【エラーメモ】BeanCreationException @RequestMappingの付け方のミス

Spring MVCの学習をしていた時に起こったエラーについての備忘録（読んでいる参考書：「Spring徹底入門」）

起こったエラーは以下

```
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'requestMappingHandlerMapping' defined in class org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration: Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'echoController' method 
public java.lang.String sampleapp.app.EchoController.echo(sampleapp.app.EchoForm)
to {[/echo],methods=[POST]}: There is already 'echoController' bean method
public java.lang.String sampleapp.app.EchoController.echo(sampleapp.app.EchoForm,org.springframework.validation.BindingResult) mapped.
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1578)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:839)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:538)
	at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:666)
	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:632)
	at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:680)
	at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:551)
	at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:492)
	at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
	at javax.servlet.GenericServlet.init(GenericServlet.java:158)
	at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1144)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1091)
	at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:983)
	at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4978)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5290)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1421)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1411)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

Caused by: java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'echoController' method 
public java.lang.String sampleapp.app.EchoController.echo(sampleapp.app.EchoForm)
to {[/echo],methods=[POST]}: There is already 'echoController' bean method
public java.lang.String sampleapp.app.EchoController.echo(sampleapp.app.EchoForm,org.springframework.validation.BindingResult) mapped.
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.assertUniqueMethodMapping(AbstractHandlerMethodMapping.java:567)
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.register(AbstractHandlerMethodMapping.java:531)
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(AbstractHandlerMethodMapping.java:255)
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.detectHandlerMethods(AbstractHandlerMethodMapping.java:241)
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods(AbstractHandlerMethodMapping.java:213)
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.afterPropertiesSet(AbstractHandlerMethodMapping.java:183)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet(RequestMappingHandlerMapping.java:125)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1637)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)
	... 28 common frames omitted
```

IllegalStateExceptionのAmbiguous mapping.というのが出ました。

ググると、
https://stackoverflow.com/questions/29949423/spring-mvc-ambiguous-mapping-found-cannot-map-controller-bean-method
↑
こんなのとか見ました。

どうやら、@RequestMapping(method = RequestMethod.POST)
を2回同じ名前のメソッドに対して付与したため起こっていたようです。


参考書の読み方のミスによって、起こっていました。

``` java:ErrorController.java
package sampleapp.app;

import javax.validation.Valid;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
@RequestMapping("echo")
public class EchoController {

	@RequestMapping(method = RequestMethod.GET)
	public String viewInput(Model model) {
		EchoForm form = new EchoForm();
		model.addAttribute(form);
		return "echo/input";
	}

	@RequestMapping(method = RequestMethod.POST)
	public String echo(EchoForm form) {
		return "echo/output";
	}

	@RequestMapping(method = RequestMethod.POST)
	public String echo(@Valid EchoForm form, BindingResult result) {
		if(result.hasErrors()) {
			return "echo/input";
		}
		return null;
	}

}
```

``` java:fixController.java
package sampleapp.app;

import javax.validation.Valid;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
@RequestMapping("echo")
public class EchoController {

	@RequestMapping(method = RequestMethod.GET)
	public String viewInput(Model model) {
		EchoForm form = new EchoForm();
		model.addAttribute(form);
		return "echo/input";
	}

	@RequestMapping(method = RequestMethod.POST)
	public String echo(@Valid EchoForm form, BindingResult result) {
		if(result.hasErrors()) {
			return "echo/input";
		}
		return "echo/output";
	}

}
```