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
<?xml version="1.0" encoding="utf-8"?>
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:color="@color/grey"
tools:targetApi="lollipop">
<item android:drawable="@color/white" />
</ripple>
配置<ripple>元素，其中 color 属性是点击时触发的颜色，而 <item> 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
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="70dp"
android:orientation="horizontal"
android:clickable="true"
android:background="@drawable/main_touchedbackground">
<ImageView
android:id="@+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:src="@mipmap/ic_launcher" />
<TextView
android:id="@+id/textView"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_weight="1"
android:gravity="center_vertical" />
</LinearLayout>
在 <LinearLayout> 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 <RecyclerView> 元素
layout/activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="16dp"
tools:context="com.example.recyclerviewdemo.MainActivity">
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical"
android:id="@+id/recyclerView">
</android.support.v7.widget.RecyclerView>
</LinearLayout>
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
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<size
android:width="1px"
android:height="1px" />
<solid android:color="#FF424242" />
</shape>
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
