“Circular view path” in a simple Spring Boot proje

问题:

I have a simple Spring Boot project with this Gradle build file:

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'spring-boot'
apply plugin: 'war'

sourceCompatibility = 1.7
targetCompatibility = 1.7

version = '1.0'

buildscript {
    ext {
        springBootVersion = '1.1.9.RELEASE'
    }
    repositories {
        maven { url "http://repo.spring.io/libs-snapshot" }
        mavenLocal()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:1.1.9.RELEASE")
    }
}

jar {
    manifest {
        attributes 'Implementation-Title': 'Potlatch Server', 'Implementation-Version': version
    }
}

war {
    baseName = 'gs-convert-jar-to-war'
    version =  '0.1.0'
}

repositories {
    mavenCentral()
    maven { url "http://repo.spring.io/libs-snapshot" }
    maven { url "http://maven.springframework.org/milestone" }
}

dependencies {
    compile("org.springframework.boot:spring-boot-starter-web:${springBootVersion}")

    compile("org.springframework.boot:spring-boot-starter-tomcat:${springBootVersion}")

    compile("org.springframework.boot:spring-boot-starter-actuator:${springBootVersion}")
    compile("org.springframework.boot:spring-boot-starter-aop:${springBootVersion}")
    compile("org.springframework.boot:spring-boot-starter-test:${springBootVersion}")
    compile("org.springframework.boot:spring-boot-starter-data-jpa:${springBootVersion}")

    compile("org.springframework.data:spring-data-rest-webmvc")

    compile("org.hsqldb:hsqldb")

    compile("com.google.guava:guava:17.0")
    compile("org.apache.httpcomponents:httpclient:4.3.4")
    compile("com.squareup.retrofit:retrofit:1.6.0")
    compile("commons-io:commons-io:2.4")

    testCompile("junit:junit")
}

This Application file:

@EnableAutoConfiguration
@Configuration
@ComponentScan
public class Application extends RepositoryRestMvcConfiguration {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Override
    public ObjectMapper halObjectMapper() {
        return new ResourcesMapper();
    }

}

This controller interface:

public interface Controller {

    @RequestMapping(value = "/test", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    public void test();
}

And this controller implementation:

@Controller
public class ControllerImpl implements Controller {

    @Override
    public void test() {
    }

}

The application starts without errors, but when a send an HTTP GET request to http://localhost:8080/test, I receive this error:

javax.servlet.ServletException: Circular view path [test]: would dispatch back to the current handler URL [/test] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)
    at org.springframework.web.servlet.view.InternalResourceView.prepareForRendering(InternalResourceView.java:263)
    at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:186)
    at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:267)
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1221)
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1005)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:952)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:110)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextHeaderFilter.doFilterInternal(EndpointWebMvcAutoConfiguration.java:280)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.boot.actuate.autoconfigure.MetricFilterAutoConfiguration$MetricsFilter.doFilterInternal(MetricFilterAutoConfiguration.java:90)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1736)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1695)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

What is my fault?

How can I modify my simple project to avoid this error?

回答1:

You've annotated the controller method as producing JSON, but it returns void. You probably want to annotate the method with @ResponseBody and change its return type to allow you to return an object representation of the JSON that you want to include in the response

回答2:

You can use @RestController in your Spring Boot project instead of @Controller annotation. In this way you don't have to use @ResponseBody annotation in your method even if your method doesn't return any value.

回答3:

Adding @ResponseBody in your controller will solve this problem as below:

 public @ResponseBody void test() {
    }