将音频输出到蓝牙 - Java

在 Java 中，我们可以使用 javax.sound.sampled 包来将音频输出到蓝牙设备上。

1. 获取蓝牙设备

首先，需要获取蓝牙设备的 BluetoothDevice 对象。可以使用 javax.bluetooth 包中的 DiscoveryAgent 类和 RemoteDevice 类来实现：

// 获取本地蓝牙适配器
LocalDevice localDevice = LocalDevice.getLocalDevice();

// 启动设备发现
DiscoveryAgent discoveryAgent = localDevice.getDiscoveryAgent();
RemoteDevice[] remoteDevices = discoveryAgent.retrieveDevices(DiscoveryAgent.PREKNOWN);

// 遍历已知设备列表，找到蓝牙音箱设备
BluetoothDevice bluetoothDevice = null;
for (RemoteDevice remoteDevice : remoteDevices) {
    if (remoteDevice.getFriendlyName(false).equals("My Bluetooth Speaker")) {
        bluetoothDevice = new BluetoothDevice(remoteDevice.getBluetoothAddress());
        break;
    }
}

2. 创建音频输出流

接下来，需要创建一个能够将音频数据输出到蓝牙设备的 SourceDataLine 对象：

AudioFormat format = new AudioFormat(44100, 16, 2, true, false);
DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);
SourceDataLine line = (SourceDataLine) AudioSystem.getLine(info);
line.open(format);
line.start();

3. 将音频数据输出到蓝牙设备

最后，将音频数据输出到蓝牙设备。这里使用 byte[] 数组来存储音频数据：

// 从音频文件读取数据
byte[] buffer = new byte[4096];
FileInputStream fis = new FileInputStream("music.mp3");
while (fis.read(buffer) != -1) {
    // 将音频数据输出到蓝牙设备
    line.write(buffer, 0, buffer.length);
}

// 关闭数据流
fis.close();
line.stop();
line.close();

完整代码如下所示：

import java.io.FileInputStream;
import javax.bluetooth.DiscoveryAgent;
import javax.bluetooth.RemoteDevice;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.SourceDataLine;
import com.intel.bluetooth.BluetoothDevice;
import com.intel.bluetooth.BluetoothConnectionListener;
import com.intel.bluetooth.BluetoothStateException;
import com.intel.bluetooth.BluetoothStateException;
import com.intel.bluetooth.BluetoothSocket;
import com.intel.bluetooth.RemoteDeviceHelper;
import com.intel.bluetooth.exception.BluetoothConnectionException;
import com.intel.bluetooth.exception.BluetoothStateException;


public class Main {
    
    public static void main(String[] args) throws Exception {
        LocalDevice localDevice = LocalDevice.getLocalDevice();
        System.out.println("本机蓝牙名称: " + localDevice.getFriendlyName());
        
        // 获取本地已知蓝牙设备
        DiscoveryAgent discoveryAgent = localDevice.getDiscoveryAgent();
        RemoteDevice[] remoteDevices = discoveryAgent.retrieveDevices(DiscoveryAgent.PREKNOWN);
        System.out.println("已知设备数: " + remoteDevices.length);
        
        // 根据设备名称查找蓝牙设备
        BluetoothDevice bluetoothDevice = null;
        for(RemoteDevice remoteDevice : remoteDevices) {
            System.out.println("设备名称: " + remoteDevice.getFriendlyName(false));
            if(remoteDevice.getFriendlyName(false).equals("HUAWEI P20 Lite")) {
                bluetoothDevice = new BluetoothDevice(remoteDevice.getBluetoothAddress());
            }
        }
        
        if(bluetoothDevice == null) {
            System.out.println("没有找到指定的设备!");
            return;
        }
        
        System.out.println("开始连接设备...");
        
        // 建立蓝牙连接
        BluetoothSocket socket = bluetoothDevice.connect();
        System.out.println("连接成功!");
        
        // 创建音频输出流
        AudioFormat format = new AudioFormat(44100, 16, 2, true, false);
        DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);
        SourceDataLine line = (SourceDataLine) AudioSystem.getLine(info);
        line.open(format);
        line.start();
        
        // 从音频文件读取数据
        byte[] buffer = new byte[4096];
        FileInputStream fis = new FileInputStream("music.mp3");
        while (fis.read(buffer) != -1) {
            // 将音频数据输出到蓝牙设备
            socket.getOutputStream().write(buffer, 0, buffer.length);
            line.write(buffer, 0, buffer.length);
        }
        
        // 关闭数据流和蓝牙连接
        fis.close();
        line.stop();
        line.close();
        socket.close();
        
        System.out.println("完成!");
    }
}

以上就是使用 Java 将音频输出到蓝牙设备的具体步骤。