Intercept request & send to external - spring-boot

Question

I am developing a Spring boot project.
One example of my controller:
#Controller
public class RestController {
#GetMapping(value = "/student/{studentId}")
public #ResponseBody Student getData(#PathVariable Integer studentId) {
Student student = new Student();
student.setName("Peter");
student.setId(studentId);
return student;
}
}
I have other endpoints implemented as well.
I need to intercept every request hits my endpoints & forward the request to another service (microservice), in other words, I need to forward each request to another web app running on the same local machine as current one, based on the response from that service to decide whether proceed forward the request or not.
My rough idea is to use HandlerIntercept , but I am not sure whether I am going to the right direction. Could someone please share some experiences what is the best way to achieve this? It would be nice if you could show some sample code. Thanks in advance.

Answer 1

You can use HandlerInterceptorAdapter.
Define the Interceptor as below.
#Component
public class RequestInterceptor extends HandlerInterceptorAdapter {
#Override
public boolean preHandle(HttpServletRequest request,
HttpServletResponse response, Object object) throws Exception {
System.out.println("In preHandle we are Intercepting the Request");
System.out.println("____________________________________________");
//Call the Rest API and Validate
if (conditionsNotMet()) {
response.getWriter().write("something");
response.setStatus(someErrorCode);
return false;
}
}
}
Register the HandlerInterceptorAdapter
#Configuration
public class PathMatchingConfigurationAdapter extends WebMvcConfigurerAdapter {
#Autowired
private RequestInterceptor requestInterceptor;
#Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(requestInterceptor);
}
}
using WebMvcConfigurer
#Configuration
public class PathMatchingConfigurationAdapter implements WebMvcConfigurer {
#Autowired
private RequestInterceptor requestInterceptor;
#Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(requestInterceptor);
}
#Override
public void addResourceHandlers(ResourceHandlerRegistry resourceHandlerRegistry) {
}
#Override
public void addCorsMappings(CorsRegistry corsRegistry) {
}
#Override
public void addViewControllers(ViewControllerRegistry viewControllerRegistry) {
}
#Override
public void configureViewResolvers(ViewResolverRegistry viewResolverRegistry) {
}
#Override
public void addArgumentResolvers(List<HandlerMethodArgumentResolver> list) {
}
#Override
public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> list) {
}
#Override
public void configureMessageConverters(List<HttpMessageConverter<?>> list) {
}
#Override
public void extendMessageConverters(List<HttpMessageConverter<?>> list) {
}
#Override
public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> list) {
}
#Override
public void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> list) {
}
#Override
public Validator getValidator() {
return null;
}
#Override
public MessageCodesResolver getMessageCodesResolver() {
return null;
}
#Override
public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
configurer.favorPathExtension(false);
}
#Override
public void configureAsyncSupport(AsyncSupportConfigurer asyncSupportConfigurer) {
}
#Override
public void configureDefaultServletHandling(DefaultServletHandlerConfigurer defaultServletHandlerConfigurer) {
}
#Override
public void addFormatters(FormatterRegistry formatterRegistry) {
}
#Override
public void configurePathMatch(PathMatchConfigurer configurer) {
configurer.setUseSuffixPatternMatch(false);
}
}