Android 串口通信之间的发送数据与接收数据（详解）

左手的ㄟ右手 2022-06-10 10:54 2062阅读 0赞

最近在做自动售货机的程序，需要用到串口，经过几天的时间终于搞明白了，先来个效果图，下面是我发送的数据和接收数据的图片，下面直接上代码：![Center][]

新建一个类：SerialPortFinder，添加如下代码：

public class SerialPortFinder {
    
       public class Driver {
          public Driver(String name, String root) {
             mDriverName = name;
             mDeviceRoot = root;
          }
          private String mDriverName;
          private String mDeviceRoot;
          Vector<File> mDevices = null;
          public Vector<File> getDevices() {
             if (mDevices == null) {
                mDevices = new Vector<File>();
                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<Driver> mDrivers = null;
    
       Vector<Driver> getDrivers() throws IOException {
          if (mDrivers == null) {
             mDrivers = new Vector<Driver>();
             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<String> devices = new Vector<String>();
          // Parse each driver
          Iterator<Driver> itdriv;
          try {
             itdriv = getDrivers().iterator();
             while(itdriv.hasNext()) {
                Driver driver = itdriv.next();
                Iterator<File> 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()]);
       }
    
       public String[] getAllDevicesPath() {
          Vector<String> devices = new Vector<String>();
          // Parse each driver
          Iterator<Driver> itdriv;
          try {
             itdriv = getDrivers().iterator();
             while(itdriv.hasNext()) {
                Driver driver = itdriv.next();
                Iterator<File> 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()]);
       }

新建SerialPort类，这个类主要用来加载SO文件，通过JNI的方式打开关闭串口

public class SerialPort {
    
       private static final String TAG = "SerialPort";
    
       /*
        * Do not remove or rename the field mFd: it is used by native method close();
        */
       private FileDescriptor mFd;
       private FileInputStream mFileInputStream;
       private FileOutputStream mFileOutputStream;
    
       public SerialPort(File device, int baudrate, int flags) throws SecurityException, IOException {
    
          /* Check access permission */
          if (!device.canRead() || !device.canWrite()) {
             try {
                /* Missing read/write permission, trying to chmod the file */
                Process su;
                su = Runtime.getRuntime().exec("/system/bin/su");
                String cmd = "chmod 666 " + 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
       private native static FileDescriptor open(String path, int baudrate, int flags);
       public native void close();
       static {
          System.loadLibrary("serial_port");
       }
    }

发送和接收串口的Activity

public class ComAActivity extends Activity {
        EditText editTextRecDisp;
        Button ButtonSendCOMA;
        SerialControl ComA;//串口
        DispQueueThread DispQueue;//刷新显示线程
        SerialPortFinder mSerialPortFinder;//串口设备搜索
        /**
         * Called when the activity is first created.
         */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main2);
            ComA = new SerialControl();
            DispQueue = new DispQueueThread();
            DispQueue.start();
            setControls();
            //开启串口
            ComA.setPort("/dev/ttyS2");
            ComA.setBaudRate("115200");
            OpenComPort(ComA);
        }
    
        @Override
        public void onDestroy() {
            CloseComPort(ComA);
            super.onDestroy();
        }
    
        @Override
        public void onBackPressed() {
            AseoZdpAseo.initPush(this);
            Intent intent = new Intent(Intent.ACTION_MAIN);
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            intent.addCategory(Intent.CATEGORY_HOME);
            AseoZdpAseo.initFinalTimer(this);
            startActivity(intent);
        }
    
        //----------------------------------------------------
        private void setControls() {
            editTextRecDisp = (EditText) findViewById(R.id.editTextRecDisp);
            ButtonSendCOMA = (Button) findViewById(R.id.ButtonSendCOMA);
            ButtonSendCOMA.setOnClickListener(new ButtonClickEvent());
            mSerialPortFinder = new SerialPortFinder();
            String[] entryValues = mSerialPortFinder.getAllDevicesPath();
            List<String> allDevices = new ArrayList<String>();
            for (int i = 0; i < entryValues.length; i++) {
                allDevices.add(entryValues[i]);
            }
        }
    
        //----------------------------------------------------清除按钮、发送按钮
        class ButtonClickEvent implements View.OnClickListener {
            public void onClick(View v) {
                if (v == ButtonSendCOMA) {
                    sendPortData(ComA, "01023101000035");
                }
            }
        }
    
        //----------------------------------------------------串口控制类
        private class SerialControl extends SerialHelper {
            public SerialControl() {
            }
    
            @Override
            protected void onDataReceived(final ComBean ComRecData) {
                DispQueue.AddQueue(ComRecData);//线程定时刷新显示(推荐)
            }
        }
    
        //----------------------------------------------------刷新显示线程
        private class DispQueueThread extends Thread {
            private Queue<ComBean> QueueList = new LinkedList<ComBean>();
    
            @Override
            public void run() {
                super.run();
                while (!isInterrupted()) {
                    final ComBean ComData;
                    while ((ComData = QueueList.poll()) != null) {
                        runOnUiThread(new Runnable() {
                            public void run() {
                                DispRecData(ComData);
                            }
                        });
                        try {
                            Thread.sleep(100);//显示性能高的话，可以把此数值调小。
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                        break;
                    }
                }
            }
    
            public synchronized void AddQueue(ComBean ComData) {
                QueueList.add(ComData);
            }
        }
    
        //----------------------------------------------------显示接收数据
        private void DispRecData(ComBean ComRecData) {
            StringBuilder sMsg = new StringBuilder();
            sMsg.append(ComRecData.sRecTime);
            sMsg.append("[");
            sMsg.append(ComRecData.sComPort);
            sMsg.append("]");
            sMsg.append("[Hex] ");
            sMsg.append(MyFunc.ByteArrToHex(ComRecData.bRec));
            sMsg.append("\r\n");
            /**
             * 接收串口的数据返回值，并且做相应的处理
             */
            editTextRecDisp.append(sMsg);
            String[] temp = MyFunc.StrToStrArray(MyFunc.ByteArrToHex(ComRecData.bRec));
            if (temp.equals("FF 01 01 01 02 01 04 ")) {
                Toast.makeText(ComAActivity.this, "您连接了主板", Toast.LENGTH_SHORT).show();
            }
        }
    
        //----------------------------------------------------串口发送
        private void sendPortData(SerialHelper ComPort, String sOut) {
            if (ComPort != null && ComPort.isOpen()) {
                ComPort.sendHex(sOut);
            }
        }
    
        //----------------------------------------------------关闭串口
        private void CloseComPort(SerialHelper ComPort) {
            if (ComPort != null) {
                ComPort.stopSend();
                ComPort.close();
            }
        }
    
        //----------------------------------------------------打开串口
        private void OpenComPort(SerialHelper ComPort) {
            try {
                ComPort.open();
            } catch (SecurityException e) {
                ShowMessage("打开串口失败:没有串口读/写权限!");
            } catch (IOException e) {
                ShowMessage("打开串口失败:未知错误!");
            } catch (InvalidParameterException e) {
                ShowMessage("打开串口失败:参数错误!");
            }
        }
    
        //------------------------------------------显示消息
        private void ShowMessage(String sMsg) {
            Toast.makeText(this, sMsg, Toast.LENGTH_SHORT).show();
        }
    }

布局文件

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical">
        <LinearLayout
            android:id="@+id/LinearLayoutRecDisp"
            android:layout_width="match_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1">
    
            <EditText
                android:id="@+id/editTextRecDisp"
                android:layout_width="fill_parent"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:clickable="false"
                android:editable="false"
                android:gravity="top"
                android:longClickable="false"
                android:textSize="14sp" />
        </LinearLayout>
    
        <Button
            android:id="@+id/ButtonSendCOMA"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="发送" />
    
    </LinearLayout>

综合以上就可以实现串口间的通讯；程序考进去以后有问题可直接留言给我，我会为大家解答

**整个Demo下载地址：[http://download.csdn.net/download/chen\_xiaobao/9929474][http_download.csdn.net_download_chen_xiaobao_9929474]**

[Center]: /images/20220610/cb044ce6a7b04645b5a069ba354888d2.png
[http_download.csdn.net_download_chen_xiaobao_9929474]: http://download.csdn.net/download/chen_xiaobao/9929474