spingmvc 返回json数据时报错,spingmvc启动失败

严重: StandardWrapper.Throwable
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter': Initialization of bean failed; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonProcessingException
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at java.lang.Thread.run(Thread.java:745)

spingmvc-servlet.xml配置如下:

        
            
            
            
                
                    
                        text/html;charset=UTF-8
                        application/json;charset=UTF-8
                    
                
            
        
    

pom.xml依赖

        
            com.fasterxml.jackson.core
            jackson-databind
            2.6.5
        

        
            com.fasterxml.jackson.core
            jackson-core
            2.6.5
        

        
            com.fasterxml.jackson.core
            jackson-annotations
            2.6.5
        

spring版本是4.x
controller代码如下

@Controller
@RequestMapping("/json")
public class UserController {
    
    //用户注册
    @RequestMapping(value = "/register.do")
    @ResponseBody
    public Map register() throws IOException {  
        
        Map map = new HashMap();
        map.put("xx", "ok");
        return map;
    }
}

浏览器输入

http://localhost:8080/MybatisDemo/json/register.do

后台就提示启动springmvc失败,说是找不json对应的类，可是相关的依赖我都添加了啊。。
前台提示Servlet.init() for servlet springmvc threw exception，忙活半天了。。网上的方案都不能解决.