Android Webview 后台播放音视频实现

Feb 9th, 2020

我们使用WebView播放音乐或视频（比如油管视频）
前台播放一直很正常，但是比较费电
进入后台后就会暂停播放
所以需求就是我们想要App在后台时同样播放音视频

重写onWindowVisibilityChanged方法，让网页任然感觉像是在前台执行。

override fun onWindowVisibilityChanged(visibility: Int) {
        super.onWindowVisibilityChanged(View.VISIBLE)

        Log.i("BackgroundMediaWebView", "onWindowVisibilityChanged " +
                "visibility=${toReadableVisibility(visibility)}")
    }

当App 进入后台（按Home键），visibility会变成Gone
我们强制调用super.onWindowVisibilityChanged(View.VISIBLE)会保持WebView继续播放音视频

package com.example.webviewvisibilitychangedsample

import android.content.Context
import android.util.AttributeSet
import android.util.Log
import android.view.View
import android.webkit.WebView

class BackgroundMediaWebView @JvmOverloads constructor(
    context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : WebView(context, attrs, defStyleAttr) {

    override fun onWindowVisibilityChanged(visibility: Int) {
        super.onWindowVisibilityChanged(View.VISIBLE)

        Log.i("BackgroundMediaWebView", "onWindowVisibilityChanged " +
                "visibility=${toReadableVisibility(visibility)}")
    }

    private fun toReadableVisibility(visibility: Int): String {
        return when(visibility) {
            View.VISIBLE -> "Visible"
            View.INVISIBLE -> "Invisible"
            View.GONE -> "Gone"
            else -> "Unknown"
        }
    }
}