RecyclerView学习笔记1_入门

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一、 前言

RecyclerView是谷歌V7包下新增的控件,用来替代ListView、GridView的使用.

要点

  • LayoutManager：布局管理器,目前SDK中提供了三种自带的LayoutManager:

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    LinearLayoutManager-----类似ListView
    GridLayoutManager-----类似GridView
    StaggeredGridLayoutManager-----瀑布流

  • ItemDecoration：Item间的分割线样式

  • ItemAnimator：Item增加、删除的动画

  • 点击、长按事件：比较麻烦

二、开发环境

  • IDE: Android Studio 2.0 Beta 6
  • SDK: Android 23

三、使用

1. 配置

app/build.gradle

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dependencies {
    ...
    compile 'com.android.support:recyclerview-v7:23.1.1'
}

2. 主布局文件

activity_main.xml

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<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.sh.recyclerviewstudy1.MainActivity">

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

    </android.support.v7.widget.RecyclerView>
</RelativeLayout>

3. 子布局文件

rv_item_book.xml

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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="@dimen/activity_horizontal_margin"
    android:orientation="vertical">

    <TextView
        android:id="@+id/tv_book"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="16sp"/>
</LinearLayout>

4. ViewHolder文件

BookViewHolder.java

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public class BookViewHolder extends RecyclerView.ViewHolder {

    public TextView tvBook;

    public BookViewHolder(View view) {
        super(view);
        tvBook = (TextView) view.findViewById(R.id.tv_book);
    }
}

5. 适配器

BookRecyclerViewAdapter.java

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public class BookRecyclerViewAdapter extends RecyclerView.Adapter<BookViewHolder> {

    private LayoutInflater mLayoutInflater;
    private Context mContext;
    private String[] mBooks;

    public BookRecyclerViewAdapter(Context context, String[] mBooks) {
        this.mBooks = mBooks;
        this.mContext = context;
        mLayoutInflater = LayoutInflater.from(context);
    }

    @Override
    public BookViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        // 创建一个View
        View view = mLayoutInflater.inflate(R.layout.rv_item_book, parent, false);
        // 创建一个ViewHolder
        BookViewHolder bookViewHolder = new BookViewHolder(view);
        return bookViewHolder;
    }

    @Override
    public void onBindViewHolder(BookViewHolder holder, int position) {
        // 绑定数据到ViewHolder上
        holder.tvBook.setText(mBooks[position]);
    }

    @Override
    public int getItemCount() {
        // item数量
        return mBooks.length;
    }
}

6. 主界面

MainActivity.java

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public class MainActivity extends AppCompatActivity {

    private RecyclerView rvBook;
    private String[] mBooks = {"认知盈余", "和喜欢的一切在一起", "从0到1", "从你的全世界路过", "打工旅行", "番茄工作法图解"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        rvBook = (RecyclerView) findViewById(R.id.rv_book);

        // 1\. 这里用线性显示,类似于ListView
        rvBook.setLayoutManager(new LinearLayoutManager(this));

        // 2\. 这里用线性宫格显示,类似于GridView
//        rvBook.setLayoutManager(new GridLayoutManager(this, 2));

        // 3\. 这里用线性宫格显示,类似于瀑布流
//        rvBook.setLayoutManager(new StaggeredGridLayoutManager(2, OrientationHelper.VERTICAL));

        rvBook.setAdapter(new BookRecyclerViewAdapter(MainActivity.this, mBooks));
    }
}

四、总结

RecyclerView的另一个特点是标准化了 ViewHolder，编写Adapter面向的是ViewHolder而不再是View了，复用的逻辑被封装了，写起来更加简单。

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