TcpInboundGateway - 读取特定字节数

Question

How should i implement service activator to read specific number of bytes ?

My context.xml,

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:int="http://www.springframework.org/schema/integration"
    xmlns:int-ip="http://www.springframework.org/schema/integration/ip"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
        http://www.springframework.org/schema/integration/ip http://www.springframework.org/schema/integration/ip/spring-integration-ip.xsd">

    <int:annotation-config />

    <context:component-scan base-package="com.spring.integration.tcp" />

<bean id="tcpDeserializer"
    class="org.springframework.integration.ip.tcp.serializer.ByteArrayLengthHeaderSerializer">
    <property name="maxMessageSize" value="300" />
</bean>

    <int-ip:tcp-connection-factory id="tcpConnectionFactory" type="server" port="9070" using-nio="true" deserializer="tcpDeserializer" />

    <int:channel id="tcpRequestChannel" />

    <int-ip:tcp-inbound-gateway id="tcpInboundGateway" connection-factory="tcpConnectionFactory" request-channel="tcpRequestChannel" />

    <bean id="messageHandler" class="com.spring.integration.tcp.MessageHandler" />

    <int:service-activator id="tcpServiceActivator" input-channel="tcpRequestChannel" ref="messageHandler" method="receiveAndSend" />

</beans>

My message handler,

package com.spring.integration.tcp;

import java.io.InputStream;
import java.util.Arrays;


public class MessageHandler
{
    public byte[] receiveAndSend(final InputStream inputStream) throws Exception
    {
        int bytesToRead = 50;
        final byte[] requestMessageBytes = new byte[bytesToRead];
        int read = 0;
        while (bytesToRead > read)
        {
            final int c = inputStream.read(requestMessageBytes, read, bytesToRead - read);
            if (c == -1)
            {

                throw new Exception("EOF");
            }
            read += c;
        }
        System.out.println("server received - length [" + requestMessageBytes.length + "] bytes " + Arrays.toString(requestMessageBytes));
        final byte[] responseMessageBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
        System.out.println("server sending - " + Arrays.toString(responseMessageBytes));
        return responseMessageBytes;
    }
}

I would like to read first 4 bytes and determine the incoming message length(from first 4 bytes) and then read message bytes whose length is specified by first 4 bytes.

After adding deserializer I get the following exception. Though i send a byte array of length 161.

final byte[] data = new byte[] { 2,....};

Exception,

Sep 28, 2015 7:03:28 PM org.springframework.integration.ip.tcp.connection.TcpNetConnection handleReadException
SEVERE: Read exception localhost:54756:9070:a580527b-95bd-42c7-b1cc-e0726b433199 IOException:Message length 38159362 exceeds max message length: 300

Should the client be based on spring integration to be able to send a message to spring integration based server ?

Answer 1

You should configure ByteArrayLengthHeaderSerializer as a deserializer on the <int-ip:tcp-connection-factory> definition.

See its JavaDocs for more info:

 * The default length field is a 4 byte signed integer. During deserialization,
 * negative values will be rejected.
 * Other options are an unsigned byte, and unsigned short.