spring-integration - Kotlin Java DSL：从 byte[] 转换为 String

Question

我正在将tcp-client-serverSpring Integration 的示例转换为使用 Java DSL 和 Kotlin。

在我的入站 TCP 服务器中，我需要将byte[]来自通道的 a转换String为我的 echo 服务的 a。

这是我当前的流程定义：

@EnableIntegration
@IntegrationComponentScan
@Configuration
class ClientServerDemoConfig {

@MessagingGateway(defaultRequestChannel = "input", name = "gw")
interface SimpleGateway {
    fun send(text: String): String
}

@Bean
fun outboundTCP() =
    IntegrationFlows.from("input")
        .handle(Tcp.outboundGateway(TcpNetClientConnectionFactory("127.0.0.1", 7777)))
        .get()

@Bean
fun inboundTCP() =
    IntegrationFlows.from(Tcp.inboundGateway(TcpNetServerConnectionFactory(7777)))
        .transform<Array<Byte>, String> { p -> String(p.toByteArray()) }
        .handle(EchoService(), "test")
        .get()

在 intellij 中运行时会导致：

Caused by: java.lang.IllegalStateException: Cannot convert value of type 'byte[]' to required type 'java.lang.String': no matching editors or conversion strategy found
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:299) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]

奇怪的是，在调试时我可以看到正在执行的转换器，但后来我迷失在细节中，试图找出它为什么不工作。

有人可以就我没有做或做错的事情提供一些意见吗？

谢谢！

dependencies {
    compile('org.springframework.boot:spring-boot-starter-integration')
    compile('org.springframework.integration:spring-integration-ip')
    compile("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
    compile("org.jetbrains.kotlin:kotlin-reflect")
    runtime('org.springframework.boot:spring-boot-devtools')
    testCompile('org.springframework.boot:spring-boot-starter-test')
}

堆栈跟踪：

2018-07-10 16:53:59.726 ERROR 20187 --- [  restartedMain] o.s.boot.SpringApplication               : Application run failed

java.lang.IllegalStateException: Failed to execute CommandLineRunner
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:800) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:781) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:335) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    at alwyn.tcpclientserver.ClientServerDemoApplicationKt.main(ClientServerDemoApplication.kt:29) [main/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_161]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_161]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_161]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_161]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.0.3.RELEASE.jar:2.0.3.RELEASE]
Caused by: org.springframework.beans.ConversionNotSupportedException: Failed to convert value of type 'byte[]' to required type 'java.lang.String'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'byte[]' to required type 'java.lang.String': no matching editors or conversion strategy found
    at org.springframework.beans.TypeConverterSupport.doConvert(TypeConverterSupport.java:77) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.TypeConverterSupport.convertIfNecessary(TypeConverterSupport.java:44) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.integration.gateway.GatewayProxyFactoryBean.convert(GatewayProxyFactoryBean.java:763) ~[spring-integration-core-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.integration.gateway.GatewayProxyFactoryBean.invokeGatewayMethod(GatewayProxyFactoryBean.java:532) ~[spring-integration-core-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.integration.gateway.GatewayProxyFactoryBean.doInvoke(GatewayProxyFactoryBean.java:469) ~[spring-integration-core-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.integration.gateway.GatewayProxyFactoryBean.invoke(GatewayProxyFactoryBean.java:460) ~[spring-integration-core-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at com.sun.proxy.$Proxy60.send(Unknown Source) ~[na:na]
    at alwyn.tcpclientserver.ClientServerDemoApplication.run(ClientServerDemoApplication.kt:19) ~[main/:na]
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:797) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
    ... 10 common frames omitted
Caused by: java.lang.IllegalStateException: Cannot convert value of type 'byte[]' to required type 'java.lang.String': no matching editors or conversion strategy found
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:299) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:99) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    at org.springframework.beans.TypeConverterSupport.doConvert(TypeConverterSupport.java:73) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
    ... 20 common frames omitted

标签： spring-integration

Answer 1

TCP/IP 确实是一种byte[]协议，因此很自然地，这种类型将被发送到出站端并从入站端接收。

对于您的fun send(text: String): String网关合同，您确实需要在byte[] -> String通过Tcp.outboundGateway(). 因此，要为您解决这种情况，您需要在客户端有这样的东西：

@Bean
fun outboundTCP() =
    IntegrationFlows.from("input")
        .handle(Tcp.outboundGateway(TcpNetClientConnectionFactory("127.0.0.1", 7777)))
        .transform(Transformers.objectToString())
        .get()