How to resolve view in thymleaf + Springboot? - spring-mvc

Question

Currently, i have function, which is to convert the data from MYSQL to CSV. The CSV function contain the webconfig where use the viewResolver. The problem is, when i used below function, the page cannot view but the CSV file can be download and vice versa. Is there anything that i need to configure ?
-Configure ContentNegotiatingViewResolver
#Bean
public ViewResolver contentNegotiatingViewResolver(ContentNegotiationManager manager) {
ContentNegotiatingViewResolver resolver = new ContentNegotiatingViewResolver();
resolver.setContentNegotiationManager(manager);
// Define all possible view resolvers
List<ViewResolver> resolvers = new ArrayList<>();
resolvers.add(csvViewResolver());
resolver.setViewResolvers(resolvers);
return resolver;
}
WebConfig- full code
package com.portal.dmtt.csvDownload.config;
import com.portal.dmtt.csvDownload.viewResolver.CsvViewResolver;
import org.springframework.context.annotation.Bean;
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.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.view.ContentNegotiatingViewResolver;
import java.util.ArrayList;
import java.util.List;
#Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
#Override
public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
configurer
.defaultContentType(MediaType.APPLICATION_JSON)
.favorPathExtension(true);
}
/*
* Configure ContentNegotiatingViewResolver
*/
#Bean
public ViewResolver contentNegotiatingViewResolver(ContentNegotiationManager manager) {
ContentNegotiatingViewResolver resolver = new ContentNegotiatingViewResolver();
resolver.setContentNegotiationManager(manager);
// Define all possible view resolvers
List<ViewResolver> resolvers = new ArrayList<>();
resolvers.add(csvViewResolver());
resolver.setViewResolvers(resolvers);
return resolver;
}
/*
* Configure View resolver to provide Csv output using Super Csv library to
* generate Csv output for an object content
*/
#Bean
public ViewResolver csvViewResolver() {
return new CsvViewResolver();
}
}
Export Controller
package com.portal.dmtt.csvDownload.controller;
import com.portal.dmtt.repo.dmttDAO;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
#Controller
public class ExportController {
#Autowired
private dmttDAO dmttDAO;
/**
* Handle request to download an Excel document
*/
#GetMapping("/dl")
public String download(Model model) {
model.addAttribute("results", dmttDAO.getAllResultSet());
return "";
}
}
Abstract View
package com.portal.dmtt.csvDownload.view;
import org.springframework.web.servlet.view.AbstractView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Map;
public abstract class AbstractCsvView extends AbstractView {
private static final String CONTENT_TYPE = "text/csv";
public AbstractCsvView() {
setContentType(CONTENT_TYPE);
}
#Override
protected boolean generatesDownloadContent() {
return true;
}
#Override
protected final void renderMergedOutputModel(
Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
response.setContentType(getContentType());
buildCsvDocument(model, request, response);
}
protected abstract void buildCsvDocument(
Map<String, Object> model, HttpServletRequest request, HttpServletResponse response)
throws Exception;
}
CSV View
package com.portal.dmtt.csvDownload.view;
import com.portal.dmtt.model.exceptionMonitoring.FN_Result_Set;
import org.supercsv.io.CsvBeanWriter;
import org.supercsv.io.ICsvBeanWriter;
import org.supercsv.prefs.CsvPreference;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.List;
import java.util.Map;
public class CsvView extends AbstractCsvView {
#Override
protected void buildCsvDocument(Map<String, Object> model, HttpServletRequest request, HttpServletResponse
response) throws Exception {
response.setHeader("Content-Disposition", "attachment; filename=\"my-csv-file.csv\"");
List<FN_Result_Set> fnResultSetList = (List<FN_Result_Set>) model.get("results");
String[] header = {"SP_ID", "SP_ID", "XFER_XMIT_STATUS", "XFER_FILE_NAME", "UPDATE_TS", "YYMM", "REMARKS"};
try {
ICsvBeanWriter csvWriter = new CsvBeanWriter(response.getWriter(),
CsvPreference.STANDARD_PREFERENCE);
csvWriter.writeHeader(header);
for (FN_Result_Set user : fnResultSetList) {
csvWriter.write(user, header);
}
csvWriter.close();
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
View Resolver
package com.portal.dmtt.csvDownload.viewResolver;
import com.portal.dmtt.csvDownload.view.CsvView;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.ViewResolver;
import java.util.Locale;
public class CsvViewResolver implements ViewResolver {
#Override
public View resolveViewName(String s, Locale locale) throws Exception {
return new CsvView();
}
}

Answer 1

One of the problems is that your CSVViewResolver is resolving a view for any view name. You may want to return null from CSVViewResolver.resolveViewName() if s, the view name, is not empty .
Another issue is that the browser (at least my Chrome) doesn't send text/csv as Accept header, but text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8
Set the media type explicitly in configureContentNegotiation for CSV:
#Override
public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
configurer
.defaultContentType(MediaType.APPLICATION_JSON)
.favorPathExtension(true)
.mediaType("csv", MediaType.parseMediaType("text/csv"));
}
Remove the Bean contentNegotiatingViewResolver
You shouldn't create a contentNegotiatingViewResolver as one is provided by Spring Boot. If you provide one, you will have two of this type, and yours will not have the Thymeleaf ViewResolver. As your CSVViewResolver will return a view for any view name, the view will be resolved in the ContentNegotiatingViewResolver provided by you, not in the one provided by Spring.
Details:
The csvViewResolver bean will be picked up by the Spring Boot's ContentNegotiatingViewResolver along others like BeanNameViewResolver, ThymeleafViewResolver, ViewResolverComposite, InternalResourceViewResolver.
To debug this set a breakpoint on DispatcherServlet.resolveViewName:
protected View resolveViewName(String viewName, Map<String, Object> model, Locale locale,
HttpServletRequest request) throws Exception {
for (ViewResolver viewResolver : this.viewResolvers) {
View view = viewResolver.resolveViewName(viewName, locale);
if (view != null) {
return view;
}
}
return null;
}