Spring MVC - Setting request and response Headers Examples

package com.logicbig.example;


import org.springframework.http.CacheControl;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import jakarta.servlet.http.HttpServletResponse;
import java.time.LocalDateTime;
import java.util.concurrent.TimeUnit;

@Controller
public class TheController {

    @RequestMapping(value = "/test1")
    public String handle1 (HttpServletResponse response) {
        String headerValue = CacheControl.maxAge(10, TimeUnit.SECONDS)
                                         .getHeaderValue();

        response.addHeader("Cache-Control", headerValue);
        return "myView";
    }

    @ResponseBody
    @RequestMapping(value = "/test2")
    public ResponseEntity<String> handle2 () {

        CacheControl cacheControl = CacheControl.maxAge(10, TimeUnit.SECONDS);

        String testBody = "<p>Response time: " + LocalDateTime.now() +
                  "</p><a href=''>test2</a>";
        return ResponseEntity.ok()
                             .cacheControl(cacheControl)
                             .body(testBody);
    }
}

package com.logicbig.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.context.request.ServletWebRequest;
import java.io.IOException;

@Controller
public class TheController {
    @Autowired
    private ResourceService resourceService;

    @ResponseBody
    @RequestMapping(value = "/test1")
    public String handle1(ServletWebRequest swr) throws IOException {

        //doesn't matter it returns false/true it will set the required headers automatically.
        //It doesn't include 'Cache-Control:no-cache' so have to do browser F5
        if (swr.checkNotModified(resourceService.lastModified())) {
            //it will return 304 with empty body
            return null;
        }

        //uncomment the following if last-modified checking is needed at every action
       /* swr.getResponse().setHeader(HttpHeaders.CACHE_CONTROL,
                                    CacheControl.noCache()
                                                .getHeaderValue());*/

        return resourceService.read();
    }


    @ResponseBody
    @RequestMapping(value = "/test2")
    public ResponseEntity<String> handle2() throws IOException {

        //returning ResponseEntity with lastModified, HttpEntityMethodProcessor will
        //take care of populating/processing the required headers.
        //As the body can be replaced with empty one and 304 status can be send back,
        // this approach should be avoided if preparing the response body is very expensive.
        return ResponseEntity.ok()
                             .lastModified(resourceService.lastModified())
                             .body(resourceService.read());
    }

    @ResponseBody
    @RequestMapping(value = "/update", method = RequestMethod.POST)
    public String updateResource(@RequestBody String content) throws IOException {
        resourceService.update(content);
        return "Resource updated";
    }
}

package com.logicbig.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.context.request.ServletWebRequest;
import org.springframework.web.context.request.WebRequest;

@Controller
public class TheController {
    @Autowired
    private ResourceStore resourceStore;

    @ResponseBody
    @RequestMapping(value = "/test1")
    public String handle1(ServletWebRequest swr) {

        if (swr.checkNotModified(getETag())) {
            //it will return 304 with empty body
            return null;
        }
        return resourceStore.getCurrentResource().getData();
    }

    @ResponseBody
    @RequestMapping(value = "/test2")
    public ResponseEntity<String> handle2(WebRequest swr) {

        return ResponseEntity
                .ok()
                .eTag(getETag())
                .body(resourceStore.getCurrentResource().getData());
    }

    @ResponseBody
    @RequestMapping(value = "/update", method = RequestMethod.POST)
    public String updateResource(@RequestBody String content) {
        resourceStore.update(content);
        return "Resource updated";
    }

    public String getETag() {
        return "version" +
                resourceStore.getCurrentResource().getVersion();
    }
}