在Android BLE中，广播器（Advertiser）的主要作用是向其他设备广播设备的信息。一个设备可以拥有多个广播器来广播多种不同的信息，但是每个设备最多只能同时使用4个广播器。如果想要使用更多的广播器，需要先停止之前的广播器才能启用新的广播器。

下面是一个使用广播器的示例代码：

private BluetoothLeAdvertiser mBluetoothLeAdvertiser;  
private AdvertiseCallback mAdvertiseCallback;

public void startAdvertising() {
     mBluetoothLeAdvertiser = BluetoothAdapter.getDefaultAdapter().getBluetoothLeAdvertiser();
     AdvertiseSettings settings = new AdvertiseSettings.Builder()
            .setAdvertiseMode(AdvertiseSettings.ADVERTISE_MODE_LOW_POWER)
            .setTxPowerLevel(AdvertiseSettings.ADVERTISE_TX_POWER_LOW)
            .setConnectable(true)
            .build();
     AdvertiseData data = new AdvertiseData.Builder()
            .setIncludeDeviceName(true)
            .addServiceUuid(ParcelUuid.fromString(SampleGattAttributes.SERVICE_UUID))
            .build();
     mAdvertiseCallback = new AdvertiseCallback() {
            @Override
            public void onStartSuccess(AdvertiseSettings settingsInEffect) {
                Log.i(TAG, "Advertising onStartSuccess");
            }

            @Override
            public void onStartFailure(int errorCode) {
                Log.e(TAG, "Advertising onStartFailure: " + errorCode);
            }
        };
     mBluetoothLeAdvertiser.startAdvertising(settings, data, mAdvertiseCallback);
}

public void stopAdvertising() {
     mBluetoothLeAdvertiser.stopAdvertising(mAdvertiseCallback);
}