rest-http-interface example code can't run

[Fabriceli]

Base info:

• JAVA version: 17
• Spring boot version: 3.2.6

Reproduce steps:

1. copy this code from rest-http-interface

interface RepositoryService {

	@GetExchange("/repos/{owner}/{repo}")
	Repository getRepository(@PathVariable String owner, @PathVariable String repo);

	// more HTTP exchange methods...

}

2. run the project got error:

2025-02-18T16:08:00.290+08:00 ERROR 41328 --- [nio-8088-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed: java.lang.IllegalArgumentException: non-public interface is not defined by the given loader] with root cause

java.lang.IllegalArgumentException: non-public interface is not defined by the given loader
	at java.base/java.lang.reflect.Proxy$ProxyBuilder.mapToModule(Proxy.java:818) ~[na:na]
	at java.base/java.lang.reflect.Proxy$ProxyBuilder.<init>(Proxy.java:651) ~[na:na]
	at java.base/java.lang.reflect.Proxy.lambda$getProxyConstructor$1(Proxy.java:440) ~[na:na]
	at java.base/jdk.internal.loader.AbstractClassLoaderValue$Memoizer.get(AbstractClassLoaderValue.java:329) ~[na:na]
	at java.base/jdk.internal.loader.AbstractClassLoaderValue.computeIfAbsent(AbstractClassLoaderValue.java:205) ~[na:na]
	at java.base/java.lang.reflect.Proxy.getProxyConstructor(Proxy.java:438) ~[na:na]
	at java.base/java.lang.reflect.Proxy.newProxyInstance(Proxy.java:1037) ~[na:na]
	at org.springframework.aop.framework.JdkDynamicAopProxy.getProxy(JdkDynamicAopProxy.java:124) ~[spring-aop-6.1.8.jar:6.1.8]
	at org.springframework.aop.framework.JdkDynamicAopProxy.getProxy(JdkDynamicAopProxy.java:116) ~[spring-aop-6.1.8.jar:6.1.8]
	at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:97) ~[spring-aop-6.1.8.jar:6.1.8]
	at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:137) ~[spring-aop-6.1.8.jar:6.1.8]
	at org.springframework.web.service.invoker.HttpServiceProxyFactory.createClient(HttpServiceProxyFactory.java:91) ~[spring-web-6.1.8.jar:6.1.8]
	at com.igwfmc.DemoController.proxy(DemoController.java:32) ~[main/:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:568) ~[na:na]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:255) ~[spring-web-6.1.8.jar:6.1.8]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:188) ~[spring-web-6.1.8.jar:6.1.8]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:118) ~[spring-webmvc-6.1.8.jar:6.1.8]

Solution

Adding 'public' before an interface class

public interface RepositoryService {

	@GetExchange("/repos/{owner}/{repo}")
	Repository getRepository(@PathVariable String owner, @PathVariable String repo);

	// more HTTP exchange methods...

}

[sdeleuze]

@Fabriceli I can't reproduce with a simple app, could you please share a reproducer?

[Fabriceli]

@Fabriceli I can't reproduce with a simple app, could you please share a reproducer?

Reproducer include 4 files:

1. Demo.java

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@Slf4j
@SpringBootApplication
public class Demo {
    public static void main(String[] args) {
        SpringApplication application = new SpringApplication(Demo20250211.class);
        application.run(args);
    }
}

2. DemoController.java

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.reactive.function.client.WebClient;
import org.springframework.web.reactive.function.client.support.WebClientAdapter;
import org.springframework.web.service.invoker.HttpServiceProxyFactory;

@Slf4j
@RestController
public class DemoController {

  @GetMapping("/proxy")
  public String proxy(){
    WebClient webClient = WebClient.builder().baseUrl("http://httpbin.org").build();
    WebClientAdapter adapter = WebClientAdapter.create(webClient);
    HttpServiceProxyFactory factory = HttpServiceProxyFactory.builderFor(adapter).build();
    Httpbin service = factory.createClient(Httpbin.class);

      return service.getIp();
  }
}

3. Httpbin.java

import org.springframework.web.service.annotation.GetExchange;

interface Httpbin {
    @GetExchange("/ip")
    String getIp();
}

4. build.gradle

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation 'org.springframework.boot:spring-boot-starter-webflux'
}

If it can reproducer, could you assign it to me to fix?

[sdeleuze]

Since this has been created as an issue and is a simple change I had already locally, I pushed it myself. Next time, feel free to directly create a PR instead of an issue.