Spring MVC项目中的@RequestAttribute不会获取值

Question

@RequestAttribute in a Spring MVC project doesn't fetch the value.

I use a @ModelAttribute . Here foo attribute is set a value of bar

@ModelAttribute  
void beforeInvokingHandlerMethod(HttpServletRequest request) 
{  
    request.setAttribute("foo", "bar");  
}

I try to invoke the request attribute value for foo using @RequestAttribute("foo") . But value is null.

Then I try using request.getAttribute("foo") and the value is printed. I don't know what is wrong in the following code:

@RequestAttribute("foo"). 
@RequestMapping(value="/data/custom", method=RequestMethod.GET)  
public @ResponseBody String custom(@RequestAttribute("foo") String foo, HttpServletRequest request) {  
    System.out.println("foo value : " + foo);    //null printed  
    System.out.println("request.getAttribute : " + request.getAttribute("foo"));    //value printed  

    return foo;  
}

Answer 1

@RequestAttribute is not a Spring annotation. If you want to pass a value a request param you can do

@RequestMapping(value="/data/custom", method=RequestMethod.GET)  
public @ResponseBody String custom(@RequestParam("foo") String foo) {  
    System.out.println("foo value : " + foo);    //null printed      
    return foo;  
}

Or if you want to pass values in the path you can do

@RequestMapping(value="/data/custom/{foo}", method=RequestMethod.GET)  
public @ResponseBody String custom(@PathVariable("foo") String foo) {  
    System.out.println("foo value : " + foo);    //null printed      
    return foo;  
}