【例3-5】录音示例

    使用MediaRecorder录音，输出AMR格式文件，AMR格式多用于人声，适合通话录音。

教学视频

布局文件activity_recorder.xml的源代码

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

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:app="http://schemas.android.com/apk/res-auto"

    android:layout_width="match_parent"

    android:layout_height="match_parent">

    <TextView

        android:id="@+id/txt"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="录音示例"

        android:textSize="24sp"

        app:layout_constraintLeft_toLeftOf="parent"

        app:layout_constraintRight_toRightOf="parent"

        app:layout_constraintTop_toTopOf="parent"

        android:layout_marginTop="80dp" />

    <Button

        android:id="@+id/button1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_marginTop="33dp"

        android:text="开始录音"

        android:textSize="18sp"

        app:layout_constraintLeft_toLeftOf="parent"

        app:layout_constraintRight_toRightOf="parent"

        app:layout_constraintTop_toBottomOf="@+id/txt" />

    <Button

        android:id="@+id/button2"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_marginTop="8dp"

        android:text="结束录音"

        android:textSize="18sp"

        app:layout_constraintBottom_toBottomOf="parent"

        app:layout_constraintLeft_toLeftOf="parent"

        app:layout_constraintRight_toRightOf="parent"

        app:layout_constraintTop_toBottomOf="@+id/button1"

        app:layout_constraintVertical_bias="0.022" />

</android.support.constraint.ConstraintLayout>

控制文件RecorderActivity.java源代码

package com.example.chap03;

import android.Manifest;

import android.app.Activity;

import android.content.pm.PackageManager;

import android.media.MediaRecorder;

import android.os.Bundle;

import android.os.Environment;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import androidx.core.app.ActivityCompat;

//录音程序只能在手机（不是虚拟机）上运行

public class RecorderActivity extends Activity

{

    MediaRecorder mRecorder;

    Button startBtn, stopBtn;

    String path;

    // Storage Permissions

    private static final int REQUEST_EXTERNAL_STORAGE = 1;

    private static String[] PERMISSIONS_STORAGE = {

            Manifest.permission.READ_EXTERNAL_STORAGE,

            Manifest.permission.WRITE_EXTERNAL_STORAGE

    };

    public static void verifyStoragePermissions(Activity activity) {

        // Check if we have write permission

        int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);

        if (permission != PackageManager.PERMISSION_GRANTED) {

            // We don't have permission so prompt the user

            ActivityCompat.requestPermissions(

                    activity,

                    PERMISSIONS_STORAGE,

                    REQUEST_EXTERNAL_STORAGE

            );

        }

    }

    @Override

    public void onCreate(Bundle savedInstanceState)

    {

        super.onCreate(savedInstanceState);

        verifyStoragePermissions(this);

        setContentView(R.layout.activity_recorder);

        path= Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)+"/audio.amr";

        startBtn = (Button)findViewById(R.id.button1);

        stopBtn = (Button)findViewById(R.id.button2);

        startBtn.setOnClickListener(new mClick());

        stopBtn.setOnClickListener(new mClick());

    }

    class mClick implements OnClickListener

    {

        @Override

        public void onClick(View v)

        {

            if(v == startBtn)

                startRecordAudio(path);

            else if(v == stopBtn)

                stopRecord();

        }

    }

    void startRecordAudio(String path)

    {

        mRecorder=new MediaRecorder();

        mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);

        mRecorder.setOutputFormat(

                MediaRecorder.OutputFormat.THREE_GPP);

        mRecorder.setAudioEncoder(

                MediaRecorder.AudioEncoder.AMR_NB);

        mRecorder.setOutputFile(path);

        try {

            mRecorder.prepare();

        }catch (Exception e) {

            System.out.println("Recorder error ");

        }

        mRecorder.start();

    }

    void stopRecord()

    {

        mRecorder.stop();   //停止录制

        mRecorder.reset();  //重置

        mRecorder.release();//释放播放器有关资源

    }

}

打开项目配置文件AndroidManifest.xml，配置启动的Activity类名

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

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.chap03">

    <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=".RecorderActivity ">

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

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

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

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

</manifest>

本案例在华为手机上做了测试，测试情况如下：

本案例在华为手机上做了测试。手机连接计算机后，测试步骤如下图1-图7：

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