AndroidRecyclerView從入門到玩壞

目錄

• 前言
• 基礎使用
• 分隔線
• 點選監聽
• 搭配CardView
• 更豐富的條目
• 增刪條目
• 快速新增檢視
• 讓RecyclerView支援複雜檢視
• 最後

---

前言

RecyclerView在Android介面開發當中是很重要的, 那掌握它也是很必要的. 但是有些時候會覺得它很厚重, 這裡就從RecyclerView的基礎一直說到擴充套件, 讓你把RecyclerView學薄了.

RecyclerView官方文件也是非常厚重.

這篇文章融合了自己原來的多篇文章, 並進行了修正和改進, 而且新增了很多很有趣的內容.
本文需要20分鐘以上的閱讀時間, 請合理安排.
多圖預警, 轉載請註明出處!

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基礎使用

要使用RecyclerView在Android Studio 2.x(以下簡稱AS), 要這樣:

compile `com.android.support:cardview-v7:25.3.1`
compile `com.android.support:recyclerview-v7:25.3.1`

到了AS 3.x, 要這樣:

implementation `com.android.support:cardview-v7:26.1.0`
implementation `com.android.support:recyclerview-v7:26.1.0`

之後在佈局檔案中寫入如下程式碼就引入了RecyclerView了.

<android.support.v7.widget.RecyclerView
    android:id="@+id/rv_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:scrollbars="vertical" />

接下來說說介紹些各種佈局. 可以看RecyclerView.LayoutManager官方文件.

佈局類	效果
LinearLayoutManager	以垂直或水平滾動列表方式顯示專案
GridLayoutManager	在網格中顯示專案
StaggeredGridLayoutManager	在分散對齊網格中顯示專案

mRvMain = (RecyclerView) findViewById(R.id.rv_main);

// 設定佈局
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
mRvMain.setLayoutManager(linearLayoutManager);

最關鍵的還是介面卡的撰寫. 但是理解起來不是很難, 你只要將ListView的介面卡寫法帶入理解就好. 這裡把全部程式碼貼出來, 因為後面要在這個基礎上不斷擴充.

public class MyRVAdapter2 extends RecyclerView.Adapter<MyRVAdapter2.MyTVHolder> {

    private final LayoutInflater mLayoutInflater;
    private final Context mContext;
    private final ArrayList<String> mData;

    public MyRVAdapter2(Context context) {
        mLayoutInflater = LayoutInflater.from(context);
        mContext = context;

        mData = new ArrayList<>();
        for (int i = 0; i < 40; i++) {
            mData.add("hello " + i);
        }
    }

    @Override
    public MyRVAdapter2.MyTVHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        return new MyRVAdapter2.MyTVHolder(mLayoutInflater.inflate(R.layout.rv_txt_item, parent, false));
    }

    @Override
    public void onBindViewHolder(final MyRVAdapter2.MyTVHolder holder, int pos) {
        holder.mTextView.setText(mData.get(pos));
    }

    @Override
    public int getItemCount() {
        return mData == null ? 0 : mData.size();
    }

    class MyTVHolder extends RecyclerView.ViewHolder {
        TextView mTextView;

        MyTVHolder(View itemView) {
            super(itemView);
            mTextView = (TextView) itemView.findViewById(R.id.tv_txt);
        }
    }
}

然後寫個最基礎的TextView條目. 讓它跑起來看看效果.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <TextView
        android:id="@+id/tv_txt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:padding="@dimen/eight_dp"
        android:text="@string/tmp"
        android:textSize="@dimen/thirty_sp" />
</LinearLayout>

---

分隔線

前面的部分已經是基礎的RecyclerView使用了. 那比起ListView是不是沒有了分隔線. 這裡上一個簡單好用的開源庫RecyclerView-FlexibleDivider.

引入:

implementation `com.yqritc:recyclerview-flexibledivider:1.4.0`

使用:

mRvMain.addItemDecoration(
        new HorizontalDividerItemDecoration.Builder(this).build());

看效果就達到了吧.

覺得不好看, 還可以自定義, 更多寫法可以參見文件內容.

mRvMain.addItemDecoration(
        new HorizontalDividerItemDecoration.Builder(this)
                .color(Color.BLUE)
                .sizeResId(R.dimen.two_dp)
                .marginResId(R.dimen.eight_dp, R.dimen.eight_dp)
                .build());

而且而且, 豎著的分隔線也大丈夫哦.

GridLayoutManager gridLayoutManager
        = new GridLayoutManager(this, 2);
mRvMain.setLayoutManager(gridLayoutManager);

mRvMain.addItemDecoration(
        new VerticalDividerItemDecoration.Builder(this).build());

---

點選監聽

再回憶一下在天國的ListView, 還有item的點選吧, 這個也要自己寫.

介面卡中:

public interface OnItemClickListener {
    void onItemClick(View view, int position);

    void onItemLongClick(View view, int position);
}

private MyRVAdapter2.OnItemClickListener mOnItemClickListener;

public void setOnItemClickListener(MyRVAdapter2.OnItemClickListener mOnItemClickListener) {
    this.mOnItemClickListener = mOnItemClickListener;
}

onBindViewHolder中設定點選監聽.

@Override
public void onBindViewHolder(final MyRVAdapter2.MyTVHolder holder, int pos) {
    holder.mTextView.setText(mData.get(pos));

    if (mOnItemClickListener != null) {
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int pos = holder.getLayoutPosition();
                mOnItemClickListener.onItemClick(holder.itemView, pos);
            }
        });
        holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View v) {
                int pos = holder.getLayoutPosition();
                mOnItemClickListener.onItemLongClick(holder.itemView, pos);
                return false;
            }
        });
    }
}

使用監聽:

mAdapter.setOnItemClickListener(new MyRVAdapter2.OnItemClickListener() {
    @Override
    public void onItemClick(View view, int position) {
        Toast.makeText(UIUtil.getContext(), "click" + position, Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onItemLongClick(View view, int position) {
        Toast.makeText(UIUtil.getContext(), "long click" + position, Toast.LENGTH_SHORT).show();
    }
});

---

搭配CardView

是不是這個點選看著沒啥感覺, 沒事, 我們換上CardView再來一次.

佈局檔案:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="@dimen/eight_dp"
    android:foreground="@drawable/card_foreground"
    card_view:cardCornerRadius="@dimen/four_dp">

    <TextView
        android:id="@+id/tv_txt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:padding="@dimen/eight_dp"
        android:text="@string/tmp"
        android:textSize="@dimen/thirty_sp" />
</android.support.v7.widget.CardView>

給CardView加上水波紋點選特效:

<?xml version="1.0" encoding="utf-8"?>
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
    android:color="@color/colorPrimary" />

在老版本就只能用選擇器了, 其實效果也還好:

<?xml version="1.0" encoding="utf-8"?>
<inset xmlns:android="http://schemas.android.com/apk/res/android"
    android:drawable="@drawable/card_foreground_selector"
    android:insetBottom="@dimen/four_dp"
    android:insetLeft="@dimen/three_dp"
    android:insetRight="@dimen/three_dp"
    android:insetTop="@dimen/four_dp" />

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <shape android:shape="rectangle">
            <solid android:color="@color/colorPrimaryTran" />
            <corners android:radius="@dimen/four_dp" />
        </shape>
    </item>
    <item android:state_enabled="true" android:state_focused="true">
        <shape android:shape="rectangle">
            <solid android:color="#0f000000" />
            <corners android:radius="@dimen/four_dp" />
        </shape>
    </item>
</selector>

---

更豐富的條目

大家應該都知道TextView可以設定圖示吧, 這裡來看下效果圖, 順帶感受下android介面設計語言的變化.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <TextView
        android:id="@+id/tv_txt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:drawableLeft="@mipmap/ic_launcher"
        android:drawablePadding="@dimen/sixteen_dp"
        android:drawableStart="@mipmap/ic_launcher"
        android:gravity="center_vertical"
        android:padding="@dimen/eight_dp"
        android:text="@string/tmp"
        android:textSize="@dimen/thirty_sp" />
</LinearLayout>

讓GridLayoutManager展示不同寬度的條目

方的是4.x上的, 圓的是8.x上的, 可以看到, 變化還是很大的. 我們回正題. GridLayoutManager佈局是可以設定寬度的, 不一定都是一樣大的, 來看下實現.

// 指定item寬度
gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
    @Override
    public int getSpanSize(int position) {
        if (position == 0
                || position == (mAdapter.getItemCount() - 1) / 2
                || position == (mAdapter.getItemCount() - 1)) {
            return gridLayoutManager.getSpanCount();
        } else {
            return 1;
        }
    }
});

來看效果圖, 發現我們的分隔線崩了是吧, 如果真想用這個分隔線也還是要自己動手修補修補, 改動改動, 開源庫再棒也猜不到你的專案需求呀.

當然了, 我還是很喜歡這個分隔線的, 我們來看看橫著滾動的效果.

佈局檔案要改動:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:orientation="horizontal">

    <TextView
        android:id="@+id/tv_txt"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:gravity="center_vertical"
        android:text="@string/tmp"
        android:textSize="@dimen/thirty_sp" />
</LinearLayout>

gridLayoutManager.setOrientation(GridLayoutManager.HORIZONTAL);

---

展示不同佈局

之前變化寬度其實還是相同條目, 現在要展示不同條目:

寫一個圖的條目:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="@dimen/eight_dp">

    <ImageView
        android:id="@+id/iv_img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:src="@mipmap/ic_launcher" />

</RelativeLayout>

public enum ITEM_TYPE {
    ITEM_TYPE_IMAGE,
    ITEM_TYPE_TEXT
}

這裡多了判斷條目型別, 還要注意返回值的變化, 用了更基類的RecyclerView.ViewHolder.

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    if (viewType == ITEM_TYPE.ITEM_TYPE_IMAGE.ordinal()) {
        return new MyRVAdapter2.MyIVHolder(mLayoutInflater.inflate(R.layout.rv_img_item, parent, false));
    } else {
        return new MyRVAdapter2.MyTVHolder(mLayoutInflater.inflate(R.layout.rv_txt_item, parent, false));
    }
}

類繼承上面也要變成RecyclerView.ViewHolder, 這些都是要對應的.

extends RecyclerView.Adapter<RecyclerView.ViewHolder>

當然了, holder也是不能少的.

public class MyIVHolder extends RecyclerView.ViewHolder {
    ImageView mImageView;

    MyIVHolder(View view) {
        super(view);
        mImageView = (ImageView) view.findViewById(R.id.iv_img);
    }
}

@Override
public void onBindViewHolder(final RecyclerView.ViewHolder holder, int pos) {
    if (holder instanceof MyRVAdapter2.MyTVHolder) {
        ((MyRVAdapter2.MyTVHolder) holder).mTextView.setText(mData.get(pos));
    } else if (holder instanceof MyRVAdapter2.MyIVHolder) {
        ((MyRVAdapter2.MyIVHolder) holder).mImageView.setImageDrawable(UIUtil.getDrawable(R.mipmap.ic_launcher));
    }

    // 點選監聽
    ...
}

順帶的, 我們把之前放寬的條目變成不同的檢視, 也就是對應起來:

@Override
public int getItemViewType(int position) {
    if (position == 0
            || position == (getItemCount() - 1) / 2
            || position == (getItemCount() - 1)) {
        return ITEM_TYPE.ITEM_TYPE_IMAGE.ordinal();
    } else {
        return ITEM_TYPE.ITEM_TYPE_TEXT.ordinal();
    }
}

看看效果:

它還能繼續地複雜, 試試瀑布流StaggeredGridLayoutManager:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="@dimen/eight_dp"
    card_view:cardCornerRadius="@dimen/four_dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <ImageView
            android:id="@+id/iv_img"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:src="@mipmap/ic_launcher" />

        <TextView
            android:id="@+id/tv_txt"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:text="@string/tmp"
            android:textSize="@dimen/thirty_sp" />
    </LinearLayout>
</android.support.v7.widget.CardView>

StaggeredGridLayoutManager staggeredGridLayoutManager
        = new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL);
mRvMain.setLayoutManager(staggeredGridLayoutManager);

分割線又崩了, 嘿嘿, 其實用上了CardView, 分割線沒什麼必要再用了.

---

增刪條目

現在介面卡中新增增刪方法:

public void addData(int position) {
    mData.add(position, "hello x");
    notifyItemInserted(position);
}

public void removeData(int position) {
    mData.remove(position);
    notifyItemRemoved(position);
}

再寫入點選事件中, 點選增加, 長按刪除:

mAdapter.setOnItemClickListener(new MyRVAdapter2.OnItemClickListener() {
    @Override
    public void onItemClick(View view, int position) {
        mAdapter.addData(position);
    }

    @Override
    public void onItemLongClick(View view, int position) {
        mAdapter.removeData(position);
    }
});

增刪條目開源庫

這裡再上一個開源庫recyclerview-animators, 可以修改增刪動畫, 種類也很豐富, 還能在它基礎上自定義:

分類	動畫類名
Cool	LandingAnimator
Scale	ScaleInAnimator, ScaleInTopAnimator, ScaleInBottomAnimator, ScaleInLeftAnimator, ScaleInRightAnimator
Fade	FadeInAnimator, FadeInDownAnimator, FadeInUpAnimator, FadeInLeftAnimator, FadeInRightAnimator
Flip	FlipInTopXAnimator, FlipInBottomXAnimator, FlipInLeftYAnimator, FlipInRightYAnimator
Slide	SlideInLeftAnimator, SlideInRightAnimator, OvershootInLeftAnimator, OvershootInRightAnimator, SlideInUpAnimator, SlideInDownAnimator

引入:

implementation `jp.wasabeef:recyclerview-animators:2.3.0`

使用:

mRvMain.setItemAnimator(new SlideInLeftAnimator());

這裡給大家展示兩種效果, 其它的自己嘗試吧.

mRvMain.setItemAnimator(new LandingAnimator());

---

快速新增檢視

還有像Header, Foot這樣的檢視, 自己寫也還是要費些功夫的, 這裡推薦Android大神的庫baseAdapter

引入:

implementation `com.zhy:base-rvadapter:3.0.3`

新增頭尾檢視

HeaderAndFooterWrapper mHeaderAndFooterWrapper = new HeaderAndFooterWrapper(mAdapter);

TextView t1 = new TextView(this);
t1.setText("Header 1");
t1.setTextSize(30);
TextView t2 = new TextView(this);
t2.setText("Foot 1");
t2.setTextSize(30);

mHeaderAndFooterWrapper.addHeaderView(t1);
mHeaderAndFooterWrapper.addFootView(t2);

mRvMain.setAdapter(mHeaderAndFooterWrapper);

新增更多檢視

LoadMoreWrapper mLoadMoreWrapper = new LoadMoreWrapper(mAdapter);
mLoadMoreWrapper.setLoadMoreView(R.layout.rv_cv_img_txt_item);
mLoadMoreWrapper.setOnLoadMoreListener(new LoadMoreWrapper.OnLoadMoreListener() {
    @Override
    public void onLoadMoreRequested() {
    }
});

mRvMain.setAdapter(mLoadMoreWrapper);

是不是感覺特別爽, 那看看更爽的, 在不寫介面卡的情況下快速新增條目:

final ArrayList<String> mData = new ArrayList<>();
for (int i = 0; i < 40; i++) {
    mData.add("hello " + i);
}

mRvMain.setAdapter(new CommonAdapter<String>(this, R.layout.rv_cv_txt_item, mData) {
    @Override
    protected void convert(ViewHolder holder, String s, int position) {
        holder.setText(R.id.tv_txt, mData.get(position));

    }
});

是不是感覺省了一萬個小時呢.

---

讓RecyclerView支援複雜檢視

每次加入新的檢視都要對介面卡進行比較大程度的改動, 這樣是很容易出錯的. 這裡引入一個非常棒的開源庫-AdapterDelegates, 降低下程式碼耦合性.

引入:

implementation `com.hannesdorfmann:adapterdelegates3:3.0.1`

先不說使用細節, 來看看實現後想加入不同檢視有多簡單吧:

ArrayList<Base> data = new ArrayList<>();
for (int i = 0; i < 10; i++) {
    data.add(new B("b " + i));
}
for (int i = 0; i < 10; i++) {
    data.add(new A("a " + i));
}
BaseAdapter animalAdapter = new BaseAdapter(this, data);
mRvMain.setAdapter(animalAdapter);

是不是驚了, 也就是說, 你只要實現了A, B這些檢視類, 直接新建放入陣列就完事了.

需要寫基礎介面卡:

public class BaseAdapter extends RecyclerView.Adapter {

    private AdapterDelegatesManager<List<Base>> delegatesManager;
    private List<Base> items;

    public BaseAdapter(Activity activity, List<Base> items) {
        this.items = items;

        delegatesManager = new AdapterDelegatesManager<>();

        delegatesManager.addDelegate(new AAdapterDelegate(activity))
                .addDelegate(new BAdapterDelegate(activity));
    }

    @Override
    public int getItemViewType(int position) {
        return delegatesManager.getItemViewType(items, position);
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        return delegatesManager.onCreateViewHolder(parent, viewType);
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        delegatesManager.onBindViewHolder(items, position, holder);
    }

    @Override
    public int getItemCount() {
        return items.size();
    }
}

需要對每個類進行進行具體設定, 這裡以A為例.

public class AAdapterDelegate extends AdapterDelegate<List<Base>> {

    private LayoutInflater inflater;

    public AAdapterDelegate(Activity activity) {
        inflater = activity.getLayoutInflater();
    }

    @Override
    public boolean isForViewType(@NonNull List<Base> items, int position) {
        return items.get(position) instanceof A;
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent) {
        return new CatViewHolder(inflater.inflate(R.layout.rv_cv_img_txt_item, parent, false));
    }

    @Override
    public void onBindViewHolder(@NonNull List<Base> items, int position,
                                 @NonNull RecyclerView.ViewHolder holder, @Nullable List<Object> payloads) {

        CatViewHolder vh = (CatViewHolder) holder;
        A cat = (A) items.get(position);

        vh.name.setText(cat.getName());
    }

    static class CatViewHolder extends RecyclerView.ViewHolder {

        public TextView name;
        public ImageView img;

        public CatViewHolder(View itemView) {
            super(itemView);
            name = (TextView) itemView.findViewById(R.id.tv_txt);
            img = (ImageView) itemView.findViewById(R.id.iv_img);
        }
    }
}

---

最後

看完這篇應該是對RecyclerView有個大體認識了, 多練習練習就會得心應手起來了. 那還是有一點, 就像分隔線庫的幾次不理想表現, 具體專案要求還是要具體對待, 開源庫也不是萬能的. 最近不是又有什麼開源專案套殼事件了嘛, 別人一開源就說自己有自主產權了真的好嗎? 喜歡記得點贊或者關注我哦, 有意見或者建議評論區見~

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