Servlet中Request,Response,Ajax,转发,重定向等的关系

Servlet中Request,Response,Ajax,转发,重定向等的关系

 

一.Request设置参数，通过转发或者重定向，跳转到页面：

if ("specialDoc".equals(action)) {
	String userName = null;
	User user = (User) request.getSession().getAttribute("user");
	if (user != null) {
		userName = user.getUsername();
	}
	long id = Long.valueOf(request.getParameter("id"));
	ProjectDao projectDao = new ProjectDao();
	List list = projectDao.getItemById(id);
	if (list != null && list.size() > 0) {
		Object[] obj = (Object[]) list.get(0);
		request.setAttribute("itemName", obj[1]);
		request.setAttribute("remark", obj[2]);
		request.setAttribute("createDate", obj[3]);
		request.setAttribute("list", list);
	}
	if (userName == null) {
		request.setAttribute("userName", "nobody");
	}
	else {
		request.setAttribute("userName", userName);
	}
	request.getRequestDispatcher("/frontShow/special-info.jsp").forward(request, response);
	return;
}

1.request设置参数：

2.获取转发器，转发地址跳回原页面或跳到新页面：

 

二.Response用于Ajax返回数据（一般返回Json字符串）：

if ("pageAjax".equals(action)) {
	String userName = null;
	User user = (User) request.getSession().getAttribute("user");
	if (user != null) {
		userName = user.getUsername();
	}
	String tableName = request.getParameter("table");
	int start = Integer.valueOf(request.getParameter("page"));
	String pageSizesString = request.getParameter("pageSize");
	int pageSize = 0;
	if (pageSizesString != null) {
		pageSize = Integer.valueOf(request.getParameter("pageSize"));
	}
	pageDao = new PageDaoImpl();
	pageDao.init(start, pageSize, tableName, level);//Page对象初始化
	Page page = pageDao.getPage();//获取Page对象
	JSONObject jObj = new JSONObject();
	jObj.put("userName", userName);
	jObj.put("currentPage", page.getCurrentPage());
	jObj.put("totalPages", page.getTotalPage());
	jObj.put("hasPrevious", page.isHasPreviousPage());
	jObj.put("hasNext", page.isHasNextPage());
	jObj.put("isFirst", page.isFirstPage());
	jObj.put("isLast", page.isLastPage());
	jObj.put("list", page.getList());
	response.setContentType("text/json;charset=UTF-8");
	PrintWriter out = response.getWriter();
	out.print(jObj);
	out.close();
	return;
}

1.创建Json字符串：

2.通过PrintWriter输出，即返回给Ajax：