Ajax请求SpringMVC

@RequestMapping(value = "/loadMenu", method = RequestMethod.GET)
    @ResponseBody
    public  ArrayList<TreeNode>  loadMenu(@RequestParam(value = "node") String nodeId) throws Exception {
        ArrayList<TreeNode> nodes = new ArrayList<TreeNode>(); 
        if (TreeNode.ROOT.equals(nodeId)) {
             TreeNode node = new TreeNode();
             node.setObjectId("12345");
             node.setText("root");
             node.setLeaf(false);
             nodes.add(node);
         } else {
             TreeNode node = new TreeNode();
             node.setObjectId("23456");
             node.setText("1");
             node.setLeaf(true);
             nodes.add(node);
         }
        return nodes;
    }

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    
    <context:annotation-config />
    <context:component-scan base-package="com" />
    
    <bean id="json"
        class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter" />
    <bean
        class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
        <property name="messageConverters">
            <list>
                <ref bean="json" />
            </list>
        </property>
    </bean>

</beans>