Android RecyclerView的使用(二)——添加分割线
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2022-06-06 09:56:02
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Android RecyclerView的使用(二)——添加分割线
前言: RecyclerView提供了一种插拔式的体验,高度的解耦,异常的灵活,通过设置它提供的不同LayoutManager,ItemDecoration , ItemAnimator实现绚丽的效果。
- 通过布局管理器LayoutManager,可以控制其显示的方式;
- 通过ItemDecoration,可以控制Item间的间隔(可定制);
- 通过ItemAnimator,可以控制Item增删的动画;
- 至于点击、长按事件,RecyclerView并没有给我们提供相应的方法接口,需要我们自己实现。
上一节我们了解了RecyclerView的基本使用,这节我们将介绍如何为RecyclerView 添加分割线。
效果图:
第一步:activity_main.xml布局文件
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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">
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</android.support.constraint.ConstraintLayout>
第二步:定义item的样式,item_single_textview.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:background="#442F2F2F"
android:layout_height="72dp">
<ImageView
android:id="@+id/imageView"
android:layout_margin="20dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/textView"
android:layout_gravity="center_vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
第三步:自定义Adapter适配器
public class MyAdapter extends RecyclerView.Adapter<MyViewHolder> {
private LayoutInflater mInflater;
private Context mContext;
private List<String> mDatas;
private int[] imgIds;
public MyAdapter(Context context, List<String> datas, int[] imgIds) {
this.mContext = context;
this.mDatas = datas;
this.imgIds = imgIds;
mInflater = LayoutInflater.from(context);
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = mInflater.inflate(R.layout.item_single_textview, parent, false);
MyViewHolder viewHolder = new MyViewHolder(view);
return viewHolder;
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
holder.textView.setText(mDatas.get(position));
holder.imageView.setBackgroundResource(imgIds[ position % 7]);
}
@Override
public int getItemCount() {
return mDatas.size();
}
}
class MyViewHolder extends RecyclerView.ViewHolder {
ImageView imageView;
TextView textView;
public MyViewHolder(View itemView) {
super(itemView);
textView = itemView.findViewById(R.id.textView);
imageView = itemView.findViewById(R.id.imageView);
}
}
第四步:自定义分割线类(说明,我所使用的分割线类是从网上找的,不是本人实现的)
public class DividerItemDecoration extends RecyclerView.ItemDecoration {
public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;
private static final int[] ATTRS = new int[]{android.R.attr.listDivider};
private Drawable mDivider;
private int mOrientation;
public DividerItemDecoration(Context context, int orientation) {
final TypedArray a = context.obtainStyledAttributes(ATTRS);
mDivider = a.getDrawable(0);
a.recycle();
setOrientation(orientation);
}
public void setOrientation(int orientation) {
if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
throw new IllegalArgumentException("invalid orientation");
}
mOrientation = orientation;
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
super.onDraw(c, parent, state);
if (mOrientation == VERTICAL_LIST) {
drawVertical(c, parent);
} else {
drawHorizontal(c, parent);
}
}
public void drawVertical(Canvas c, RecyclerView parent) {
final int left = parent.getPaddingLeft();
final int right = parent.getWidth() - parent.getPaddingRight();
final int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);
RecyclerView v = new RecyclerView(
parent.getContext());
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
.getLayoutParams();
final int top = child.getBottom() + params.bottomMargin;
final int bottom = top + mDivider.getIntrinsicHeight();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
public void drawHorizontal(Canvas c, RecyclerView parent) {
final int top = parent.getPaddingTop();
final int bottom = parent.getHeight() - parent.getPaddingBottom();
final int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
.getLayoutParams();
final int left = child.getRight() + params.rightMargin;
final int right = left + mDivider.getIntrinsicHeight();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
if (mOrientation == VERTICAL_LIST) {
outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
} else {
outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
}
}
}
第五步:MainActivity.java
public class MainActivity extends AppCompatActivity {
private RecyclerView recyclerView;
private List<String> mDatas;
private int[] imgIds;
private MyAdapter mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initDatas();
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
mAdapter = new MyAdapter(this, mDatas, imgIds);
recyclerView.setAdapter(mAdapter);
//设置RecyclerView的布局管理
LinearLayoutManager manager = new LinearLayoutManager(this,
LinearLayoutManager.VERTICAL, false);
recyclerView.setLayoutManager(manager);
//设置RecyclerView的item间分割线
recyclerView.addItemDecoration(new DividerItemDecoration(this,
DividerItemDecoration.VERTICAL_LIST));
}
private void initDatas() {
imgIds = new int[]{R.mipmap.pic01, R.mipmap.pic02, R.mipmap.pic03, R.mipmap.pic04,
R.mipmap.pic05, R.mipmap.pic06, R.mipmap.pic07};
mDatas = new ArrayList<>();
mDatas.add("亳州"); // 亳[bó]属于不常见的二级汉字
mDatas.add("大娃");
mDatas.add("二娃");
mDatas.add("三娃");
mDatas.add("四娃");
mDatas.add("五娃");
mDatas.add("六娃");
mDatas.add("七娃");
mDatas.add("喜羊羊");
mDatas.add("美羊羊");
mDatas.add("懒羊羊");
mDatas.add("沸羊羊");
mDatas.add("暖羊羊");
mDatas.add("慢羊羊");
mDatas.add("灰太狼");
mDatas.add("红太狼");
mDatas.add("孙悟空");
mDatas.add("黑猫警长");
mDatas.add("舒克");
mDatas.add("贝塔");
mDatas.add("海尔");
mDatas.add("阿凡提");
mDatas.add("邋遢大王");
mDatas.add("哪吒");
mDatas.add("没头脑");
mDatas.add("不高兴");
mDatas.add("蓝皮鼠");
mDatas.add("大脸猫");
mDatas.add("大头儿子");
mDatas.add("小头爸爸");
mDatas.add("蓝猫");
mDatas.add("淘气");
mDatas.add("叶峰");
mDatas.add("楚天歌");
mDatas.add("江流儿");
mDatas.add("Tom");
mDatas.add("Jerry");
mDatas.add("12345");
mDatas.add("54321");
mDatas.add("_(:з」∠)_");
mDatas.add("……%¥#¥%#");
}
}
拓展: 同样,我们也可以自定义分割线的样式。
在drawable目录下自定义样式divider_item.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<size android:height="2dp"/>
<gradient android:startColor="#00FF00"
android:centerColor="#FFFF00"
android:endColor="#FF0000"
android:type="linear"/>
</shape>
在values目录的styles.xml文件中引用自定义的分割线样式
<resources>
<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
<item name="colorPrimary">@color/colorPrimary</item>
<item name="colorPrimaryDark">@color/colorPrimaryDark</item>
<item name="colorAccent">@color/colorAccent</item>
<item name="android:listDivider">@drawable/divider_item</item>
</style>
</resources>
item name=”android:listDivider”>@drawable/divider_item
就这样我们完成了RecyclerView分割线的定义,我们可以自定义我们分割线的样式,让分割线更加绚丽多彩。
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