前言

Android系统在实现录音以及录像的功能均是通过使用MediaRecorder实现的。本篇文章主要介绍如何借助MediaRecorder实现后台录音功能。

MediaRecoder

MediaRecoder主要方法介绍

• void prepar():准备录制
• void start():开始录制
• void stop():停止录制
• void reset():重置MediaRecorder
• void release():释放MediaRecorder占用的资源
• void setAudioEncoder(int)：设置音频记录的编码格式
• void setAudioSource(int)：设置音频记录的音频源
• void setOutoutFormat(int)：设置记录的媒体文件的输出转换格式
• void setOutputFile(String)：媒体文件输出路径

audiosource的来源设定

编码格式以及输出格式

编码格式

• ACC、ACC-ELD、AMR_NB、AMR_WB、DEFAULT、HE_AAC、OPUS、VORBIS

输出格式

• AAC_ADTS、AMR_NB、AMR_WB、DEFAULT、MPEG_2_TS、MPEG_4、OGG、THREE_GPP、WEBM

录音部分源码

开始录音

public void startRecord() {

        if (mMediaRecorder == null)
            mMediaRecorder = new MediaRecorder();
        try {

            mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);// 设置麦克风

            mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);

            mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);
            fileName = DateFormat.format("yyyyMMdd_HHmmss", Calendar.getInstance(Locale.CHINA)) + ".m4a";
            File destDir = new File(Environment.getExternalStorageDirectory()+"/test/");
            if (!destDir.exists()) {
                destDir.mkdirs();
            }
            filePath =  Environment.getExternalStorageDirectory()+"/test/"+ fileName;

            mMediaRecorder.setOutputFile(filePath);
            mMediaRecorder.prepare();
            mMediaRecorder.start();
        } catch (IllegalStateException e) {
            Log.i("failed!" , e.getMessage());
        } catch (IOException e) {
            Log.i("failed!" ,e.getMessage());
        }

结束录音

public void stopRecord() {
        try {
            mMediaRecorder.stop();
            mMediaRecorder.release();
            mMediaRecorder = null;
        } catch (RuntimeException e) {
            mMediaRecorder.reset();
            mMediaRecorder.release();
            mMediaRecorder = null;

            File file = new File(filePath);
            if (file.exists())
                file.delete();
        }
    }

权限部分

• 为实现录音以及将录音后的文件保存到手机当中，需要在Manifest里面声明申请的权限

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

申请权限

• 其中的权限是需要动态申请的
• 动态权限申请的类如下
• 此类具有申请权限的通用性，可以拓展使用
• 其使用方法是

    RequestPermission requestPermission = new RequestPermission();
    requestPermission.RequestPermission(this);

• 权限申请类

package com.example.intent.recordbackgroud;

import android.Manifest;
import android.app.Activity;
import android.content.pm.PackageManager;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.util.Log;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by baoqingyang on 2018/3/8.
 */

public class RequestPermission {


    public static final String PERMISSION_FILE = Manifest.permission.WRITE_EXTERNAL_STORAGE;
    public static final String PERMISSION_RECORD = Manifest.permission.RECORD_AUDIO;
    public static final String PERMISSION_READ = Manifest.permission.READ_EXTERNAL_STORAGE;


    private static final String[] requestPermissions = {

            PERMISSION_FILE,
            PERMISSION_RECORD,
            PERMISSION_READ
    };

    public RequestPermission(){

    }
    interface PermissionGrant {
        void onPermissionGranted(int requestCode);
    }

    public void  RequestPermission(Activity activity){
        String[] permissions;
        List<String> mPermissionList = new ArrayList<>();

        mPermissionList.clear();
        for (int i = 0; i < requestPermissions.length; i++) {
            if (ContextCompat.checkSelfPermission(activity, requestPermissions[i]) != PackageManager.PERMISSION_GRANTED) {
                mPermissionList.add(requestPermissions[i]);
            }
        }

        if (mPermissionList.isEmpty()) {//未授予的权限为空，表示都授予了

        } else {//请求权限方法
            permissions = mPermissionList.toArray(new String[mPermissionList.size()]);//将List转为数组
            ActivityCompat.requestPermissions(activity, permissions, 1);
        }
        String res = getProperty("CAPTURE_AUDIO_OUTPUT","1111");
        Log.d("show",res);

    }
    public  String getProperty(String key, String defaultValue) {
        String value = defaultValue;
        try {
            Class<?> c = Class.forName("android.os.SystemProperties");
            Method get = c.getMethod("get", String.class, String.class);
            value = (String)(get.invoke(c, key, "unknown" ));
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            return value;
        }
    }
    public static  void setprop(String key, String defaultValue) {

        String value = defaultValue;

        try {

            Class<?> c = Class.forName("android.os.SystemProperties");

            Method get = c.getMethod("set", String.class, String.class );

            get.invoke(c, key, value );

        } catch (Exception e) {

            e.printStackTrace();

        }
    }


}