类似文章在CSDN上有很多，但是几经查找之后原文其实产于简书的一位作者；

综合几篇文章，在原有基础上我会尽可能全面总结一下

代码区

使用部分

MainActivity

package com.advance.yongliu.haulview;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        DragFloatActionButtonJava mBtn = findViewById(R.id.img_btn);
        mBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this,"点击了可拖拽按钮的点击事件",Toast.LENGTH_SHORT).show();
            }
        });
    }
}

MainActivity Xml

<?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"
    tools:context="com.advance.yongliu.haulview.MainActivity">

    <com.advance.yongliu.haulview.DragFloatActionButton
        android:id="@+id/img_btn"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:src="@mipmap/ic_launcher_round"
        />
</android.support.constraint.ConstraintLayout>

关于自定义的拖拽View (核心部分)

继承类(均可实现拖拽)

• 有的继承AppCompatImageView下的ImageView
• 有的继承FloatingActionButton

DragFloatActionButton

package com.advance.yongliu.haulview;

import android.animation.ObjectAnimator;
import android.annotation.SuppressLint;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ViewGroup;
import android.view.animation.DecelerateInterpolator;
import android.widget.ImageView;

/**
 * author  YongLiu
 * date  2019/2/22.
 * desc:
 */

@SuppressLint("AppCompatCustomView")
public class DragFloatActionButton extends ImageView {
    private int parentHeight;
    private int parentWidth;

    public DragFloatActionButtonJava(Context context) {
        super(context);
    }

    public DragFloatActionButtonJava(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public DragFloatActionButtonJava(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    private int lastX;
    private int lastY;

    private boolean isDrag;

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        int rawX = (int) event.getRawX();
        int rawY = (int) event.getRawY();
        switch (event.getAction() & MotionEvent.ACTION_MASK) {
            case MotionEvent.ACTION_DOWN:
                setPressed(true);
                isDrag = false;
                getParent().requestDisallowInterceptTouchEvent(true);
                lastX = rawX;
                lastY = rawY;
                ViewGroup parent;
                if (getParent() != null) {
                    parent = (ViewGroup) getParent();
                    parentHeight = parent.getHeight();
                    parentWidth = parent.getWidth();
                }
                break;
            case MotionEvent.ACTION_MOVE:
                if (parentHeight <= 0 || parentWidth == 0) {
                    isDrag = false;
                    break;
                } else {
                    isDrag = true;
                }
                int dx = rawX - lastX;
                int dy = rawY - lastY;
                //这里修复一些华为手机无法触发点击事件
                int distance = (int) Math.sqrt(dx * dx + dy * dy);
                if (distance == 0) {
                    isDrag = false;
                    break;
                }
                float x = getX() + dx;
                float y = getY() + dy;
                //检测是否到达边缘 左上右下
                x = x < 0 ? 0 : x > parentWidth - getWidth() ? parentWidth - getWidth() : x;
                y = getY() < 0 ? 0 : getY() + getHeight() > parentHeight ? parentHeight - getHeight() : y;
                setX(x);
                setY(y);
                lastX = rawX;
                lastY = rawY;
                Log.i("aa", "isDrag=" + isDrag + "getX=" + getX() + ";getY=" + getY() + ";parentWidth=" + parentWidth);
                break;
            case MotionEvent.ACTION_UP:
                if (!isNotDrag()) {
                    //恢复按压效果
                    setPressed(false);
                    if (rawX >= parentWidth / 2) {
                        //靠右吸附
                        animate().setInterpolator(new DecelerateInterpolator())
                                .setDuration(500)
                                .xBy(parentWidth - getWidth() - getX())
                                .start();
                    } else {
                        //靠左吸附
                        ObjectAnimator oa = ObjectAnimator.ofFloat(this, "x", getX(), 0);
                        oa.setInterpolator(new DecelerateInterpolator());
                        oa.setDuration(500);
                        oa.start();
                    }
                }
                break;
            default:
                break;
        }
        //如果是拖拽则消s耗事件，否则正常传递即可。
        return !isNotDrag() || super.onTouchEvent(event);
    }

    private boolean isNotDrag() {
        return !isDrag && (getX() == 0|| (getX() == parentWidth - getWidth()));
    }
}