首先看下面的代码

@Controller@RequestMapping("/users")public class UserController {    @RequestMapping(method=RequestMethod.GET)    public HttpResponse getList(HttpServletRequest req,HttpServletResponse rep){        String id = req.getSession().getId();        return new HttpResponse(id);    }}

在通过ajax访问的时候会出现

javax.servlet.ServletException: Circular view path [users]: would dispatch back to the current handler URL [/users] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)

这个异常，它的意思是没有指定视图结果，让你检查一下你的视图配置，在springmvc中我们是使用viewResolver，通过在controller中return的前缀来决定跳转到相应的视图

那么在springBoot怎么解决这个问题?

两个方案:

1、添加@ResponseBody

@Controller

@RequestMapping("/users")

public class UserController {

　　@RequestMapping(method=RequestMethod.GET)

　　@ResponseBody

　　public HttpResponse getList(HttpServletRequest req,HttpServletResponse rep){

　　　　　　String id = req.getSession().getId();

　　　　　　return new HttpResponse(id);

　　　　}

}

2、将@Controller换成@RestController// 标记为：restful

@RestController@RequestMapping("/users")public class UserController {    @RequestMapping(method=RequestMethod.GET)    public HttpResponse getList(HttpServletRequest req,HttpServletResponse rep){        String id = req.getSession().getId();        return new HttpResponse(id);    }}

 

Controller源码类

org.springframework.stereotype.Controller

RestController源码类

org.springframework.web.bind.annotation.RestController

 

两者区别在于

 

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ok