SpringBoot exception distinguishes between page requests or Json requests

 

@RestController

public class RestErrorEndpoint implements ErrorController {

 

@Override

public String getErrorPath () {

return null;

}

 

    @RequestMapping(value = {"${server.error.path:${error.path:/error}}"},produces="application/json")  

    @ResponseBody  

    public String error(HttpServletRequest request) {  

    System.out.println("json");

    return "helloError";

    } 

 

@RequestMapping(  value = {"${server.error.path:${error.path:/error}}"},  produces = {"text/html"}  )  

   public ModelAndView errorHtml(HttpServletRequest request) {  

System.out.println("html");

       return new ModelAndView("/error/error");  

   }  

 

//    @RequestMapping({"${error.path:/error}"})  

//    @ResponseBody  

//    public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {  

//        Map body = this.getErrorAttributes(request, this.getTraceParameter(request));  

//        HttpStatus status = this.getStatus(request);  

//        return new ResponseEntity(body, status);  

//    } 

 

}

 

Spring boot  outputs error responses in different formats according to the content of the Accept header. For example, html pages are generated for browser requests, and json-formatted returns are generated for other requests. The field is judged by the content of text/html of accept.

produces = {"text/html"} page requests.

produces="application/json" for json or ajax requests

 

 

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Recently started to use springboot, found a strange phenomenon, a url error

Use the browser address request to return an html interface

 

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1. Whitelabel Error Page  
2.   
3. This application has no explicit mapping for /error, so you are seeing this as a fallback.  
4.   
5. Tue Nov 29 10:48:26 CST 2016  
6. There was an unexpected error (type=Bad Request, status=400).  
7. Required String parameter 'fileName' is not present  

Use postman request to return a response in json format

 

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1. {  
2.     "timestamp": 1480388264722,  
3.     "status": 400,  
4.     "error": "Bad Request",  
5.     "exception": "org.springframework.web.bind.MissingServletRequestParameterException",  
6.     "message": "Required String parameter 'fileName' is not present",  
7.     "path": "/file/delete"  
8. }  

How does spring boot distinguish data in different formats returned by this request? After a step by step follow up. The essence is on the BasicErrorController class

 

[java]  view plain copy  

 

1. @RequestMapping(  
2.         value = {"${error.path:/error}"},  
3.         produces = {"text/html"}  
4.     )  
5.     public ModelAndView errorHtml(HttpServletRequest request) {  
6.         return new ModelAndView("error", this.getErrorAttributes(request, false));  
7.     }  
8.   
9.     @RequestMapping({"${error.path:/error}"})  
10.     @ResponseBody  
11.     public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {  
12.         Map body = this.getErrorAttributes(request, this.getTraceParameter(request));  
13.         HttpStatus status = this.getStatus(request);  
14.         returnnew ResponseEntity(body, status);   
15.     }  

 

Spring boot  outputs error responses in different formats according to the content of the Accept header. For example, html pages are generated for browser requests, and json-formatted returns are generated for other requests. The content of text/html whose field is accept is judged