java - 无法读取调制解调器的所有消息

Question

我需要帮助才能使用命令 AT+CMGL="ALL"读取所有收件箱消息。使用我的java代码，我只能显示两条消息向上。实际上，当我在 super 终端中尝试该命令时，有 10 条消息。

这是我的代码:

    /*
     * To change this template, choose Tools | Templates
     * and open the template in the editor.
     */
    package consoledmt;

    /**
     *
     * @author user
     */
    import javax.comm.*;
    import java.util.*;
    import java.io.*;
    public class Main {

    public Main() {
    }

    public static void main(String[] args) {

        Enumeration portIdentifiers = CommPortIdentifier.getPortIdentifiers();
        CommPortIdentifier portId = null; // will be set if port found
        String wantedPortName = "COM17";
        while (portIdentifiers.hasMoreElements()) {
            CommPortIdentifier pid = (CommPortIdentifier) portIdentifiers
                    .nextElement();
            if (pid.getPortType() == CommPortIdentifier.PORT_SERIAL
                    && pid.getName().equals(wantedPortName)) {
                portId = pid;
                break;
            }
        }
        if (portId == null) {
            System.err.println("Could not find serial port " + wantedPortName);
            System.exit(0);
        }

        SerialPort port = null;
        try {
            port = (SerialPort) portId.open("Wavecom", 10000); // Wait max. 10
        } catch (PortInUseException e) {
            System.err.println("Port already in use: " + e);
            System.exit(1);
        }
        try {
            port.setSerialPortParams(115200, SerialPort.DATABITS_8,
                    SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
        } catch (Exception e) {
            System.out.println(e.toString());
        }

        BufferedReader is = null;
        PrintStream os = null;

        try {
            is = new BufferedReader(new InputStreamReader(port.getInputStream()));
        } catch (IOException e) {
            System.err.println("Can't open input stream");
            is = null;
        }

        try {
            os = new PrintStream(port.getOutputStream(), true);
        } catch (IOException e) {
            System.err.println("Can't open output stream");
            is = null;
        }
        os.print("AT+CMGL=\"ALL\"");
        os.print("\r\n");
        try {
            System.out.println(is.readLine());
            System.out.println(is.readLine());
            System.out.println(is.readLine());
        }

        catch (IOException e) {
            System.err.println("Can't recieve input signals");
        }
        port.close();
    }
}

以下消息是我从 super 终端收到的消息。

+CMGL: 1,"REC READ","777",,"15/08/12,11:03:30+28"
Total saldo DompetKu anda adalah 100000
+CMGL: 2,"REC READ","INDOSAT",,"15/08/12,08:00:00+00"
Total saldo DompetKu anda adalah 100000
+CMGL: 3,"REC READ","777",,"15/08/12,11:08:49+28"
Total saldo DompetKu anda adalah 100000
+CMGL: 4,"REC READ","777",,"15/08/12,16:24:49+28"
Total saldo DompetKu anda adalah 100000
+CMGL: 5,"REC READ","777",,"15/08/12,16:31:36+28"
Total saldo DompetKu anda adalah 100000
+CMGL: 6,"REC READ","777",,"15/08/12,16:32:58+28"
Total saldo DompetKu anda adalah 100000
+CMGL: 7,"REC READ","777",,"15/08/12,16:34:15+28"
Total saldo DompetKu anda adalah 100000
+CMGL: 8,"REC READ","777",,"15/08/12,16:41:00+28"
Total saldo DompetKu anda adalah 100000
+CMGL: 9,"REC READ","777",,"15/08/12,16:42:54+28"
Total saldo DompetKu anda adalah 100000
+CMGL: 10,"REC READ","777",,"15/08/12,16:45:18+28"
Total saldo DompetKu anda adalah 100000

如何在 Java 中获得相同的结果？

Answer 1

首先是一般性评论:您应该能够通过这个简单的请求访问您的端口:

String String wantedPortName = "COM17";= "COM17";
try {
    CommPortIdentifier portId = CommPortIdentifier(wantedPortName);
}
catch(NoSuchPortException ex) {
    System.err.println("Could not find serial port " + wantedPortName);
    System.exit(0);
}

但你真正的问题是你只从串口读取了 3 行，而不是循环读取所有内容。读取串口时最困难的部分是你很难知道数据是否即将到达。常见的处理方法有两种:

1. 您的驱动程序支持读取超时:

   首先启用它:

   port.enableReceiveTimeout(2000); // assume 2 s is long enough to wait
   if (! port.isReceiveTimeout) {
       System.out.println("Receive timeout is not supported");
       port.close(); // maybe more housekeeping is needed...
       System.exit(0);
   }
   

   next 只是循环直到空读取(注意在 Java 中未经测试):

   os.print("AT+CMGL=\"ALL\"");
   os.print("\r\n");
   try {
       String line;
       while(true) {
           line = is.readLine());
           if (is.isEmpty()) { break; }
           System.out.println(is.readLine());
   }
   catch (IOException e) {
       System.err.println("Can't recieve input signals");
   }
   

2. 使用一个专用线程来处理输入行，并在没有更多需要处理的地方终止它。