Java 实现并行端口打印机打印 （communications API）

[java]代码库

import java.io.*;
import java.util.*;
import javax.comm.*;
public class SimpleLPTPort  {
       Enumeration ports;
       CommPortIdentifier portId;
      
       ParallelPort LPTPort;
      
    protected OutputStream out;
   
    String outPrintStr = "When an \n\rinput method \n\ris activated, ";
       public SimpleLPTPort() {
              checkLPTPort();
       }
      
       public void checkLPTPort() {
             
              ports = CommPortIdentifier.getPortIdentifiers();
             
              if (ports == null) {
                     System.out.println("No comm ports found!");
                     System.exit(0);
              }
             
              while (ports.hasMoreElements()) {
                     // Get the specific port
                     portId = (CommPortIdentifier)ports.nextElement();
                    
                     // Is this a parallel port?
                     if (portId.getPortType() == CommPortIdentifier.PORT_PARALLEL) {
                            // Is the port in use?
                            if (portId.isCurrentlyOwned()) {
                                   System.out.println("Detected "
                                                                      + portId.getName()
                                                                      + " in use by "
                                                                      + portId.getCurrentOwner());
                            }
                           
                            // Try to open the port.
                            try {
                                  
                                   try {
                                          //for(int i = 0; i <=2; i++) {
                                                 LPTPort = (ParallelPort)portId.open("ParallelPort", 2000);
                                                
                                                 System.out.println(LPTPort.getName() + " a LPT port is opened.");
                                                
                                                 if (LPTPort == null) {
                                                        System.out.println("Error opening LPT port "
                                                        + LPTPort.getName());
                                                 }
                                                
                                                 // Get the output stream                                          
                                                 try
                                                 {
                                                        out = LPTPort.getOutputStream();
                                                 }
                                                
                                                 catch (IOException e)
                                                 {
                                                        System.out.println("Cannot open output stream");
                                                 }
                                                
                                                 out.write(outPrintStr.getBytes()); 
                                                 System.out.println(outPrintStr.getBytes());
                                                 LPTPort.close();
                                                 System.out.println(LPTPort.getName() + " is closing.");
                                          //}
                                          System.out.println("Output stream complete.");
                                          //LPTPort.close();
                                          System.exit(0);
                                         
                                   } catch (IOException ex) {
                                          System.out.println("Output stream fail.");
                                          System.out.println(LPTPort.getName()
                                                                             + ": Cannot write to output stream");
                                          LPTPort.close();
                                          System.exit(0);
                                   }
                           
                            } catch (PortInUseException e) {
                                   System.out.println("Queueing open for "
                                                                     + portId.getName()
                                                                     + ": port in use by "
                                                                    + e.currentOwner);
                            }
                     }
              }
             
       }
      
       public static void main(String[] args) {
              new SimpleLPTPort();
       }
      
}