Android应用USB设备连接事件处理与Activity启动模式优化

<application>
    <!-- ... 其他应用配置 ... -->
    <activity
        android:name=".YourMainActivity"
        android:launchMode="singleTop" <!-- 关键配置 -->
        android:exported="true"> <!-- Android 12+ 需要明确声明 exported -->

        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>

        <intent-filter>
            <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
        </intent-filter>

        <meta-data android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
                   android:resource="@xml/device_filter" />

    </activity>        
</application>

import android.content.Intent;
import android.hardware.usb.UsbDevice;
import android.hardware.usb.UsbManager;
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import android.util.Log;

public class YourMainActivity extends AppCompatActivity {

    private static final String TAG = "USB_APP";
    private UsbManager usbManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        usbManager = (UsbManager) getSystemService(USB_SERVICE);

        // 初始启动时处理USB连接
        handleUsbIntent(getIntent());
    }

    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);
        // 将新的Intent设置为当前Activity的Intent，以便后续调用getIntent()获取的是最新的
        setIntent(intent); 
        handleUsbIntent(intent);
    }

    private void handleUsbIntent(Intent intent) {
        if (intent != null) {
            String action = intent.getAction();
            if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action)) {
                UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
                if (device != null) {
                    Log.d(TAG, "USB Device Attached: " + device.getDeviceName());
                    // 在这里处理USB设备的连接逻辑，例如：
                    // 1. 检查并请求USB设备权限
                    // 2. 查找并打开对应的串口设备
                    // 3. 更新UI显示连接状态
                    // 4. 重新初始化通信通道

                    // 示例：请求权限
                    if (!usbManager.hasPermission(device)) {
                        // 通常需要一个PendingIntent来处理权限请求结果
                        // PendingIntent permissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
                        // usbManager.requestPermission(device, permissionIntent);
                        Log.d(TAG, "Requesting permission for device: " + device.getDeviceName());
                    } else {
                        Log.d(TAG, "Permission already granted for device: " + device.getDeviceName());
                        // 设备已连接且有权限，可以开始通信
                        // 例如：初始化串口
                    }
                }
            } else if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action)) {
                 UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
                 if (device != null) {
                     Log.d(TAG, "USB Device Detached: " + device.getDeviceName());
                     // 处理设备断开逻辑，例如关闭串口，更新UI
                 }
            }
        }
    }

    // ... 其他Activity生命周期方法和业务逻辑 ...
}