R.layout.item, parent, false);   viewHolder = new BaseViewHolder(convertView);  } else {   viewHolder = (BaseViewHolder) convertView.getTag();  }  viewHolder.bindData(getItem(position));  return convertView; } public class BaseViewHolder {  private View itemView;  private ImageView icon;  private TextView title;  private TextView date;  public BaseViewHolder(View itemView) {   this.itemView = itemView;   date = itemView.findViewById(R.id.date);   icon = itemView.findViewById(R.id.icon);   itemView.setTag(this);  }  public void bindData(DataItem dataItem) {   title.setText(dataItem.getTitle());   date.setText(dataItem.getId());   ImageLoader.getInstance().displayImage(dataItem.getFirstImageUrl(), icon,     ImageLoaderConfigs.getDefaultDisplayImageOptions(icon.getContext()));  } }}ImageLoader.java  public class ImageLoaderConfigs { public static ImageLoaderConfiguration getImageLoaderConfiguration(Context context) {  ImageLoaderConfiguration configuration = new ImageLoaderConfiguration.Builder(context)    //内在缓存额外选项， 最大的宽度，高度    //.memoryCacheExtraOptions(480, 800) // default = device screen dimensions 内存缓存文件的最大长宽    //.diskCacheExtraOptions(480, 800, null) // 本地缓存的详细信息(缓存的最大长宽)，最好不要设置这个    //线程池配置    //.taskExecutor()    //.taskExecutorForCachedImages()    //.threadPoolSize(3) // default 线程池内加载的数量    //.threadPriority(Thread.NORM_PRIORITY - 2) // default 设置当前线程的优先级    //任务处理优先级 Fist In Fist Out    //.tasksProcessingOrder(QueueProcessingType.FIFO) // default    //内存中不缓存一张图片的多个尺寸大小    //.denyCacheImageMultipleSizesInMemory()    //内在缓存策略    //.memoryCache(new LruMemoryCache(2 * 1024 * 1024)) //可以通过自己的内存缓存实现    //内存缓存大小    //.memoryCacheSize(2 * 1024 * 1024) // 内存缓存的最大值    //内在缓存大小：占用百分比    .memoryCacheSizePercentage(13) // default    //磁盘缓存策略    //.diskCache(new LruDiskCache()) // default 可以自定义缓存路径    //磁盘缓存大小    .diskCacheSize(50 * 1024 * 1024) // 50 Mb sd卡(本地)缓存的最大值    //.diskCacheFileCount(100) // 可以缓存的文件数量    // default为使用HASHCODE对UIL进行加密命名， 还可以用MD5(new Md5FileNameGenerator())加密    //.diskCacheFileNameGenerator(new HashCodeFileNameGenerator())    //.imageDownloader(new BaseImageDownloader(context)) // default    //(new BaseImageDecoder(false)) // default    //加载具体图片时的一些配置    .defaultDisplayImageOptions(DisplayImageOptions.createSimple()) // default    .writeDebugLogs() // 打印debug log    .build();  return configuration; } public static DisplayImageOptions getDefaultDisplayImageOptions(Context context) {  DisplayImageOptions displayImageOptions = new DisplayImageOptions.Builder()    //是否缓存    .cacheInMemory(true)    .cacheOnDisk(true)    //RGB 565  r红色占5  g绿色占6  b蓝色占5 -> 2字节    //alpha    //ARGB 4444  4 4 4 4 -> 2字节    //ARGB 8888  -> 4字节    //10 * 10 用rgb565 -> 10*10*2    .bitmapConfig(Bitmap.Config.RGB_565)    //加载时、加载错误时展示什么内容    .showImageOnLoading(R.mipmap.ic_launcher)    .showImageOnFail(R.mipmap.ic_launcher)    //    .imageScaleType(ImageScaleType.EXACTLY_STRETCHED)    //加载效果    //ctrl + p    .displayer(new CircleBitmapDisplayer())    .build();  //ctrl + h  //BitmapDisplayer;  return displayImageOptions; }}