SpringBoot how to Send response to other URL - java

I have the following code:
#RequestMapping(
consumes = {MediaType.APPLICATION_FORM_URLENCODED_VALUE},
path = "api/api1",
method = RequestMethod.POST,
produces = MediaType.ALL_VALUE
)
public ResponseEntity<?> api1CallBack(#RequestBody String requestBody, HttpServletRequest request) throws IOException, GeneralSecurityException, URISyntaxException {
String response="{SOME_JSON}";
URI callbackURL = new URI("http://otherAPIEnv/api2");
HttpHeaders httpHeaders = new HttpHeaders();
httpHeaders.setLocation(callbackURL);
return new ResponseEntity<String>(response,httpHeaders, HttpStatus.OK);
}
I tried the above code, but when I hit the api1 through my curl I get the response on the same machine, but I want the response to be redirected to api2 at otherAPIEnv machine.
Could someone please suggest how to achieve this kind of request and response?


When you send a request to a URL it should respond to the same otherwise client will be in waiting for it until it times out.
So, the approach should be different in this scenario.
First, in your main rest API you have to send a response code to release the client.
Then, in the API method you have to call another method asynchronously which calls api2 and performs the desired operation.
Here is a simple example.
#Autowired
API2Caller api2Caller;
#RequestMapping(
consumes = {MediaType.APPLICATION_FORM_URLENCODED_VALUE},
path = "api/api1",
method = RequestMethod.POST,
produces = MediaType.ALL_VALUE
)
#ResponseStatus(HttpStatus.ACCEPTED)
public void api1CallBack(#RequestBody String requestBody, HttpServletRequest request) throws IOException, GeneralSecurityException, URISyntaxException {
api2Caller.callApi2(requestBody);
}
and the APICaller should look like following
#Component
public class API2Caller {
#Async
public SomeResultPojo callApi2() {
// use RestTemplate to call the api2
return restTemplate.postForObject("http://otherAPIEnv/api2", request, SomeResultPojo.class);
}
}
But you can choose your most comfortable way to perform asynchronous operation.


Look like a job for redirect.
String redirectMe() {
return "redirect:http://otherAPIEnv/api2"
}
As for the curl. You have POST mapping of the method so be sure to try it with curl -X POST... or change it to GET.


This the more modular and more generic way to do such kind of things:
public #ResponseBody ClientResponse updateDocStatus(MyRequest myRequest) {
ClientResponse clientResponse = new ClientResponse(CTConstants.FAILURE);
try {
HttpHeaders headers = prepareHeaders();
ClientRequest request = prepareRequestData(myRequest);
logger.info("cpa request is " + new Gson().toJson(request));
HttpEntity<ClientRequest> entity = new HttpEntity<ClientRequest>(request, headers);
String uri = cpaBaseUrl + updateDocUrl ;
ClientResponse serviceResponse = Utilities.sendHTTPRequest(uri, entity);
clientResponse = serviceResponse;
if (serviceResponse != null) {
if (CTConstants.SUCCESS.equalsIgnoreCase(serviceResponse.getStatus())) {
clientResponse.setStatus(CTConstants.SUCCESS);
clientResponse.setMessage(" update success.");
}
}
} catch (Exception e) {
logger.error("exception occurred ", e);
clientResponse.setStatus(CTConstants.ERROR);
clientResponse.setMessage(e.getMessage());
}
return clientResponse;
}
public static ClientResponse sendHTTPRequest(String uri, HttpEntity<ClientRequest> entity) {
RestTemplate restTemplate = new RestTemplate();
restTemplate.setRequestFactory(new SimpleClientHttpRequestFactory());
SimpleClientHttpRequestFactory rf = (SimpleClientHttpRequestFactory) restTemplate.getRequestFactory();
rf.setReadTimeout(CTConstants.SERVICE_TIMEOUT);
rf.setConnectTimeout(CTConstants.SERVICE_TIMEOUT);
ParameterizedTypeReference<ClientResponse> ptr = new ParameterizedTypeReference<ClientResponse>() {
};
ResponseEntity<ClientResponse> postForObject = restTemplate.exchange(uri, HttpMethod.POST, entity, ptr);
return postForObject.getBody();
}


You need to use redirect and modify the return type of your method
public String api1CallBack(#RequestBody String requestBody, HttpServletRequest request) throws IOException {
return "redirect:http://otherAPIEnv/api2";
}

Related

Why one request triggered CORS policy but the other not?

I use the same request func to yield call two api on the server.
Model func code:
const pomdata = yield call(pullInfo1, payload)
const data = yield call(pullinfo2, payload)
And server code is :
#RestController
#RequestMapping(value = "/intf")
public class IntfController {
#Transactional
#RequestMapping(path ="/pullinfo1", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public Map<String, Object> pullinfo1(HttpServletRequest request) throws Exception {
try{
xxxxx
return successMap //This one return the right reponse
} catch {
return FailMap;
}
}
#Transactional
#RequestMapping(path ="/pullinfo2", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public Map<String, Object> pullinfo2(HttpServletRequest request) throws Exception {
try{
xxxxx
return successMap //This one return the wrong reponse which Triggered CORS policy
} catch {
return FailMap;
}
}
one api give the right reponse but the other triggered the CORS policy. They are all running on the same mcrsverice and under the same #RequestMappingroute.
The Server CORS Filter get the origin and typed on the console.
CORSFilter get the origin image
And according to the code:
String origin = request.getHeader("origin");
String origin = request.getHeader("origin");
logger.info("#### req origin ####" + origin);
HttpServletResponse response = (HttpServletResponse) res;
if (origin != null) {
response.setHeader("Access-Control-Allow-Origin", origin);
}
The response shall have the Access-Control-Allow-Origin,But it doesn't.
Here is the right reponse like pullinfo1:
right reponse and Header
Here is the wrong reponse like pullinfo2:
wrong response and Header
By the way,they all have same request header except request url.

Java Spring error 404 while trying to get JSON from API. Works in postman

I am trying to get a JSON Object from an API while using an API key in the header.
This works perfectly when I test it in Postman, but when I try it in my Spring application.
I got an error:
There was an unexpected error (type=Not Found, status=404). No message available.
API-Key and the URL are changed out with dummy data
#RequestMapping(value = "/apitest", method = RequestMethod.GET, headers ="APIKey=12345")
public #ResponseBody void testingAPI() throws ParseException {
final RestTemplate restTemplate = new RestTemplate();
final String response = restTemplate.getForObject("url", String.class);
System.out.println(response);
}

If your are testing your API in Postman and it works perfectly, and in your application it's not working, this means that your method mapping isn't correct or it's not correctly called.
But from the comments where you said that the same configuration works if you don't have an API key, this means that your header isn't correctly mapped, in this case I'd recommend using #RequestHeader annotation to handle your API key.
Your method mapping will be like this:
#RequestMapping(value = "/apitest", method = RequestMethod.GET)
public #ResponseBody void testingAPI(#RequestHeader("APIKey") String apiKey) throws ParseException {
final RestTemplate restTemplate = new RestTemplate();
final String response = restTemplate.getForObject("url", String.class);
System.out.println(response);
}
If you want to use 12345 as a default value for your API key param you can write:
#RequestMapping(value = "/apitest", method = RequestMethod.GET)
public #ResponseBody void testingAPI(#RequestHeader(name = "APIKey", defaultValue = "12345") String apiKey) throws ParseException {
You can check How to Read HTTP Headers in Spring REST Controllers tutorial for further reading about the #RequestHeader annotation.

A quick fix could be to change the void to a Class. like
#RequestMapping(value = "/apitest", method = RequestMethod.GET, headers ="APIKey=12345")
#ResponseBody
public XXXResponse testingAPI() throws ParseException {
...
return new XXXRepsonse();
}
or:
#RequestMapping(value = "/apitest", method = RequestMethod.GET, headers ="APIKey=12345")
public void testingAPI() throws ParseException {
...
}

Where are you add header in your request? You controller should look like this:
#RestController
public class DemoController {
#GetMapping("/apitest" )
public void doRequest(#RequestHeader(name = "Ocp-Apim-Subscription-Key", defaultValue = "12345") String apiKey) {
RestTemplate restTemplate = new RestTemplate();
MultiValueMap<String, String> headers = new LinkedMultiValueMap<>();
headers.add("Ocp-Apim-Subscription-Key", apiKey);
ResponseEntity<String> responseEntity = restTemplate.exchange("https://api.kognif.ai/AIS/v1/aispositioncurrent?vesselimo=8505941&output=json",
HttpMethod.GET, new HttpEntity<String>(headers), String.class);
System.out.println(responseEntity.toString());
}
}
Postman request to your Spring app must be :
And of course, specify valid Ocp-Apim-Subscription-Key

Spring rest service not returning body

I have one rest service with following implementation -
#RequestMapping(method = RequestMethod.GET, consumes = MediaType.APPLICATION_JSON_VALUE)
#ResponseBody
#JsonSerialize
public ResponseEntity<String> handleData(HttpMethod method, HttpServletRequest httpRequest)
throws URISyntaxException, IOException {
BackendRequest request = new BackendRequest();
request.setHttpRequest(httpRequest);
request.setMethod(method);
BackendResponse backendResponse = service.getresponse(request);
ResponseEntity<String> response = backendResponse.getResponse();
return new ResponseEntity<String>(response.getBody(), response.getHeaders(), response.getStatusCode());
// return response;
}
I am getting all the headers and response status correctly but I am not getting the json response. What is wrong here?
I am trying to do following -
https://stackoverflow.com/a/23736527/2197994
Somewhere deep inside the nested calls, I am getting the response from some other backend using spring rest template.
public BackendResponse callBackend(BackendRequest request) throws URISyntaxException, IOException {
String body = null;
ResponseEntity<String> responseEntity = null;
URI uri = new URI("http", null, "localhost", 8080, request.getRequestURL(), request.getQueryString(), null);
MultiValueMap<String, String> requestHeaders = getHeadersInfo(request.getHttpRequest());
if (HttpMethod.POST.equals(request.getMethod())) {
body = request.getHttpRequest().getReader().lines().collect(Collectors.joining(System.lineSeparator()));
responseEntity = restTemplate.exchange(uri, request.getMethod(),
new HttpEntity<String>(body, requestHeaders), String.class);
} else if (HttpMethod.GET.equals(request.getMethod())) {
responseEntity = restTemplate.exchange(uri, request.getMethod(),
new HttpEntity<String>(body, requestHeaders), String.class);
} else {
LOG.warn("Method:{} not supported yet", request.getMethod());
}
BackendResponse response = new BackendResponse();
response.setResponse(responseEntity);
return response;
}

BackendResponse backendResponse = service.getresponse(request) could be the problem. Could you post the content of the method ?

Spring forward rest request to another rest service [duplicate]

I have build a web application using spring mvc framework to publish REST services.
For example:
#Controller
#RequestMapping("/movie")
public class MovieController {
#RequestMapping(value = "/{id}", method = RequestMethod.GET)
public #ResponseBody Movie getMovie(#PathVariable String id, #RequestBody user) {
return dataProvider.getMovieById(user,id);
}
Now I need to deploy my application but I have the following problem:
The clients do not have direct access to the computer on which the application resides (There is a firewall). Therefore I need a redirection layer on a proxy machine (accessible by the clients) which calls the actual rest service.
I tried making a new call using RestTemplate:
For Example:
#Controller
#RequestMapping("/movieProxy")
public class MovieProxyController {
private String address= "http://xxx.xxx.xxx.xxx:xx/MyApp";
#RequestMapping(value = "/{id}", method = RequestMethod.GET)
public #ResponseBody Movie getMovie(#PathVariable String id,#RequestBody user,final HttpServletResponse response,final HttpServletRequest request) {
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
RestTemplate restTemplate = new RestTemplate();
return restTemplate.exchange( address+ request.getPathInfo(), request.getMethod(), new HttpEntity<T>(user, headers), Movie.class);
}
This is ok but I need to rewrite each method in the controller to use the resttemplate. Also, this causes redundant serialization/deserialization on the proxy machine.
I tried writing a generic function using restemplate, but it did not work out:
#Controller
#RequestMapping("/movieProxy")
public class MovieProxyController {
private String address= "http://xxx.xxx.xxx.xxx:xx/MyApp";
#RequestMapping(value = "/**")
public ? redirect(final HttpServletResponse response,final HttpServletRequest request) {
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
RestTemplate restTemplate = new RestTemplate();
return restTemplate.exchange( address+ request.getPathInfo(), request.getMethod(), ? , ?);
}
I could not find a method of resttemplate which works with request and response objects.
I also tried spring redirect and forward. But redirect does not change the request's client ip address so i think it is useless in this case. I could not forward to another URL either.
Is there a more appropriate way to achieve this?

You can mirror/proxy all requests with this:
private String server = "localhost";
private int port = 8080;
#RequestMapping("/**")
#ResponseBody
public String mirrorRest(#RequestBody String body, HttpMethod method, HttpServletRequest request) throws URISyntaxException
{
URI uri = new URI("http", null, server, port, request.getRequestURI(), request.getQueryString(), null);
ResponseEntity<String> responseEntity =
restTemplate.exchange(uri, method, new HttpEntity<String>(body), String.class);
return responseEntity.getBody();
}
This will not mirror any headers.

Here's my modified version of the original answer, which differs in four points:
It does not make the request body mandatory, and as such does not let GET requests fail.
It copies all headers present in the original request. If you are using another proxy/web server, this can cause issues due to content length/gzip compression. Limit the headers to the ones you really need.
It does not reencode the query params or the path. We expect them to be encoded anyway. Note that other parts of your URL might also be encoded. If that is the case for you, leverage the full potential of UriComponentsBuilder.
It does return error codes from the server properly.
#RequestMapping("/**")
public ResponseEntity mirrorRest(#RequestBody(required = false) String body,
HttpMethod method, HttpServletRequest request, HttpServletResponse response)
throws URISyntaxException {
String requestUrl = request.getRequestURI();
URI uri = new URI("http", null, server, port, null, null, null);
uri = UriComponentsBuilder.fromUri(uri)
.path(requestUrl)
.query(request.getQueryString())
.build(true).toUri();
HttpHeaders headers = new HttpHeaders();
Enumeration<String> headerNames = request.getHeaderNames();
while (headerNames.hasMoreElements()) {
String headerName = headerNames.nextElement();
headers.set(headerName, request.getHeader(headerName));
}
HttpEntity<String> httpEntity = new HttpEntity<>(body, headers);
RestTemplate restTemplate = new RestTemplate();
try {
return restTemplate.exchange(uri, method, httpEntity, String.class);
} catch(HttpStatusCodeException e) {
return ResponseEntity.status(e.getRawStatusCode())
.headers(e.getResponseHeaders())
.body(e.getResponseBodyAsString());
}
}

You can use Netflix Zuul to route requests coming to a spring application to another spring application.
Let's say you have two application: 1.songs-app, 2.api-gateway
In the api-gateway application, first add the zuul dependecy, then you can simply define your routing rule in application.yml as follows:
pom.xml
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-zuul</artifactId>
<version>LATEST</version>
</dependency>
application.yml
server:
port: 8080
zuul:
routes:
foos:
path: /api/songs/**
url: http://localhost:8081/songs/
and lastly run the api-gateway application like:
#EnableZuulProxy
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
Now, the gateway will route all the /api/songs/ requests to http://localhost:8081/songs/.
A working example is here: https://github.com/muatik/spring-playground/tree/master/spring-api-gateway
Another resource: http://www.baeldung.com/spring-rest-with-zuul-proxy

#derkoe has posted a great answer that helped me a lot!
Trying this in 2021, I was able to improve on it a little:
You don't need #ResponseBody if your class is a #RestController
#RequestBody(required = false) allows for requests without a body (e.g. GET)
https and port 443 for those ssl encrypted endpoints (if your server serves https on port 443)
If you return the entire responseEntity instead of only the body, you also get the headers and response code.
Example of added (optional) headers, e.g. headers.put("Authorization", Arrays.asList(String[] { "Bearer 234asdf234"})
Exception handling (catches and forwards HttpStatuses like 404 instead of throwing a 500 Server Error)
private String server = "localhost";
private int port = 443;
#Autowired
MultiValueMap<String, String> headers;
#Autowired
RestTemplate restTemplate;
#RequestMapping("/**")
public ResponseEntity<String> mirrorRest(#RequestBody(required = false) String body, HttpMethod method, HttpServletRequest request) throws URISyntaxException
{
URI uri = new URI("https", null, server, port, request.getRequestURI(), request.getQueryString(), null);
HttpEntity<String> entity = new HttpEntity<>(body, headers);
try {
ResponseEntity<String> responseEntity =
restTemplate.exchange(uri, method, entity, String.class);
return responseEntity;
} catch (HttpClientErrorException ex) {
return ResponseEntity
.status(ex.getStatusCode())
.headers(ex.getResponseHeaders())
.body(ex.getResponseBodyAsString());
}
return responseEntity;
}

proxy controller with oauth2
#RequestMapping("v9")
#RestController
#EnableConfigurationProperties
public class ProxyRestController {
Logger logger = LoggerFactory.getLogger(this.getClass());
#Autowired
OAuth2ProtectedResourceDetails oAuth2ProtectedResourceDetails;
#Autowired
private ClientCredentialsResourceDetails clientCredentialsResourceDetails;
#Autowired
OAuth2RestTemplate oAuth2RestTemplate;
#Value("${gateway.url:http://gateway/}")
String gatewayUrl;
#RequestMapping(value = "/proxy/**")
public String proxy(#RequestBody(required = false) String body, HttpMethod method, HttpServletRequest request, HttpServletResponse response,
#RequestHeader HttpHeaders headers) throws ServletException, IOException, URISyntaxException {
body = body == null ? "" : body;
String path = request.getRequestURI();
String query = request.getQueryString();
path = path.replaceAll(".*/v9/proxy", "");
StringBuffer urlBuilder = new StringBuffer(gatewayUrl);
if (path != null) {
urlBuilder.append(path);
}
if (query != null) {
urlBuilder.append('?');
urlBuilder.append(query);
}
URI url = new URI(urlBuilder.toString());
if (logger.isInfoEnabled()) {
logger.info("url: {} ", url);
logger.info("method: {} ", method);
logger.info("body: {} ", body);
logger.info("headers: {} ", headers);
}
ResponseEntity<String> responseEntity
= oAuth2RestTemplate.exchange(url, method, new HttpEntity<String>(body, headers), String.class);
return responseEntity.getBody();
}
#Bean
#ConfigurationProperties("security.oauth2.client")
#ConditionalOnMissingBean(ClientCredentialsResourceDetails.class)
public ClientCredentialsResourceDetails clientCredentialsResourceDetails() {
return new ClientCredentialsResourceDetails();
}
#Bean
#ConditionalOnMissingBean
public OAuth2RestTemplate oAuth2RestTemplate() {
return new OAuth2RestTemplate(clientCredentialsResourceDetails);
}

If you can get away with using a lower-level solution like mod_proxy that would be the simpler way to go, but if you need more control (e.g. security, translation, business logic) you may want to take a look at Apache Camel: http://camel.apache.org/how-to-use-camel-as-a-http-proxy-between-a-client-and-server.html

I got inspired by Veluria's solution, but I had issues with gzip compression sent from the target resource.
The goal was to omit Accept-Encoding header:
#RequestMapping("/**")
public ResponseEntity mirrorRest(#RequestBody(required = false) String body,
HttpMethod method, HttpServletRequest request, HttpServletResponse response)
throws URISyntaxException {
String requestUrl = request.getRequestURI();
URI uri = new URI("http", null, server, port, null, null, null);
uri = UriComponentsBuilder.fromUri(uri)
.path(requestUrl)
.query(request.getQueryString())
.build(true).toUri();
HttpHeaders headers = new HttpHeaders();
Enumeration<String> headerNames = request.getHeaderNames();
while (headerNames.hasMoreElements()) {
String headerName = headerNames.nextElement();
if (!headerName.equals("Accept-Encoding")) {
headers.set(headerName, request.getHeader(headerName));
}
}
HttpEntity<String> httpEntity = new HttpEntity<>(body, headers);
RestTemplate restTemplate = new RestTemplate();
try {
return restTemplate.exchange(uri, method, httpEntity, String.class);
} catch(HttpStatusCodeException e) {
return ResponseEntity.status(e.getRawStatusCode())
.headers(e.getResponseHeaders())
.body(e.getResponseBodyAsString());
}
}

You need something like jetty transparent proxy, which actually will redirect your call, and you get a chance to overwrite the request if you needed. You may get its detail at http://reanimatter.com/2016/01/25/embedded-jetty-as-http-proxy/

How to serve huge file over streaming rest?

I have 2 Spring Web applications: Application1 and Application2. In Application1, I have an endpoint at "http://application1/getbigcsv" that uses streaming in order to serve a gigantic 150MB CSV file back to the user if they hit that URL.
I dont want users to hit Application1 directly, but hit Application2 instead.
If I have the following method in my controller in Application2
#RequestMapping(value = "/large.csv", method = GET, produces = "text/csv")
#ResponseStatus(value = HttpStatus.OK)
public String streamLargeCSV() {
// Make an HTTP Request to http://application1/getbigcsv
// Return its response
}
My worry is the above is not doing "streaming" whereas Application1 is doing streaming. Is there some way I can make sure that the application2 will be serving back the same data from application1's rest endpoint in a streaming fashion? Or is the method above actually returning things in a "Streaming" method already because Application1 is serving its endpoint as streaming?

First of all: you can but not with that method signature.
Unfortunately, you have not shown how you produce that CSV file in app1, whether this is truly streaming. Let's assume it is.
You signature will look like this:
#RequestMapping(value = "/large.csv", method = GET, produces = "text/csv")
#ResponseStatus(value = HttpStatus.OK)
public void streamLargeCSV(OutputStream out) {
// Make an HTTP Request to http://application1/getbigcsv
// Return its response
}
Now we have to grab the input stream from app1 first. Use Apache HttpClient to get your HttpEntity. This entity has a writeTo(OutputStream) method which will receive your out parameter. It will block until all bytes are consumed/streamed. When you are done, free all HttpClient resources.
Complete code:
#RequestMapping(value = "/large.csv", method = GET, produces = "text/csv")
#ResponseStatus(value = HttpStatus.OK)
public void streamLargeCSV(OutputStream out) {
// Make an HTTP Request to http://application1/getbigcsv
CloseableHttpClient httpclient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet("http://application1/getbigcsv");
CloseableHttpResponse response = httpclient.execute(httpGet);
try {
HttpEntity entity = response.getEntity();
// Return its response
entity.writeTo(out);
} finally {
response.close();
}
}
Here is my real world example. Start reading from "Interesting to say what I have achieved in particular with this:"

In java.ws.rs.core package you have classes: StreamingOutput and ResponseBuilder.
Not sure if it will help you, but you may try.
Example:
#Produces("application/octet-stream")
public Response doThings () {
...
StreamingOutput so;
try {
so = new StreamingOutput() {
public void write(OutputStream output) {
…
}
};
} catch (Exception e) {
...
}
ResponseBuilder response = Response.ok(so);
response.header("Content-Type", ... + ";charset=utf-8");
return response.build();
}

Change your methods return type to ResponseEntity<?> and return as following:
#GetMapping("/download")
public ResponseEntity<?> fetchActivities(
#RequestParam("filename") String filename) {
String string = "some large text"
InputStream is = new ByteArrayInputStream(string.getBytest());
HttpHeaders headers = new HttpHeaders();
headers.add(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=large.txt");
headers.add(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_OCTET_STREAM_VALUE);
return ResponseEntity.ok().headers(headers).body(new InputStreamResource(is));
}

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