java - 应用强制关闭 - OutOfMemoryError

Question

我一直在尝试测量麦克风在我的设备后台运行时使用的电池电量，所以我编写了一个小应用程序来测试它。

在我手机的外部存储设备上，我有一个 600mb 的 PCM 文件记录，该记录是使用该应用程序创建的，还有另一个 100mb 的文件。

当我运行应用程序并尝试播放 100mb 文件时，它工作正常。然而，当我尝试播放更大的 600mb 时，它在代码行上崩溃了:

InputStream is = new FileInputStream(file);

并且 logcat 给出了错误:

`11-03 16:31:03.654  16916-16916/com.bacon.corey.audiotimeshift I/art﹕ Alloc sticky concurrent mark sweep GC freed 6307(421KB) AllocSpace objects, 1(12KB) LOS objects, 33% free, 15MB/23MB, paused 678us total 14.444ms
11-03 16:31:03.663  16916-16916/com.bacon.corey.audiotimeshift I/art﹕ Alloc partial concurrent mark sweep GC freed 213(22KB) AllocSpace objects, 0(0B) LOS objects, 40% free, 15MB/26MB, paused 659us total 7.132ms
11-03 16:31:03.679  16916-16916/com.bacon.corey.audiotimeshift I/art﹕ Alloc concurrent mark sweep GC freed 15(12KB) AllocSpace objects, 0(0B) LOS objects, 40% free, 15MB/26MB, paused 830us total 14.191ms
11-03 16:31:03.681  16916-16916/com.bacon.corey.audiotimeshift I/art﹕ Forcing collection of SoftReferences for 641MB allocation
11-03 16:31:03.695  16916-16916/com.bacon.corey.audiotimeshift I/art﹕ Alloc concurrent mark sweep GC freed 11(344B) AllocSpace objects, 0(0B) LOS objects, 39% free, 15MB/26MB, paused 645us total 13.989ms
11-03 16:31:03.700  16916-16916/com.bacon.corey.audiotimeshift E/art﹕ Throwing OutOfMemoryError "Failed to allocate a 672164876 byte allocation with 11094652 free bytes and 176MB until OOM"
11-03 16:31:03.703  16916-16916/com.bacon.corey.audiotimeshift D/AndroidRuntime﹕ Shutting down VM
11-03 16:31:03.713  16916-16916/com.bacon.corey.audiotimeshift E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.bacon.corey.audiotimeshift, PID: 16916
    java.lang.IllegalStateException: Could not execute method of the activity
            at android.view.View$1.onClick(View.java:4007)
            at android.view.View.performClick(View.java:4756)
            at android.view.View$PerformClick.run(View.java:19749)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: java.lang.reflect.InvocationTargetException
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at android.view.View$1.onClick(View.java:4002)
            at android.view.View.performClick(View.java:4756)
            at android.view.View$PerformClick.run(View.java:19749)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: java.lang.OutOfMemoryError: Failed to allocate a 672164876 byte allocation with 11094652 free bytes and 176MB until OOM
            at com.bacon.corey.audiotimeshift.MainActivity.play(MainActivity.java:87)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at android.view.View$1.onClick(View.java:4002)
            at android.view.View.performClick(View.java:4756)
            at android.view.View$PerformClick.run(View.java:19749)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)`

我没有用 android 做过很多文件 IO 的事情，所以我不太确定我在这里做错了什么。如果有人不介意指出我哪里出错了，我将不胜感激。

类的代码如下。

提前致谢科里:)

        public void play(View view) {
        Toast.makeText(this, "play", Toast.LENGTH_SHORT).show();

// Get the file we want to playback.
        File file = new File(Environment.getExternalStorageDirectory() + File.separator + "ACS.pcm");
// Get the length of the audio stored in the file (16 bit so 2 bytes per short)
// and create a short array to store the recorded audio.
        int musicLength = (int)(file.length()/2);
        short[] music = new short[musicLength];


        try {
// Create a DataInputStream to read the audio data back from the saved file.
            InputStream is = new FileInputStream(file);
            BufferedInputStream bis = new BufferedInputStream(is);
            DataInputStream dis = new DataInputStream(bis);

// Read the file into the music array.
            int i = 0;
            while (dis.available() > 0) {
                music[musicLength-1-i] = dis.readShort();
                i++;
            }


// Close the input streams.
            dis.close();


// Create a new AudioTrack object using the same parameters as the AudioRecord
// object used to create the file.
            AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
                    44100,
                    AudioFormat.CHANNEL_OUT_MONO,
                    AudioFormat.ENCODING_PCM_16BIT,
                    musicLength,
                    AudioTrack.MODE_STREAM);
// Start playback
            audioTrack.play();

// Write the music buffer to the AudioTrack object
            audioTrack.write(music, 0, musicLength);


        } catch (Throwable t) {
            Log.e("AudioTrack","Playback Failed");
        }
    }

Answer 1

看起来您正在将整个音频文件加载到内存中，然后再尝试对其进行任何操作。这是一个糟糕的方法，因为您的文件看起来像 672164876 字节 (641MB)，而且我猜这比您允许在最多有 1-总共 2GB 的 RAM 可在所有正在运行的应用程序(加上 Android 操作系统本身)之间共享。

虽然您尝试在如此低的级别上执行此操作(读取所有字节并将它们直接写入将播放它们的内容)有点棒，但我建议您查看内置的 Android 媒体 API，例如MediaPlayer解释 in this other StackOverflow post或一些更高级别的库，其中任何一个都应该处理将文件流式传输到内存并播放它的所有细节，因此您不必这样做。