从嵌入式android打印到USB或预选的网络打印机

Question

My product is an industrial measurement instrument that uses embedded Android. The instrument needs to print results to a pre-selected network printer or to a USB printer. The instrument operator cannot be burdened with the standard Android printer interface, and Cloud printing is not acceptable. I would think this situation is fairly common in products with embedded Android (eg, POS thermal printers)

I have code which can find the available printers on the network and return the IP address and port numbers, and I can write plain ANSI text to the printer. However, Unicode characters do not print correctly. A few other non-ANSI characters also print (some European letter variants). I believe this is because of the default "symbol set".

My expectation is that I will use PCL or IPP to control the printer. All text starting with "@PCL" is printed as plain text. All text started with ESC is not printed, but I don't have any reason to believe that such commands are being processed.

Searching the 'web, I see this question has been asked a few times, but not well answered.

I am wondering whether there is something wrong with my Socket/InputStream/BufferedReader usage.

Has anyone designed a solution for this usage?

final char ESC = 0x1b;
final String UEL = ESC + "%-12345X";
final String CRLF = "\r\n";
Socket socket = new Socket(printer.getIpAddr(), 9100);
InputStream inputStream = socket.getInputStream();
DataOutputStream oStream = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream()));
write(oStream, UEL + "@PJL" + "\r\n");
write(oStream, "@PJL COMMENT some comments"  + CRLF);
write(oStream, "@PJL ECHO RRE" + CRLF);
write(oStream, UEL + "\r\n");
oStream.flush();

BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream);
int count = bufferedInputStream.available();

The local 'write' method creates a byte array in UTF-8 from the Java String and writes the bytes to the stream. Note that for these characters, UTF-8 is ANSI

Answer 1

Firstly, are you sure the printer speaks PJL and PCL ? Some special printers have their own languages.

Secondly, I think your PJL has an extra newline. It seem that the First PJL command has no newline from the PJL escape.

Sample PJL from the HP PJL reference manual.

%–12345X@PJL COMMENT *Start Job* 
@PJL JOB NAME = "Sample Job #1" 
@PJL SET COPIES = 3 
@PJL SET RET = OFF 
@PJL ENTER LANGUAGE = PCL 
E. . . . PCL job . . . .E
~
%–12345X@PJL 
@PJL EOJ
%–12345X

PJL reference