在 restTemplate 之后设置弹簧过滤器

Question

I have a few endpoints without http error codes. What I receive is a 200OK with a message error on the response. What I want to do is, after every single restTemplate GET, set some custom logic to check if the response is an error or not. What I have tried so far is implementing a filter class which is working with my endpoints

@Component
class ErrorFilter implements Filter {

   @Override
   void doFilter(ServletRequest servletRequest, ServletResponse 
servletResponse, FilterChain filterChain) {
       System.out.println("Filter called")
       filterChain.doFilter(servletRequest, servletResponse)
   }
}

when I implement an endpoint, this is working nice and I can add logic after every request. but it is not working when I call an external endpoint using restTemplate like this:

restTemplatie.exchange(url, HttpMethod.GET, request, String.class)

So, what I want to do is, after the above code, implement a logic similar to this:

if(response.body == customErrorMessage){
    thrown Exception
}

And I want this working in every single restTemplate call. Can I achieve this somehow with spring boot?

maybe with something similar to a restTemplate interceptor but the iterceptor is working BEFORE the call and I need it after (because I want to access to the response)

Answer 1

You can use Interceptor for handling response. in your case you can do the following:

public class ResponseInterceptor implements ClientHttpRequestInterceptor {

final static Logger log = LoggerFactory.getLogger(LoggingRequestInterceptor.class);

@Override
public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
    ClientHttpResponse response = execution.execute(request, body);
    //add your code
    if(response.getBody() == customErrorMessage){ // TODO 
      thrown new Exception("customErrorMessage");
    }
    return response;
}

To get the response body you need to read it as:

StringBuilder inputStringBuilder = new StringBuilder();
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(response.getBody(), "UTF-8"));
        String line = bufferedReader.readLine();
        while (line != null) {
            inputStringBuilder.append(line);
            inputStringBuilder.append('\n');
            line = bufferedReader.readLine();
        }

and then check inputStringBuilder.toString() (or you can check by line )