How to create a Tcp Connection in spring boot to accept connections?

Question

I have been through this and understood that I need to create a TcpReceivingChannelAdapter to accept connections. But I don't know how to proceed with that.

Could someone guide me over this?

Answer 1

See the tcp-client-server sample for some pointers using XML configuration.

For Java configuration; here's a simple Spring Boot app...

package com.example;

import java.net.Socket;

import javax.net.SocketFactory;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.integration.annotation.ServiceActivator;
import org.springframework.integration.annotation.Transformer;
import org.springframework.integration.channel.DirectChannel;
import org.springframework.integration.ip.tcp.TcpReceivingChannelAdapter;
import org.springframework.integration.ip.tcp.connection.AbstractServerConnectionFactory;
import org.springframework.integration.ip.tcp.connection.TcpNetServerConnectionFactory;
import org.springframework.integration.transformer.ObjectToStringTransformer;
import org.springframework.messaging.MessageChannel;

@SpringBootApplication
public class So39290834Application {

    public static void main(String[] args) throws Exception {
        ConfigurableApplicationContext context = SpringApplication.run(So39290834Application.class, args);
        Socket socket = SocketFactory.getDefault().createSocket("localhost", 9999);
        socket.getOutputStream().write("foo\r\n".getBytes());
        socket.close();
        Thread.sleep(1000);
        context.close();
    }

    @Bean
    public TcpNetServerConnectionFactory cf() {
        return new TcpNetServerConnectionFactory(9999);
    }

    @Bean
    public TcpReceivingChannelAdapter inbound(AbstractServerConnectionFactory cf) {
        TcpReceivingChannelAdapter adapter = new TcpReceivingChannelAdapter();
        adapter.setConnectionFactory(cf);
        adapter.setOutputChannel(tcpIn());
        return adapter;
    }

    @Bean
    public MessageChannel tcpIn() {
        return new DirectChannel();
    }

    @Transformer(inputChannel = "tcpIn", outputChannel = "serviceChannel")
    @Bean
    public ObjectToStringTransformer transformer() {
        return new ObjectToStringTransformer();
    }

    @ServiceActivator(inputChannel = "serviceChannel")
    public void service(String in) {
        System.out.println(in);
    }

}