Java/Arduino

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我有一个 Java 程序，我必须在其中读取 Arduino 发送的信息.我从 here 获取了 Java 代码.现在，我真的不明白它是如何工作的，但我尝试修改它并得到了这个:

I've got a program in Java where I have to read the information that an Arduino is sending. I took the Java code from here. Now, I didn't really understand how it works, but I tried to modify it and I got this:

import java.io.BufferedReader; import java.io.InputStreamReader; import java.io.OutputStream; import gnu.io.CommPortIdentifier; import gnu.io.SerialPort; import gnu.io.SerialPortEvent; import gnu.io.SerialPortEventListener; import java.util.Enumeration; public class Serial implements SerialPortEventListener { SerialPort serialPort; private static final String PORT_NAMES[] = { "/dev/tty.usbserial-A9007UX1", // Mac OS X "/dev/ttyUSB0", // Linux "COM3", // Windows }; private BufferedReader input; private static OutputStream output; private static final int TIME_OUT = 2000; private static final int DATA_RATE = 115200; public void initialize() { CommPortIdentifier portId = null; Enumeration portEnum = CommPortIdentifier.getPortIdentifiers(); while (portEnum.hasMoreElements()) { CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement(); for (String portName : PORT_NAMES) { if (currPortId.getName().equals(portName)) { portId = currPortId; break; } } } if (portId == null) { System.out.println("Could not find COM port."); return; } try { serialPort = (SerialPort) portId.open(this.getClass().getName(),TIME_OUT); serialPort.setSerialPortParams(DATA_RATE, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE); input = new BufferedReader(new InputStreamReader(serialPort.getInputStream())); output = serialPort.getOutputStream(); serialPort.addEventListener(this); serialPort.notifyOnDataAvailable(true); } catch (Exception e) { System.err.println(e.toString()); } } public synchronized void serialEvent(SerialPortEvent oEvent) { if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) { try { String inputLine=input.readLine(); System.out.println(inputLine); } catch (Exception e) { System.err.println(e.toString()); } } } public synchronized void close() { if (serialPort != null) { serialPort.removeEventListener(); serialPort.close(); } } public Serial(String ncom){ if(Integer.parseInt(ncom)>=3 && Integer.parseInt(ncom)<=9) PORT_NAMES[2] = "COM" + ncom; initialize(); Thread t=new Thread() { public void run() { try {Thread.sleep(1000000);} catch (InterruptedException ie) {} } }; t.start(); System.out.println("Serial Comms Started"); } public synchronized void send(int b){ try{ output.write(b); } catch (Exception e) { System.err.println(e.toString()); } } public synchronized int read(){ int b = 0; try{ b = (int)input.read(); } catch (Exception e) { System.err.println(e.toString()); } return b; } }

我在主程序中使用 COM 端口 创建对象 Serial，然后我在需要时使用 Serial.read 和 Serial.write.

I create the object Serial with the COM port I need in the main program, then I use Serial.read and Serial.write when I need it.

Serial.write 效果很好，Arduino 获取数据并将其显示在 LCD 显示器中.问题是 Serial.read.当程序运行时，它会从串口读取数据(大约每 40 毫秒)，但这并不意味着 Arduino 发送了一些东西.Arduino 仅在按下按钮时发送一个字节.因此，当 Java 代码运行时，它会在读取内容之前抛出n"异常，这会造成很大的延迟.

Serial.write works great, Arduino gets the data and show it in a LCD Display. The problem is Serial.read. When the program is running, it keep read from serial port (around every 40ms), but that doesn't mean Arduino sent something. Arduino sends a byte only when a button is pushed. So, when the Java code is running, it throws "n" Exception before read something, and this couses so much lag.

我知道我需要类似 Serial.available() 的东西，我尝试了 input.available()，但它不起作用.我不知道如何解决这个问题.

I know I need something like Serial.available(), I tried input.available(), but it doesn't work. I don't know how to solve this problem.

如果你有一个有效的代码，如果你能把它给我，我会非常感激.我只需要两种方法，读和写，我不在乎代码是如何工作的:D

If you have a code that working, I'd be so much grateful if you could give it to me. I just need two methods, read and write, I don't care how the code works :D

我更改了 Serial 类，现在它又像 apremalal 所说的那样具有这种方法

I changed the Serial class, now it has again this method as apremalal said

public synchronized void serialEvent(SerialPortEvent oEvent) { if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) { try { String inputLine=null; if (input.ready()) { inputLine = input.readLine(); panel.read(inputLine); } } catch (Exception e) { System.err.println(e.toString()); } } }

在另一个班级(在这种情况下为面板)我有这个:

and in the other class (Panel in this case) I've got this:

public void read(String data){ System.out.println(data); System.out.println(data == "255"); if(data == "255") //code here }

它正确打印值，但 data == "255" 总是错误的，即使我真的得到 255....我试图做 Integer.parseInt 但没有任何改变.为什么?

It print the values correctly but data == "255" is always false, even if I really get a 255 ....I tried to do Integer.parseInt but nothing changed. Why the hell?

好的解决了:

public void read(String data){ serialRead = Integer.parseInt(data); if(serialRead == 255) //code here }

现在它的工作..不知道为什么我必须这样做...嗯，随便 :)

Now it's work..don't know why I had to do this... meh whatever :)

推荐答案

您不想专门编写一个读取函数，它已经存在于示例代码中.正如 TheMerovingian 指出的，您可以在读取之前检查输入缓冲区.这里是我在其中一个项目中使用的工作代码.

You don't want to specifically write a read function it's already there in the sample code.As TheMerovingian pointed out you can check the input Buffer before reading.Here is the working code which I have used in one of my projects.

import java.io.BufferedReader; import java.io.InputStreamReader; import java.io.OutputStream; import gnu.io.CommPortIdentifier; import gnu.io.SerialPort; import gnu.io.SerialPortEvent; import gnu.io.SerialPortEventListener; import java.util.Enumeration; public class SerialTest implements SerialPortEventListener { SerialPort serialPort; /** The port we're normally going to use. */ private static final String PORT_NAMES[] = { "/dev/tty.usbserial-A9007UX1", // Mac OS X "/dev/ttyUSB0", // Linux "COM35", // Windows }; private BufferedReader input; private OutputStream output; private static final int TIME_OUT = 2000; private static final int DATA_RATE = 9600; public void initialize() { CommPortIdentifier portId = null; Enumeration portEnum = CommPortIdentifier.getPortIdentifiers(); //First, Find an instance of serial port as set in PORT_NAMES. while (portEnum.hasMoreElements()) { CommPortIdentifier currPortId = (CommPortIdentifier) portEnum.nextElement(); for (String portName : PORT_NAMES) { if (currPortId.getName().equals(portName)) { portId = currPortId; break; } } } if (portId == null) { System.out.println("Could not find COM port."); return; } try { serialPort = (SerialPort) portId.open(this.getClass().getName(), TIME_OUT); serialPort.setSerialPortParams(DATA_RATE, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE); // open the streams input = new BufferedReader(new InputStreamReader(serialPort.getInputStream())); output = serialPort.getOutputStream(); serialPort.addEventListener(this); serialPort.notifyOnDataAvailable(true); } catch (Exception e) { System.err.println(e.toString()); } } public synchronized void close() { if (serialPort != null) { serialPort.removeEventListener(); serialPort.close(); } } public synchronized void serialEvent(SerialPortEvent oEvent) { if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) { try { String inputLine=null; if (input.ready()) { inputLine = input.readLine(); System.out.println(inputLine); } } catch (Exception e) { System.err.println(e.toString()); } } // Ignore all the other eventTypes, but you should consider the other ones. } public static void main(String[] args) throws Exception { SerialTest main = new SerialTest(); main.initialize(); Thread t=new Thread() { public void run() { //the following line will keep this app alive for 1000 seconds, //waiting for events to occur and responding to them (printing incoming messages to console). try {Thread.sleep(1000000);} catch (InterruptedException ie) {} } }; t.start(); System.out.println("Started"); } }

serialEvent 函数负责读取缓冲区.

EDIT : serialEvent function is responsible for reading the buffer.

public synchronized void serialEvent(SerialPortEvent oEvent) { if (oEvent.getEventType() == SerialPortEvent.DATA_AVAILABLE) { try { String inputLine=null; if (input.ready()) { inputLine = input.readLine(); System.out.println(inputLine); } } catch (Exception e) { System.err.println(e.toString()); } } // Ignore all the other eventTypes, but you should consider the other ones. }