springmvc前后台交互json

首先在springmvc.xml中加入来设置json

    <bean id="jacksonMessageConverter"
        class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
        <property name="supportedMediaTypes">
            <list>
                <value>text/html;charset=UTF-8</value>
            </list>
        </property>
    </bean>
    <!-- 启动Spring MVC的注解功能，完成请求和注解POJO的映射 设置后可自动解释json -->
    <bean
        class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping">
    </bean>
    <bean
        class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
        <property name="messageConverters">
            <list>
                <bean
                    class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" />
            </list>
        </property>
    </bean>

设置controller

@RequestMapping("/json")
    public @ResponseBody Priv_User login(HttpServletRequest request,
            HttpServletResponse response, String user_id) {
        Priv_User priv_User = priv_UserService.queryByUserId(user_id);
        if (priv_User != null) {
            return priv_User;
        } else {
            return null;
        }
    }

jsp页面发出的json请求

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>MySpringMVC首次测试</title>
<script type="text/javascript" src="static/js/jquery-1.9.1.min.js" ></script>
<script type="text/javascript">

function dj(){
    $.ajax({
                type : "POST",
                async : false,
                dataType : "json",
                data : {
                    user_id:2
                },
                url : "json",
                success : function(rstObj) {
                    if(rstObj!=null&&rstObj!=""){
                        alert(rstObj.user_name);
                    }else{
                        alert("这是空的啊");
                    }
                },
            });
}
</script>
</head>
<body>
<div>
<input type="button" value="这是一个按钮"  onclick="dj()">
</div>

</body>
</html>

一个简单的例子