RecycleView结合ItemTouchHelper实现拖动排序

最近项目中需要实现对某一类条目进行拖动排序功能，实现技术方案就是利用ItemTouchHelper绑定RecyclerView、ItemTouchHelper.Callback来实现UI更新，并且实现动态控制是否开启拖动功能。其中，ItemTouchHelper是Google在androidx包中添加的，其于RecyclerView配合可以比较容易地实现这个功能。

1、布局文件

a、activity的布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/cf5f5f5">
    <include layout="@layout/title_layout"/>
    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="@color/ce5e5e5"/>
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="@color/white">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/custom_order"
            android:textColor="@color/c333333"
            android:textSize="14sp"
            android:layout_centerVertical="true"
            android:layout_marginLeft="12dp"/>
        <ToggleButton
            android:id="@+id/toggleBtn"
            android:layout_width="48dp"
            android:layout_height="28dp"
            android:layout_centerVertical="true"
            android:layout_marginRight="12dp"
            android:background="@drawable/toggle_drawable_selector"
            android:button="@null"
            android:textOff=""
            android:textOn=""
            android:layout_alignParentRight="true"/>
    </RelativeLayout>
    <RelativeLayout
        android:id="@+id/tipLayout"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_marginTop="20dp">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/custom_order_tip1"
            android:textColor="@color/c808080"
            android:textSize="12sp"
            android:layout_centerVertical="true"
            android:layout_marginLeft="12dp"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/custom_order_tip2"
            android:textColor="@color/c808080"
            android:textSize="12sp"
            android:layout_centerVertical="true"
            android:layout_marginRight="12dp"
            android:layout_alignParentRight="true"/>
    </RelativeLayout>
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycleView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</LinearLayout>

b、RecycleView的listitem布局文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="50dp">
    <ImageView
        android:id="@+id/image"
        android:layout_width="24dp"
        android:layout_height="24dp"
        android:layout_alignParentLeft="true"
        android:layout_centerVertical="true"
        android:layout_marginLeft="12dp"
        android:src="@mipmap/icon_bank_others"/>
    <TextView
        android:id="@+id/cardTypeTxt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="xx借记卡"
        android:textColor="@color/c333333"
        android:textSize="14sp"
        android:layout_centerVertical="true"
        android:layout_marginLeft="12dp"
        android:layout_toRightOf="@id/image"/>
    <TextView
        android:id="@+id/cardNoTxt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="(8800)"
        android:textColor="@color/c808080"
        android:textSize="14sp"
        android:layout_centerVertical="true"
        android:layout_marginLeft="6dp"
        android:layout_toRightOf="@id/cardTypeTxt"/>
    <ImageView
        android:id="@+id/selectImage"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:scaleType="center"
        android:layout_alignParentRight="true"
        android:layout_centerVertical="true"
        android:src="@mipmap/sort_line"/>
</RelativeLayout>

2、实现ItemTouchHelper.Callback

private ItemTouchHelper.Callback callback = 
new ItemTouchHelper.Callback() {
            public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
                //首先回调的方法,返回int表示是否监听该方向
                int dragFlag = ItemTouchHelper.DOWN | ItemTouchHelper.UP;//拖拽
                int swipeFlag = 0;//侧滑删除
                return makeMovementFlags(dragFlag, swipeFlag);
            }

            @Override
            public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {

            }

            public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
                if (mAdapter != null) {
                    mAdapter.onMove(viewHolder.getAdapterPosition(), target.getAdapterPosition());
                }
                return true;
            }

            public void onSelectedChanged(ViewHolder viewHolder, int actionState) {
                if (actionState != 0) {
                    viewHolder.itemView.setAlpha(0.9f);
                }
                super.onSelectedChanged(viewHolder, actionState);
            }

            public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
                super.clearView(recyclerView, viewHolder);
                viewHolder.itemView.setAlpha(1.0f);
                if (mAdapter != null) {
                    mAdapter.notifyDataSetChanged();
                    mSortedList = mAdapter.getSortedDataList();
                    LogUtils.debug(TAG, "callback clearView: " + JSONObject.toJSONString(mSortedList));
                    refreshCardSort(mSortedList);
                }
            }
        };

3、初始化RecycleView，并绑定ItemTouchHelper

 mAdapter = new MyAdapter(mSortedList);
        recyclerView.setAdapter(mAdapter);
        LinearLayoutManager llm = new LinearLayoutManager(mContext, LinearLayoutManager.VERTICAL, false);
        recyclerView.setLayoutManager(llm);
	
	//这两句是关键，完成RecycleView和ItemTouchHelper的绑定
	ItemTouchHelper helper = new ItemTouchHelper(callback);
	helper.attachToRecyclerView(recyclerView);

4、定义自己的Adapter

private class MyAdapter extends RecyclerView.Adapter<ViewHolder> {
        private List<AccountInfo> mDataList;

        public MyAdapter (List<AccountInfo> dataList) {
            this.mDataList = dataList;
        }

        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            return new ViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.card_order_listitem, parent, false));
        }

        public void onBindViewHolder(ViewHolder holder, final int position) {
            final AccountInfo item = mDataList.get(position);
            if (item != null) {
                holder.tvContentType.setText(getCardNoType(item.getAccountType()));
                holder.tvContentNo.setText(getCardNo(item.getAccountNo()));
            }
        }

        public int getItemCount() {
            return mDataList.size();
        }

        public void onMove(int fromPosition, int toPosition) {
            //对原数据进行移动
            Collections.swap(mDataList, fromPosition, toPosition);
            //通知数据移动
            notifyItemMoved(fromPosition, toPosition);
            LogUtils.debug(TAG, "MyAdapter onMove fromPosition: " + fromPosition + ", toPosition: " + toPosition);
        }

        public List<AccountInfo> getSortedDataList() {
            return this.mDataList;
        }
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        public TextView tvContentType;
        public TextView tvContentNo;
        public ViewHolder(View view) {
            super(view);
            this.tvContentType = (TextView)view.findViewById(R.id.cardTypeTxt);
            this.tvContentNo = (TextView)view.findViewById(R.id.cardNoTxt);
        }
    }

其他参数定义：
 private List<AccountInfo> mSortedList;
 private MyAdapter mAdapter;


bean定义如下：
package com.qdone.qrcode.pay.qrcodesdkdemo.model;

/**
 * Time: 2024/1/26
 * Author:
 * Description:
 */
public class AccountInfo {

   private String accountId;

   private String custId;
   private String accountNo;
   private String accountType;

   private String bankName;
   private String displayOrder;
   /**
    * 是否是默认账户，0-普通账户 1-默认账户
    */
   private String defaultFlag;

   @Override
   public String toString() {
      return "AccountInfo{" +
              "accountId='" + accountId + '\'' +
              ", custId='" + custId + '\'' +
              ", accountNo='" + accountNo + '\'' +
              ", accountType='" + accountType + '\'' +
              ", bankName='" + bankName + '\'' +
              ", displayOrder='" + displayOrder + '\'' +
              ", defaultFlag='" + defaultFlag + '\'' +
              '}';
   }

   public String getAccountId() {
      return accountId;
   }

   public void setAccountId(String accountId) {
      this.accountId = accountId;
   }

   public String getCustId() {
      return custId;
   }

   public void setCustId(String custId) {
      this.custId = custId;
   }

   public String getAccountNo() {
      return accountNo;
   }

   public void setAccountNo(String accountNo) {
      this.accountNo = accountNo;
   }

   public String getAccountType() {
      return accountType;
   }

   public void setAccountType(String accountType) {
      this.accountType = accountType;
   }

   public String getBankName() {
      return bankName;
   }

   public void setBankName(String bankName) {
      this.bankName = bankName;
   }

   public String getDisplayOrder() {
      return displayOrder;
   }

   public void setDisplayOrder(String displayOrder) {
      this.displayOrder = displayOrder;
   }

   public String getDefaultFlag() {
      return defaultFlag;
   }

   public void setDefaultFlag(String defaultFlag) {
      this.defaultFlag = defaultFlag;
   }
}