Android(安卓)串口开发（一） 串口读写操作
16lz
2021-01-24
开发串口程序首先要求你的设备需要支持串口通信，可以在设备上装一个App端的串口工具来检测一下
链接：https://pan.baidu.com/s/11L4aZI9orBhbnztka6H1Og
提取码：bvot
或者在电脑端下载一个友善串口助手检测一下，一般在Android工控主板上面都会带有串口。
首先我们是用到了谷歌开源的API serialPort
先贴出来下载地址 https://github.com/cepr/android-serialport-api
第一步 配置环境
1、开发工具Android studio，2.2-3.1.2都可以
2、配置NDK（http://blog.csdn.net/yehui928186846/article/details/52787773），网上教程很多，这里不做重点讲解，查看配置是否成功
3、Android studio配置ndk
二、用开源库代码复制到自己项目里
1、如下图所示
里面的操作类我做了重构，可能会跟开源里面的不一样，不过都是为了达到自己的需求嘛
2、配置build-gridle
配置信息直接粘上去就可以了
在project目录下的gradle.properties文件内加上
Android.useDeprecatedNdk=true这句话 ，为了兼容新老版本ndk3、类的讲解
public class SerialPortFinder { public class Driver { public Driver(String name, String root) { mDriverName = name; mDeviceRoot = root; } private String mDriverName; private String mDeviceRoot; Vector mDevices = null; public Vector getDevices() { if (mDevices == null) { mDevices = new Vector(); File dev = new File("/dev"); File[] files = dev.listFiles(); int i; for (i = 0; i < files.length; i++) { if (files[i].getAbsolutePath().startsWith(mDeviceRoot)) { Log.d(TAG, "Found new device: " + files[i]); mDevices.add(files[i]); } } } return mDevices; } public String getName() { return mDriverName; } } private static final String TAG = "SerialPort"; private Vector mDrivers = null; Vector getDrivers() throws IOException { if (mDrivers == null) { mDrivers = new Vector(); LineNumberReader r = new LineNumberReader(new FileReader("/proc/tty/drivers")); String l; while ((l = r.readLine()) != null) { // Issue 3: // Since driver name may contain spaces, we do not extract driver name with split() String drivername = l.substring(0, 0x15).trim(); String[] w = l.split(" +"); if ((w.length >= 5) && (w[w.length - 1].equals("serial"))) { Log.d(TAG, "Found new driver " + drivername + " on " + w[w.length - 4]); mDrivers.add(new Driver(drivername, w[w.length - 4])); } } r.close(); } return mDrivers; } public String[] getAllDevices() { Vector devices = new Vector(); // Parse each driver Iterator itdriv; try { itdriv = getDrivers().iterator(); while (itdriv.hasNext()) { Driver driver = itdriv.next(); Iterator itdev = driver.getDevices().iterator(); while (itdev.hasNext()) { String device = itdev.next().getName(); String value = String.format("%s (%s)", device, driver.getName()); devices.add(value); } } } catch (IOException e) { e.printStackTrace(); } return devices.toArray(new String[devices.size()]); }//获取设备上所有的串口节点 public String[] getAllDevicesPath() { Vector devices = new Vector(); // Parse each driver Iterator itdriv; try { itdriv = getDrivers().iterator(); while (itdriv.hasNext()) { Driver driver = itdriv.next(); Iterator itdev = driver.getDevices().iterator(); while (itdev.hasNext()) { String device = itdev.next().getAbsolutePath(); devices.add(device); } } } catch (IOException e) { e.printStackTrace(); } return devices.toArray(new String[devices.size()]); }} 这个类一般不用，不占主要作用，主要用于可以获取设备上的所有可用的串口节点，用来选择设置，根据需求添加
public class SerialPort { private static final String TAG = "SerialPort"; private FileDescriptor mFd; private FileInputStream mFileInputStream; private FileOutputStream mFileOutputStream; public SerialPort(File device, int baudrate, int flags) throws SecurityException, IOException { //检查访问权限，如果没有读写权限，进行文件操作，修改文件访问权限 if (!device.canRead() || !device.canWrite()) { try { //通过挂载到linux的方式，修改文件的操作权限 Process su = Runtime.getRuntime().exec("/system/bin/su"); String cmd = "chmod 777 " + device.getAbsolutePath() + "\n" + "exit\n"; su.getOutputStream().write(cmd.getBytes()); if ((su.waitFor() != 0) || !device.canRead() || !device.canWrite()) { throw new SecurityException(); } } catch (Exception e) { e.printStackTrace(); throw new SecurityException(); } } mFd = open(device.getAbsolutePath(), baudrate, flags); if (mFd == null) { Log.e(TAG, "native open returns null"); throw new IOException(); } mFileInputStream = new FileInputStream(mFd); mFileOutputStream = new FileOutputStream(mFd); } // Getters and setters public InputStream getInputStream() { return mFileInputStream; } public OutputStream getOutputStream() { return mFileOutputStream; } // JNI(调用java本地接口，实现串口的打开和关闭) /** * 串口有五个重要的参数：串口设备名，波特率，检验位，数据位，停止位 * 其中检验位一般默认位NONE,数据位一般默认为8，停止位默认为1 */ /** * @param path 串口设备的绝对路径 * @param baudrate 波特率 * @param flags 校验位 */ private native static FileDescriptor open(String path, int baudrate, int flags); public native void close(); static {//加载jni下的C文件库 System.loadLibrary("serial_port"); }}这个SerialPort类是开源的，没有经过修改，Android可以，里面的直接调用，native方法直接和C通信，我们做Android的不需要管
jni目录下放着c源码和h头文件，
jniLibs下面放的就是so库。
注意：因为用的谷歌原生so库，所以SerialPort类的包名一定要是android_serialport_api，如果想修改这个包名，就需要重新生成对应的so库
public class SerialPortUtil { public static String TAG = "SerialPortUtil"; /** * 标记当前串口状态(true:打开,false:关闭) **/ public static boolean isFlagSerial = false; public static SerialPort serialPort = null; public static InputStream inputStream = null; public static OutputStream outputStream = null; public static Thread receiveThread = null; public static String strData = ""; public static Handler mHandler; /** * 打开串口 */ public static boolean open() { boolean isopen = false; if(isFlagSerial){ LogUtils.e(TAG,"串口已经打开,打开失败"); return false; } try { serialPort = new SerialPort(new File("/dev/ttyS3"), 115200, 0); inputStream = serialPort.getInputStream(); outputStream = serialPort.getOutputStream(); receive(); isopen = true; isFlagSerial = true; } catch (IOException e) { e.printStackTrace(); isopen = false; } return isopen; } /** * 关闭串口 */ public static boolean close() { if(isFlagSerial){ LogUtils.e(TAG,"串口关闭失败"); return false; } boolean isClose = false; LogUtils.e(TAG, "关闭串口"); try { if (inputStream != null) { inputStream.close(); } if (outputStream != null) { outputStream.close(); } isClose = true; isFlagSerial = false;//关闭串口时，连接状态标记为false } catch (IOException e) { e.printStackTrace(); isClose = false; } return isClose; } /** * 发送串口指令 */ public static void sendString(String data, Handler handler) { mHandler = handler; if (!isFlagSerial) { LogUtils.e(TAG, "串口未打开,发送失败" + data); return; } try { outputStream.write(ByteUtil.hex2byte(data)); outputStream.flush(); LogUtils.e(TAG, "sendSerialData:" + data); } catch (IOException e) { e.printStackTrace(); LogUtils.e(TAG, "发送指令出现异常"); } } /** * 接收串口数据的方法 */ public static void receive() { if (receiveThread != null && !isFlagSerial) { return; } receiveThread = new Thread() { @Override public void run() { while (isFlagSerial) { try { byte[] readData = new byte[32]; if (inputStream == null) { return; } int size = inputStream.read(readData); if (size > 0 && isFlagSerial) { strData = ByteUtil.byteToStr(readData, size); LogUtils.e(TAG, "readSerialData:" + strData); } } catch (IOException e) { e.printStackTrace(); } } } }; receiveThread.start(); }}这个类就比较重要了，打开串口、关闭串口、读写操作，都在这个类里面写了详细的注释，另外下面在贴一个工具类出来
package com.sqy.scancode.util;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.util.Base64;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import Decoder.BASE64Decoder;import Decoder.BASE64Encoder;/** * Created by Administrator on 2018/6/15. */public class ByteUtil { /** * 字符串转化成为16进制字符串 * * @param s * @return */ public static String strTo16(String s) { String str = ""; for (int i = 0; i < s.length(); i++) { int ch = (int) s.charAt(i); String s4 = Integer.toHexString(ch); str = str + s4; } return str; } /** * 16进制转换成为string类型字符串 * * @param s * @return */ public static String hexStringToString(String s) { if (s == null || s.equals("")) { return null; } s = s.replace(" ", ""); byte[] baKeyword = new byte[s.length() / 2]; for (int i = 0; i < baKeyword.length; i++) { try { baKeyword[i] = (byte) (0xff & Integer.parseInt(s.substring(i * 2, i * 2 + 2), 16)); } catch (Exception e) { e.printStackTrace(); } } try { s = new String(baKeyword, "UTF-8"); new String(); } catch (Exception e1) { e1.printStackTrace(); } return s; } /** * 向串口发送数据转为字节数组 */ public static byte[] hex2byte(String hex) { String digital = "0123456789ABCDEF"; String hex1 = hex.replace(" ", ""); char[] hex2char = hex1.toCharArray(); byte[] bytes = new byte[hex1.length() / 2]; byte temp; for (int p = 0; p < bytes.length; p++) { temp = (byte) (digital.indexOf(hex2char[2 * p]) * 16); temp += digital.indexOf(hex2char[2 * p + 1]); bytes[p] = (byte) (temp & 0xff); } return bytes; } /** * 接收到的字节数组转换16进制字符串 */ public static String bytes2HexString(byte[] b, int size) { String ret = ""; for (int i = 0; i < size; i++) { String hex = Integer.toHexString(b[i] & 0xFF); if (hex.length() == 1) { hex = '0' + hex; } ret += hex.toUpperCase(); } return ret; } public static String bytesToHexString(byte[] src) { StringBuilder stringBuilder = new StringBuilder(""); if (src == null || src.length <= 0) { return null; } for (int i = 0; i < src.length; i++) { int v = src[i] & 0xFF; String hv = Integer.toHexString(v); if (hv.length() < 2) { stringBuilder.append(0); } stringBuilder.append(hv); } return stringBuilder.toString(); } /** * 接收到的字节数组转换16进制字符串 */ public static String byteToStr(byte[] b, int size) { String ret = ""; for (int i = 0; i < size; i++) { String hex = Integer.toHexString(b[i] & 0xFF); if (hex.length() == 1) { hex = '0' + hex; } ret += hex.toUpperCase(); } return ret; } /** * BASE64码解密成图片 */ public static Bitmap Base64ToImage(String imgStr) { // 对字节数组字符串进行Base64解码并生成图片 BASE64Decoder decoder = new BASE64Decoder(); Bitmap bitmap = null; try { // Base64解码 byte[] b = decoder.decodeBuffer(imgStr); for (int i = 0; i < b.length; ++i) { if (b[i] < 0) {// 调整异常数据 b[i] += 256; } } bitmap = BitmapFactory.decodeByteArray(b,0,b.length); return bitmap; } catch (Exception e) { LogUtils.e("TAG","解析异常"); return bitmap; } } /** * 将图片转换为base64加密数据 */ public static String ImageToBase64(String imgFile) { InputStream in = null; byte[] data = null; try { in = new FileInputStream(imgFile); data = new byte[in.available()]; in.read(data); in.close(); } catch (IOException e) { LogUtils.e("TAG","加密异常"); e.printStackTrace(); } BASE64Encoder encoder = new BASE64Encoder(); return encoder.encode(data); } /** * 计算CRC16校验码 * 逐个求和 * * @param bytes 字节数组 * @return {@link String} 校验码 * @since 1.0 */ public static String getCRC_16(byte[] bytes) { int CRC = 0x0000ffff; int POLYNOMIAL = 0x0000a001; int i, j; for (i = 0; i < bytes.length; i++) { CRC ^= ((int) bytes[i] & 0x000000ff); for (j = 0; j < 8; j++) { if ((CRC & 0x00000001) != 0) { CRC >>= 1; CRC ^= POLYNOMIAL; } else { CRC >>= 1; } } } if (Integer.toHexString(CRC).toUpperCase().length() == 2) { return byteToStr(bytes, bytes.length) + "00" + Integer.toHexString(CRC).toUpperCase(); } else if (Integer.toHexString(CRC).toUpperCase().length() == 3) { return byteToStr(bytes, bytes.length) + "0" + Integer.toHexString(CRC).toUpperCase(); } return byteToStr(bytes, bytes.length) + Integer.toHexString(CRC).toUpperCase(); } /** * 指令校验和,并取出后两位字节 * */ public static String getSum16(byte[] msg, int length) { long mSum = 0; byte[] mByte = new byte[length]; /** 逐Byte添加位数和 */ for (byte byteMsg : msg) { long mNum = ((long) byteMsg >= 0) ? (long) byteMsg : ((long) byteMsg + 256); mSum += mNum; } /** end of for (byte byteMsg : msg) */ /** 位数和转化为Byte数组 */ for (int liv_Count = 0; liv_Count < length; liv_Count++) { mByte[length - liv_Count - 1] = (byte) (mSum >> (liv_Count * 8) & 0xff); } /** end of for (int liv_Count = 0; liv_Count < length; liv_Count++) */ return byteToStr(msg, length) + byteToStr(mByte, mByte.length).substring(byteToStr(mByte, mByte.length).length() - 4, byteToStr(mByte, mByte.length).length()); }}4、demo下载地址 ： https://github.com/z-jc/ScanCode 里面可能还会有一些别的功能，需要的话自行下载
5、另外再提供一个自己封装好的module,https://github.com/z-jc/SerialProject-master,app导入module
然后在activity内直接这样调用
省心又省劲是不是，用到串口的项目可以直接当一个libray导入项目，不过需要检验的话还是得根据自己的校验方法来进行校验
以上全为原创，如有讲解不到之处，还请广大朋友指点一下
下一篇 Android 串口开发（二） 支持设置奇偶校验、数据位、停止位
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