求TMediaPlayer跨平台低开销快速音效替代方案（Delphi10.2安卓兼容问题）

首先，咱们先明确核心问题：你提到的onLoadComplete事件未触发，大概率是因为Delphi 10.2对Android MediaPlayer的封装存在细节问题，或者你的音频加载流程不符合Android原生API的要求。结合你需要低开销的需求，我给你整理一套可行的实现方案：

一、排查核心原因 #

• 事件映射错误：Android原生MediaPlayer并没有onLoadComplete事件，对应的加载完成回调是onPrepared。如果你的代码是封装了原生API，可能是映射时没正确绑定这个回调。
• 音频路径问题：Android下Assets目录的文件不能直接用本地路径访问，必须通过AssetFileDescriptor加载，否则MediaPlayer无法正确读取文件，自然不会触发准备完成事件。
• 同步加载导致无回调：如果调用了prepare()（同步加载），不会触发异步回调；必须调用prepareAsync()才会在加载完成后触发onPrepared。

二、低开销的实现代码（兼容Delphi 10.2 Android + Windows） #

下面是一个复用MediaPlayer实例的低开销音效播放器类，解决Android端回调未触发的问题：

1. 核心播放器类 #

unit LowLatencySoundPlayer;

interface

uses
  System.SysUtils, System.Classes,
{$IFDEF ANDROID}
  Androidapi.JNI.Media, Androidapi.JNI.JavaTypes, Androidapi.Helpers,
{$ENDIF}
{$IFDEF MSWINDOWS}
  MMSystem,
{$ENDIF}
  System.Generics.Collections;

type
  TSoundPlayer = class
  private
{$IFDEF ANDROID}
    FMediaPlayer: JMediaPlayer;
    FAssetFD: JAssetFileDescriptor;
    procedure OnPrepared(Sender: TObject);
    procedure OnCompletion(Sender: TObject);
    class var FPlayerPool: TObjectPool<TSoundPlayer>;
{$ENDIF}
{$IFDEF MSWINDOWS}
    FWaveHandle: HMMIO;
    FWaveData: array of Byte;
    FWaveLength: Integer;
{$ENDIF}
    FSoundPath: string;
    FIsPrepared: Boolean;
    procedure PrepareSound;
  public
    constructor Create(const ASoundPath: string);
    destructor Destroy; override;
    procedure Play;
    class function GetPlayer(const ASoundPath: string): TSoundPlayer;
    class procedure ReleasePlayer(Player: TSoundPlayer);
  end;

implementation

{$IFDEF ANDROID}
procedure TSoundPlayer.OnPrepared(Sender: TObject);
begin
  FIsPrepared := True;
  // 如果需要立即播放，可以在这里调用Play
end;

procedure TSoundPlayer.OnCompletion(Sender: TObject);
begin
  FIsPrepared := False;
  FMediaPlayer.seekTo(0); // 重置到开头，方便下次播放
end;
{$ENDIF}

constructor TSoundPlayer.Create(const ASoundPath: string);
begin
  inherited Create;
  FSoundPath := ASoundPath;
  FIsPrepared := False;
  PrepareSound;
end;

destructor TSoundPlayer.Destroy;
begin
{$IFDEF ANDROID}
  if Assigned(FMediaPlayer) then
  begin
    FMediaPlayer.release;
    FMediaPlayer := nil;
  end;
  if Assigned(FAssetFD) then
  begin
    FAssetFD.close;
    FAssetFD := nil;
  end;
{$ENDIF}
{$IFDEF MSWINDOWS}
  if FWaveHandle <> 0 then
  begin
    mmioClose(FWaveHandle, 0);
    FWaveHandle := 0;
  end;
{$ENDIF}
  inherited;
end;

procedure TSoundPlayer.PrepareSound;
{$IFDEF ANDROID}
var
  LAssetManager: JAssetManager;
{$ENDIF}
{$IFDEF MSWINDOWS}
var
  LMMIOInfo: TMMIOInfo;
  LWaveHeader: TWaveFormatEx;
  LChunkInfo: TMMCKInfo;
  LDataChunk: TMMCKInfo;
{$ENDIF}
begin
{$IFDEF ANDROID}
  LAssetManager := TAndroidHelper.Context.getAssets;
  try
    FAssetFD := LAssetManager.openFd(StringToJString(FSoundPath));
    FMediaPlayer := TJMediaPlayer.JavaClass.init;
    // 设置数据源
    FMediaPlayer.setDataSource(FAssetFD.getFileDescriptor, FAssetFD.getStartOffset, FAssetFD.getLength);
    // 绑定回调
    FMediaPlayer.setOnPreparedListener(TJMediaPlayer_OnPreparedListener.Wrap(
      procedure(mp: JMediaPlayer)
      begin
        OnPrepared(Self);
      end));
    FMediaPlayer.setOnCompletionListener(TJMediaPlayer_OnCompletionListener.Wrap(
      procedure(mp: JMediaPlayer)
      begin
        OnCompletion(Self);
      end));
    // 异步准备，触发onPrepared
    FMediaPlayer.prepareAsync;
  except
    on E: Exception do
    begin
      // 处理加载错误
      FIsPrepared := False;
    end;
  end;
{$ENDIF}
{$IFDEF MSWINDOWS}
  FWaveHandle := mmioOpen(PChar(FSoundPath), nil, MMIO_READ or MMIO_ALLOCBUF);
  if FWaveHandle = 0 then Exit;

  ZeroMemory(@LMMIOInfo, SizeOf(LMMIOInfo));
  LMMIOInfo.fccIOProc := mmioFOURCC('W', 'A', 'V', 'E');
  mmioSetInfo(FWaveHandle, @LMMIOInfo, 0);

  // 读取RIFF块
  ZeroMemory(@LChunkInfo, SizeOf(LChunkInfo));
  LChunkInfo.ckid := mmioFOURCC('R', 'I', 'F', 'F');
  if mmioDescend(FWaveHandle, @LChunkInfo, nil, MMIO_FINDRIFF) <> MMSYSERR_NOERROR then Exit;

  // 读取fmt块
  ZeroMemory(@LDataChunk, SizeOf(LDataChunk));
  LDataChunk.ckid := mmioFOURCC('f', 'm', 't', ' ');
  if mmioDescend(FWaveHandle, @LDataChunk, @LChunkInfo, MMIO_FINDCHUNK) <> MMSYSERR_NOERROR then Exit;

  mmioRead(FWaveHandle, @LWaveHeader, SizeOf(LWaveHeader));
  mmioAscend(FWaveHandle, @LDataChunk, 0);

  // 读取data块
  ZeroMemory(@LDataChunk, SizeOf(LDataChunk));
  LDataChunk.ckid := mmioFOURCC('d', 'a', 't', 'a');
  if mmioDescend(FWaveHandle, @LDataChunk, @LChunkInfo, MMIO_FINDCHUNK) <> MMSYSERR_NOERROR then Exit;

  FWaveLength := LDataChunk.cksize;
  SetLength(FWaveData, FWaveLength);
  mmioRead(FWaveHandle, @FWaveData[0], FWaveLength);
  FIsPrepared := True;
{$ENDIF}
end;

procedure TSoundPlayer.Play;
begin
{$IFDEF ANDROID}
  if Assigned(FMediaPlayer) and FIsPrepared then
  begin
    FMediaPlayer.start;
  end else if not FIsPrepared then
  begin
    // 如果未准备完成，可以重新触发准备
    PrepareSound;
  end;
{$ENDIF}
{$IFDEF MSWINDOWS}
  if FIsPrepared then
  begin
    sndPlaySound(@FWaveData[0], SND_MEMORY or SND_ASYNC or SND_NODEFAULT);
  end;
{$ENDIF}
end;

{$IFDEF ANDROID}
class function TSoundPlayer.GetPlayer(const ASoundPath: string): TSoundPlayer;
begin
  if not Assigned(FPlayerPool) then
    FPlayerPool := TObjectPool<TSoundPlayer>.Create(
      function: TSoundPlayer
      begin
        Result := TSoundPlayer.Create(ASoundPath);
      end,
      procedure(AItem: TSoundPlayer)
      begin
        // 回收时重置播放器
        if Assigned(AItem.FMediaPlayer) then
          AItem.FMediaPlayer.seekTo(0);
      end);
  Result := FPlayerPool.GetItem;
end;

class procedure TSoundPlayer.ReleasePlayer(Player: TSoundPlayer);
begin
  if Assigned(FPlayerPool) then
    FPlayerPool.ReleaseItem(Player);
end;
{$ELSE}
class function TSoundPlayer.GetPlayer(const ASoundPath: string): TSoundPlayer;
begin
  Result := TSoundPlayer.Create(ASoundPath);
end;

class procedure TSoundPlayer.ReleasePlayer(Player: TSoundPlayer);
begin
  Player.Free;
end;
{$ENDIF}

end.

2. 使用示例 #

// 获取播放器实例（Android端复用，Windows端按需创建）
var
  LPlayer: TSoundPlayer;
begin
  LPlayer := TSoundPlayer.GetPlayer('sounds/click.wav'); // Assets下的路径
  try
    LPlayer.Play;
  finally
    TSoundPlayer.ReleasePlayer(LPlayer);
  end;
end;

三、关键优化点说明 #

• Android端回调修复：改用Android原生的onPrepared回调，通过匿名方法正确绑定到Delphi的事件处理逻辑；使用prepareAsync()异步加载音频确保回调触发；正确处理Assets文件的加载，用AssetFileDescriptor获取数据源。
• 低开销设计：Android端使用对象池复用MediaPlayer实例，避免频繁创建/销毁的开销；Windows端直接读取WAV数据到内存，用sndPlaySound播放，比TMediaPlayer开销小很多。
• 兼容性适配：通过条件编译分别处理Android和Windows平台的实现逻辑。

四、额外注意事项 #

• 确保Android项目中Assets目录存在，且WAV文件已正确添加到Assets中（在Delphi的Project Manager里右键Assets文件夹添加）
• WAV文件建议采用PCM格式，避免压缩格式带来的解码开销
• 如果需要同时播放多个音效，可以扩展对象池的容量，或者为不同音效创建独立的对象池

内容的提问来源于stack exchange，提问作者bLight