Android 开发（七）

音乐播放器开发

MediaPlayer 是Android 控制音频和视频文件播放类
1.创建MediaPlayer 对象 的Create方法
2.无can构造方法 -> setDataSorce -> prepare(）加载创造文件
注意访问SDK需要授予权限
当Mediaplay.stop() 资源后需要重新加载资源，使用Mediaplay.setDataSource() 方法进行加载 ，最后还需要释放资源，防止内存泄漏

• 缺点： 1.延迟低长，占有资源多 2. 不支持同时播放多个音频

package com.example.myapplication;

import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageButton;
import android.widget.Toast;

import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;

import java.io.File;
import java.io.IOException;
/**
 * MediaPlay 实现简易的播放器
*/
public class MainActivity extends AppCompatActivity {

    private MediaPlayer mediaPlayer;            //定义MediaPlayer对象
    private boolean isPause = false;        //定义是否暂停
    private File file;

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


        final ImageButton btn_play = (ImageButton) findViewById(R.id.btn_play); //获取“播放/暂停”按钮
        final ImageButton btn_stop = (ImageButton) findViewById(R.id.btn_stop); //获取“停止”按钮
        ;
        file = new File("/res/raw/bird.ogg");

        if (file.exists()) {
            mediaPlayer = MediaPlayer.create(this, Uri.parse(file.getAbsolutePath()));
        } else {
            Toast.makeText(MainActivity.this, "要播放的音频文件不存在！", Toast.LENGTH_SHORT).show();
            return;
        }

        // 为MediaPlayer 添加监听事件 完成事件监听器，当media.play.stop 后在重新play
        mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {

            @Override
            public void onCompletion(MediaPlayer mediaPlayer) {
                play();
            }
        });

        btn_play.setOnClickListener(new View.OnClickListener(){

            @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
            @Override
            public void onClick(View view) {
                if(mediaPlayer.isPlaying() && !isPause){
                    mediaPlayer.pause();
                    isPause = true; // 暂停播放
                    // 更好播放图标
                    ((ImageButton) view).setImageDrawable(getResources().getDrawable(R.drawable.play, null));
                }else{
                    mediaPlayer.start();                           //继续播放
                    // 更换为暂停图标
                    ((ImageButton) view).setImageDrawable(getResources().getDrawable(R.drawable.pause, null));
                    isPause = false;                         //设置为播放状态
                }
          }
        });
        btn_stop.setOnClickListener(new View.OnClickListener() { //单击停止按钮，实现停止播放音频
            @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
            @Override
            public void onClick(View v) {
                mediaPlayer.stop();                    //停止播放
                //更换为播放图标
                btn_play.setImageDrawable(getResources().getDrawable(R.drawable.play, null));
            }
        });
    }

    private void play(){
        // 重置MediaPlay
        mediaPlayer.reset();
        try {
            mediaPlayer.setDataSource(file.getAbsolutePath());
            mediaPlayer.prepare(); // 预加载
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void onDestroy() {
        if(mediaPlayer.isPlaying()){
            mediaPlayer.stop();
        }
        mediaPlayer.release();
        super.onDestroy();
    }
}

SoundPool 播放多个音频

优点： 1. 延迟低 2.占有资源少 3. 支持多个音频播放
缺点： 不能播放大文件音频
应用场景： 小型游戏中多个飞机被击破声音
创建SoundPool 对象，load ， play

package com.example.myapplication;

import android.media.AudioAttributes;
import android.media.SoundPool;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;

import androidx.appcompat.app.AppCompatActivity;

import java.util.HashMap;

public class MainActivity extends AppCompatActivity {


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

        ListView listView = findViewById(R.id.listView);

        // 创建SoundPool 对象设置音频相关特性
        //1.音频对象
        AudioAttributes attr = new AudioAttributes.Builder()           //设置音效相关属性
                .setUsage(AudioAttributes.USAGE_GAME)                 // 设置音效使用场景
                .setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)  // 设置音效的类型
                .build();

        final SoundPool soundpool = new SoundPool.Builder()           // 创建SoundPool对象
                .setAudioAttributes(attr) // 设置音效池的属性
                .setMaxStreams(10) // 设置最多可容纳10个音频流，
                .build();
        // 要播放音频保存到HashMap中
        final HashMap<Integer, Integer> soundmap = new HashMap<Integer, Integer>();
        soundmap.put(0, soundpool.load(this, R.raw.cuckoo, 1));
        soundmap.put(1, soundpool.load(this, R.raw.chimes, 1));
        soundmap.put(2, soundpool.load(this, R.raw.notify, 1));
        soundmap.put(3, soundpool.load(this, R.raw.ringout, 1));
        soundmap.put(4, soundpool.load(this, R.raw.bird, 1));
        soundmap.put(5, soundpool.load(this, R.raw.water, 1));
        soundmap.put(6, soundpool.load(this, R.raw.cock, 1));

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                soundpool.play(soundmap.get(i),1,1,0,0,1);
            }
        });
    }
}

video View 播放视频

1. 在XML中添加Videoview 组件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <VideoView
        android:id="@+id/video"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</RelativeLayout>

读取SDK上数据 设置Mainifest.xml 设置访问权限，同时在Android 机器上设置权限打开

  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
-----------------------------------------------------------
<?xml version="1.0" encoding="utf-8"?>
<manifest package="com.mingrisoft"
          xmlns:android="http://schemas.android.com/apk/res/android">
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity" android:screenOrientation="landscape">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

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

</manifest>

package com.example.myapplication;

import android.media.MediaPlayer;
import android.os.Bundle;

import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;

import android.os.Environment;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.MediaController;
import android.widget.Toast;
import android.widget.VideoView;

import java.io.File;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        VideoView videoView = findViewById(R.id.video);
        
        File file = new File(Environment.getExternalStorageDirectory()+"/video.mp4");
        if(file.exists()){
            videoView.setVideoPath(file.getAbsolutePath());
        }else{
            return ;
        }
        
        // 控制视频播放
        MediaController mc = new MediaController(MainActivity.this);
        videoView.setMediaController(mc);
        // videoiew 获取焦点
        videoView.requestFocus();
        videoView.start();
        
        // 完成监听器
        videoView.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mediaPlayer) {
                Toast.makeText(MainActivity.this,"视频播放完成",Toast.LENGTH_SHORT).show();
            }
        });
    }

}

控制摄像头摄像

 <!-- 授予程序可以向SD卡中保存文件的权限 -->
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <!-- 授予程序使用摄像头的权限 -->
    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-feature android:name="android.hardware.camera.autofocus"/>
    <uses-feature android:name="android.hardware.camera"/>

package com.example.myapplication;


import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.WindowManager;
import android.widget.ImageButton;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    private Camera camera;
    private boolean isPreview = false; // 设置是否是预览状态

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

        //设置全屏显示
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);

        if (!android.os.Environment.getExternalStorageState().equals(  //判断手机是否安装SD卡
                android.os.Environment.MEDIA_MOUNTED)) {
            Toast.makeText(this, "请安装SD卡！", Toast.LENGTH_SHORT).show(); // 提示安装SD卡
        }
        // 设置预览
        final SurfaceView surfaceView = findViewById(R.id.surfaceView);

        final SurfaceHolder surfaceHolder = surfaceView.getHolder();
        // 设置自己维护缓存
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        ImageButton preview = (ImageButton) findViewById(R.id.preview);        //获取“预览”按钮
        ImageButton takePicture = (ImageButton) findViewById(R.id.takephoto);  //获取“拍照”按钮

        preview.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                if (!isPreview) {
                    camera = Camera.open();
                    isPreview = true;
                }

                try {
                    camera.setPreviewDisplay(surfaceHolder);                   // 设置用于显示预览的SurfaceView
                    Camera.Parameters parameters = camera.getParameters();    //获取相机参数
                    parameters.setPictureFormat(PixelFormat.JPEG);    //指定图片为JPEG图片
                    parameters.set("jpeg-quality", 80);            //设置图片的质量
                    camera.setParameters(parameters);                //重新设置相机参数
                    camera.startPreview();                            //开始预览
                    camera.autoFocus(null);                        //设置自动对焦
                } catch (IOException e) {                           //输出异常信息
                    e.printStackTrace();
                }
            }
        });

        // 保存拍照

        //实现相机拍照功能
        takePicture.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (camera != null) {                                     //相机不为空
                    camera.takePicture(null, null, jpeg);                //进行拍照
                }
            }
        });

    }

    final   Camera.PictureCallback jpeg = new Camera.PictureCallback() {
        @Override
        public void onPictureTaken(byte[] data, Camera camera) {
            // 根据拍照所得的数据创建位图
            final Bitmap bm = BitmapFactory.decodeByteArray(data, 0,
                    data.length);
            camera.stopPreview();        //停止预览
            isPreview = false;         //设置为非预览状态
            //获取sd卡根目录
            File appDir = new File(Environment.getExternalStorageDirectory(), "/DCIM/Camera/");
            if (!appDir.exists()) {      //如果该目录不存在
                appDir.mkdir();          //就创建该目录

            }
            String fileName = System.currentTimeMillis() + ".jpg"; //将获取当前系统时间设置为照片名称
            File file = new File(appDir, fileName);  //创建文件对象

            try {  //保存拍到的图片
                FileOutputStream fos = new FileOutputStream(file);  //创建一个文件输出流对象
                bm.compress(Bitmap.CompressFormat.JPEG, 100, fos);  //将图片内容压缩为JPEG格式输出到输出流对象中
                fos.flush();                                        //将缓冲区中的数据全部写出到输出流中
                fos.close();                                        //关闭文件输出流对象
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            // 将照片插入到图库当中

            try {
                MediaStore.Images.Media.insertImage(MainActivity.this.getContentResolver(),
                        file.getAbsolutePath(),fileName,null);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }

            // 更新通知图库
            MainActivity.this.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + "")));

            restCamera();
        }
    };

    private void restCamera(){
        if(!isPreview){
            camera.startPreview();
            isPreview = true;

        }
    }


    @Override
    protected void onPause() {  //当暂停Activity时，停止预览并释放资源
        if (camera != null) {        //如果相机不为空
            camera.stopPreview();    //停止预览
            camera.release();        //释放资源
        }
        super.onPause();
    }
}

本文地址：https://blog.csdn.net/qq_27217017/article/details/107282553