Introduction

The other day, "PureJavaComm introduced in" Issues and alternative research of Java serial communication library RXTX Here is a sample of "purejavacomm / purejavacomm.php)". Actually, in addition to "PureJavaComm", "[netty-transport-purejavacomm](https://github.com/steveturner/netty-transport-" I also use purejavacomm) ".

sample

maven Add purejavacomm to pom.xml. Also, "netty-transport-purejavacomm" is copied and used.

`pom.xml`


...
	<dependencies>
		<dependency>
			<groupId>io.netty</groupId>
			<artifactId>netty-all</artifactId>
		</dependency>

		<!-- https://mvnrepository.com/artifact/com.github.purejavacomm/purejavacomm -->
		<dependency>
			<groupId>com.github.purejavacomm</groupId>
			<artifactId>purejavacomm</artifactId>
			<version>1.0.2.RELEASE</version>
		</dependency>
	</dependencies>
...

Java source

This time, I'm creating a sample that simply connects to COM5 and keeps receiving text. For COM5, I used my MONO Wireless TWE-Lite-USB.

`PureJavaCommClient.java`


package net.kyosho.serial.pjc;

import java.util.Enumeration;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.oio.OioEventLoopGroup;
import io.netty.handler.codec.LineBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import purejavacomm.CommPortIdentifier;

public final class PureJavaCommClient {

	public static void main(String[] args) throws Exception {
		CommPortIdentifier portid = null;
		Enumeration<CommPortIdentifier> e = CommPortIdentifier.getPortIdentifiers();
		while (e.hasMoreElements()) {
			portid = (CommPortIdentifier) e.nextElement();
			System.out.println("found " + portid.getName());
		}
		EventLoopGroup group = new OioEventLoopGroup();
		try {
			Bootstrap b = new Bootstrap();
			b.group(group).channel(PureJavaCommChannel.class).handler(new ChannelInitializer<PureJavaCommChannel>() {
				@Override
				public void initChannel(PureJavaCommChannel ch) throws Exception {
					ch.config().setBaudrate(115200).setParitybit(Paritybit.NONE).setStopbits(Stopbits.STOPBITS_1);
					ch.pipeline().addLast(new LineBasedFrameDecoder(32768), new StringEncoder(), new StringDecoder(),
							new PureJavaCommClientHandler());
				}
			});

			ChannelFuture f = b.connect(new PureJavaCommDeviceAddress("COM5")).sync();

			f.channel().closeFuture().sync();
		} finally {
			group.shutdownGracefully();
		}
	}

	private PureJavaCommClient() {
	}
}

`PureJavaCommClientHandler.java`


package net.kyosho.serial.pjc;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

public class PureJavaCommClientHandler extends SimpleChannelInboundHandler<String> {

	@Override
	public void channelActive(ChannelHandlerContext ctx) {
		ctx.writeAndFlush("AT\n");
	}

	@Override
	public void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
		if ("OK".equals(msg)) {
			System.out.println("Serial port responded to AT");
		} else {
			System.out.println("Serial port responded with not-OK: " + msg);
		}
//		ctx.close();
	}
}

Execution result

When executed, the following output will be obtained. For the time being, it can be read that TWE-Lite-USB outputs a counter at 1-second intervals. Alright! I'm connected!

`output`


found COM5
found COM1
found COM3
Serial port responded with not-OK: ::ts=2743
Serial port responded with not-OK: ::ts=2744
Serial port responded with not-OK: ::ts=2745
Serial port responded with not-OK: ::ts=2746
Serial port responded with not-OK: ::ts=2747
Serial port responded with not-OK: ::ts=2748

Evaluation

I'm a little worried that I have to copy and use "netty-transport-purejavacomm", but be aware of the native library. It's easy because you don't have to. How about when you want to communicate easily?

Serial communication sample using purejavacomm

Introduction

sample

pom.xml