我有一个应用程序，我需要将一些数据写入串口并从中获取响应。现在的顺序如下：
我应该如何解决这个问题并解决它？我不擅长串口编程。我尝试了一个代码但是当我执行发送消息时我的应用程序停止了。可能是因为我在发送消息后正在阅读消息。我真的不知道要解决这个问题。我是否必须在应用程序启动期间开始收听端口？我必须保持端口开放吗？如果我每次需要打开端口都可以吗？以及如何使程序等待响应，直到从端口读取响应消息？请帮我解决这个问题..
- 编辑 -
package testConn;
import forms_helper.global_variables;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.comm.*;
import java.util.*;
/** Check each port to see if it is open. **/
public class openPort implements SerialPortEventListener {
static Enumeration portList;
static CommPortIdentifier portId;
static String messageString;
public static SerialPort serialPort;
static OutputStream outputStream;
InputStream inputStream;
static boolean outputBufferEmptyFlag = false;
public void open() {
Enumeration port_list = CommPortIdentifier.getPortIdentifiers();
while (port_list.hasMoreElements()) {
// Get the list of ports
CommPortIdentifier port_id = (CommPortIdentifier) port_list.nextElement();
if (port_id.getName().equals("/dev/ttyS1")) {
// Attempt to open it
try {
SerialPort port = (SerialPort) port_id.open("PortListOpen", 20);
System.out.println("Opened successfully");
try {
int baudRate = 9600; //
port.setSerialPortParams(
baudRate,
SerialPort.DATABITS_7,
SerialPort.STOPBITS_1,
SerialPort.PARITY_EVEN);
port.setDTR(true);
/*
port.setFlowControlMode(
SerialPort.FLOWCONTROL_NONE);
*
*/
System.out.println("properties are set");
} catch (UnsupportedCommOperationException e) {
System.out.println(e);
}
try {
//input = new SerialReader(in);
port.addEventListener(this);
System.out.println("listeners attached" + this);
} catch (TooManyListenersException e) {
System.out.println("too many listeners");
}
port.notifyOnDataAvailable(true);
//port.notifyOnOutputEmpty(true);
//sendMessage(port,"@PL");
//port.close ();
try {
inputStream = port.getInputStream();
System.out.println("inputstream" + inputStream.available());
outputStream = (OutputStream) port.getOutputStream();
} catch (IOException e) {
System.out.println(e);
}
//set the created variables to global variables
global_variables.port = port;
global_variables.inputStream = inputStream;
global_variables.outputStream = outputStream;
} catch (PortInUseException pe) {
System.out.println("Open failed");
String owner_name = port_id.getCurrentOwner();
if (owner_name == null) {
System.out.println("Port Owned by unidentified app");
} else // The owner name not returned correctly unless it is
// a Java program.
{
System.out.println(" " + owner_name);
}
}
}
}
}
public static void sendMessage(SerialPort port, String msg) {
if (port != null) {
try {
global_variables.outputStream.write(msg.getBytes());
global_variables.outputStream.flush();
try {
Thread.sleep(2000); // Be sure data is xferred before closing
System.out.println("read called");
//SimpleRead read = new SimpleRead();
//int read = global_variables.inputStream.read();
//System.out.println("read call ended"+read);
} catch (Exception e) {
}
} catch (IOException ex) {
Logger.getLogger(openPort.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
public void serialEvent(SerialPortEvent event) {
System.out.println(event.getEventType());
switch (event.getEventType()) {
/*
case SerialPortEvent.BI:
case SerialPortEvent.OE:
case SerialPortEvent.FE:
case SerialPortEvent.PE:
case SerialPortEvent.CD:
case SerialPortEvent.CTS:
case SerialPortEvent.DSR:
case SerialPortEvent.RI:
case SerialPortEvent.OUTPUT_BUFFER_EMPTY:
System.out.println("event.getEventType()");
break;
*
*/
case SerialPortEvent.DATA_AVAILABLE:
System.out.println("inside event handler data available");
byte[] readBuffer = new byte[20];
try {
while (inputStream.available() > 0) {
int numBytes = inputStream.read(readBuffer);
}
System.out.print(new String(readBuffer));
System.exit(1);
} catch (IOException e) {
System.out.println(e);
}
break;
}
}
}
这段代码有什么问题？当我发送轮询消息时，我无法看到终端连接到serialport的响应。我在应用程序启动时打开连接，当我单击应用程序中的按钮时，我正在发送消息。我该如何解决这个问题？
答案 0 :(得分：2)
请参阅this wikibook，事件驱动的串行通信部分。
答案 1 :(得分：2)
之前回答的问题，在这里：How do I get Java to use the serial port in Linux?
根据您的平台（如果您位于* NIX框中），您通常可以使用stty设置波特率/端口设置，然后只需打开/dev/tty*端口即可一个FileInputStream / FileOutputStream。我曾经有一大堆代码可以做到这一点而且运行得非常可靠，但是现在我去寻找它似乎错了。悲伤。