扩展Spring MVC 用以支持Controller对Ajax的处理

Spring Mvc中没有特别针对于Ajax请求的处理Controller.但是AbstractController和 
SimpleFormController也是可以针对Ajax的请求给与相应的.但显得有一点点的不自然. 

@Override
protected ModelAndView onSubmit(HttpServletRequest request, HttpServletResponse response, Object cmd,
        BindException ex) {
    String userId=request.getParamater("userId");
                 Map userInfoMap=userDao.getUserBaseInfo(userId);
                 JSONObject object = new JSONObject();
                 object.put("userInfoMap",userInfoMap);
    response.setContentType("text/Xml;charset=gbk");
    PrintWriter out = null;
    try {
        out = response.getWriter();
             out.println(object.toString());

    }
    catch (IOException ex1) {
        ex1.printStackTrace();
    }finally{
                           out.close();
                  }
    return null;
}

说明一下我向客户端页面response的是一个JSon对象,选择JSon这种数据格式的两个原因是: 

1. 体积小可降低流量.
2. Js端解码十分方便,Js对JSon格式数据有原生的支持.

使用Spring Mvc原有的SimpleFormController,从上边的例子上看是可以实现的,但是每次都要写"将JSonObject写入流,关流的代码.很累,很麻纺." 
所以,扩展了两个新的Controller,以简化对Ajax请求的处理. 
JSONObjectAbstractController 用于简单的从request.getParamater参数的情况. 
JSONObjectAbstractController 的原代码: 

package com.javaest.ext.spring.mvc.controller;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONObject;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;

public abstract class JSONObjectAbstractController extends AbstractController {

    @Override
    protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)
            throws Exception {
        JSONObject jsonObject = handleAjaxRequestInternal(request, response);
        response.setContentType("text/Xml;charset=gbk");
        PrintWriter out = null;
        try {
            out = response.getWriter();
            out.println(jsonObject.toString());
        }
        catch (IOException ex1) {
            ex1.printStackTrace();
        }
        finally {
            out.close();
        }

        return null;
    }

    protected abstract JSONObject handleAjaxRequestInternal(HttpServletRequest httpServletRequest,
            HttpServletResponse httpServletResponse) throws Exception;

}

JSONObjectSimpleFormController 用于自动将请求参数绑定到Command对象的情况. 
JSONObjectSimpleFormController 的代码: 

package com.javaest.ext.spring.mvc.controller;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONObject;

import org.springframework.validation.BindException;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.SimpleFormController;

public abstract class JSONObjectSimpleFormController extends SimpleFormController {

    @Override
    protected ModelAndView onSubmit(HttpServletRequest request, HttpServletResponse response, Object cmd,
            BindException ex) {
        JSONObject object = onAjaxSubmit(request, response, cmd, ex);

        response.setContentType("text/Xml;charset=gbk");
        PrintWriter out = null;
        try {
            out = response.getWriter();
            out.println(object.toString());
        }
        catch (IOException ex1) {
            ex1.printStackTrace();
        }
        finally {
            out.close();
        }

        return null;
    }

    public abstract JSONObject onAjaxSubmit(HttpServletRequest request, HttpServletResponse response, Object cmd,
            BindException ex);

}

以下就是我为了支持Ajax请求的处理所扩展的SpringMvc Controller. 

注：JSONObject 是json-lib-2.3-jdk15.jar中的，请自己下载导入
原帖：http://javaest.iteye.com/blog/187504