Java從后台重定向（redirect）到另一個項目的方法

（1）通過ModelAndView跳轉

@RequestMapping("alipayforward")
    public ModelAndView alipayforward(HttpServletRequest req, HttpServletResponse resp) throws Exception {
        String contNo =req.getParameter("contNo");
        logger.info("訪問/downloadRequestElecCont.action");
        String url = "redirect:http://baidu.com/downloadRequestElecCont.action?contNo="+contNo; 
        return new ModelAndView(url);
    }

（2）通過HttpServletResponse跳轉

@RequestMapping("alipayforward/{contNo}")
    public void alipayforward(@PathVariable("contNo") String contNo, HttpServletRequest req, HttpServletResponse resp) throws Exception {
        //String contNo =req.getParameter("contNo"); //保單號
        logger.info("訪問/downloadRequestElecCont.action");
        resp.sendRedirect("http://baidu.com/downloadRequestElecCont.action?contNo="+contNo);
    }

（3）通過redirect返回String類型跳轉

注意：這種方法不允許Spring控制器用@RestController注解，因為@RestController相當於類中的所有方法都標注了@ResponseBody，這些方法不會返回一個視圖，而是返回一個json對象，這樣的話只是在頁面上打印出字符串，而不跳轉。控制器用@Controller注解即可

@RequestMapping("alipayforward")
    public String alipayforward(@RequestParam("contNo") String contNo, HttpServletRequest req, HttpServletResponse resp) throws Exception {
        //String contNo =req.getParameter("contNo"); //保單號
        logger.info("訪問/downloadRequestElecCont.action");
        return "redirect:http://baidu.com/downloadRequestElecCont.action?contNo="+contNo;
    }

下面是關於傳參問題

重定向傳參為get方式，如果傳參數較多，可以封裝到map或modelMap中

@RequestMapping(params = "action=alipayforward")
    public String alipayforward(Map modelMap){
        modelMap.put("userName", "呵呵");
        modelMap.put("password", "123456");
        modelMap.put("age", "25");
        return "redirect:http://localhost:8088/era/user/alipayforward4?modelMap="+modelMap;
    }

另一個項目用實體類對象接收

@RequestMapping("alipayforward4")
    public void alipayforward4(User user, HttpServletRequest req) throws Exception {
        System.out.println(user.getPassword());
        String modelMap = req.getParameter("modelMap");
        System.out.println(modelMap);
    }