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Android RecyclerView的使用（二）——添加分割线

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：

Android RecyclerView的使用（二）——添加分割线

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 % ]);
    }

    @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();
        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 = ; 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 = ; 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(, , , mDivider.getIntrinsicHeight());
        } else {
            outRect.set(, , mDivider.getIntrinsicWidth(), );
        }
    }

}

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。

android 布局 分割线 recyclerview
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