Spring MVC Version: 4.3.25
Spring Boot: 1.5.22 (Stuck to this due an old webshpere server version :( compatible only with JEE6)
Jackson Data-Bind: 2.10.3
My UI form submits POST request with parameters sent (inspected through browser tools).
Content-Type on Http Request is "application/x-www-form-urlencoded; charset=UTF-8"
changedValues[contacts[0]] 12312312313
changedValues[contacts[1]] 345354535
changedValues[contacts[2]] 35534534
name Sam
My Spring MVC controller goes like this.
Controller Code
#PostMapping("/saveMyPage")
public String saveMyPage(Model model,HttpServletRequest request, HttpServletResponse response,
HttpSession session,#ModelAttribute("myBean") MyBean oBean,BindingResult result){
Map <String,Object> uiChanged = oBean.changedValues;
... Other Code
}
Bean Code
public class MyBean implements Serializable{
private List<String> contacts;
private Map<String,Object> changedValues;
... Getters & Setters
}
On debugging, my Spring MVC controller I am hoping to get the list of only the changed contacts via the "changedValues" Hash Map. This is where the square brackets seem to break -
The key that Spring Binding maps now looks like
contacts[0 12312312313
contacts[1 345354535
contacts[2 35534534
name Sam
This breaks my code as the second square brackets were not understood by Spring Data Binding.
Still exploring if I can make Spring understand this binding of mine.
Related
Problem
I have a simple Spring Boot app with a basic RestController (full code available here). It consumes JSON and uses Jackson to convert request from JSON and response to JSON.
#RestController("/")
#RequestMapping(consumes = MediaType.APPLICATION_JSON_VALUE)
public class SomeController {
#Autowired
private SomeService someService;
#PostMapping
public ResponseEntity<SomeResponseDto> post(#RequestBody #Valid SomeRequestDto someRequestDto) {
final SomeResponseDto responseDto = new SomeResponseDto();
responseDto.setMessage(someRequestDto.getInputMessage());
responseDto.setUuid(someService.getUuid());
return ResponseEntity.ok(responseDto);
}
After start-up, the 1st request is about 10-times slower than any sub-sequent request. I debugged and profiled the app and it seems that on first request a Jackson JSON parser is getting initialized somewhere in AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters and AbstractJackson2HttpMessageConverter.
In sub-sequent requests, it seems to get re-used.
Question
How do I initialize Jackson JSON parsing during start-up so that also 1st request is fast?
I know how to trigger a method after Spring started. In PreloadComponent I added as an example how to do a REST request against the controller.
#Component
public class PreloadComponent implements ApplicationListener<ApplicationReadyEvent> {
private final Logger logger = LoggerFactory.getLogger(PreloadComponent.class);
#Autowired
private Environment environment;
#Autowired
private WebClient.Builder webClientBuilder;
#Override
public void onApplicationEvent(ApplicationReadyEvent event) {
// uncomment following line to directly send a REST request on app start-up
// sendRestRequest();
}
private void sendRestRequest() {
final String serverPort = environment.getProperty("local.server.port");
final String baseUrl = "http://localhost:" + serverPort;
final String warmUpEndpoint = baseUrl + "/warmup";
logger.info("Sending REST request to force initialization of Jackson...");
final SomeResponseDto response = webClientBuilder.build().post()
.uri(warmUpEndpoint)
.header(CONTENT_TYPE, APPLICATION_JSON_VALUE)
.body(Mono.just(createSampleMessage()), SomeRequestDto.class)
.retrieve()
.bodyToMono(SomeResponseDto.class)
.timeout(Duration.ofSeconds(5))
.block();
logger.info("...done, response received: " + response.toString());
}
private SomeRequestDto createSampleMessage() {
final SomeRequestDto someRequestDto = new SomeRequestDto();
someRequestDto.setInputMessage("our input message");
return someRequestDto;
}
}
This only works in this toy example. In reality, I have many REST endpoints with complex DTOs and I would need to add a "warm-up" endpoint next to each "real" endpoint as I can't call my real endpoints.
What I already tried?
I added a second endpoint with a different DTO and called it in my PreloadComponent. This doesn't solve the problem. I assume that an Jackson / whatever instance is created for each type.
I autowired ObjectMapper into my PreloadComponent and parsed JSON to my DTO. Again, this doesn't solve the issue.
Full source available at: https://github.com/steinsag/warm-me-up
It turns out that Jackson validation is the problem. I added the JVM option
-verbose:class
to see when classes get loaded. I noticed that on 1st request, there are many Jackson validation classes getting loaded.
To confirm my assumption, I re-worked my example and added another independent warm-up controller with a distinct DTO.
This DTO uses all Java validation annotations also present like in the real DTO, e.g. #NotNull, #Min, etc. In addition, it also has a custom enum to also have validation of sub-types.
During start-up, I now do a REST request to this warm-up endpoint, which doesn't need to contain any business logic.
After start-up, my 1st request is now only 2-3 times slower than any sub-sequent requests. This is is acceptable. Before, the 1st request was 20-40 times slower.
I also evaluated if really a REST request is needed or if it is sufficient to just do JSON parsing or validation of a DTO (see PreloadComponent). This reduces runtime of 1st request a bit, but it is still 5-15 times slower than with proper warm-up. So I guess a REST request is needed to also load other classes in Spring Dispatcher, etc.
I updated my example at: https://github.com/steinsag/warm-me-up
I believe, that a lot of classes will be lazy-loaded. If first call performance is important, then I think warming up by calling each endpoint is the way to go.
Why do you say, that you cannot call the endpoints? If you have a database and you don't want to change the data, wrap everything in a transaction and roll it back after the warm up calls.
I haven't seen any other method to solve this, which doesn't necessarily mean, that it doesn't exist ;)
I'm integrating spring web sockets capability into an existing spring mvc application, everything works as expected, except for enabling custom Spring Conversion on my inbound messages via #DestinationVariable.
Now I already have custom converters fully working for the http side, ex #RequestParam or #PathVariable but the same conversion on a websocket controller method throws a ConverterNotFoundException
Ex. I have a custom converter that converts String into Users
public class StringToUserConverter implements Converter<String,User>{
#Autowired UserDAO userDAO;
#Override
public User convert(String id) {
return userDAO.getUser(Integer.parseInt(id));
}
}
And this works exactly as expected in my http controllers, where I can pass in an id, and its automatically converted to the domain class
public String myControllerMethod(#RequestParam User user)
However the same does not work for my websocket controller for a parameter annotated with #DestinationVariable
#MessageMapping("/users/{user}")
#SendTo("/users/greetings")
public String send(#DestinationVariable User user) {
return "hello"
}
I stepped through the code and I can see that the DestinationVariableMethodArgumentResolver has the default conversion service which doesnt include my custom coverters
So how do I register custom converters, or a custom ConversionService so that it works for web sockets like it already does for http controllers
So now I'm running into the same issue with #Header annotation for JmsListener methods.
Same idea, #Header User user, throws the ConverterNotFound exception.
#JmsListener(destination = "testTopic")
public void testJmsListener(Message m, #Header User user)..
Here I was trying to pass the user id on the message header, and have spring convert it, but to no avail, only basic default conversions are supported, like strings or numbers.
I have stepped through quite a bit of initialization code in Spring here, and I can see that a new DefaultConversionService gets instantiated in many places, without any consideration for external configuration.
It looks like these modules are not nearly as mature as Spring MVC or the developers took a shortcut. But based on my inspection there is no way to easily configure custom converters.
Ok and here is the very hacky, not recommended, approach that did work. Its pretty convoluted and brittle, Im not going to use it, but just for illustration purposes here is what it took to register a custom converter for #Header jms mapping.
Here Im passing in a user_email on the jms message header, and wanted spring to automatically convert the id/email into the actual domain object User. I already had a working converter that does this well in mvc/http mode.
public class StringToUserConverter implements Converter<String,User>{
#Autowired
UserDAO userDAO;
public User convert(String email) {
return userDAO.getByEmail(email);
}
}
The above part is pretty standard and straight forward. Here comes the idiotically convoluted part. I stepped through the spring jms listener initialization code and found lowest spot where I could cut-in with my custom converter for jms #Header.
I created a service, that will #Autowire one of springs Jms beans, and then sets a custom conversion service on it using #PostConstruct. Even here some of the properties were private, so I had to use reflection to read them
#Service
public class JmsCustomeConverterSetter {
#Autowired
StringToUserConverter stringToUserConverter;
#Autowired
JmsListenerAnnotationBeanPostProcessor jmsPostProcessor;
#PostConstruct
public void attachCustomConverters() throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException {
//create custom converter service that includes my custom converter
GenericConversionService converterService = new GenericConversionService();
converterService.addConverter(stringToUserConverter); //add custom converter, could add multiple here
DefaultConversionService.addDefaultConverters(converterService); //attach some default converters
//reflection to read the private field so i can use it later
Field field = jmsPostProcessor.getClass().getDeclaredField("beanFactory"); //NoSuchFieldException
field.setAccessible(true);
BeanFactory beanFactory = (BeanFactory) field.get(jmsPostProcessor); //IllegalAccessException
DefaultMessageHandlerMethodFactory f = new DefaultMessageHandlerMethodFactory();
f.setConversionService(converterService);
f.setBeanFactory(beanFactory); //set bean factory read using reflection
f.afterPropertiesSet();
jmsPostProcessor.setMessageHandlerMethodFactory(f);
}
}
Creating the DefaultMessageHandlerMethodFactory was based on code I saw in org.springframework.messaging.handler.annotation.support.MessageHandlerMethodFactory.
I would definitely not recommend using this in production. It is fairly brittle and unnecessarily complex.
Spring...sometimes it's a breath of fresh air... and sometimes it's convoluted-clap-trap
tl;dr: how to enable spring's ResourceUrlEncodingFilter for spring boot Error pages?
(Question written while using spring boot 1.3.7.RELEASE and Spring Framework/MVC 4.2.4.RELEASE)
Some background: We have a fairly standard spring boot/spring webmvc project using Thymeleaf as the view layer. We have the out-of-the-box spring boot Resource Chain enabled to serve static assets.
Our thymeleaf views have standard url-encoding syntax in them such as <script th:src="#{/js/some-page.js}"></script>. This relies on Spring's org.springframework.web.servlet.resource.ResourceUrlEncodingFilter to transform the url into an appropriately-versioned url such as /v1.6/js/some-page.js.
Our error handling is done by:
setting server.error.whitelabel.enabled=false
subclassing spring boot's default BasicErrorController to override public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response)
relying on our already-configured thymeleaf view resolvers to render our custom error page
The problem is: the ResourceUrlEncodingFilter isn't applying on our error pages. I assume it's a lack of the filter being registered for ERROR dispatched requests, but it's not obvious to me: a) how to customize this in spring boot; and b) why this wasn't done by default.
Update 1:
The issue seems to be with a combination of OncePerRequestFilter and the ERROR dispatcher. Namely:
ResouceUrlEncodingFilter does not bind to the ERROR dispatcher by default. While overriding this is messy it's not impossible, but doesn't help due to:
OncePerRequestFilter (parent of ResourceUrlEncodingFilter) sets an attribute on the Request indicating it's been applied so as to not re-apply. It then wraps the response object. However, when an ERROR is dispatched, the wrapped response is not used and the filter does not re-wrap due to the request attribute still being present.
Worse still, the logic for customizing boolean hasAlreadyFilteredAttribute is not overridable by request. OncePerRequestFilter's doFilter() method is final, and getAlreadyFilteredAttributeName() (the extension point) does not have access to the current request object to get the dispatcher.
I feel like I must be missing something; it seems impossible to use versioned resources on a 404 page in spring boot.
Update 2: A working but messy solution
This is the best I've been able to come up with, which still seems awfully messy:
public abstract class OncePerErrorRequestFilter extends OncePerRequestFilter {
#Override
protected String getAlreadyFilteredAttributeName() {
return super.getAlreadyFilteredAttributeName() + ".ERROR";
}
#Override
protected boolean shouldNotFilterErrorDispatch() {
return false;
}
}
public class ErrorPageCapableResourceUrlEncodingFilter extends OncePerErrorRequestFilter {
// everything in here is a perfect copy-paste of ResourceUrlEncodingFilter since the internal ResourceUrlEncodingResponseWrapper is private
}
// register the error-supporting version if the whitelabel error page has been disabled ... could/should use a dedicated property for this
#Configuration
#AutoConfigureAfter(WebMvcAutoConfiguration.class)
#ConditionalOnClass(OncePerErrorRequestFilter.class)
#ConditionalOnWebApplication
#ConditionalOnEnabledResourceChain
#ConditionalOnProperty(prefix = "server.error.whitelabel", name = "enabled", havingValue="false", matchIfMissing = false)
public static class ThymeleafResourceUrlEncodingFilterErrorConfiguration {
#Bean
public FilterRegistrationBean errorPageResourceUrlEncodingFilterRegistration() {
FilterRegistrationBean reg = new FilterRegistrationBean();
reg.setFilter(new ErrorPageCapableResourceUrlEncodingFilter());
reg.setDispatcherTypes(DispatcherType.ERROR);
return reg;
}
}
Better solutions?
This has been reported in spring-projects/spring-boot#7348 and a fix is on its way.
It seems you've made an extensive analysis of the issue; too bad you didn't report this issue earlier. Next time, please consider raising those on the Spring Boot tracker.
Thanks!
I use spring mvc and I want to undestand some stuff.
At this code:
#RequestMapping(value="/enregistrerLostCard")
public #ResponseBody
void enregistrerLostCard(#ModelAttribute(value="auth") Auth auth2, HttpServletRequest request) {
Auth auth1 = (Auth) request.getAttribute("auth");
System.out.println(auth2.getLogin()); //print the right value
System.out.println(auth1.getLogin()); //i got nullpointer exception
}
#ModelAttribute(value="auth") and request.getAttribute("auth") isn't the same ?
HttpServletRequest is a Servlet container managed object. Its attribute store holds attributes that are useful in any part of the request handling by the Servlet container.
Model, ModelMap, ModelAndView, etc. are managed by Spring MVC (the DispatcherServlet stack). The attributes inside those are useful to the Spring side of the application.
In some cases, the Model attributes will be inserted into the HttpServletRequest attributes if needed. This typically happens when your handler method returns a String value as a view name. The model attributes will be pushed as HttpServletRequest attributes so that they can be used in the view, for example, in jsps.
Related:
how to pass variables from java to jsp in Spring
I am trying to do a simple android application that communicates with a Spring server.
I'd like to use Sessions to store data of each logged in User.
My App exchange Json objects with the server and the Request Mapping is like this:
#Controller
public class LoginController {
#Autowired
private IUserDao userDao;
#RequestMapping( value = "/loginJson",method = RequestMethod.POST)
public #ResponseBody loginResponse login(#RequestBody loginModel login) {
loginResponse response=userDao.checkCredentials(login.getUsername(),login.getPassword());
System.out.println("Result="+response.isSuccess());
System.out.println("Received:"+login.getUsername()+" "+login.getPassword());
return response;
}
}
The controller is working fine, but I can't figure out how to store a sessione variable. I found many documents explaining Spring Sessions, but each of them different from the other.
Someone can suggest me some simple way to do this or some kind of good tutorial?
Not sure what you mean by saying Spring session, but you can declare additional HttpSession parameter in your method, and then do whatever you like inside of the method. Is this what you wanted to find out?