//data：拖放操作要傳遞的數(shù)據(jù)
//shadowBuilder：拖放陰影
//myLocalState：一個(gè)包含與拖放操作有關(guān)的數(shù)據(jù)的對(duì)象
//flags：控制拖放操作的標(biāo)志位
public final boolean startDragAndDrop(ClipData data, DragShadowBuilder shadowBuilder,Object myLocalState, int flags)

//DragEvent.ACTION_DRAG_STARTED:表示拖動(dòng)已經(jīng)開始
//DragEvent.ACTION_DRAG_ENTERED:表示拖動(dòng)陰影已經(jīng)進(jìn)入目標(biāo)View
//DragEvent.ACTION_DRAG_LOCATION：拖動(dòng)陰影在目標(biāo)View邊界內(nèi)移動(dòng)時(shí)會(huì)多次響應(yīng)此事件
//DragEvent.ACTION_DRAG_EXITED：表示拖動(dòng)陰影離開了目標(biāo)View的邊界
//DragEvent.ACTION_DROP：表示拖動(dòng)陰影被釋放
//DragEvent.ACTION_DRAG_ENDED：表示拖放操作即將結(jié)束，在此處需要通過調(diào)用event.getResult()的返回值來判斷拖放操作是否成功

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/iv_drag"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_centerHorizontal="true"
        android:src="@mipmap/ic_launcher" />

    <LinearLayout
        android:id="@+id/ll_accept"
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="50dp"
        android:background="@drawable/black_bac"
        android:orientation="vertical">
    </LinearLayout>
</RelativeLayout>

iv_drag.setOnLongClickListener(new View.OnLongClickListener() {
    @Override
    public boolean onLongClick(View v) {
        CharSequence charSequence = (CharSequence) iv_drag.getTag();
        ClipData.Item item = new ClipData.Item(charSequence);
        ClipData clipData = new ClipData(charSequence, new String[]{ClipDescription.MIMETYPE_TEXT_PLAIN}, item);
        View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(iv_drag);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            iv_drag.startDragAndDrop(clipData, shadowBuilder, null, 0);
        } else {
            iv_drag.startDrag(clipData, shadowBuilder, null, 0);
        }
        return true;
    }
});   

ll_accept.setOnDragListener(new View.OnDragListener() {
    @Override
    public boolean onDrag(View v, DragEvent event) {
        switch (event.getAction()) {
            case DragEvent.ACTION_DRAG_STARTED:
                iv_drag.setVisibility(View.GONE);
                if (event.getClipDescription().hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN)) {
                    return true;
                }
                return false;

            case DragEvent.ACTION_DRAG_ENTERED:
                isChangePos = true;
                ll_accept.setBackgroundResource(R.drawable.green_bac);
                return true;

            case DragEvent.ACTION_DRAG_LOCATION:
                x = event.getX();
                y = event.getY();
                return true;

            case DragEvent.ACTION_DRAG_EXITED:
                isChangePos = false;
                ll_accept.setBackgroundResource(R.drawable.black_bac);
                return true;

            case DragEvent.ACTION_DROP:

                return true;

            case DragEvent.ACTION_DRAG_ENDED:
                ll_accept.setBackgroundResource(R.drawable.black_bac);
                if (isChangePos && event.getResult()) {
                    int left = ll_accept.getLeft();
                    int top = ll_accept.getTop();
                    x = x + left - (iv_drag.getWidth() / 2);
                    y = y + top - (iv_drag.getHeight() / 2);
                    iv_drag.setX(x);
                    iv_drag.setY(y);
                }
                iv_drag.setVisibility(View.VISIBLE);
                return true;
        }
        return false;
    }
});