Android:使用 WebView 播放资产声音 [英] Android: Playing an Asset Sound Using WebView

问题描述

当用户单击我的应用程序的 WebView 上的标签时，我试图从资产文件夹播放声音.我发现我可以使用一个扩展 WebViewClient 的新类来检测链接的扩展名，如果它是一个 mp3 文件，它可以通过默认的音频播放器播放它.但我希望它在不启动新活动的情况下在活动中播放.

I am trying to play a sound from the assets folder when a user clicks on an tag on my application's WebView. I found that I can use a new class extending WebViewClient to detect the extension of a link and if it is an mp3 file it can play it via the default Audio Player. But I want it to play within the activity without starting a new activity.

我使用以下链接作为参考:Webview 中的声音和 使用 Uri 或资产中的文件创建 MediaPlayer 时出错

I used the following links as references: Sound in Webview and Error creating MediaPlayer with Uri or file in assets

但是没有用.

我尝试使用以下代码来做到这一点:

I tried using the following codes to do so:

package com.rangga.test.webview.sound;

import android.content.Intent;
import android.content.res.AssetFileDescriptor;
import android.media.MediaPlayer;
import android.net.Uri;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MyWebViewClient extends WebViewClient{

    public MediaPlayer mp;

    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url){
        if(url.endsWith(".mp3")){
            mp = new MediaPlayer();
            AssetFileDescriptor afd = getAssets().openFd(url);
            mp.setDataSource(afd.getFileDescriptor());
            mp.start();

            return true;
        }else{
            return true;
        }


    }

}

我在 getAssets() 上遇到了一个未定义的方法错误，我尝试在 Google 上搜索它，它说明了有关传递上下文的信息.我对 Android 和面向对象编程非常陌生，所以我想知道这是否是正确的方法，以及是否有关于 Context 是什么的简单解释.谢谢.

I get an undefined method error on the getAssets(), I tried Googleing it and it says something about passing a Context. I am very new to Android and Object Oriented programming, so I am wondering if this the right way to do it and if there is a simple explanation on what a Context is. Thank you.

以下是我的完整代码:

MainActivity.class

MainActivity.class

package com.rangga.test.webview.sound;

import android.app.Activity;
import android.os.Bundle;
import android.webkit.WebView;

public class MainActivity extends Activity {

    WebView webMain;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        webMain = (WebView) findViewById(R.id.webMain);

        webMain.loadUrl("file:///android_asset/webpages/test.html");
        webMain.setWebViewClient(new MyWebViewClient());
    }


}

编辑

由于 https://stackoverflow.com/users/488241/squonk，代码才有效，但现在又出现了另一个问题发生时，我将 MyWebViewClient 更新为以下内容:

So the codes works thanks to https://stackoverflow.com/users/488241/squonk but now another problem occurs, I updated the MyWebViewClient into the following:

package com.rangga.test.webview.sound;

import java.io.IOException;

import android.content.Context;
import android.content.res.AssetFileDescriptor;
import android.media.MediaPlayer;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MyWebViewClient extends WebViewClient{

    public MediaPlayer mp;
    private Context context = null;

    public MyWebViewClient(Context c){
        this.context = c;
    }

    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url){
        if(url.endsWith(".mp3")){

            mp = new MediaPlayer();
            try {
                AssetFileDescriptor afd = context.getAssets().openFd(url);
                mp.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
                afd.close();
                mp.prepare();
                mp.start();
            } catch (IllegalArgumentException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }


            return true;
        }else{
            return true;
        }   
    }
}

但是我得到一个 java.io.FileNotFoundException，虽然路径似乎是正确的.我已经将 2 个 mp3 文件放在 assets/webpages/sounds/1.mp3 和 assets/webpages/1.mp3 中，并使用以下 html 代码对其进行测试:

But I get a java.io.FileNotFoundException, the path seems right though. I've put 2 mp3 files in assets/webpages/sounds/1.mp3 and assets/webpages/1.mp3 and used the following html codes to test it:

<html>
    <head>
        <title>Test Audio</title>
    </head>
    <body>
        <a href="file:///android_asset/webpages/sounds/1.mp3">File Asset</a><br/>
        <a href="1.mp3">Same Folder</a>
    </body>
</html>

但我在 LogCat 上收到以下错误:

But I get the following error on LogCat:

06-11 06:20:37.955: W/System.err(377): java.io.FileNotFoundException: file:///android_asset/webpages/1.mp3
06-11 06:20:37.966: W/System.err(377):  at android.content.res.AssetManager.openAssetFd(Native Method)
06-11 06:20:37.974: W/System.err(377):  at android.content.res.AssetManager.openFd(AssetManager.java:314)
06-11 06:20:37.974: W/System.err(377):  at com.rangga.test.webview.sound.MyWebViewClient.shouldOverrideUrlLoading(MyWebViewClient.java:30)
06-11 06:20:37.985: W/System.err(377):  at android.webkit.CallbackProxy.uiOverrideUrlLoading(CallbackProxy.java:193)
06-11 06:20:38.000: W/System.err(377):  at android.webkit.CallbackProxy.handleMessage(CallbackProxy.java:304)
06-11 06:20:38.005: W/System.err(377):  at android.os.Handler.dispatchMessage(Handler.java:99)
06-11 06:20:38.005: W/System.err(377):  at android.os.Looper.loop(Looper.java:123)
06-11 06:20:38.014: W/System.err(377):  at android.app.ActivityThread.main(ActivityThread.java:4363)
06-11 06:20:38.014: W/System.err(377):  at java.lang.reflect.Method.invokeNative(Native Method)
06-11 06:20:38.024: W/System.err(377):  at java.lang.reflect.Method.invoke(Method.java:521)
06-11 06:20:38.024: W/System.err(377):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
06-11 06:20:38.024: W/System.err(377):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
06-11 06:20:38.054: W/System.err(377):  at dalvik.system.NativeStart.main(Native Method)

我调用文件的方式有问题吗?先谢谢了.

Is there something wrong with the way I called the file? Thanks before.

已解决

感谢squonk的建议，我尝试了以下代码使其工作并且运行良好，谢谢squonk！

Thx to squonk's suggestions, I tried the following codes to make it work and it worked well, thank you squonk!

package com.rangga.test.webview.sound;

import java.io.IOException;

import android.content.Context;
import android.content.res.AssetFileDescriptor;
import android.media.MediaPlayer;
import android.util.Log;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MyWebViewClient extends WebViewClient{

    public MediaPlayer mp;
    private Context context = null;

    public MyWebViewClient(Context c){
        this.context = c;
        mp = new MediaPlayer();
    }

    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url){
        if(url.endsWith(".mp3")){
            url = url.replace("file:///android_asset/webpages/", "");
            Log.i("MyWebViewClient", url);
            try {
                AssetFileDescriptor afd = context.getAssets().openFd(url);
                mp = new MediaPlayer();
                mp.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
                afd.close();
                mp.prepare();
                mp.start();
            } catch (IllegalArgumentException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }


            return true;
        }else{
            return true;
        }   
    }
}

和测试它的html:

<html>
    <head>
        <title>Test Audio</title>
    </head>
    <body>
        <a href="webpages/1.mp3">File Asset</a><br/>
    </body>
</html>

虽然如果我反复点击它确实会出错，但这是另一个问题:D如何结束一个人的问题?>.<

Though I did get an error if I repeatedly click it, but that's another question :D How does one close one's question? >.<

推荐答案

在 MyWebViewClient 中声明 MediaPLayer 的地方，添加以下内容...

Where you declare your MediaPLayer in MyWebViewClient, add the following...

public class MyWebViewClient extends WebViewClient{

    public MediaPlayer mp;
    private Context context = null; // Add this line

    ...
}

然后在MyWebViewClient中添加一个构造函数，如下...

Then add a constructor to MyWebViewClient as follows...

public MyWebViewClient(Context context) {
    this.context = context;
}

然后在 shouldOverrideUrlLoading(...) 中获取您的资产如下...

Then in shouldOverrideUrlLoading(...) get your assets as follows...

AssetFileDescriptor afd = context.getAssets().openFd(url);

在您的 MainActivity 中，通过传递 this(即 Activity Context)来设置 WebViewClient，如下所示...

In your MainActivity set the WebViewClient by passing this (which is the Activity Context) as follows...

webMain.setWebViewClient(new MyWebViewClient(this));

如果 url 以.mp3"结尾，你也应该从 shouldOverrideUrlLoading(...) 返回 false - 这会显示你的 WebView正在处理事情，主机"应用程序不应启动股票网络浏览器的实例.

Also you should return false from shouldOverrideUrlLoading(...) if the url ends with '.mp3' - this shows your WebView is handling things and the 'host' application should not start an instance of the stock web browser.

要播放资产目录中的音频文件，您需要以不同方式设置数据源 - 请参阅播放音频文件来自资产目录.

To play audio files from the assets directory, you need to set the data source differently - see the accepted answer to play-audio-file-from-the-assets-directory.

你也应该在调用 mp.start() 之前调用 mp.prepare().

Also you should call mp.prepare() before calling mp.start().

这篇关于Android:使用 WebView 播放资产声音的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！