自定义PopWindow

package com.example.custompopdemo;

import android.app.Activity;
import android.content.Context;
import android.graphics.drawable.ColorDrawable;
import android.util.DisplayMetrics;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.PopupWindow;

/**
 * Created by 袁磊 on 2017/3/11.
 */
public class MyPopWindow extends PopupWindow {
    private View contentView;

    public MyPopWindow(Activity activity) {
        //获得LayoutInfalter实例
        LayoutInflater inflater = (LayoutInflater) activity
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        contentView = inflater.inflate(R.layout.pop_layout, null);
        /**
         * 获取屏幕的宽高
         */
        DisplayMetrics dm = new DisplayMetrics();
        activity.getWindowManager().getDefaultDisplay().getMetrics(dm);
        int w = dm.widthPixels;
        int h = dm.heightPixels;

        this.setContentView(contentView);//设置Pop的View
        this.setWidth(w / 2 + 50);//设置Pop的宽
        this.setHeight(ViewGroup.LayoutParams.WRAP_CONTENT);//设置Pop的高
        this.setFocusable(true);//设置Pop可点击
        this.setOutsideTouchable(true);
        this.update();//刷新状态
        ColorDrawable dw = new ColorDrawable(0000000000); //实例化一个ColorDrawable颜色为半透明
        // 点back键和其他地方使其消失,设置了这个才能触发OnDismisslistener ，设置其他控件变化等操作
        this.setBackgroundDrawable(dw);
        this.setAnimationStyle(R.style.AnimationPreview);//设置Pop动画效果
        LinearLayout first = (LinearLayout) contentView.findViewById(R.id.lin_first);
        LinearLayout second = (LinearLayout) contentView.findViewById(R.id.lin_second);

        first.setOnClickListener(my);
        second.setOnClickListener(my);
    }

    private View.OnClickListener my = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //通过自定义接口将回调方法公布出去
            if (popOnclickListener != null) {
                popOnclickListener.onClick(v);
            }
        }
    };

    /**
     * 显示Pop
     *
     * @param parent
     */
    public void showPopupWindow(View parent) {
        if (!this.isShowing()) {
            //以下拉方式显示Pop
            /**
             * showAsDropDown 的对齐方式是v控件的左下角与popupWindow的控件左上角对齐
             * 而popupWindow不会超出屏幕，所以显示效果是紧贴右边框
             * 先除去控件的宽度，这样popupWindow的控件右上角和v控件的左下角是对齐的，
             * 然后在设置偏移量就可以正常显示了
             * 此方法亦适用于右下角弹出
             */
            this.showAsDropDown(parent, -this.getWidth() + parent.getWidth() - 20, 0);
        } else {
            this.dismiss();
        }
    }

    /**
     * 自定义接口
     * 复制源代码中的三个抽象方法
     */
    public interface PopOnclickListener {
        void onClick(View v);
    }

    private PopOnclickListener popOnclickListener;

    public void setPopOnclickListener(PopOnclickListener popOnclickListener) {
        this.popOnclickListener = popOnclickListener;
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#55000000"
    android:orientation="vertical">


    <LinearLayout
        android:id="@+id/lin_first"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center_vertical"
        android:orientation="horizontal">

        <ImageView
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_marginRight="10dp"
            android:src="@mipmap/ic_launcher" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="第一个项"
            android:textColor="#000000"
            android:textSize="18sp" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/lin_second"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center_vertical"
        android:orientation="horizontal">

        <ImageView
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_marginRight="10dp"
            android:src="@mipmap/ic_launcher" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="第二个项"
            android:textColor="#000000"
            android:textSize="18sp" />
    </LinearLayout>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<scale xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="200"
    android:fromXScale="0.001"
    android:fromYScale="0.001"
    android:interpolator="@android:anim/accelerate_decelerate_interpolator"
    android:pivotX="100%"
    android:pivotY="10%"
    android:toXScale="1.0"
    android:toYScale="1.0" />

<?xml version="1.0" encoding="utf-8"?>
<scale xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="200"
    android:fromXScale="1.0"
    android:fromYScale="1.0"
    android:interpolator="@android:anim/accelerate_decelerate_interpolator"
    android:pivotX="100%"
    android:pivotY="10%"
    android:toXScale="0.001"
    android:toYScale="0.001" />

package com.example.custompopdemo;

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

public class MainActivity extends AppCompatActivity {


    private RelativeLayout relTop;
    private ImageView ivPlus;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ivPlus = (ImageView) findViewById(R.id.iv_plus);
        relTop = (RelativeLayout) findViewById(R.id.rel_top);

        ivPlus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                MyPopWindow pop = new MyPopWindow(MainActivity.this);
                pop.showPopupWindow(ivPlus);
                pop.setPopOnclickListener(new MyPopWindow.PopOnclickListener() {
                    @Override
                    public void onClick(View v) {
                        switch (v.getId()) {
                            case R.id.lin_first:
                                Toast.makeText(MainActivity.this, "第一个选项", Toast.LENGTH_SHORT).show();
                                break;
                            case R.id.lin_second:
                                Toast.makeText(MainActivity.this, "第二个选项", Toast.LENGTH_SHORT).show();
                                break;
                        }
                    }
                });
            }
        });

    }
}

<?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="match_parent">

    <RelativeLayout
        android:id="@+id/rel_top"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#33000000">

        <ImageView
            android:id="@+id/iv_plus"
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:layout_alignParentRight="true"
            android:padding="8dp"
            android:src="@mipmap/plus" />
    </RelativeLayout>
</RelativeLayout>