Spring Controller returns unformatted json
===

I have configured my application to return html, json or xml views.
html and xml views are fine but there is a problem with the json views.

The returned json is always prefixed with an "{} &&"

example

    {} && {"asd":{"name":"Practical Spring LDAP","isbn":"978-1475265453","author":"Balaji Varanasi"}}



my spring configuration to render the views is

    <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
    	  <property name="mediaTypes">
    	    <map>
    	      <entry key="html" value="text/html"/>
    	      <entry key="json" value="application/json"/>
    	      <entry key="xml" value="application/xml"/> 
    	    </map>
    	  </property>
    	  <property name="viewResolvers">
    	    <list>
    	      <bean class="org.springframework.web.servlet.view.UrlBasedViewResolver">
    	        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
    	        <property name="prefix" value="/WEB-INF/jsp/"/>
    	        <property name="suffix" value=".jsp"/>
    	      </bean>
    	    </list>
    	  </property>
    	  <property name="defaultViews">
    	    <list>
    	      <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView">
    	        <property name="prefixJson" value="true"/>
    	      </bean>
    	      
    	      <bean class="org.springframework.web.servlet.view.xml.MarshallingView">  
                 <constructor-arg>  
                     <bean class="org.springframework.oxm.jaxb.Jaxb2Marshaller">  
                         <property name="classesToBeBound">  
                             <list>  
                                 <value>com.sam.beans.Book</value>  
                              </list>  
                         </property>  
                     </bean>  
                 </constructor-arg>  
             </bean>  
    	    </list>
    	  </property>
    	</bean>

sample controller

    @RequestMapping("/getBook")
    public String showBook(Model model)  
    {  
        model.addAttribute("book", new Book("Practical Spring LDAP", "978-1475265453", "Balaji Varanasi"));  
      
        return "book";  
    }

 help needed...