android 使用USB通讯

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mob64ca12e41d46 2024-06-21 06:48:44 ©著作权

文章标签 java Android 开发者 文章分类 Android 移动开发

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Android使用USB通讯实现指南

介绍

作为一名经验丰富的开发者，我将帮助你学习如何在Android应用中实现USB通讯。这对于刚入行的开发者来说可能有些困难，但我会通过一步一步的指导来帮助你完成这个任务。

流程图

flowchart TD
    Start(开始)
    Step1(连接USB设备)
    Step2(检测USB权限)
    Step3(发送数据)
    Step4(接收数据)
    End(完成)
    Start --> Step1
    Step1 --> Step2
    Step2 --> Step3
    Step3 --> Step4
    Step4 --> End

教程步骤

步骤	描述
1	连接USB设备
2	检测USB权限
3	发送数据
4	接收数据

步骤详解

步骤1：连接USB设备

在AndroidManifest.xml文件中添加USB权限：

<uses-permission android:name="android.permission.USB_PERMISSION"/>

步骤2：检测USB权限

在Activity中实现USB设备的连接和权限检测：

private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
private UsbManager mUsbManager;
private UsbDevice mUsbDevice;
private UsbDeviceConnection mUsbDeviceConnection;
private PendingIntent mPermissionIntent;
private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if (ACTION_USB_PERMISSION.equals(action)) {
            synchronized (this) {
                UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
                if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
                    if(device != null){
                        // 通过mUsbManager.openDevice(device)打开设备连接
                    }
                } 
                else {
                    Log.d(TAG, "permission denied for device " + device);
                }
            }
        }
    }
};

// 在onCreate方法中初始化
mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);

// 寻找设备并请求权限
HashMap<String, UsbDevice> deviceList = mUsbManager.getDeviceList();
for (UsbDevice device : deviceList.values()) {
    if (device.getVendorId() == YOUR_VENDOR_ID && device.getProductId() == YOUR_PRODUCT_ID) {
        mUsbDevice = device;
        mUsbManager.requestPermission(mUsbDevice, mPermissionIntent);
        break;
    }
}

步骤3：发送数据

发送数据到USB设备：

UsbEndpoint endpointOut = null;
UsbInterface usbInterface = mUsbDevice.getInterface(0);
for (int i = 0; i < usbInterface.getEndpointCount(); i++) {
    UsbEndpoint endpoint = usbInterface.getEndpoint(i);
    if (endpoint.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK && endpoint.getDirection() == UsbConstants.USB_DIR_OUT) {
        endpointOut = endpoint;
    }
}

UsbDeviceConnection connection = mUsbManager.openDevice(mUsbDevice);
if (connection != null && connection.claimInterface(usbInterface, true)) {
    byte[] dataToSend = "Hello USB Device".getBytes();
    connection.bulkTransfer(endpointOut, dataToSend, dataToSend.length, TIMEOUT);
}

步骤4：接收数据

接收来自USB设备的数据：

UsbEndpoint endpointIn = null;
UsbInterface usbInterface = mUsbDevice.getInterface(0);
for (int i = 0; i < usbInterface.getEndpointCount(); i++) {
    UsbEndpoint endpoint = usbInterface.getEndpoint(i);
    if (endpoint.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK && endpoint.getDirection() == UsbConstants.USB_DIR_IN) {
        endpointIn = endpoint;
    }
}

UsbDeviceConnection connection = mUsbManager.openDevice(mUsbDevice);
if (connection != null && connection.claimInterface(usbInterface, true)) {
    byte[] buffer = new byte[endpointIn.getMaxPacketSize()];
    connection.bulkTransfer(endpointIn, buffer, buffer.length, TIMEOUT);
    String receivedData = new String(buffer, Charset.forName("UTF-8"));
    Log.d(TAG, "Received data: " + receivedData);
}