Configuring Multiple View Resolvers (Thymeleaf and Json) Spring - spring-mvc

Question

I am trying to configure a Spring based app, where I want to configure two view resolvers. From my controller, if I return just the string name like "login", then it should be handled by the Thymeleaf resolver, whereas if the controller's method returns an object, then appropriate json view should be used. When I try to run my application as configured below, I get the following error
"Could not resolve view with name 'login' in servlet with name
'dispatcher'"
Requesting you guys to look at the Java classes below. The first is the configuration class, the second is the Controller I am trying to use.
package com.gojha.web;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.web.accept.ContentNegotiationManager;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.ContentNegotiationConfigurer;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.view.ContentNegotiatingViewResolver;
import org.thymeleaf.TemplateEngine;
import org.thymeleaf.spring4.SpringTemplateEngine;
import org.thymeleaf.spring4.view.ThymeleafViewResolver;
import org.thymeleaf.templateresolver.ServletContextTemplateResolver;
import org.thymeleaf.templateresolver.TemplateResolver;
#Configuration
#EnableWebMvc
#ComponentScan("com.gojha.web")
public class WebConfig extends WebMvcConfigurerAdapter {
#Override
public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
configurer.enable();
}
#Bean
public ViewResolver viewResolver(ContentNegotiationManager cnm) {
ContentNegotiatingViewResolver cnvr = new ContentNegotiatingViewResolver();
cnvr.setContentNegotiationManager(cnm);
return cnvr;
}
#Override
public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
configurer.defaultContentType(MediaType.APPLICATION_JSON);
}
#Bean
public TemplateResolver templateResolver() {
TemplateResolver templateResolver = new ServletContextTemplateResolver();
templateResolver.setPrefix("/WEB-INF/templates/");
templateResolver.setSuffix(".html");
templateResolver.setTemplateMode("HTML5");
return templateResolver;
}
#Bean
public TemplateEngine templateEngine() {
SpringTemplateEngine templateEngine = new SpringTemplateEngine();
templateEngine.setTemplateResolver(templateResolver());
return templateEngine;
}
#Bean
public ViewResolver viewResolver() {
ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
viewResolver.setTemplateEngine((SpringTemplateEngine) templateEngine());
return viewResolver;
}
}
Controller
package com.gojha.web;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.client.RestTemplate;
import static org.springframework.web.bind.annotation.RequestMethod.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
#Controller
#RequestMapping("/")
public class LoginController {
private RestTemplate restTemplate;
private class Test {
private String a;
public Test() {
super();
}
public Test(String a) {
super();
this.a = a;
}
public String getA() {
return a;
}
public void setA(String a) {
this.a = a;
}
}
#Autowired
public LoginController(RestTemplate restTemplate) {
this.restTemplate = restTemplate;
}
#RequestMapping(method=GET)
public String testing(){
return "login";
}
#RequestMapping(method=GET, produces="application/json")
public Test testing2(){
return new Test("wow");
}
}
I hope the code is self-explanatory.

Answer 1

I got it working by changing the configuration file and allocating orders to view resolvers. From what I understand, it looks like first it tries to resolve the view using ContentNegotiation, and if it fails, falls back to Thymeleaf resolver. I am marking this as the answer, if someone has a better approach, or a suggested correction, let me know.
package com.gojha.web;
import java.util.ArrayList;
import java.util.List;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.web.accept.ContentNegotiationManager;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.ContentNegotiationConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.view.ContentNegotiatingViewResolver;
import org.springframework.web.servlet.view.json.MappingJackson2JsonView;
import org.thymeleaf.spring4.SpringTemplateEngine;
import org.thymeleaf.spring4.view.ThymeleafViewResolver;
import org.thymeleaf.templateresolver.ServletContextTemplateResolver;
import org.thymeleaf.templateresolver.TemplateResolver;
#Configuration
#EnableWebMvc
#ComponentScan("com.gojha.web")
public class WebConfig extends WebMvcConfigurerAdapter {
#Override
public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
configurer.defaultContentType(MediaType.APPLICATION_JSON);
}
#Bean
public ViewResolver viewResolver() {
TemplateResolver templateResolver = new ServletContextTemplateResolver();
templateResolver.setPrefix("/WEB-INF/templates/");
templateResolver.setSuffix(".html");
templateResolver.setTemplateMode("HTML5");
SpringTemplateEngine templateEngine = new SpringTemplateEngine();
templateEngine.setTemplateResolver(templateResolver);
ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
viewResolver.setTemplateEngine(templateEngine);
viewResolver.setOrder(2);
return viewResolver;
}
#Bean
public ViewResolver cnViewResolver(ContentNegotiationManager cnm) {
ContentNegotiatingViewResolver cnvr = new ContentNegotiatingViewResolver();
cnvr.setContentNegotiationManager(cnm);
cnvr.setOrder(1);
List<View> views = new ArrayList<View>();
views.add(jsonView());
cnvr.setDefaultViews(views);
return cnvr;
}
#Bean
public View jsonView() {
MappingJackson2JsonView view = new MappingJackson2JsonView();
view.setPrettyPrint(true);
return view;
}
}