- 用Gson代替JsonObeject处理JSON数据(挑战练习：Gson)
- 增加了上拉下拉加载更多和刷新（挑战练习：分页)
- 挑战练习：动态调整布局
- 使用Okttp代替HttpURLConnection 访问网络
- 使用Glide处理图片
- 挑战练习：使用后退键浏览历史网页
- 挑战练习：非HTTP 链接支持
- Gson
public class FlickrJson {
JsonPhotos photos;
public class JsonPhotos{
private int page;
private int pages;
private int perpage;
private int total;
@SerializedName("photo")
private List<GalleryItem> mPhotos;
public int getPage() {
return page;
}
public int getPages() {
return pages;
}
public int getPerpage() {
return perpage;
}
public int getTotal() {
return total;
}
public List<GalleryItem> getPhoto() {
return mPhotos;
}
}
}获取图片数据
items=flickrJson.photos.getPhoto();- 下拉刷新
<android.support.v4.widget.SwipeRefreshLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/swipe_refresh_layout"
android:layout_height="match_parent"
android:layout_width="match_parent">
<RecyclerView
......
/>
</android.support.v4.widget.SwipeRefreshLayout> mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
+ @Override
+ public void onRefresh() {
+ new Thread(new Runnable() {
+ @Override
+ public void run() {
+ refreshItems();
+ }
+ }).start();
+ }
+ });- 上拉加载更多
实现RecyclerView.OnScrollListener 并在onScrolled判断 是否拉到最低实现加载更多
+ private abstract class PhotoScrollListener extends RecyclerView.OnScrollListener{
+ private LinearLayoutManager mLayoutManager;
+ private final int MAX_PHOTOS=1000;
+ private boolean loading = true;
+ private int previousTotal = 0;
+ private int firstVisibleItem, visibleItemCount, totalItemCount;
+ private int currentPage = 1;
+
+ public PhotoScrollListener(LinearLayoutManager layoutManager) {
+ this.mLayoutManager=layoutManager;
+ }
+ @Override
+ public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
+ super.onScrolled(recyclerView, dx, dy);
+ //已经滑出去的viewHolder
+ visibleItemCount=recyclerView.getChildCount();
+ //Returns the number of items in the adapter bound to the parent RecyclerView
+ totalItemCount=mLayoutManager.getItemCount();
+ firstVisibleItem=mLayoutManager.findFirstVisibleItemPosition();
+
+ if (loading) {
+ if (totalItemCount > previousTotal) {
+ loading = false;
+ previousTotal = totalItemCount;
+ }
+ }
+ if (!loading
+ && (totalItemCount - visibleItemCount) <= firstVisibleItem) {
+
+ final int per_page=Integer.parseInt(FlickrFetchr.PER_PAGE);
+ if(MAX_PHOTOS/per_page>currentPage){
+ onLoadMore(++currentPage);
+ loading = true;
+ }
+
+ }
+ }- 动态调整布局
实现ViewTreeObserver.OnGlobalLayoutListener 监听器方法和计算列数的onGlobalLayout()方法，然后使用addOnGlobalLayoutListener()把监听器添加给RecyclerView视图。
+ ViewTreeObserver treeObserver=v.getViewTreeObserver();
+ treeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
+ public void onGlobalLayout() {
+ v.getViewTreeObserver().removeOnGlobalLayoutListener(this);
+ int w=mPhotoRecyclerView.getWidth();
+ LinearLayoutManager layoutManager=new GridLayoutManager(getActivity(), w/350);
+ mPhotoRecyclerView.setLayoutManager(layoutManager);
+ mPhotoRecyclerView.addOnScrollListener(new PhotoScrollListener(layoutManager) {
+ @Override
+ public void onLoadMore(int page) {
+ loadMorePhoto(page);
+ Log.d(TAG, "onLoadMore: ");
+ }
+ });
}
});- 使用Okhttp
+ public byte[] getUrlBytesByOkHttp(String urlSpec)throws IOException{
+ OkHttpClient client=new OkHttpClient();
+ Request request=new Request.Builder()
+ .url(urlSpec)
+ .build();
+ Response response=client.newCall(request).execute();
+ return response.body().bytes();
}- 使用Glide
+ public void bindDrawable(byte[] bitmapBytes) {
+ Glide.with(PhotoGalleryFragment.this)
+ .load(bitmapBytes)
+ .asBitmap()
+ .placeholder(R.drawable.bill_up_close)
+ .error(R.drawable.error)
+ .into(mImageView);
+ }- 使用后退键浏览历史网页
覆盖后退键方法Activity.onBackPressed()就能实现这个行为。在该方法内，再搭配使用 WebView的历史记录浏览方法（WebView.canGoBack()和WebView.goBack()）实现我们的浏览 逻辑。如果WebView 里有历史浏览记录， 就回到前一个历史网页， 否则调用super. onBackPressed()方法回到PhotoPageActivity。
@Override
public void onBackPressed(){
CallBacks callBacks=(CallBacks) getSupportFragmentManager().findFragmentById(R.id.activity_container);
if(callBacks.doGoback()){
super.onBackPressed();
}
}
public interface CallBacks{
boolean doGoback();
} //实现回调接口
@Override
public boolean doGoback() {
if(mWebView.canGoBack()){
mWebView.goBack();
return false;
}
return true;
}- 非HTTP 链接支持
加载URI前，先检查它的scheme，如果不是HTTP或HTTPS，就发送一个针对目标URI的Intent.ACTION_VIEW。
mWebView.setWebViewClient(new WebViewClient() {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
Uri uri = Uri.parse(url);
String scheme = uri.getScheme();
Log.d(TAG, "shouldOverrideUrlLoading: "+scheme);
if(scheme.equalsIgnoreCase("HTTP")||scheme.equalsIgnoreCase("HTTPS")){
return false;
} else {
Intent intent = new Intent(Intent.ACTION_VIEW, uri);
getActivity().startActivity(intent);
return true;
}
}
});