添加 @ResponseBody出现错误的问题

maven配置：

<dependency>
  <groupId>org.codehaus.jackson</groupId>
  <artifactId>jackson-core-asl</artifactId>
  <version>1.9.12</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.codehaus.jackson/jackson-mapper-asl -->
<dependency>
  <groupId>org.codehaus.jackson</groupId>
  <artifactId>jackson-mapper-asl</artifactId>
  <version>1.9.12</version>
</dependency>

代码：

@RequestMapping("/user/create")
@ResponseBody
public User createUser(){
    User user=new User();
    user.setEmail("@192777585@qq.com");
    user.setFirstname("hello tom");
    user.setLastname("good name");
    user.setPhone(123145);
    return user;
}

出现错误：

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.IllegalArgumentException: No converter found for return value of type: class com.shangsheng.entity.User
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
	org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
	org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

Root Cause

java.lang.IllegalArgumentException: No converter found for return value of type: class com.shangsheng.entity.User
	org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:187)
	org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:174)
	org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:81)
	org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:113)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandler

解决问题：
1.修改maven，去掉之前json配置,添加以下配置

<!--apache shiro end-->
<!-- 映入JSON -->
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.9.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-annotations -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.9.2</version>
</dependency>