什么是PopupWindow？

话不多说，直接上图吧！

Screenshot_20190602232830668_com.netease.cl_.png

TIM图片20190602232703.jpg

TIM图片20190602232711.jpg

PopupWindow有什么用？

常用的地方在上面图片里啦，讲这个是因为我想在喜马拉雅实战项目里使用这个玩意，你觉得怎么样呢？

PopupWindow怎么用？

怎么使用呢？来，看代码！

第一步是创建吧！直接new，那么我们看构造方法：

常用的

无参构造方法

/**
     * <p>Create a new empty, non focusable popup window of dimension (0,0).</p>
     *
     * <p>The popup does not provide any background. This should be handled
     * by the content view.</p>
     */
    public PopupWindow() {
        this(null, 0, 0);
    }

要显示的内容作为参数的构造方法

  /**
     * <p>Create a new non focusable popup window which can display the
     * <tt>contentView</tt>. The dimension of the window are (0,0).</p>
     *
     * <p>The popup does not provide any background. This should be handled
     * by the content view.</p>
     *
     * @param contentView the popup's content
     */
    public PopupWindow(View contentView) {
        this(contentView, 0, 0);
    }

高度和宽度作为参数的构造方法

  /**
     * <p>Create a new empty, non focusable popup window. The dimension of the
     * window must be passed to this constructor.</p>
     *
     * <p>The popup does not provide any background. This should be handled
     * by the content view.</p>
     *
     * @param width the popup's width
     * @param height the popup's height
     */
    public PopupWindow(int width, int height) {
        this(null, width, height);
    }

内容和高度作为参数的构造方法

/**
     * <p>Create a new non focusable popup window which can display the
     * <tt>contentView</tt>. The dimension of the window must be passed to
     * this constructor.</p>
     *
     * <p>The popup does not provide any background. This should be handled
     * by the content view.</p>
     *
     * @param contentView the popup's content
     * @param width the popup's width
     * @param height the popup's height
     */
    public PopupWindow(View contentView, int width, int height) {
        this(contentView, width, height, false);
    }

其他的大家去看了。内容、高度、宽度这些都有提供getter和setter方法去获取和设置对应的值。

创建好，我们要设置内容吧！

如果在构造方法里设置了，那么就不用调用setContentView()来设置了！

比如说，我这样写：

package com.sunofbeaches.popwindowdemo;

import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.PopupWindow;

public class MainActivity extends AppCompatActivity {

    private PopupWindow mPopupWindow;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //创建pop
        mPopupWindow = new PopupWindow(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        //设置backgroud为透明的
        mPopupWindow.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
        //设置点击pop以外的地方让pop小时，不设置上面这个无效
        mPopupWindow.setOutsideTouchable(true);
        //载pop的界面
        View popView = LayoutInflater.from(this).inflate(R.layout.pop_view, null);
        //设置界面
        mPopupWindow.setContentView(popView);
    }


    public void showPop(View view) {
        if (!mPopupWindow.isShowing()) {
            //显示在这个控件的下方
            mPopupWindow.showAsDropDown(view);
        }
    }
}

布局代码：

就一个按钮而已，添加一个点击事件

弹出的pop布局内容如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="https://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="200dp"
    android:gravity="center"
    android:background="@drawable/shape_rectangle"
    android:layout_height="200dp">

    <TextView
        android:textColor="#ffffff"
        android:textSize="20sp"
        android:layout_width="wrap_content"
        android:text="弹出的内容..."
        android:layout_height="wrap_content" />

</LinearLayout>

看一下运行效果吧：

如果我要展示在上面怎么办呢？

那就得看它展示的方法参数了：

 /**
     * Display the content view in a popup window anchored to the bottom-left
     * corner of the anchor view. If there is not enough room on screen to show
     * the popup in its entirety, this method tries to find a parent scroll
     * view to scroll. If no parent scroll view can be scrolled, the
     * bottom-left corner of the popup is pinned at the top left corner of the
     * anchor view.
     *
     * @param anchor the view on which to pin the popup window
     *
     * @see #dismiss()
     */
    public void showAsDropDown(View anchor) {
        showAsDropDown(anchor, 0, 0);
    }

展示在anchor的下方，anchor就是参考的view

 /**
     * Display the content view in a popup window anchored to the bottom-left
     * corner of the anchor view offset by the specified x and y coordinates.
     * If there is not enough room on screen to show the popup in its entirety,
     * this method tries to find a parent scroll view to scroll. If no parent
     * scroll view can be scrolled, the bottom-left corner of the popup is
     * pinned at the top left corner of the anchor view.
     * <p>
     * If the view later scrolls to move <code>anchor</code> to a different
     * location, the popup will be moved correspondingly.
     *
     * @param anchor the view on which to pin the popup window
     * @param xoff A horizontal offset from the anchor in pixels
     * @param yoff A vertical offset from the anchor in pixels
     *
     * @see #dismiss()
     */
    public void showAsDropDown(View anchor, int xoff, int yoff) {
        showAsDropDown(anchor, xoff, yoff, DEFAULT_ANCHORED_GRAVITY);
    }

第一个参数是参考的view，第二第三个参数是x方向和y方向上的偏移量。

 /**
     * Displays the content view in a popup window anchored to the corner of
     * another view. The window is positioned according to the specified
     * gravity and offset by the specified x and y coordinates.
     * <p>
     * If there is not enough room on screen to show the popup in its entirety,
     * this method tries to find a parent scroll view to scroll. If no parent
     * view can be scrolled, the specified vertical gravity will be ignored and
     * the popup will anchor itself such that it is visible.
     * <p>
     * If the view later scrolls to move <code>anchor</code> to a different
     * location, the popup will be moved correspondingly.
     *
     * @param anchor the view on which to pin the popup window
     * @param xoff A horizontal offset from the anchor in pixels
     * @param yoff A vertical offset from the anchor in pixels
     * @param gravity Alignment of the popup relative to the anchor
     *
     * @see #dismiss()
     */
    public void showAsDropDown(View anchor, int xoff, int yoff, int gravity)

最后一个参数是摆放方式，比如说在顶Gravity.TOP

比如说在左边，在右边，在底部…

还有一个这玩意，

 /**
     * <p>
     * Display the content view in a popup window at the specified location. If the popup window
     * cannot fit on screen, it will be clipped. See {@link android.view.WindowManager.LayoutParams}
     * for more information on how gravity and the x and y parameters are related. Specifying
     * a gravity of {@link android.view.Gravity#NO_GRAVITY} is similar to specifying
     * <code>Gravity.LEFT | Gravity.TOP</code>.
     * </p>
     *
     * @param parent a parent view to get the {@link android.view.View#getWindowToken()} token from
     * @param gravity the gravity which controls the placement of the popup window
     * @param x the popup's x location offset
     * @param y the popup's y location offset
     */
    public void showAtLocation(View parent, int gravity, int x, int y) {
        mParentRootView = new WeakReference<>(parent.getRootView());
        showAtLocation(parent.getWindowToken(), gravity, x, y);
    }

这个方法的参考是全屏幕呢，所以这里的y值基本上不使用。我们实现音乐的列表，使用这种方式即可，比如说：

遇到问题就去看源码吧，这个还是比较简单的！

安卓PopupWindow的使用