Android仿新浪微博自定义ListView下拉刷新(4)

2019-12-12 04:34:08

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自定义PullToRefreshListView继承ListView，在ListView头部添加一个下拉的头部布局。跟ListView用法完全一致。

该自定义Listview代码详解具体可参考： //www.VeVB.COm/article/97845.htm

此处详细介绍Adapter的详细代码。

1.首先给Adapter绑定ListView布局。
2.其次创建一个层次对应组件的类，将对应的组件和对象进行关联，提高效率。
3.然后跟陆获得的图片路径异步下载图片，由于不知道该微博图片的数量，所以在listview中添加一个GirlView控件或者GirlLayout布局，然后将得到的图片添加到其中，并按指定属性值排列好。

** * Created by D&LL on 2016/6/2. */public class WeiboAdapter extends BaseAdapter { /**  * 为提高效率，缓存数据准备的一个自定义类 对应一条微博数据  */ class WeiboHolder {  public ImageView wbicon;  public TextView wbtext, wbtime, wbuser; } private HomeActivity homeActivity = null; //数据集 public ArrayList<WeiBoInfo> weiboList = null; public WeiboAdapter(HomeActivity homeActivity, ArrayList<WeiBoInfo> weiboList) {  this.homeActivity = homeActivity;  this.weiboList = weiboList; } //微博图片的异步下载类 AsyncImageLoader asyncImageLoader; @Override public View getView(int position, View convertView, ViewGroup parent) {  asyncImageLoader = new AsyncImageLoader();  //记载微博的每条需要显示在什么布局上的布局对象  convertView = LayoutInflater.from(this.homeActivity.getApplicationContext()).inflate(R.layout.listview,    null);  //创建一个层次对应组件的类  WeiboHolder wh = new WeiboHolder();  //将对应的组件和对象进行关联，提高效率  wh.wbicon = (ImageView) convertView.findViewById(R.id.wbicon);  wh.wbtext = (TextView) convertView.findViewById(R.id.wbtext);  wh.wbtime = (TextView) convertView.findViewById(R.id.wbtime);  wh.wbuser = (TextView) convertView.findViewById(R.id.wbuser);  /* wh.wbimage = (ImageView) convertView.findViewById(R.id.wbimage);*/  //获得一条微博数据  WeiBoInfo wb = this.weiboList.get(position);  if (wb != null) {   convertView.setTag(wb.getId());   wh.wbuser.setText(wb.getUserName());   wh.wbtime.setText(wb.getTime());   wh.wbtext.setText(StringUtils.getEmotionContent(convertView.getContext(), wh.wbtext, wb.getText()   ), TextView.BufferType.SPANNABLE);   if (wb.getHaveImage()) {    // 是否有图片信息    //异步加载图片内容    Drawable[] wb_image = new Drawable[wb.getImage_context().length];    ImageView[] wbimage = new ImageView[wb.getImage_context().length];    GridLayout layout = (GridLayout) convertView.findViewById(R.id.imagelayout);    //遍历下载所有图片 并添加到listview中    for (int i = 0; i < wb.getImage_context().length; i++) {     wbimage[i] = new ImageView(this.homeActivity.getApplicationContext());     wbimage[i].setPadding(5, 5, 5, 5);     wbimage[i].setScaleType(ImageView.ScaleType.FIT_XY);     GridLayout.Spec row = GridLayout.spec(i / 3);     GridLayout.Spec colum = GridLayout.spec(i % 3);     GridLayout.LayoutParams params = new GridLayout.LayoutParams(row, colum);     params.setGravity(Gravity.FILL);     params.width = 250;     params.height = 250;     wb_image[i] = asyncImageLoader.loadDrawable(wb.getImage_context()[i],       wbimage[i], new AsyncImageLoader.ImageCallback() {        @Override        public void imageLoaded(Drawable imageDrawable, ImageView imageView, String imageUrl) {         imageView.setImageDrawable(imageDrawable);        }       });     wbimage[i].setImageDrawable(wb_image[i]);     layout.addView(wbimage[i], params);    }   }   //异步加载用户头像数据   Drawable cachedImage = asyncImageLoader.loadDrawable(wb.getUserIcon(), wh.wbicon, new AsyncImageLoader.ImageCallback() {    @Override    public void imageLoaded(Drawable imageDrawable, ImageView imageView, String imageUrl) {     imageView.setImageDrawable(imageDrawable);    }   });   if (cachedImage == null) {   } else {    wh.wbicon.setImageDrawable(cachedImage);   }  }  return convertView; } @Override public int getCount() {  return this.weiboList.size(); } @Override public Object getItem(int position) {  return this.weiboList.get(position); } @Override public long getItemId(int position) {  return position; }}

异步下载图片的方法。使用SoftReference是软引用，是为了系统更好的回收变量；从缓存中获取图片路径后，建立新一个新的线程下载图片。

** * Created by D&LL on 2016/6/2. */public class AsyncImageLoader { //SoftReference是软引用，是为了更好的为了系统回收变量 private HashMap<String, SoftReference<Drawable>> imageCache; public AsyncImageLoader() {  imageCache = new HashMap<String, SoftReference<Drawable>>(); } public Drawable loadDrawable(final String imageUrl, final ImageView imageView, final ImageCallback imageCallback) {  if (imageCache.containsKey(imageUrl)) {//从缓存中获取   SoftReference<Drawable> softReference = imageCache.get(imageUrl);   Drawable drawable = softReference.get();   if (drawable != null) {    return drawable;   }  }  final Handler handler = new Handler() {   public void handleMessage(Message message) {    imageCallback.imageLoaded((Drawable) message.obj, imageView, imageUrl);   }  };//建立新一个新的线程下载图片  new Thread() {   @Override   public void run() {    Drawable drawable = loadImageFromUrl(imageUrl);    imageCache.put(imageUrl, new SoftReference<Drawable>(drawable));    Message message = handler.obtainMessage(0, drawable);    handler.sendMessage(message);   }  }.start();  return null; } public static Drawable loadImageFromUrl(String url) {  URL m;  InputStream i = null;  try {   m = new URL(url);   i = (InputStream) m.getContent();  } catch (MalformedURLException e1) {   e1.printStackTrace();  } catch (IOException e) {   e.printStackTrace();  }  Drawable d = Drawable.createFromStream(i, "src");  return d; } //回调接口 public interface ImageCallback {  public void imageLoaded(Drawable imageDrawable, ImageView imageView, String imageUrl); }}

效果图：