Android 拖拽操作demo

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记录一下Android 拖拽的小demo

官网（https://developer.android.com/guide/topics/ui/drag-drop.html）对拖拽的说明已经很详细了，可以在官网对它了解。

自己实现了一下将拖拽后的阴影改变成自定义的小图片，当拖拽时影藏了View。

直接上代码：

package com.example.myapplication;import android.app.Activity;import android.content.ClipData;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.drawable.Drawable;import android.os.Build;import android.os.Bundle;import android.support.annotation.Nullable;import android.support.annotation.RequiresApi;import android.util.Log;import android.view.DragEvent;import android.view.Gravity;import android.view.View;import android.view.ViewGroup;import android.widget.FrameLayout;import android.widget.TextView;/** * 拖拽操作 */public class TestDrogActivity extends Activity {    private static final String TAG = "TestDrogActivity";    @Override    protected void onCreate(@Nullable Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        FrameLayout container = new FrameLayout(this);        final TextView textView = new TextView(this);        textView.setBackgroundColor(Color.CYAN);        textView.setText("test drag");        textView.setTextSize(20);        FrameLayout.LayoutParams flk = new FrameLayout.LayoutParams(                ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);        flk.gravity = Gravity.CENTER;        container.addView(textView,flk);        textView.setOnLongClickListener(new View.OnLongClickListener() {            @RequiresApi(api = Build.VERSION_CODES.N)            @Override            public boolean onLongClick(View v) {                textView.startDragAndDrop(null,new MyDrogBuild(v),v,0);                return true;            }        });        textView.setOnDragListener(new View.OnDragListener() {            @Override            public boolean onDrag(View v, DragEvent event) {                int action = event.getAction();                switch (action){                    case DragEvent.ACTION_DRAG_STARTED:                        v.invalidate();                        Log.d(TAG,"ACTION_DRAG_STARTED...");                        return true;                    case DragEvent.ACTION_DROP:                        v.invalidate();                        Log.d(TAG,"ACTION_DROP...");                        return true;                    case DragEvent.ACTION_DRAG_ENDED:                        Log.d(TAG,"ACTION_DRAG_ENDED...");                        v.invalidate();                        return true;                    case DragEvent.ACTION_DRAG_ENTERED:                        Log.d(TAG,"ACTION_DRAG_ENTERED...");                        v.invalidate();                        return true;                    case DragEvent.ACTION_DRAG_EXITED:                        Log.d(TAG,"ACTION_DRAG_EXITED...");                        v.invalidate();                        return true;                    case DragEvent.ACTION_DRAG_LOCATION:                        Log.d(TAG,"ACTION_DRAG_LOCATION...");                        v.invalidate();                        return true;                }                return true;            }        });        setContentView(container,new ViewGroup.LayoutParams(                ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));    }    private class MyDrogBuild extends View.DragShadowBuilder{        public MyDrogBuild(View v){            super(v);        }        @Override        public void onDrawShadow(Canvas canvas) {            //当长安拖拽时，改变阴影view 为自定义小图片            Bitmap bitmap = BitmapFactory.decodeResource(                    TestDrogActivity.this.getResources(),R.mipmap.ic_launcher);            canvas.drawBitmap(bitmap,0,0,null);//            super.onDrawShadow(canvas);        }    }}

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