輪播圖記錄篇

RecyclerView做的一個輪播效果，適配器有視圖緩存，避免了一些記憶體問題

首先是藉助 PagerSnapHelper 讓RecyclerView每次只滑動一個，然後添加一個指示器，這裡指示器是動態生成的，自己做了個簡單的view

很簡單的一個效果，直接上代碼

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/bg_indicator_point_selected"
    android:gravity="center"
    android:orientation="vertical">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center" />

    <com.hanmaker.bryan.hc.widget.LinIndicate
        android:id="@+id/lin_indicate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|center_horizontal"
        android:gravity="center"
        android:orientation="horizontal"/>

</FrameLayout>

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="@dimen/d20.0">

    <com.hanmaker.bryan.hc.widget.MyPhotoView android:id="@+id/img_icon"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="fitCenter"
        android:layout_gravity="center" />

</FrameLayout>

public class ImageListAdapter extends BaseQuickAdapter<String,BaseViewHolder> {

    private CallBack callBack;

    public ImageListAdapter(int layoutResId,CallBack callBack) {
        super(layoutResId);
        this.callBack = callBack;
    }

    @Override
    protected void convert(BaseViewHolder helper, String item) {

        if (item != null && !item.isEmpty()){
            MyPhotoView img =helper.getView(R.id.img_icon);
            GlideApp.with(AndroidApplication.getInstance().getApplicationContext())
                    .load(item)
                    .skipMemoryCache(true)
                    .fitCenter()
                    .into(img);
            img.setOnPhotoTapListener((view, x, y) -> callBack.click());
        }

    }

    public interface CallBack{
        void click();
    }


}

@Override
    protected void initData() {
        Bundle bundle = getArguments();
        ArrayList<String> list = bundle.getStringArrayList("Photo");
        int position = bundle.getInt("Photo_p", 0);
        adapter = new ImageListAdapter(R.layout.item_imagelist, new ImageListAdapter.CallBack() {
            @Override
            public void click() {
                if (getActivity() != null) {
                    getActivity().finish();
                }
            }
        });
        adapter.addData(list);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getContext(), LinearLayoutManager.HORIZONTAL, false);
        recyclerView.setLayoutManager(linearLayoutManager);
        linearLayoutManager.scrollToPositionWithOffset(position, 0);
        linearLayoutManager.setStackFromEnd(true);
        recyclerView.setAdapter(adapter);
        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                if (newState == RecyclerView.SCROLL_STATE_IDLE && lin_indicate != null) {//不滑動的時候，避免多次觸發
                    int lastItemPosition = linearLayoutManager.findLastCompletelyVisibleItemPosition();
                    lin_indicate.setIndicatePosition(lastItemPosition);
                }
            }
        });
        new PagerSnapHelper().attachToRecyclerView(recyclerView);
        int count = list.size();
        lin_indicate.load(count,position);
        adapter.setOnItemClickListener(new BaseQuickAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(BaseQuickAdapter adapter, View view, int position) {
                if (getActivity() != null) {
                    getActivity().finish();
                }
            }
        });
    }

public class LinIndicate extends LinearLayout {


    public LinIndicate(Context context) {
        super(context);
    }

    public LinIndicate(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public LinIndicate(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public void load(int count){
        removeAllViews();
        for (int i = 0; i < count; i++) {
            ImageView imageView = new ImageView(getContext());
            ViewGroup.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
            imageView.setLayoutParams(params);
            imageView.setPadding(10,10,10,20);
            addView(imageView);
        }
    }

    /**
     * @param count 指示器數量
     * @param position 預設顯示下標
     */
    public void load(int count,int position){
        removeAllViews();
        for (int i = 0; i < count; i++) {
            ImageView imageView = new ImageView(getContext());
            ViewGroup.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
            imageView.setLayoutParams(params);
            imageView.setPadding(10,10,10,20);
            addView(imageView);
        }
        setIndicatePosition(position);
    }

    public void setIndicatePosition(int position){
        int count = getChildCount();
        if (position > count)
            return;
        for (int i = 0; i < count; i++) {
            ImageView imageView = (ImageView) getChildAt(i);
            if (position == i){
                imageView.setImageResource(R.mipmap.ic_page_indicator_focused);
            }else{
                imageView.setImageResource(R.mipmap.ic_page_indicator);
            }
        }
    }

}

雖然簡單，但是也記錄一下，說不定哪天就能幫上忙呢，有的時候遇到很多問題解決過但是想不起來，可是當你看到相關聯的一些代碼，或許記憶片段就來了