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Get request header in spring boot

How do I get the header and body of the current request from an application which called my Springboot application? I need to extract this information. Unfortunately this does not work. I tried to get the current request with this code sample (https://stackoverflow.com/a/26323545/5762515):
public static HttpServletRequest getCurrentHttpRequest(){
RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
if (requestAttributes instanceof ServletRequestAttributes) {
HttpServletRequest request = ((ServletRequestAttributes)requestAttributes).getRequest();
return request;
}
throw new IllegalArgumentException("Request must not be null!");
}
And then I tried to get the body
ContentCachingRequestWrapper requestWrapper = (ContentCachingRequestWrapper) currentRequest;
String requestBody = new String(requestWrapper.getContentAsByteArray());
Can someone tell me what im doing wrong?
Thanks in advance

#RestController
public class SampleController {
#PostMapping("/RestEndpoint")
public ResponseEntity<?> sampleEndpoint(#RequestHeader Map<String, String> headers,#RequestBody Map<String,String> body) {
//Do something with header / body
return null;
}
}
If the application's are communicating through a rest endpoint I believe this would be the simplest solution. In spring you can add RequestHeader and RequestBody annotations to method arguments to have them setup to be used.
Of course you can map RequestBody directly to some POJO instead of using a map but just as an example.
Let me know if this is what you were looking for !

#TryHard, You're using spring boot then following way is more preferable for you,
#RestController
public class SampleController {
#RequestMapping("/get-header-data")
public ResponseEntity<?> sampleEndpoint(HttpServletRequest request) {
// request object comes with various in-built methods use as per your requirement.
request.getHeader("<key>");
}
}

you can get header with your code but need apply some changes.
private String getRequest() throws Exception {
RequestAttributes attribs = RequestContextHolder.getRequestAttributes();
if (attribs != null) {
HttpServletRequest request = ((ServletRequestAttributes) attribs).getRequest();
return request ;
}
throw new IllegalArgumentException("Request must not be null!");
}
after you can extract header info from request. For example if you want get Accept-Encoding
String headerEncoding = getRequest().getHeader("Accept-Encoding");
obliviusly you don't use this approce if not necessary.
If you want exract the body NOT use this solution

How to throw exception based on feign.Response?

I have a Feign client with a method returning the feign.Response class. When another service throws an exception, feign puts an exception message on response body and puts status, but my service does not throw an exception. Can I throw an exception based on what I received in response like when I use ResponseEntity.
Feign client
#FeignClient(name = "ms-filestorage")
#RequestMapping(value = "/files", produces = "application/json")
public interface FileStorageApi {
#GetMapping(value = "/{id}")
Response getFileById(#PathVariable String id);
}
Usage of client
#Override
public Response getFileFromStorage(String fileId) {
Response fileStorageResponse = fileStorageApi.getFileById(fileId);
// NOW I USE THIS WAY FOR CHECKING RESPONSE BUT IT DOESN'T LOOK GOOD
//if (fileStorageResponse.status() != HttpStatus.OK.value()) {
// throw new OsagoServiceException();
//}
return fileStorageResponse;
}

Usually, if a Feign client call receives an error response from the API it is calling, it throws a FeignException.
This can be caught in a try / catch block (or a Feign ErrorDecoder if you want to be more sophisticated, but that's another post).
However, this is not the case if you map the error response into a Feign.Response return type - see this Github issue.
Instead of returning Feign.Response from getFileFromStorage(), you should create a custom Java object to hold the response, and you will then have access to the FeignException which you can handle as you wish.
Note that if you don't need access to the data that is returned from the API you are calling, changing the return type to void will also resolve this issue.

How to return completely empty response in Spring

I have a Spring MVC Rest controller with one of the URL mappings being :
myhost:8080/helloworldexample/testnullresponse
Now, is it possible to return nothing at all when I call this URL
Nothing means: no body, no response, no status code simply nothing at all, almost like the server listening to the request did not do anything.
I would appreciate any help on this. I have tried the following options but nothing worked:
return new ResponseEntity<Void>(null);
AND
#RequestMapping(value = "/helloworldexample/testnullresponse", produces = "application/json; charset=UTF-8", method = RequestMethod.GET)
public void nullResponse(HttpServletRequest request) {
}

Actually your controller's method could return void.
Here is an example
#RequestMapping(value = "/helloworldexample/testnullresponse", method = RequestMethod.HEAD)
public void nullResponse(HttpServletResponse response) {
...
}

How to parse a URL and run a method with Spring MVC 'reflectively'?

I have a Spring Boot application that uses Spring MVC in the usual manner, with a bunch of #RequestMapping methods, Freemarker definitions, and the like. This is all tied together with a WebMvcConfigurerAdapter class.
I'd like to provide a service where the user submits a list of valid URLs, and the webapp would work out which controller would be called, passes in the parameters, and returns a combined result for every URL — all in one request.
This would save the user from having to make hundreds of HTTP calls, but would still allow them to make one-off requests if need be. Ideally, I'd just inject an auto-configured Spring bean, so I don't have to repeat the URL resolving and adapting and handling that Spring does internally, and the controller's list of other controllers would never go out of sync with the real list of controllers.
I expected to write something like this (simplified to only deal with one URL, which is pointless but easier to understand):
#Autowired BeanThatSolvesAllMyProblems allMappings;
#PostMapping(path = "/encode", consumes = MediaType.TEXT_PLAIN_VALUE)
#ResponseBody
public String encode(#RequestBody String inputPath) {
if (allMappings.hasMappingForPath(inputPath)) {
return allMappings.getMapping(inputPath).execute();
} else {
return "URL didn't match, sorry";
}
}
Instead, I've had to define Spring beans I don't know what they do and have been repeating some of what Spring is meant to do for me, which I'm worried won't work quite the same as it would if the user just made the call themselves:
// these two are #Beans, with just their default constructor called.
#Autowired RequestMappingHandlerMapping handlers;
#Autowired RequestMappingHandlerAdapter adapter;
#PostMapping(path = "/encode", consumes = MediaType.TEXT_PLAIN_VALUE)
#ResponseBody
public String encode(#RequestBody String inputText) {
final HttpServletRequest mockRequest = new MockHttpServletRequest(null, inputText);
final StringBuilder result = new StringBuilder();
this.handlers.getHandlerMethods().forEach((requestMappingInfo, handlerMethod) -> {
if (requestMappingInfo.getPatternsCondition().getMatchingCondition(mockRequest) != null) {
try {
final MockHttpServletResponse mockResponse = new MockHttpServletResponse();
result.append("Result: ").append(adapter.handle(mockRequest, mockResponse, handlerMethod));
result.append(", ").append(mockResponse.getContentAsString());
result.append("\n");
} catch (Exception e) {
logger.error(e.getMessage(), e);
}
}
});
return result.toString();
}
I thought I was doing quite well going down this path, but it's failing with Missing URI template variable errors, and not only do I have no idea how to put the request parameters in (another thing which Spring could be able to handle itself), but I'm not even sure that this is the right way to go about doing this. So how do I simulate a Spring MVC request "reflectively", from within the webapp itself?

JSON API spec. solves this problem by allowing sending multiple operations per request. There even exists a quite mature implementation that supports this feature which is called Elide. But I guess this is might not fully meet your requirements.
Anyway, here's what you can do.
You have to take into consideration that DispatcherServlet holds handlerMappings list that is used to detect appropriate request handler and handlerAdaptors. The selection strategy for both lists is configurable (see DispatcherServlet#initHandlerMappings and #initHandlerAdapters).
You should work out a way you would prefer to retrieve this lists of handlerMappings/initHandlerAdapters and stay in sync with DispatcherServlet.
After that you can implement your own HandlerMapping/HandlerAdaptor (or present a Controller method as in your example) that would handle the request to /encode path.
Btw, HandlerMapping as javadoc says is
Interface to be implemented by objects that define a mapping between
requests and handler objects
or simply saying if we take DefaultAnnotationHandlerMapping that would map our HttpServletRequests to #Controller methods annotated with #RequestMapping. Having this mapping HandlerAdapter prepares incoming request to consuming controller method, f.ex. extracting request params, body and using them to call controller's method.
Having this, you can extract URLs from main request, create a list of stub HttpRequests holding the information needed for further processing and loop through them calling this:
HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
for (HandlerMapping hm : this.handlerMappings) {
if (logger.isTraceEnabled()) {
logger.trace(
"Testing handler map [" + hm + "] in DispatcherServlet with name '" + getServletName() + "'");
}
HandlerExecutionChain handler = hm.getHandler(request);
if (handler != null) {
return handler;
}
}
return null;
}
having a handlerMapping you call
HandlerAdapter getHandlerAdapter(Object handler) throws ServletException {
for (HandlerAdapter ha : this.handlerAdapters) {
if (logger.isTraceEnabled()) {
logger.trace("Testing handler adapter [" + ha + "]");
}
if (ha.supports(handler)) {
return ha;
}
}
and then you can finally call
ha.handle(processedRequest, response, mappedHandler.getHandler());
which in turn would execute the controller's method with params.
But having all this, I would not recommend to following this approach, instead, think about usage of JSON API spec or any other.

How about using Springs RestTemplate as client for this? You could call your controllers within the spring controller as if it would be an external resource:
#ResponseBody
public List<String> encode(#RequestBody List inputPaths) {
List<String> response = new ArrayList<>(inputPaths.size());
for (Object inputPathObj : inputPaths) {
String inputPath = (String) inputPathObj;
try {
RequestEntity.BodyBuilder requestBodyBuilder = RequestEntity.method(HttpMethod.GET, new URI(inputPath)); // change to appropriate HttpMethod, maybe some mapping?
// add headers and stuff....
final RequestEntity<Void> requestEntity = requestBodyBuilder.build(); // when you have a request body change Void to e.g. String
ResponseEntity<String> responseEntity = null;
try {
responseEntity = restTemplate.exchange(requestEntity, String.class);
} catch (final HttpClientErrorException ex) {
// add your exception handling here, e.g.
responseEntity = new ResponseEntity<>(ex.getResponseHeaders(), ex.getStatusCode());
throw ex;
} finally {
response.add(responseEntity.getBody());
}
} catch (URISyntaxException e) {
// exception handling here
}
}
return response;
}
Note that generic do not work for the #RequestBody inputPaths.
See alse http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/client/RestTemplate.html and https://spring.io/guides/gs/consuming-rest/ .

I agree with the other answers that you should consider this feature outside of your project, instead of having it in the code. It is a question of design and you can choose the approach you want. Based on your comment that these are GET requests, you can achieve what you want with a request dispatcher to trigger your requests within your special Controller service method for each URL and capture the response with a HttpServletResponseWrapper instance.
In the following code sample, the "consolidate" method takes comma separated URLs like this ("http://localhost:8080/index/index1,index2", here "index1,index2" is the URL list), consolidates their text output into a single payload and returns it. For this example URL, the consolidated outputs of http://localhost:8080/index1 and http://localhost:8080/index2 will be returned. You might want to extend/modify this with added parameters, validation, etc for the URLs. I tested this code with Spring Boot 1.2.x.
#Controller
public class MyController {
#RequestMapping("/index/{urls}")
#ResponseBody
String consolidate(#PathVariable String[] urls, HttpServletRequest request, HttpServletResponse response) {
StringBuilder responseBody = new StringBuilder();
//iterate for each URL provided
for (String url : urls) {
RequestDispatcher dispatcher = request.getServletContext().getRequestDispatcher("/" + url);
HttpServletResponseWrapper wrapper = new HttpServletResponseWrapper((HttpServletResponse) response) {
private CharArrayWriter output = new CharArrayWriter();
#Override
public PrintWriter getWriter() {
return new PrintWriter(output);
}
#Override
public String toString() {
return output.toString();
}
};
try {
dispatcher.include(request, wrapper);
//append the response text
responseBody.append(wrapper.toString());
} catch (ServletException | IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//This holds the consolidated output
return responseBody.toString();
}
#RequestMapping("/index1")
String index1() {
return "index1";
}
#RequestMapping("/index2")
String index2() {
return "index2";
}
}

How to write a Controller variable value back to the HTML page that sent the Ajax request without a page refresh?

The following JavaScript
new Ajax.Request('/orders/check_first_last/A15Z2W2',
{asynchronous:true, evalScripts:true,
parameters:{first:$('input_initial').value,
last:$('input_final').value,
order_quantity:$('input_quantity').value}});
triggers an Ajax call to the checkFirstLast method in the OrderController:
#Controller
#RequestMapping("/orders")
public OrderController {
#RequestMapping("/check_first_last/{code}")
#ResponseBody
public String checkFirstLast(#PathVariable String code,
#RequestParam int first,
#RequestParam int last,
#RequestParam("order_quantity") int orderQuantity) {
Integer newResult = new Integer(last - first);
return newResult.toString();
}
}
If I want to write the newResult String from the checkFirstLast method into the result_text HTML element on the page that sends the Ajax request, replacing the value set by the initialResult JSTL variable:
<h2 id="result_text"><c:out value="${initialResult}"/></h2>
what change would I need to make to the controller method above (checkFirstLast), now that I have already included the Jackson JSON library in my project?

the flow in ajax is:
send request with javascript to server
process request on server
sent response back to client
process response with javascript and update the page
The 4th step is missing in the code you provide.
It seems to me you are using the prototype javascript framework, is this correct?
If you look at the documentation for ajax requests and the ajax options you will see you can specify callback function when the requests was handled with success, or when a failure occured.
Change your javascript to:
new Ajax.Request(
'/orders/check_first_last/A15Z2W2',
{
asynchronous:true,
evalScripts:true,
parameters:
{
first:$('input_initial').value,
last:$('input_final').value,
order_quantity:$('input_quantity').value
},
onSuccess: function(transport)
{
$('result_text').update(transport.responseText);
}
}
);
and let me know what it gives.

This is an abstract controller that I wrote to handle Ajax. This actually is from the Struts example on DispatchAction.
public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
// TODO Auto-generated method stub
AjaxResponse ajaxResponse = null;
String parameter = "command";
try {
String methodName = request.getParameter(parameter);
Method method = getMethod(methodName);
ajaxResponse = invokeMethod(request, response, method);
} catch (Exception e) {
// TODO Auto-generated catch block
logger.error(e.getLocalizedMessage());
ajaxResponse = toXmlException(e);
}
if (ajaxResponse != null) {
//Finally
response.setContentType(ajaxResponse.getContentType());
response.setHeader("Cache-Control", "no-cache");
OutputStream out = response.getOutputStream();
out.write(ajaxResponse.getResponseText().getBytes());
out.flush();
}
return null;
}
As you can see, A javascript is sent to the server, which is then dispatched by the DispatcherServlet to the controller. The controller then invokes the correct method call and returns a response through response.getOutputStream().write(....).
The controller then must return a null so that the DispatcherServlet does nothing in return.
In my case, AjaxResponse is an interface and the response can be either XmlAjaxResponse or JsonAjaxResponse.
The java client then handles the response returned from the server (in this case, controller).
You need to add in a response to your side. Hope this helps.