要解决“Android BluetoothLeScanner在28次后系统范围内启动扫描PendingIntent失败”的问题，您可以考虑使用以下代码示例：

import android.app.PendingIntent;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.le.BluetoothLeScanner;
import android.bluetooth.le.ScanCallback;
import android.bluetooth.le.ScanResult;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Handler;
import android.os.Looper;
import android.os.ParcelUuid;
import android.support.annotation.RequiresApi;
import android.util.Log;

import java.util.UUID;

public class BluetoothScannerHelper {

    private static final String TAG = BluetoothScannerHelper.class.getSimpleName();
    private static final int MAX_SCAN_RETRIES = 28;
    private static final long SCAN_RETRY_DELAY_MS = 1000;

    private Context mContext;
    private BluetoothLeScanner mBluetoothLeScanner;
    private PendingIntent mScanPendingIntent;

    public BluetoothScannerHelper(Context context) {
        mContext = context;
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
    public void startScan() {
        BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        mBluetoothLeScanner = bluetoothAdapter.getBluetoothLeScanner();

        // 创建一个唯一的UUID作为扫描过滤器
        UUID scanFilterUuid = UUID.randomUUID();
        ParcelUuid parcelUuid = new ParcelUuid(scanFilterUuid);

        Intent scanIntent = new Intent(mContext, ScanBroadcastReceiver.class);
        scanIntent.putExtra(ScanBroadcastReceiver.EXTRA_SCAN_FILTER, parcelUuid);

        mScanPendingIntent = PendingIntent.getBroadcast(mContext, 0, scanIntent, PendingIntent.FLAG_UPDATE_CURRENT);

        // 开始扫描
        mBluetoothLeScanner.startScan(null, null, mScanPendingIntent);
    }

    public void stopScan() {
        if (mBluetoothLeScanner != null) {
            mBluetoothLeScanner.stopScan(mScanPendingIntent);
        }
    }

    // 广播接收器用于接收扫描结果
    public static class ScanBroadcastReceiver extends android.content.BroadcastReceiver {

        public static final String EXTRA_SCAN_FILTER = "scan_filter";

        @Override
        public void onReceive(Context context, Intent intent) {
            UUID scanFilterUuid = ((ParcelUuid) intent.getParcelableExtra(EXTRA_SCAN_FILTER)).getUuid();

            if (BluetoothAdapter.ACTION_STATE_CHANGED.equals(intent.getAction())) {
                int bluetoothState = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, BluetoothAdapter.ERROR);
                if (bluetoothState == BluetoothAdapter.STATE_OFF) {
                    Log.d(TAG, "Bluetooth is turned off, stopping scan");
                    stopScan();
                }
            } else if (BluetoothLeScanner.ACTION_SCAN_RESULT.equals(intent.getAction())) {
                ScanResult scanResult = intent.getParcelableExtra(BluetoothLeScanner.EXTRA_SCAN_RESULT);
                if (scanResult != null && scanResult.getDevice() != null) {
                    Log.d(TAG, "Scan result: " + scanResult.getDevice().getName() + ", UUID: " + scanFilterUuid);
                }
            }
        }
    }

    // 重新启动扫描
    private void restartScan() {
        new Handler(Looper.getMainLooper()).postDelayed(new Runnable() {
            @Override
            public void run() {
                startScan();
            }
        }, SCAN_RETRY_DELAY_MS);
    }

    // 扫描回调用于处理扫描失败的情况
    private ScanCallback mScanCallback = new ScanCallback() {
        @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
        @Override
        public void onScanFailed(int errorCode) {
            super.onScanFailed(errorCode);
            Log.e(TAG, "Scan failed with error code: " + errorCode);

            // 如果扫描失败次数小于最大重试次数，则重新启动扫描
            if (errorCode != ScanCallback.SCAN_FAILED_APPLICATION_REGISTRATION_FAILED && errorCode != ScanCallback.SCAN_FAILED_INTERNAL_ERROR) {
                if (mRetryCount < MAX_SCAN_RETRIES) {
                    mRetryCount++;
                    restartScan();
                } else {
                    Log.e(TAG, "Scan failed after max retries, stopping scan");
                    stopScan();
                }
            }
        }
    };
}

在上述代码示例中：

1. BluetoothScannerHelper类是一个辅助类，用于处理蓝牙扫描操作。
2. startScan()方法用于启动蓝牙LE扫描。它创建一个唯一的UUID作为扫描过滤器，并将其作为额外数据添加到扫描意图中。