http://stackoverflow.com/questions/4917329/return-json-or-view-from-spring-mvc-controller
http://stackoverflow.com/questions/6173093/spring-return-json-from-controller-as-modelandview?lq=1

项目碰到这种场景，方法正常执行时，返回一个view；当执行出错，返回JSON，然后弹框提示。

开始找到了这个方法，但是感觉有点不太好..

然后参考了这里，但是执行过程中总是报错，异常类似如下：

org.codehaus.jackson.map.JsonMappingException: No serializer found for class com.bean.I18nObject and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: java.util.HashMap["i18n"])
    at org.codehaus.jackson.map.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:52)
    at org.codehaus.jackson.map.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:25)
    at org.codehaus.jackson.map.ser.std.MapSerializer.serializeFields(MapSerializer.java:262)
    at org.codehaus.jackson.map.ser.std.MapSerializer.serialize(MapSerializer.java:186)
    at org.codehaus.jackson.map.ser.std.MapSerializer.serialize(MapSerializer.java:23)
    at org.codehaus.jackson.map.ser.StdSerializerProvider._serializeValue(StdSerializerProvider.java:610)
    at org.codehaus.jackson.map.ser.StdSerializerProvider.serializeValue(StdSerializerProvider.java:256)
    at org.codehaus.jackson.map.ObjectMapper.writeValue(ObjectMapper.java:1613)
    at org.springframework.web.servlet.view.json.MappingJacksonJsonView.writeContent(MappingJacksonJsonView.java:302)
    at org.springframework.web.servlet.view.json.MappingJacksonJsonView.renderMergedOutputModel(MappingJacksonJsonView.java:257)

最后，DEBUG发现，项目中添加了拦截器，如果返回view，就向model中添加两个对象，一个是当前用户，一个国际化的对象，而这两个对象，Jackson不知道怎么去转成JSON，所以总是失败。

最后修改拦截器，如果view是MappingJacksonJsonView，就不向model中添加这两个对象，搞定！

最后的代码如下：
Controller:

@RequestMapping("/ajaxPaymentBatchApproveProcess")
public ModelAndView ajaxPaymentBatchApproveProcess(String packageIds) {      
    try { 
        // ....          
        PaymentApproveResultVo paymentApproveResult = new PaymentApproveResultVo();
        
        ModelAndView mav = new ModelAndView("payment_package_approve_result");
        mav.addObject("tagMode", "accountUnitGatherList");
        mav.addObject("par", paymentApproveResult);
        return mav;
    } catch (Exception e) {
        log.error("ajaxPaymentBatchApproveProcess method failed, Exception:", e);
        ModelAndView mav = new ModelAndView(new MappingJacksonJsonView());
        mav.addObject("result", "failed"); 
        return mav;
    }
}

JS:

$.ajax({
    url: '${ctx}/ajaxPaymentBatchApproveProcess',
    type: "post",
    data: {packageIds: pids},
    success: function (data) {
        if(typeof data == 'object' && data.result == 'failed') {
            // json
            jAlert('error', '出错啦!', '提示');
        } else {
            // view
            $('#paymentBatchApproveResultPopup').html(data);
        }
    }
});

拦截器：

public class CommonInterceptor extends HandlerInterceptorAdapter {
    /**
     * 拦截共通处理
     * 目前功能主要包含3部分：
     * 1：使所有页面支持currentUser的el表达式调用
     * 2：使所有页面支持国际化i18n的支持
     * 3：清除缓存
     */
    public void postHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler, ModelAndView model)
            throws Exception {
        if (model != null && !(model.getView() instanceof MappingJacksonJsonView)) {
            model.addObject("currentUser",
                    new PermissionSubject(SecurityUtils.getSubject()));

            model.addObject("i18n", new I18nObject((InternationalizationGuiService) CommonHelper
                    .getSpringService("internationalizationGuiServiceImpl")));
        }

        response.setHeader("Cache-Control", "no-cache"); // HTTP 1.1
        response.setHeader("Pragma", "no-cache"); // HTTP 1.0
        response.setDateHeader("Expires", -1); // Proxies.
    }
}