第七章：Paging添加header和footer

paging使用：https://huangxiaoguo.blog.csdn.net/article/details/106567399

效果

封装可添加Header和Footer的BaseAdapter


import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.paging.PagedListAdapter;
import androidx.recyclerview.widget.DiffUtil;
import androidx.recyclerview.widget.RecyclerView;/*** 一个能够添加HeaderView,FooterView的PagedListAdapter。* 解决了添加HeaderView和FooterView时 RecyclerView定位不准确的问题** @param <T>  Java Bean* @param <VH>*/
public abstract class AbsPagedListAdapter<T, VH extends RecyclerView.ViewHolder> extends PagedListAdapter<T, VH> {private SparseArray<View> mHeaders = new SparseArray<>();private SparseArray<View> mFooters = new SparseArray<>();private int BASE_ITEM_TYPE_HEADER = 100000;private int BASE_ITEM_TYPE_FOOTER = 200000;protected AbsPagedListAdapter(@NonNull DiffUtil.ItemCallback<T> diffCallback) {super(diffCallback);}public void addHeaderView(View view) {//判断给View对象是否还没有处在mHeaders数组里面if (mHeaders.indexOfValue(view) < 0) {mHeaders.put(BASE_ITEM_TYPE_HEADER++, view);notifyDataSetChanged();}}public void addFooterView(View view) {//判断给View对象是否还没有处在mFooters数组里面if (mFooters.indexOfValue(view) < 0) {mFooters.put(BASE_ITEM_TYPE_FOOTER++, view);notifyDataSetChanged();}}// 移除头部public void removeHeaderView(View view) {int index = mHeaders.indexOfValue(view);if (index < 0) return;mHeaders.removeAt(index);notifyDataSetChanged();}// 移除底部public void removeFooterView(View view) {int index = mFooters.indexOfValue(view);if (index < 0) return;mFooters.removeAt(index);notifyDataSetChanged();}public int getHeaderCount() {return mHeaders.size();}public int getFooterCount() {return mFooters.size();}@Overridepublic int getItemCount() {int itemCount = super.getItemCount();return itemCount + mHeaders.size() + mFooters.size();}/*** 得到列表中正常item数量** @return*/public int getOriginalItemCount() {return getItemCount() - mHeaders.size() - mFooters.size();}@Overridepublic int getItemViewType(int position) {if (isHeaderPosition(position)) {//返回该position对应的headerview的  viewTypereturn mHeaders.keyAt(position);}if (isFooterPosition(position)) {//footer类型的，需要计算一下它的position实际大小position = position - getOriginalItemCount() - mHeaders.size();return mFooters.keyAt(position);}position = position - mHeaders.size();return getItemViewType2(position);}protected int getItemViewType2(int position) {return 0;}private boolean isFooterPosition(int position) {return position >= getOriginalItemCount() + mHeaders.size();}private boolean isHeaderPosition(int position) {return position < mHeaders.size();}@NonNull@Overridepublic VH onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {if (mHeaders.indexOfKey(viewType) >= 0) {View view = mHeaders.get(viewType);return (VH) new RecyclerView.ViewHolder(view) {};}if (mFooters.indexOfKey(viewType) >= 0) {View view = mFooters.get(viewType);return (VH) new RecyclerView.ViewHolder(view) {};}return onCreateViewHolder2(parent, viewType);}protected abstract VH onCreateViewHolder2(ViewGroup parent, int viewType);@Overridepublic void onBindViewHolder(@NonNull VH holder, int position) {if (isHeaderPosition(position) || isFooterPosition(position))return;//列表中正常类型的itemView的 position 咱们需要减去添加headerView的个数position = position - mHeaders.size();onBindViewHolder2(holder, position);}protected abstract void onBindViewHolder2(VH holder, int position);@Overridepublic void onViewAttachedToWindow(@NonNull RecyclerView.ViewHolder holder) {if (!isHeaderPosition(holder.getAdapterPosition()) && !isFooterPosition(holder.getAdapterPosition())) {this.onViewAttachedToWindow2((VH) holder);}}public void onViewAttachedToWindow2(VH holder) {}@Overridepublic void onViewDetachedFromWindow(@NonNull RecyclerView.ViewHolder holder) {if (!isHeaderPosition(holder.getAdapterPosition()) && !isFooterPosition(holder.getAdapterPosition())) {this.onViewDetachedFromWindow2((VH) holder);}}public void onViewDetachedFromWindow2(VH holder) {}@Overridepublic void registerAdapterDataObserver(@NonNull RecyclerView.AdapterDataObserver observer) {super.registerAdapterDataObserver(new AdapterDataObserverProxy(observer));}//如果我们先添加了headerView,而后网络数据回来了再更新到列表上//由于Paging在计算列表上item的位置时 并不会顾及我们有没有添加headerView，就会出现列表定位的问题//实际上 RecyclerView#setAdapter方法，它会给Adapter注册了一个AdapterDataObserver//咱么可以代理registerAdapterDataObserver()传递进来的observer。在各个方法的实现中，把headerView的个数算上，再中转出去即可private class AdapterDataObserverProxy extends RecyclerView.AdapterDataObserver {private RecyclerView.AdapterDataObserver mObserver;public AdapterDataObserverProxy(RecyclerView.AdapterDataObserver observer) {mObserver = observer;}public void onChanged() {mObserver.onChanged();}public void onItemRangeChanged(int positionStart, int itemCount) {mObserver.onItemRangeChanged(positionStart + mHeaders.size(), itemCount);}public void onItemRangeChanged(int positionStart, int itemCount, @Nullable Object payload) {mObserver.onItemRangeChanged(positionStart + mHeaders.size(), itemCount, payload);}public void onItemRangeInserted(int positionStart, int itemCount) {mObserver.onItemRangeInserted(positionStart + mHeaders.size(), itemCount);}public void onItemRangeRemoved(int positionStart, int itemCount) {mObserver.onItemRangeRemoved(positionStart + mHeaders.size(), itemCount);}public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {mObserver.onItemRangeMoved(fromPosition + mHeaders.size(), toPosition + mHeaders.size(), itemCount);}}
}

AbsPageListFragment


import com.paging.study.viewmodel.AbsViewModel;
import com.scwang.smartrefresh.layout.SmartRefreshLayout;
import com.scwang.smartrefresh.layout.constant.RefreshState;
import com.scwang.smartrefresh.layout.listener.OnLoadMoreListener;
import com.scwang.smartrefresh.layout.listener.OnRefreshListener;import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;import cn.yumakeji.jetpackroomstudy.databinding.LayoutRefreshViewBinding;
import cn.yumakeji.lib_common.adapter.AbsPagedListAdapter;public abstract class AbsPageListFragment<T, M extends AbsViewModel<T>> extends Fragment implements OnRefreshListener, OnLoadMoreListener {protected Context mContext;protected Activity mActivity;private LayoutRefreshViewBinding binding;protected RecyclerView mRecyclerView;protected SmartRefreshLayout mRefreshLayout;protected EmptyView mEmptyView;protected AbsPagedListAdapter<T, RecyclerView.ViewHolder> adapter;protected M mViewModel;@Nullable@Overridepublic View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {mContext = getContext();mActivity = getActivity();/*** DataBindingUtil.inflate(inflater, getLayoutId(), container, false);* 区别* LayoutRefreshViewBinding直接可以拿到当前布局的填充器*/binding = LayoutRefreshViewBinding.inflate(inflater, container, false);mRecyclerView = binding.recyclerView;mRefreshLayout = binding.refreshLayout;mEmptyView = binding.emptyView;//配置mRefreshLayout.setEnableRefresh(true);mRefreshLayout.setEnableLoadMore(true);mRefreshLayout.setOnRefreshListener(this);mRefreshLayout.setOnLoadMoreListener(this);adapter = getAdapter();mRecyclerView.setAdapter(adapter);mRecyclerView.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false));mRecyclerView.setItemAnimator(null);onCreateViewFrame(inflater, container, savedInstanceState);genericViewModel();return binding.getRoot();}protected abstract void onCreateViewFrame(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState);private void genericViewModel() {//利用 子类传递的 泛型参数实例化出absViewModel 对象。ParameterizedType type = (ParameterizedType) getClass().getGenericSuperclass();Type[] arguments = type.getActualTypeArguments();if (arguments.length > 1) {Type argument = arguments[1];Class modelClaz = ((Class) argument).asSubclass(AbsViewModel.class);mViewModel = (M) new ViewModelProvider(this).get(modelClaz);//触发页面初始化数据加载的逻辑mViewModel.getPageData().observe(getViewLifecycleOwner(), pagedList -> submitList(pagedList));//监听分页时有无更多数据,以决定是否关闭上拉加载的动画mViewModel.getBoundaryPageData().observe(getViewLifecycleOwner(), hasData -> finishRefresh(hasData));}}/*** 添加数据到adapter** @param result*/public void submitList(PagedList<T> result) {//只有当新数据集合大于0 的时候，才调用adapter.submitList//否则可能会出现 页面----有数据----->被清空-----空布局if (result.size() > 0) {adapter.submitList(result);}finishRefresh(result.size() > 0);}/*** 刷新完成** @param hasData*/public void finishRefresh(boolean hasData) {PagedList<T> currentList = adapter.getCurrentList();hasData = hasData || currentList != null && currentList.size() > 0;RefreshState state = mRefreshLayout.getState();if (state.isFooter && state.isOpening) {mRefreshLayout.finishLoadMore();} else if (state.isHeader && state.isOpening) {mRefreshLayout.finishRefresh();}if (hasData) {mEmptyView.setVisibility(View.GONE);} else {mEmptyView.setVisibility(View.VISIBLE);}}public abstract AbsPagedListAdapter getAdapter();
}

头布局和脚布局

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"><data><variablename="url"type="java.lang.String" /><import type="com.paging.study.fragemnt.ClickPresenter" /></data><LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="vertical"><TextViewandroid:layout_width="match_parent"android:layout_height="wrap_content"android:gravity="center"android:padding="20dp"android:text="我是列表尾布局" /><Buttonandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_gravity="center_horizontal"android:onClick="@{()->ClickPresenter.clickFooterBtn(url)}"android:text="尾布局上的按钮" /><cn.yumakeji.lib_common.view.PPImageViewandroid:layout_width="150dp"android:layout_height="150dp"android:layout_gravity="center_horizontal"android:layout_marginTop="20dp"android:scaleType="centerCrop"app:image_url="@{url}" /><cn.yumakeji.lib_common.view.PPImageViewandroid:layout_width="150dp"android:layout_height="150dp"android:layout_gravity="center_horizontal"android:layout_marginTop="20dp"app:image_url="@{url}"app:isCircle="@{true}" /><cn.yumakeji.lib_common.view.PPImageViewandroid:layout_width="150dp"android:layout_height="150dp"android:layout_gravity="center_horizontal"android:layout_marginTop="20dp"android:scaleType="centerInside"app:image_url="@{url}"app:radius="@{10}" /><cn.yumakeji.lib_common.view.PPImageViewandroid:layout_width="150dp"android:layout_height="150dp"android:layout_gravity="center_horizontal"android:layout_marginTop="20dp"android:scaleType="centerCrop"app:clip_radius="10dp"app:clip_side="left"app:image_url="@{url}" /></LinearLayout>
</layout>

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"><data><variablename="url"type="java.lang.String" /><import type="com.paging.study.fragemnt.ClickPresenter" /></data><LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="vertical"><TextViewandroid:layout_width="match_parent"android:layout_height="wrap_content"android:gravity="center"android:padding="20dp"android:text="我是列表头布局" /><Buttonandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_gravity="center_horizontal"android:onClick="@{()->ClickPresenter.clickHeaderBtn(url)}"android:text="头布局上的按钮" /><cn.yumakeji.lib_common.view.PPImageViewandroid:layout_width="150dp"android:layout_height="150dp"android:layout_gravity="center_horizontal"android:layout_marginTop="20dp"android:scaleType="centerCrop"app:image_url="@{url}" /><cn.yumakeji.lib_common.view.PPImageViewandroid:layout_width="150dp"android:layout_height="150dp"android:layout_gravity="center_horizontal"android:layout_marginTop="20dp"app:image_url="@{url}"app:isCircle="@{true}" /><cn.yumakeji.lib_common.view.PPImageViewandroid:layout_width="150dp"android:layout_height="150dp"android:layout_gravity="center_horizontal"android:layout_marginTop="20dp"android:scaleType="centerInside"app:image_url="@{url}"app:radius="@{10}" /><cn.yumakeji.lib_common.view.PPImageViewandroid:layout_width="150dp"android:layout_height="150dp"android:layout_gravity="center_horizontal"android:layout_marginTop="20dp"android:scaleType="centerCrop"app:clip_radius="10dp"app:clip_side="left"app:image_url="@{url}" /></LinearLayout>
</layout>

HeaderAdapter


import com.paging.study.bean.Teacher;import cn.yumakeji.jetpackroomstudy.databinding.LayoutTeacherTypeBinding;
import cn.yumakeji.lib_common.adapter.AbsPagedListAdapter;
import cn.yumakeji.lib_common.global.AppGlobals;public class HeaderAdapter extends AbsPagedListAdapter<Teacher.RecordsBean, HeaderAdapter.ViewHolder> {protected Context mContext;public HeaderAdapter(Context context) {super(new DiffUtil.ItemCallback<Teacher.RecordsBean>() {@Overridepublic boolean areItemsTheSame(@NonNull Teacher.RecordsBean oldItem, @NonNull Teacher.RecordsBean newItem) {//判断item是否相等（这里根据id来判断）return oldItem.getPaintingId() == newItem.getPaintingId();}@Overridepublic boolean areContentsTheSame(@NonNull Teacher.RecordsBean oldItem, @NonNull Teacher.RecordsBean newItem) {//判断内容是否相等（重写equals方法）return oldItem.equals(newItem);}});this.mContext = context;}@Overrideprotected ViewHolder onCreateViewHolder2(ViewGroup parent, int viewType) {LayoutTeacherTypeBinding binding = LayoutTeacherTypeBinding.inflate(LayoutInflater.from(mContext), parent, false);return new ViewHolder(binding.getRoot(), binding);}@Overrideprotected void onBindViewHolder2(ViewHolder holder, int position) {holder.binData(getItem(position));holder.itemView.setOnClickListener(v -> {Toast.makeText(AppGlobals.getApplication(), getItem(position).getPaintingName(), Toast.LENGTH_LONG).show();});}public class ViewHolder extends RecyclerView.ViewHolder {private LayoutTeacherTypeBinding mBinding;public ViewHolder(@NonNull View itemView, LayoutTeacherTypeBinding binding) {super(itemView);this.mBinding = binding;}public void binData(Teacher.RecordsBean item) {mBinding.setItem(item);}}
}

ViewModel


import java.util.Collections;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;public class HeaderViewModel extends AbsViewModel<Teacher.RecordsBean> {public HeaderViewModel(@NonNull Application application) {super(application);}/*** 同步位置标记，防止paging和我们自己的分页重复*/private AtomicBoolean loadAfter = new AtomicBoolean();@Overrideprotected DataSource createDataSource() {return new TeacherDataSource();}/*** DataSource<Key,Value>数据源：* key 对应加载数据的条件信息，value对应数据实体类* <p>* PageKeyedDataSource<Key,Value>：* 适用于目标数据根据页面信息请求数据的场景* <p>* ItemKeyedDataSource<Key,Value>：* 适用于目标数据的加载依赖特定item的信息* <p>* PositionalDataSource<Key,Value>：* 适用于目标数据总数固定，通过特定的位置加载数据*/class TeacherDataSource extends ItemKeyedDataSource<String, Teacher.RecordsBean> {@Overridepublic void loadInitial(@NonNull LoadInitialParams<String> params,@NonNull LoadInitialCallback<Teacher.RecordsBean> callback) {pageCurrent = 1;//加载初始化数据的loadData(params.requestedInitialKey, callback);}@Overridepublic void loadAfter(@NonNull LoadParams<String> params, @NonNull LoadCallback<Teacher.RecordsBean> callback) {//向后加载分页数据的callback.onResult(Collections.<Teacher.RecordsBean>emptyList());}@Overridepublic void loadBefore(@NonNull LoadParams<String> params, @NonNull LoadCallback<Teacher.RecordsBean> callback) {callback.onResult(Collections.<Teacher.RecordsBean>emptyList());//能够向前加载数据的(例如初始化进入加载的是第3页，向上翻的时候加载第二第一页)}@NonNull@Overridepublic String getKey(@NonNull Teacher.RecordsBean item) {//通过最后一条item的信息加载数据return item.getPaintingId();}}/*** 进行网络请求** @param key* @param callback*/private void loadData(String key, ItemKeyedDataSource.LoadCallback<Teacher.RecordsBean> callback) {if (!key.equals("0")) {loadAfter.set(true);}/*** 当前线程为子线程** 这里有坑，一定要使用同步请求，因为方法执行完毕是，监听者就收到监听*/Map<String, Object> map = new ArrayMap<>();map.put("searchContent", "");map.put("size", config.pageSize);map.put("current", pageCurrent);PagingHttpClient.getInstance().get("home/paintingList", map, new PagingHttpCallback<Teacher>() {@Overrideprotected void onNext(Teacher data) {//标记分页页数if (data.getRecords() != null && data.getRecords().size() > 0) {pageCurrent = data.getCurrent() + 1;}callback.onResult(data.getRecords());if (!key.equals("0")) {//通过LiveData发送数据，告诉UI层 是否应该主动关闭上拉加载分页的动画getBoundaryPageData().postValue(data.getRecords().size() > 0);loadAfter.set(false);}Log.e("TTT", "data===>" + data.toString());}@Overrideprotected void onFail(int code, String message) {}});}
}

调用

public class HeaderAndFooterFragment extends AbsPageListFragment<Teacher.RecordsBean, HeaderViewModel> {private HeaderViewBinding mHeaderViewBinding;private FooterViewBinding mFooterViewBinding;private HeaderAndFooterFragment() {}public static HeaderAndFooterFragment newInstance() {HeaderAndFooterFragment fragment = new HeaderAndFooterFragment();return fragment;}@Overrideprotected void onCreateViewFrame(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {mRefreshLayout.setEnableLoadMore(false);initHeader();initFooter();}private void initFooter() {mFooterViewBinding = FooterViewBinding.inflate(LayoutInflater.from(mActivity), mRecyclerView, false);mFooterViewBinding.setUrl("http://img5.imgtn.bdimg.com/it/u=3416930540,2666479333&fm=26&gp=0.jpg");adapter.addFooterView(mFooterViewBinding.getRoot());}private void initHeader() {mHeaderViewBinding = HeaderViewBinding.inflate(LayoutInflater.from(mActivity), mRecyclerView, false);mHeaderViewBinding.setUrl("http://n.sinaimg.cn/front/379/w750h429/20181218/eElr-hqhtqsp9656052.jpg");adapter.addHeaderView(mHeaderViewBinding.getRoot());}@Overridepublic AbsPagedListAdapter getAdapter() {return new HeaderAdapter(mContext);}@Overridepublic void onLoadMore(@NonNull RefreshLayout refreshLayout) {}//invalidate 之后Paging会重新创建一个DataSource 重新调用它的loadInitial方法加载初始化数据//详情见：LivePagedListBuilder#compute方法@Overridepublic void onRefresh(@NonNull RefreshLayout refreshLayout) {mViewModel.getDataSource().invalidate();}
}

ClickPresenter

public class ClickPresenter {public static void clickHeaderBtn(String text) {Toast.makeText(AppGlobals.getApplication(), text, Toast.LENGTH_LONG).show();}public static void clickFooterBtn(String text) {Toast.makeText(AppGlobals.getApplication(), text, Toast.LENGTH_LONG).show();}
}

自定义ImageView

引入

//图片加载api 'com.github.bumptech.glide:glide:4.11.0'api 'jp.wasabeef:glide-transformations:4.0.0'annotationProcessor 'com.github.bumptech.glide:compiler:4.11.0'

PPImageView


public class PPImageView extends AppCompatImageView {public PPImageView(Context context) {this(context, null);}public PPImageView(Context context, AttributeSet attrs) {this(context, attrs, 0);}public PPImageView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);ViewHelper.setViewOutline(this, attrs, defStyleAttr, 0);}public void setImageUrl(String imageUrl) {setImageUrl(this, imageUrl, false);}@BindingAdapter(value = {"image_url", "isCircle"})public static void setImageUrl(PPImageView view, String imageUrl, boolean isCircle) {view.setImageUrl(view, imageUrl, isCircle, 0);}@BindingAdapter(value = {"image_url", "isCircle", "radius"}, requireAll = false)public static void setImageUrl(PPImageView view, String imageUrl, boolean isCircle, int radius) {RequestBuilder<Drawable> builder = Glide.with(view).load(imageUrl);if (isCircle) {builder.transform(new CircleCrop());} else if (radius > 0) {builder.transform(new RoundedCornersTransformation(PixUtils.dp2px(radius), 0));}ViewGroup.LayoutParams layoutParams = view.getLayoutParams();if (layoutParams != null && layoutParams.width > 0 && layoutParams.height > 0) {builder.override(layoutParams.width, layoutParams.height);}builder.into(view);}public void bindData(int widthPx, int heightPx, int marginLeft, String imageUrl) {bindData(widthPx, heightPx, marginLeft, PixUtils.getScreenWidth(), PixUtils.getScreenWidth(), imageUrl);}public void bindData(int widthPx, int heightPx, final int marginLeft, final int maxWidth, final int maxHeight, String imageUrl) {if (TextUtils.isEmpty(imageUrl)) {setVisibility(GONE);return;} else {setVisibility(VISIBLE);}if (widthPx <= 0 || heightPx <= 0) {Glide.with(this).load(imageUrl).into(new SimpleTarget<Drawable>() {@Overridepublic void onResourceReady(@NonNull Drawable resource, @Nullable Transition<? super Drawable> transition) {int height = resource.getIntrinsicHeight();int width = resource.getIntrinsicWidth();setSize(width, height, marginLeft, maxWidth, maxHeight);setImageDrawable(resource);}});return;}setSize(widthPx, heightPx, marginLeft, maxWidth, maxHeight);setImageUrl(this, imageUrl, false);}private void setSize(int width, int height, int marginLeft, int maxWidth, int maxHeight) {int finalWidth, finalHeight;if (width > height) {finalWidth = maxWidth;finalHeight = (int) (height / (width * 1.0f / finalWidth));} else {finalHeight = maxHeight;finalWidth = (int) (width / (height * 1.0f / finalHeight));}ViewGroup.LayoutParams params = getLayoutParams();params.width = finalWidth;params.height = finalHeight;if (params instanceof FrameLayout.LayoutParams) {((FrameLayout.LayoutParams) params).leftMargin = height > width ? PixUtils.dp2px(marginLeft) : 0;} else if (params instanceof LinearLayout.LayoutParams) {((LinearLayout.LayoutParams) params).leftMargin = height > width ? PixUtils.dp2px(marginLeft) : 0;}setLayoutParams(params);}@BindingAdapter(value = {"blur_url", "radius"})public static void setBlurImageUrl(ImageView imageView, String blurUrl, int radius) {Glide.with(imageView).load(blurUrl).override(radius).transform(new BlurTransformation()).dontAnimate().into(new SimpleTarget<Drawable>() {@Overridepublic void onResourceReady(@NonNull Drawable resource, @Nullable Transition<? super Drawable> transition) {imageView.setBackground(resource);}});}
}

ViewHelper


public class ViewHelper {public static final int RADIUS_ALL = 0;public static final int RADIUS_LEFT = 1;public static final int RADIUS_TOP = 2;public static final int RADIUS_RIGHT = 3;public static final int RADIUS_BOTTOM = 4;public static void setViewOutline(View view, AttributeSet attributes, int defStyleAttr, int defStyleRes) {TypedArray array = view.getContext().obtainStyledAttributes(attributes, R.styleable.viewOutLineStrategy, defStyleAttr, defStyleRes);int radius = array.getDimensionPixelSize(R.styleable.viewOutLineStrategy_clip_radius, 0);int hideSide = array.getInt(R.styleable.viewOutLineStrategy_clip_side, 0);array.recycle();setViewOutline(view, radius, hideSide);}public static void setViewOutline(View owner, final int radius, final int radiusSide) {owner.setOutlineProvider(new ViewOutlineProvider() {@Override@TargetApi(21)public void getOutline(View view, Outline outline) {int w = view.getWidth(), h = view.getHeight();if (w == 0 || h == 0) {return;}if (radiusSide != RADIUS_ALL) {int left = 0, top = 0, right = w, bottom = h;if (radiusSide == RADIUS_LEFT) {right += radius;} else if (radiusSide == RADIUS_TOP) {bottom += radius;} else if (radiusSide == RADIUS_RIGHT) {left -= radius;} else if (radiusSide == RADIUS_BOTTOM) {top -= radius;}outline.setRoundRect(left, top, right, bottom, radius);return;}int top = 0, bottom = h, left = 0, right = w;if (radius <= 0) {outline.setRect(left, top, right, bottom);} else {outline.setRoundRect(left, top, right, bottom, radius);}}});owner.setClipToOutline(radius > 0);owner.invalidate();}
}

viewOutLineStrategy

<resources><declare-styleable name="viewOutLineStrategy"><attr name="clip_radius" format="dimension"></attr><attr name="clip_side" format="enum"><enum name="all" value="0"></enum><enum name="left" value="1"></enum><enum name="top" value="2"></enum><enum name="right" value="3"></enum><enum name="bottom" value="4"></enum></attr></declare-styleable>
</resources>

Demo地址：https://gitee.com/huangxiaoguo/jetpackandrxjava

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