How to enable HTTP response caching in Spring Boot

问题:

I have implemented a REST server using Spring Boot 1.0.2. I'm having trouble preventing Spring from setting HTTP headers that disable HTTP caching.

My controller is as following:

@Controller
public class MyRestController {
    @RequestMapping(value = "/someUrl", method = RequestMethod.GET)
    public @ResponseBody ResponseEntity<String> myMethod(
            HttpServletResponse httpResponse) throws SQLException {
        return new ResponseEntity<String>("{}", HttpStatus.OK);
    }
}

All HTTP responses contain the following headers:

Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Expires: 0
Pragma: no-cache

I've tried the following to remove or change those headers:

1. Call setCacheSeconds(-1) in the controller.
2. Call httpResponse.setHeader("Cache-Control", "max-age=123") in the controller.
3. Define @Bean that returns WebContentInterceptor for which I've called setCacheSeconds(-1).
4. Set property spring.resources.cache-period to -1 or a positive value in application.properties.

None of the above have had any effect. How do I disable or change these headers for all or individual requests in Spring Boot?

回答1:

Turns out the no-cache HTTP headers are set by Spring Security. This is discussed in http://docs.spring.io/spring-security/site/docs/current/reference/htmlsingle/#headers.

The following disables the HTTP response header Pragma: no-cache, but doesn't otherwise solve the problem:

import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.config.annotation.web.servlet.configuration.EnableWebMvcSecurity;

@Configuration
@EnableWebMvcSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        // Prevent the HTTP response header of "Pragma: no-cache".
        http.headers().cacheControl().disable();
    }
}

I ended up disabling Spring Security completely for public static resources as following (in the same class as above):

@Override
public void configure(WebSecurity web) throws Exception {
    web.ignoring().antMatchers("/static/public/**");
}

This requires configuring two resource handlers to get cache control headers right:

@Configuration
public class MvcConfigurer extends WebMvcConfigurerAdapter
        implements EmbeddedServletContainerCustomizer {
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        // Resources without Spring Security. No cache control response headers.
        registry.addResourceHandler("/static/public/**")
            .addResourceLocations("classpath:/static/public/");

        // Resources controlled by Spring Security, which
        // adds "Cache-Control: must-revalidate".
        registry.addResourceHandler("/static/**")
            .addResourceLocations("classpath:/static/")
            .setCachePeriod(3600*24);
    }
}

See also Serving static web resources in Spring Boot & Spring Security application.

回答2:

I have found this Spring extension: https://github.com/foo4u/spring-mvc-cache-control.

You just have to do three steps.

Step 1 (pom.xml):

<dependency>
    <groupId>net.rossillo.mvc.cache</groupId>
    <artifactId>spring-mvc-cache-control</artifactId>
    <version>1.1.1-RELEASE</version>
    <scope>compile</scope>
</dependency>

Step 2 (WebMvcConfiguration.java):

@Configuration
public class WebMvcConfig extends WebMvcConfigurerAdapter implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new CacheControlHandlerInterceptor());
    }
}

Step 3 (Controller):

@Controller
public class MyRestController {

    @CacheControl(maxAge=31556926)
    @RequestMapping(value = "/someUrl", method = RequestMethod.GET)
    public @ResponseBody ResponseEntity<String> myMethod(
            HttpServletResponse httpResponse) throws SQLException {
        return new ResponseEntity<String>("{}", HttpStatus.OK);
    }
}

回答3:

I run into similar problem. I wanted to get just some of dynamic resources (images) cached in the browser. If image changes (not very often) I change the part of uri... This is my sollution

    http.headers().cacheControl().disable();
    http.headers().addHeaderWriter(new HeaderWriter() {

        CacheControlHeadersWriter originalWriter = new CacheControlHeadersWriter();

        @Override
        public void writeHeaders(HttpServletRequest request, HttpServletResponse response) {
            Collection<String> headerNames = response.getHeaderNames();
            String requestUri = request.getRequestURI();
            if(!requestUri.startsWith("/web/eventImage")) {
                originalWriter.writeHeaders(request, response);
            } else {
               //write header here or do nothing if it was set in the code
            }       
        }
    });

回答4:

@Configuration
@EnableAutoConfiguration
public class WebMvcConfiguration extends WebMvcConfigurerAdapter {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {

        registry.addResourceHandler("/resources/**")
                .addResourceLocations("/resources/")
                .setCachePeriod(31556926);

    }
}

回答5:

If you don't care to have your static resources authenticated, you could do this:

import static org.springframework.boot.autoconfigure.security.servlet.PathRequest.toStaticResources;

@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
...
    @Override
    public void configure(WebSecurity webSecurity) throws Exception {
        webSecurity
                .ignoring()
                .requestMatchers(toStaticResources().atCommonLocations());
    }
...
}

and in your application.properties:

spring.resources.cache.cachecontrol.max-age=43200

See ResourceProperties.java for more properties that can be set.