RecyclerView：模仿ListVIew的点击波纹效果和分隔线

使用 RecyclerView 之前先需要导入依赖包，有两种方法：
方法1：直接在 build.gradle(module:app) 中写 compile 'com.android.support:recyclerview-v7:24.2.0'
方法2：File -> Project Structure -> app-> Dependencies -> 点击"+"号 -> LibraryDepencies 搜索recyclerview，找到下图高亮的library

supportrecyclerview

波纹效果

波纹效果通过 drawable文件，有个系统自带的 ripple 元素
注意：系统的波纹效果需要 API 21以上的支持。

创建 drawable 文件：

drawable/main_touchedbackground.xml

配置元素，其中 color 属性是点击时触发的颜色，而 配置的是正常状态时显示的颜色。（grey:#D7D7D7, white:#FAFAFA）。

创建 item，并应用到 Layout 中：

layout/item_main.xml

在 中配置 android:clickable 和 android:background属性，clickable不设置为true的话会没有点击效果。

在主 Layout 中添加 元素

layout/activity_main.xml

创建一个继承自 RecyclerView.Adapter 的类：

com.example.recyclerviewdemo.CustomAdapter

public class CustomAdapter extends RecyclerView.Adapter{

    private String[] items;

    public CustomAdapter(String[] items) {
        this.items = items;
    }

    //显示图片
    public class ItemViewHolder extends RecyclerView.ViewHolder {
        private TextView textView;

        public ItemViewHolder(View itemView) {
            super(itemView);
            textView = (TextView) itemView.findViewById(R.id.textView);
        }
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        return new ItemViewHolder(LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item_main, parent, false));
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (holder instanceof ItemViewHolder) {
            ((ItemViewHolder) holder).textView.setText(items[position]);
        }
    }

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

    @Override
    public int getItemViewType(int position) {
        return 0;
    }
}

MainActivity的配置

com.example.recyclerviewdemo.MainActivity

public class MainActivity extends AppCompatActivity {

    private RecyclerView recyclerView;
    private CustomAdapter adapter;
    private String[] text = {"Java", "C", "C#", "C++", "PHP", "Ruby", "R", "Swift", "Groovy",
            "Objective-C", "Lisp"};

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

        recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        adapter = new CustomAdapter(text);
        recyclerView.setAdapter(adapter);
    }
}

ripple

添加分隔线

有两种方法，一种是直接使用 DividerItemDecoration，它也是继承 RecyclerView.ItemDecoration 的。
接下来添加分隔线需要重写装饰类 RecyclerView.ItemDecoration，画分隔线：
com.example.recyclerviewdemo.CustomItemDecoration

public class CustomItemDecoration extends RecyclerView.ItemDecoration {
    public static final String TAG = "decoration";
    private Drawable dividerLine;

    public CustomItemDecoration(Context context) {
        dividerLine = context.getDrawable(R.drawable.main_divider);
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - left;

        int childViewCount = parent.getChildCount();
        for (int i = 0; i < childViewCount; i++) {
            View childView = parent.getChildAt(i);
            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) childView.getLayoutParams();
            //top = childView's bottom + childView's end margin
            int top = childView.getBottom() + params.getMarginEnd();
            //bottom = top + 分隔线的真实高度
            int bottom = top + dividerLine.getIntrinsicHeight();

            //画分隔线
            dividerLine.setBounds(left, top, right, bottom);
            dividerLine.draw(c);
        }
    }

    //重写此方法，防止设置的波纹背景把分隔线覆盖掉。
    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        //除最后一行外，向下位移分隔线
        int currentItemPosition = parent.getChildAdapterPosition(view);
        int endItemPosition = parent.getAdapter().getItemCount() - 1;
        if (currentItemPosition != endItemPosition ) {
            outRect.bottom = dividerLine.getIntrinsicHeight();
        }
    }
}

相当于是通过各个角的位置来画一个矩形。

自定义的分隔线

drawable/main_divider.xml

代码中添加配置的 ItemDecoration

com.jkxy.recyclerviewdemo.MainActivity 中添加代码

recyclerView.addItemDecoration(new CustomItemDecoration(this));

最终的显示效果：

finall