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 javax.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.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.context.request.ServletWebRequest;
import org.springframework.web.context.request.WebRequest;

import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;

@Controller
public class TheController {

    public static long getResourceLastModified () {
        ZonedDateTime zdt = ZonedDateTime.of(LocalDateTime.of(2017, 1, 9,
                                                              10, 30, 20),
                                             ZoneId.of("GMT"));
        return zdt.toInstant().toEpochMilli();
    }

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

        //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(getResourceLastModified())) {
            //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 "myView";
    }

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

        if (swr.checkNotModified(getResourceLastModified())) {
            return null;
        }

        String testBody = "<p>Response time: " + LocalDateTime.now() +
                  "</p><a href='test2'>test2</a>";

        return testBody;
    }

    @ResponseBody
    @RequestMapping(value = "/test3")
    public ResponseEntity<String> handle3 (WebRequest swr) {

        String testBody = "<p>Response time: " + LocalDateTime.now() +
                  "</p><a href='test3'>test3</a>";

        //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(getResourceLastModified())
                             .body(testBody);
    }
}

package com.logicbig.example;

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 org.springframework.web.context.request.ServletWebRequest;
import org.springframework.web.context.request.WebRequest;

import java.time.LocalDateTime;

@Controller
public class TheController {

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

        if (swr.checkNotModified(getETag())) {
            //it will return 304 with empty body
            return null;
        }
        return "myView";
    }

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

        if (swr.checkNotModified(getETag())) {
            return null;
        }

        String testBody = "<p>Response time: " + LocalDateTime.now() +
                  "</p><a href='test2'>test2</a>";

        return testBody;
    }

    @ResponseBody
    @RequestMapping(value = "/test3")
    public ResponseEntity<String> handle3 (WebRequest swr) {

        String version = getETag();

        String testBody = "<p>Response time: " + LocalDateTime.now() +
                  "</p><a href='test3'>test3</a>";
        return ResponseEntity
                  .ok()
                  .eTag(version)
                  .body(testBody);
    }

    public String getETag () {
        return "version1";
    }
}