RecyclerView的基本使用

ListView功能是很强大的,直到现在还有很多程序在继续使用着ListView。不过ListView并不是没有缺点的,比如当数据量非常大的时候,如果不使用一些技巧提升它的运行效率,那么ListView的性能会非常差的。还有,ListView的扩展性也不够好,他只能实现数据纵向滚动的效果,如果想实现横向滚动的话,ListView是做不到的。

那么这时就需要一个更强大的滚动控件——RecyclerView。它可以说是一个增强版的ListView,不仅可以轻松实现和ListView同样的效果,还有优化了ListView中存在的各种不足之处。

RecyclerView的基本使用
首先在app的build.gradle中添加依赖:

implementation 'com.android.support:recyclerview-v7:26.1.0'

接着在activity_main.xml中修改代码:


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

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

然后为RecyclerView准备一个适配器:

/**
 * Created by Layne_Yao on 2018/6/8.
 * CSDN:http://blog.csdn.net/Jsagacity
 */
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {
    private List personList;

    static class ViewHolder extends RecyclerView.ViewHolder {
        ImageView imgPortrait;
        TextView tvName, tvFruitAbility;

        /**
         * ViewHolder的构造方法
         * @param itemView 这个布局是RecyclerView子项最外层的布局
         */
        public ViewHolder(View itemView) {
            super(itemView);
            imgPortrait = itemView.findViewById(R.id.imgPortrait);
            tvName = itemView.findViewById(R.id.tvName);
            tvFruitAbility = itemView.findViewById(R.id.tvFruitAbility);
        }
    }

    /**
     * RecyclerViewAdapter的构造方法,
     * @param personList 传入的数据源
     */
    public RecyclerViewAdapter(List personList) {
        this.personList = personList;
    }

    /**
     * 此方法用于创建ViewHolder实例,并将要加载的布局传入到构造函数中
     * @param parent
     * @param viewType
     * @return
     */
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_person, parent, false);
        ViewHolder holder = new ViewHolder(view);

        return holder;
    }

    /**
     * 此方法用于对RecyclerView子项的数据进行赋值的,会在每个子项被滚动到屏幕内的时候执行
     * @param holder
     * @param position
     */
    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Person person = personList.get(position);
        holder.imgPortrait.setImageResource(person.getPortrait());
        holder.tvName.setText(person.getName());
        holder.tvFruitAbility.setText(person.getFruitAbility());

    }

    /**
     * 告诉RecyclerView一共有多少个子项
     * @return
     */
    @Override
    public int getItemCount() {
        return personList.size();
    }
}

上面会用到一个Person的实体类:

/**
 * Created by Layne_Yao on 2018/5/28.
 * CSDN:http://blog.csdn.net/Jsagacity
 */
public class Person {
    private int portrait;
    private String name;
    private String fruitAbility;

    public Person(int portrait, String name, String fruitAbility) {
        this.portrait = portrait;
        this.name = name;
        this.fruitAbility = fruitAbility;
    }

    public int getPortrait() {
        return portrait;
    }

    public void setPortrait(int portrait) {
        this.portrait = portrait;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getFruitAbility() {
        return fruitAbility;
    }

    public void setFruitAbility(String fruitAbility) {
        this.fruitAbility = fruitAbility;
    }
}

还缺一个item_person的子布局:


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:padding="8dp">

    <ImageView
        android:id="@+id/imgPortrait"
        android:layout_width="50dp"
        android:layout_height="50dp" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:orientation="vertical"
        android:paddingLeft="8dp">

        <TextView
            android:id="@+id/tvName"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textColor="#333333"
            android:textSize="16sp" />

        <TextView
            android:id="@+id/tvFruitAbility"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textColor="#888888"
            android:textSize="14sp" />

    LinearLayout>


LinearLayout>

最后就是MainActivity.java的代码实现:

public class MainActivity extends AppCompatActivity {
    private List personList;
    private RecyclerView recyclerView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initData();
        recyclerView = findViewById(R.id.recyclerView);
        //纵向布局
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);

        recyclerView.setLayoutManager(layoutManager);
        RecyclerViewAdapter adapter = new RecyclerViewAdapter(personList);
        recyclerView.setAdapter(adapter);
    }

    private void initData() {
        personList = new ArrayList<>();
        personList.add(new Person(R.drawable.aisi, "艾斯", "烧烧果实,控制火的能力"));
        personList.add(new Person(R.drawable.lufei, "路飞", "橡皮果实,是一个橡皮人"));
        personList.add(new Person(R.drawable.luo, "罗", "手术果实,是一个很厉害的医生"));
        personList.add(new Person(R.drawable.aisi, "艾斯", "烧烧果实,控制火的能力"));
        personList.add(new Person(R.drawable.lufei, "路飞", "橡皮果实,是一个橡皮人"));
        personList.add(new Person(R.drawable.luo, "罗", "手术果实,是一个很厉害的医生"));
        personList.add(new Person(R.drawable.aisi, "艾斯", "烧烧果实,控制火的能力"));
        personList.add(new Person(R.drawable.lufei, "路飞", "橡皮果实,是一个橡皮人"));
        personList.add(new Person(R.drawable.luo, "罗", "手术果实,是一个很厉害的医生"));
        personList.add(new Person(R.drawable.aisi, "艾斯", "烧烧果实,控制火的能力"));
        personList.add(new Person(R.drawable.lufei, "路飞", "橡皮果实,是一个橡皮人"));
        personList.add(new Person(R.drawable.luo, "罗", "手术果实,是一个很厉害的医生"));
        personList.add(new Person(R.drawable.aisi, "艾斯", "烧烧果实,控制火的能力"));
        personList.add(new Person(R.drawable.lufei, "路飞", "橡皮果实,是一个橡皮人"));
        personList.add(new Person(R.drawable.luo, "罗", "手术果实,是一个很厉害的医生"));

    }

}

就这样最基本的显示就完成了,运行结果如下:
RecyclerView的基本使用_第1张图片

上面是最简单的数据展示了,RecyclerView其实还有很多布局,上面是纵向布局LinearLayoutManager,还可以切换成横向布局,瀑布流布局StaggeredGridLayoutManager和网格布局GridLayoutManager。





里就不一一说明,直接在上面的例子改成个布局的切换,以及item的点击事件。
点击事件要改的是适配器里面的代码:

/**
 * Created by Layne_Yao on 2018/6/8.
 * CSDN:http://blog.csdn.net/Jsagacity
 */
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {
    private List personList;

    static class ViewHolder extends RecyclerView.ViewHolder {
        View personView;
        ImageView imgPortrait;
        TextView tvName, tvFruitAbility;

        /**
         * ViewHolder的构造方法
         * @param itemView 这个布局是RecyclerView子项最外层的布局
         */
        public ViewHolder(View itemView) {
            super(itemView);
            personView = itemView;
            imgPortrait = itemView.findViewById(R.id.imgPortrait);
            tvName = itemView.findViewById(R.id.tvName);
            tvFruitAbility = itemView.findViewById(R.id.tvFruitAbility);
        }
    }

    /**
     * RecyclerViewAdapter的构造方法,
     * @param personList 传入的数据源
     */
    public RecyclerViewAdapter(List personList) {
        this.personList = personList;
    }

    /**
     * 此方法用于创建ViewHolder实例,并将要加载的布局传入到构造函数中
     * @param parent
     * @param viewType
     * @return
     */
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_person, parent, false);
        final ViewHolder holder = new ViewHolder(view);
        //子项的点击事件
        holder.personView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int position = holder.getAdapterPosition();
                Person person = personList.get(position);
                Toast.makeText(view.getContext(),position+":"+person.getName(),Toast.LENGTH_SHORT).show();
            }
        });

        //图片的点击事件
        holder.imgPortrait.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int position = holder.getAdapterPosition();
                Person person = personList.get(position);
                Toast.makeText(view.getContext(),position+":"+person.getName(),Toast.LENGTH_SHORT).show();
            }
        });
        return holder;
    }

    /**
     * 此方法用于对RecyclerView子项的数据进行赋值的,会在每个子项被滚动到屏幕内的时候执行
     * @param holder
     * @param position
     */
    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Person person = personList.get(position);
        holder.imgPortrait.setImageResource(person.getPortrait());
        holder.tvName.setText(person.getName());
        holder.tvFruitAbility.setText(person.getFruitAbility());

    }

    /**
     * 告诉RecyclerView一共有多少个子项
     * @return
     */
    @Override
    public int getItemCount() {
        return personList.size();
    }
}

MainActivity中的代码修改成:

public class MainActivity extends AppCompatActivity {
    private List personList;
    private RecyclerView recyclerView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initData();
        recyclerView = findViewById(R.id.recyclerView);
        //纵向布局
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);

        recyclerView.setLayoutManager(layoutManager);
        RecyclerViewAdapter adapter = new RecyclerViewAdapter(personList);
        recyclerView.setAdapter(adapter);
    }

    private void initData() {
        personList = new ArrayList<>();
        personList.add(new Person(R.drawable.aisi, "艾斯", "烧烧果实,控制火的能力"));
        personList.add(new Person(R.drawable.lufei, "路飞", "橡皮果实,是一个橡皮人"));
        personList.add(new Person(R.drawable.luo, "罗", "手术果实,是一个很厉害的医生"));
        personList.add(new Person(R.drawable.aisi, "艾斯", "烧烧果实,控制火的能力"));
        personList.add(new Person(R.drawable.lufei, "路飞", "橡皮果实,是一个橡皮人"));
        personList.add(new Person(R.drawable.luo, "罗", "手术果实,是一个很厉害的医生"));
        personList.add(new Person(R.drawable.aisi, "艾斯", "烧烧果实,控制火的能力"));
        personList.add(new Person(R.drawable.lufei, "路飞", "橡皮果实,是一个橡皮人"));
        personList.add(new Person(R.drawable.luo, "罗", "手术果实,是一个很厉害的医生"));
        personList.add(new Person(R.drawable.aisi, "艾斯", "烧烧果实,控制火的能力"));
        personList.add(new Person(R.drawable.lufei, "路飞", "橡皮果实,是一个橡皮人"));
        personList.add(new Person(R.drawable.luo, "罗", "手术果实,是一个很厉害的医生"));
        personList.add(new Person(R.drawable.aisi, "艾斯", "烧烧果实,控制火的能力"));
        personList.add(new Person(R.drawable.lufei, "路飞", "橡皮果实,是一个橡皮人"));
        personList.add(new Person(R.drawable.luo, "罗", "手术果实,是一个很厉害的医生"));

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        menu.add(0, 1, 0, "切换LinearLayoutManager");
        menu.add(0, 2, 0, "切换成横向布局");
        menu.add(0, 3, 0, "切换StaggeredGridLayoutManager");
        menu.add(0, 4, 0, "切换GridLayoutManager");
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case 1:
                //纵向布局
                LinearLayoutManager layoutManager = new LinearLayoutManager(this);
                recyclerView.setLayoutManager(layoutManager);
                break;
            case 2:
                LinearLayoutManager layoutManager1 = new LinearLayoutManager(this);
                //横向布局
                layoutManager1.setOrientation(LinearLayoutManager.HORIZONTAL);
                recyclerView.setLayoutManager(layoutManager1);
                break;
            case 3:
                //瀑布流布局
                StaggeredGridLayoutManager layoutManager2 = new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL);
                recyclerView.setLayoutManager(layoutManager2);
                break;
            case 4:
                //网格布局
                GridLayoutManager layoutManager3 = new GridLayoutManager(this, 2);
                recyclerView.setLayoutManager(layoutManager3);
                break;
        }
        return true;
    }
}

运行结果:
RecyclerView的基本使用_第2张图片
源码已经全部贴出来了,所以就不提供源码下载了

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