Android MediaRecorder 不工作并在 stop() 方法上崩溃

Question

我正在学习 android 开发并且我正在使用 MediaRecorder class 来录制音频。 logcat 表示应用程序在 stop() 方法中崩溃并抛出 IllegalStateException。我不明白为什么它会崩溃，我在开始之前调用了方法停止。

public class MainActivity extends AppCompatActivity {

private MediaRecorder grabacion;
private String archivoSalida = null;
private Button btn_recorder;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btn_recorder = (Button)findViewById(R.id.btn_rec);

    if (ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.RECORD_AUDIO) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.RECORD_AUDIO,}, 1000);
    }
}

public void Recorder(View view){
    if(grabacion == null){
        archivoSalida = Environment.getExternalStorageDirectory().getAbsolutePath() + "/Grabacion.mp3";
        grabacion = new MediaRecorder();
        grabacion.setAudioSource(MediaRecorder.AudioSource.MIC);
        grabacion.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
        grabacion.setAudioEncoder(MediaRecorder.OutputFormat.AMR_NB);
        grabacion.setOutputFile(archivoSalida);

        try{
            grabacion.prepare();
            grabacion.start();
        } catch (IOException e){
        }

        btn_recorder.setBackgroundResource(R.drawable.rec);
        Toast.makeText(getApplicationContext(), "Grabando...", Toast.LENGTH_SHORT).show();
    } else if(grabacion != null){
        grabacion.stop();
        grabacion.release();
        grabacion = null;
        btn_recorder.setBackgroundResource(R.drawable.stop_rec);
        Toast.makeText(getApplicationContext(), "Grabación finalizada", Toast.LENGTH_SHORT).show();
    }
}

public void reproducir(View view) {

    MediaPlayer mediaPlayer = new MediaPlayer();
    try {
        mediaPlayer.setDataSource(archivoSalida);
        mediaPlayer.prepare();
    } catch (IOException e){
    }

    mediaPlayer.start();
    Toast.makeText(getApplicationContext(), "Reproduciendo audio", Toast.LENGTH_SHORT).show();
}}

这是清单文件：

<?xml version="1.0" encoding="utf-8"?>

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.RECORD_AUDIO"/>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

logcat 说的是：

E/MediaRecorder: stop called in an invalid state: 4
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.recorder, PID: 5386
    java.lang.IllegalStateException: Could not execute method for android:onClick
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:414)
        at android.view.View.performClick(View.java:7870)
        at android.widget.TextView.performClick(TextView.java:14970)
        at android.view.View.performClickInternal(View.java:7839)
        at android.view.View.access00(View.java:886)
        at android.view.View$PerformClick.run(View.java:29363)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:237)
        at android.app.ActivityThread.main(ActivityThread.java:7948)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075)
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409)
        at android.view.View.performClick(View.java:7870) 
        at android.widget.TextView.performClick(TextView.java:14970) 
        at android.view.View.performClickInternal(View.java:7839) 
        at android.view.View.access00(View.java:886) 
        at android.view.View$PerformClick.run(View.java:29363) 
        at android.os.Handler.handleCallback(Handler.java:883) 
        at android.os.Handler.dispatchMessage(Handler.java:100) 
        at android.os.Looper.loop(Looper.java:237) 
        at android.app.ActivityThread.main(ActivityThread.java:7948) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075) 
     Caused by: java.lang.IllegalStateException
        at android.media.MediaRecorder._stop(Native Method)
        at android.media.MediaRecorder.stop(MediaRecorder.java:1440)
        at com.example.recorder.MainActivity.Recorder(MainActivity.java:55)
        at java.lang.reflect.Method.invoke(Native Method) 
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409) 
        at android.view.View.performClick(View.java:7870) 
        at android.widget.TextView.performClick(TextView.java:14970) 
        at android.view.View.performClickInternal(View.java:7839) 
        at android.view.View.access00(View.java:886) 
        at android.view.View$PerformClick.run(View.java:29363) 
        at android.os.Handler.handleCallback(Handler.java:883) 
        at android.os.Handler.dispatchMessage(Handler.java:100) 
        at android.os.Looper.loop(Looper.java:237) 
        at android.app.ActivityThread.main(ActivityThread.java:7948) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075) 
I/Process: Sending signal. PID: 5386 SIG: 9

谢谢！

Answer 1

stop() 方法的 documentation 指出它将抛出 IllegalStateException

if it is called before start()

因为这似乎是唯一一次抛出此错误，所以这很可能也是您遇到的情况。

看看你的Recorder()方法。唯一一次调用 stop() 是当您的变量不为空时。这意味着您的实例已正确初始化。但是，由于抛出了异常，这意味着即使您的变量引用了 MediaRecorder 的实例，它也没有启动。

要找出原因，请查看应该启动 MediaRecorder:

的代码

    try {
        grabacion.prepare();
        grabacion.start();
    } catch (IOException e){
    }

虽然它被放置在 try-catch 结构中，但 catch 块实际上不包含任何代码，导致任何错误都被简单地忽略。因此，您遇到的问题是 grabacion.prepare(); 或 grabacion.start(); 未成功导致记录器无法启动的结果。

鉴于 start() 仅根据其 documentation 抛出 IllegalStateException，对 prepare() 的调用应该是问题的原因。这也符合我自己的经验，因为调用 prepare() 时可能会出错很多。根据 docs:

中的描述，这是它的作用

Prepares the recorder to begin capturing and encoding data. This method must be called after setting up the desired audio and video sources, encoders, file format, etc., but before start().

所以，如您所知，现在要确定我的确切原因并不容易。但是，我可能要补充的是，您使用了 Environment.getExternalStorageDirectory()，从 API 29 开始，它是 deprecated 来改善用户隐私。虽然这可能是您遇到的问题，但我无法完全确定。

要准确找出导致错误的原因，您应该使用 IOException 您在 try-catch 中遇到的问题。例如，您可以记录其堆栈跟踪以了解有关该问题的更多信息。

Android MediaRecorder 不工作并在 stop() 方法上崩溃

Android MediaRecorder is not working and crashes on stop() method

java

android

illegalstateexception

mediarecorder

android-mediarecorder