高级UI-RecyclerView简单使用

RecyclerView从Android 5.0开始引入，用以替代ListView、GridView控件，RecyclerView的存在，使得控件的耦合度更低，在ListView中需要使用ViewHolder做优化，而在RecyclerView里面自带了ViewHolder那么这篇文章就来写一写关于RecyclerView的基本使用，后面还会有文章继续对RecyclerView的使用做介绍

使用RecyclerView的准备

RecyclerView存在于support-v7中，这是为了更好的兼容各个版本，这这里说明以下V4，v7等包的作用，在系统中的很多控件在这个包里面都能找到，其主要作用就是各个不同系统版本的兼容，说简单一点就是为了在不同Android系统版本上有着相同的体验

在使用RecyclerView之前，需要导入依赖

在Android Studio中，直接在gradle中添加

implementation'com.android.support:recyclerview-v7:25.4.0'

注：这里注意两点，3.0以前的ide使用的是complie而3.0以后的ide使用的是implementation，还有一个地方是25.4.0，这里指的是编译版本，要和上面的compileSdkVersion相一致，比如compileSdkVersion 25那么这里应该是25.x.x，后面是小版本号，在SDK下载的地方可以看到

依赖导入完成，那么就可以开始使用RecycleView，其使用过程和ListView极其类似

数据准备

这里是模拟使用，就直接使用一个数据工具来生成数据，根据输入的个数返回数据

public class DataUtils {

    public static List<String> initData(int num){

        List<String> list = new ArrayList<>();

        for (int i = 0; i < num; i++) {

            list.add("item " + i);

        }

        return list;

    }

}

适配器准备

和ListView一样，使用RecyclerView也需要准备适配器，不过在实现上稍有不同，RecyclerView的适配器是其内部类，需要实现onCreateViewHolder，onBindViewHolder，getItemCount三个方法

public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.MyViewHolder> {

    private List<String> list;

    class MyViewHolder extends RecyclerView.ViewHolder {

        private TextView textView;

        public MyViewHolder(View itemView) {

            super(itemView);

            textView = (TextView) itemView.findViewById(android.R.id.text1);

        }

    }

    public MyRecyclerViewAdapter(List<String> list) {

        this.list = list;

    }

    @Override

    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());

        View view = layoutInflater.inflate(android.R.layout.simple_list_item_1,parent,false);

        MyViewHolder holder = new MyViewHolder(view);

        return holder;

    }

    @Override

    public void onBindViewHolder(MyViewHolder holder, int position) {

        holder.textView.setText(list.get(position));

    }

    @Override

    public int getItemCount() {

        return list.size();

    }

}

网格布局

网格布局直接使用以上数据和适配器即可

public class GridActivity extends AppCompatActivity {

    private RecyclerView recyclerView;

    private MyRecyclerViewAdapter adapter;

    private List<String> list;

    @Override

    protected void onCreate(@Nullable Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_grid);

        recyclerView = (RecyclerView) findViewById(R.id.grid_recyclerview);

        list = DataUtils.initData(100);

        adapter = new MyRecyclerViewAdapter(list);

        //设置样式，后面的参数代表设置三列

        recyclerView.setLayoutManager(new GridLayoutManager(this, 3));

        recyclerView.setAdapter(adapter);

    }

}

线性布局

线性布局只是在设置样式的时候不同，其他地方和网格布局相同，这里可以实现水平布局，这是ListView做不到的，可以是正序，也可以是反序

public class LineActivity extends AppCompatActivity {

    private RecyclerView recyclerView;

    private MyRecyclerViewAdapter adapter;

    private List<String> list;

    @Override

    protected void onCreate(@Nullable Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_line);

        recyclerView = (RecyclerView) findViewById(R.id.line_recyclerview);

        list = DataUtils.initData(100);

        adapter = new MyRecyclerViewAdapter(list);

        //设置样式，默认垂直

        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        //水平布局

        //recyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, true));

        recyclerView.setAdapter(adapter);

    }

}

瀑布流

在使用瀑布流的时候会获取填充布局的宽高，这里使用一个随机数模拟，同时加上随机背景，方便查看

所以在这里需要修改适配器，使其达到想要的结果

public class StaggedAdapter extends RecyclerView.Adapter<StaggedAdapter.MyViewHolder> {

    private List<String> list;

    private List<Integer> height;

    class MyViewHolder extends RecyclerView.ViewHolder {

        private TextView textView;

        public MyViewHolder(View itemView) {

            super(itemView);

            textView = (TextView) itemView.findViewById(android.R.id.text1);

        }

    }

    public StaggedAdapter(List<String> list) {

        this.list = list;

        height = new ArrayList<>();

        for (int i = 0; i < list.size(); i++) {

            //模拟瀑布流高度

            int viewHeight = (int)Math.max(200,Math.random() *500);

            height.add(viewHeight);

        }

    }

    @Override

    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());

        View view = layoutInflater.inflate(android.R.layout.simple_list_item_1,parent,false);

        MyViewHolder holder = new MyViewHolder(view);

        return holder;

    }

    @Override

    public void onBindViewHolder(MyViewHolder holder, int position) {

        //设置背景颜色

        ViewGroup.LayoutParams params = holder.textView.getLayoutParams();

        params.height = height.get(position);

        int color = Color.rgb(100, (int) (Math.random() * 255), (int) (Math.random() * 255));

        holder.textView.setBackgroundColor(color);

        holder.textView.setLayoutParams(params);

        holder.textView.setText(list.get(position));

    }

    @Override

    public int getItemCount() {

        return list.size();

    }

}

其调用方法与前面的类似，这样便完成了瀑布流效果的实现

public class StaggedActivity extends AppCompatActivity {

    private RecyclerView recyclerView;

    private StaggedAdapter adapter;

    private List<String> list;

    @Override

    protected void onCreate(@Nullable Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_stagged);

        recyclerView = (RecyclerView) findViewById(R.id.stagged_recyclerview);

        list = DataUtils.initData(100);

        adapter = new StaggedAdapter(list);

        //设置样式

        recyclerView.setLayoutManager(new StaggeredGridLayoutManager(3, LinearLayoutManager.VERTICAL));

        recyclerView.setAdapter(adapter);

    }

}

以下是Demo的测试效果

源代码：链接：https://pan.baidu.com/s/1oEU5JyJLS5538GOZrFf1cQ 密码：95ip

给RecyclerView添加点击事件

在RecyclerView当中，是没有点击事件的，那么要实现点击，就需要自己去实现，这里就来实现一下RecycleView的点击监听

在适配器中添加点击方法和监听接口

public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.MyViewHolder> {

    private List<String> list;

    private OnItemClickListener onItemClickListener;

    class MyViewHolder extends RecyclerView.ViewHolder {

        private TextView textView;

        public MyViewHolder(View itemView) {

            super(itemView);

            textView = (TextView) itemView.findViewById(android.R.id.text1);

        }

    }

    public MyRecyclerViewAdapter(List<String> list) {

        this.list = list;

    }

    @Override

    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());

        View view = layoutInflater.inflate(android.R.layout.simple_list_item_1,parent,false);

        MyViewHolder holder = new MyViewHolder(view);

        return holder;

    }

    @Override

    public void onBindViewHolder(MyViewHolder holder, int position) {

        holder.textView.setText(list.get(position));

        if (onItemClickListener != null) {

            holder.textView.setOnClickListener(new MyClickLister(position));

        }

    }

    @Override

    public int getItemCount() {

        return list.size();

    }

    public interface OnItemClickListener {

        void onItemClick(View view, int position);

    }

    public void setOnItemClickListener(OnItemClickListener onItemClickListener) {

        this.onItemClickListener = onItemClickListener;

    }

    class MyClickLister implements View.OnClickListener {

        private int position;

        public MyClickLister(int position) {

            this.position = position;

        }

        @Override

        public void onClick(View v) {

            onItemClickListener.onItemClick(v, position);

        }

    }

}

在活动中设置监听

public class LineActivity extends AppCompatActivity {

    private RecyclerView recyclerView;

    private MyRecyclerViewAdapter adapter;

    private List<String> list;

    @Override

    protected void onCreate(@Nullable Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_line);

        recyclerView = (RecyclerView) findViewById(R.id.line_recyclerview);

        list = DataUtils.initData(100);

        adapter = new MyRecyclerViewAdapter(list);

        //设置点击监听

        adapter.setOnItemClickListener(new MyRecyclerViewAdapter.OnItemClickListener() {

            @Override

            public void onItemClick(View view, int position) {

                Toast.makeText(LineActivity.this, "点击 " + position, Toast.LENGTH_SHORT).show();

            }

        });

        //设置样式，默认垂直

        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        //水平布局

        recyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, true));

        recyclerView.setAdapter(adapter);

    }

}

测试效果如下

源代码：链接：https://pan.baidu.com/s/1FCHqwlRhdbpB-qcozkQXJA 密码：ls7y

相同的做法，还可以实现长按等监听

巴特西