Android仿新浪微博自定义ListView下拉刷新(4)
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: http://www.jb51.net/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:
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