How can I refresh Spring configuration file without restarting my servlet container?
I am looking for a solution other than JRebel.
For those stumbling on this more recently -- the current and modern way to solve this problem is to use Spring Boot's Cloud Config.
Just add the #RefreshScope annotation on your refreshable beans and #EnableConfigServer on your main/configuration.
So, for example, this Controller class:
#RefreshScope
#RestController
class MessageRestController {
#Value("${message}")
private String message;
#RequestMapping("/message")
String getMessage() {
return this.message;
}
}
Will return the new value of your message String property for the /message endpoint when refresh is invoked on Spring Boot Actuator (via HTTP endpoint or JMX).
See the official Spring Guide for Centralized Configuration example for more implementation details.
Well, it can be useful to perform such a context reload while testing your app.
You can try the refresh method of one of the AbstractRefreshableApplicationContext class: it won't refresh your previously instanciated beans, but next call on the context will return refreshed beans.
import java.io.File;
import java.io.IOException;
import org.apache.commons.io.FileUtils;
import org.springframework.context.support.FileSystemXmlApplicationContext;
public class ReloadSpringContext {
final static String header = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
"<!DOCTYPE beans PUBLIC \"-//SPRING//DTD BEAN//EN\"\n" +
" \t\"http://www.springframework.org/dtd/spring-beans.dtd\">\n";
final static String contextA =
"<beans><bean id=\"test\" class=\"java.lang.String\">\n" +
"\t\t<constructor-arg value=\"fromContextA\"/>\n" +
"</bean></beans>";
final static String contextB =
"<beans><bean id=\"test\" class=\"java.lang.String\">\n" +
"\t\t<constructor-arg value=\"fromContextB\"/>\n" +
"</bean></beans>";
public static void main(String[] args) throws IOException {
//create a single context file
final File contextFile = File.createTempFile("testSpringContext", ".xml");
//write the first context into it
FileUtils.writeStringToFile(contextFile, header + contextA);
//create a spring context
FileSystemXmlApplicationContext context = new FileSystemXmlApplicationContext(
new String[]{contextFile.getPath()}
);
//echo the bean 'test' on stdout
System.out.println(context.getBean("test"));
//write the second context into it
FileUtils.writeStringToFile(contextFile, header + contextB);
//refresh the context
context.refresh();
//echo the bean 'test' on stdout
System.out.println(context.getBean("test"));
}
}
And you get this result
fromContextA
fromContextB
Another way to achieve this (and maybe a more simple one) is to use the Refreshable Bean feature of Spring 2.5+
With dynamic language (groovy, etc) and spring you can even change your bean behavior. Have a look to the spring reference for dynamic language:
24.3.1.2. Refreshable beans
One of the (if not the) most
compelling value adds of the dynamic
language support in Spring is the
'refreshable bean' feature.
A refreshable bean is a
dynamic-language-backed bean that with
a small amount of configuration, a
dynamic-language-backed bean can
monitor changes in its underlying
source file resource, and then reload
itself when the dynamic language
source file is changed (for example
when a developer edits and saves
changes to the file on the
filesystem).
I wouldn't recommend you to do that.
What do you expect to happen to singleton beans which their configuration modified? do you expect all singletons to reload? but some objects may hold references to that singletons.
See this post as well Automatic configuration reinitialization in Spring
You can take a look at this http://www.wuenschenswert.net/wunschdenken/archives/138 where once you change any thing in the properties file and save it the beans will be reloaded with the new values.
Related
I have created a myApp.properties in resources folder location and mentioned the server.port in this file.
myApp.properties
myApp.server.port=8020
Now I want to read load this property into my application. But I have to read this before I actually a server.
Here I am trying to do like this
#SpringBootApplication
#ComponentScan(basePackages = {"com.myorg.myapp" })
#EnableConfigurationProperties
#PropertySource("classpath:myApp.properties")
#Component
public class MyAppApplication {
#Value("${myApp.server.port}")
private static String serverPort;
public static void main(String[] args) throws Exception{
try {
SpringApplication appCtxt = new SpringApplication(MyAppApplication.class);
appCtxt.setDefaultProperties(Collections
.singletonMap("server.port", serverPort));
appCtxt.run(args);
} catch (Exception e) {
e.printStackTrace();
}
}
But serverPort is coming as null.
I also tried to create a separate Config file like this but it can't be accessed in static main
#Configuration
#PropertySource("myApp.properties")
#ConfigurationProperties
public class MyAppConfig {
#Value("${myApp.server.port}")
private String serverPort;
/**
* #return the serverPort
*/
public String getServerPort() {
return serverPort;
}
}
Any suggestion would be helpful.
Spring boot injects properties during the initialization of the application context.
This happens (gets triggered) in the line:
appCtxt.run(args);
But you try to access the property before this line - that why it doesn't work.
So bottom line, using "#Value" in the main method doesn't work and it shouldn't.
Now from the code snippet, it looks like you could merely follow the "standards" of spring boot and create the file application.properties with:
server.port=1234
The process of starting the embedded web server in spring boot honors this property and bottom line it will have the same effect and Tomcat will be started on port 1234
Update 1
Based on OP's comment:
So, how can I have multiple application.properties.
In the Spring Boot's documentation it is written that application.properties are resolved from the classpath. So you can try the following assuming you have different modules A,B,C and web app D:
Create src/main/resources/application.properties inside each of 4 modules and pack everything together. The configuration values will be merged (hopefully they won't clash)
If you insist on naming properties A.properties, B.properties and C.properties for each of non-web modules, you can do the following (I'll show for module A, but B and C can do the same).
#Configuration
#PropertySource("classpath:A.properties")
public class AConfiguration {
}
Create in Module A: src/main/resources/A.properties
If you need to load the AConfiguration automatically - make the module A starter (using autoconfig feature of spring-boot):
Create src/resources/META-INF/spring.factories file with the following content:
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
<package_of_AConfiguration>.AConfiguration
Also this has been the requirement to separate C from entire bundle where it might run as bundle for some and as a separate for some others
Although I haven't totally understood the requirement, but you can use #ConditionalOnProperty for configuration CConfiguration (that will be created just like AConfiguration.java in my previous example) but this times for module C.
If the conditional is met, configuration will run and load some beans / load its own properties or whatever. All in all conditionals (and in particular Profiles in spring) can help to reach the desired flexibility.
By default, the application.properties file can be used to store property pairs, though you can also define any number of additional property files.
If you save myApp.server.port=8020 in application.properties, it will work fine.
To register a custome property file, you can annotate a #Configuration class with the additional #PropertySource annotation:
#Configuration
#PropertySource("classpath:custom.properties")
#PropertySource("classpath:another.properties")
public class ConfigClass {
// Configuration
}
make sure, your class path is correct.
When I run my app, metadataFile is always null when the bean below is created. I have a Spring Cloud Config Server which I see is hit before my breakpoint and the YML is successfully retrieved.
Even if the Config Server was down, the SPEL should provide a default. Has anyone run into #Value not evaluating and injecting values before their #Bean? I have many years using XML annotations, so perhaps I never have hit this with Annotation driven config, but it seems hard to believe I would not have run into this before. Very confused...
Within it:
#Configuration
public class Test {
#Value("${someplace.saml.idp.metadata.file:'classpath:idp-metadata.xml'}")
String metadataFile;
#Bean
MetadataProvider metadataProvider() {
if(!StringUtils.isBlank(metadataFile) && metadataFile.startsWith("classpath:/")) {
// do some stuff
} else {
File metadatFile = new File(metadataFile);
}
}
UPDATE:
I shortened my example above for sake of brevity. The culprit wiping out the configuration values is this SAMLBootstrap bean. It seems to be required for annotation-configured Spring SAML2.
#Bean
SAMLBootstrap samlBootstrap() {
return new SAMLBootstrap();
}
UPDATE 2 (THE SOLUTION):
The SAMLBootstrap bean needs to be declared with static. I found this in the last comment on another post: Spring Bean without id or name in Java Config
This question already has answers here:
Why is my Spring #Autowired field null?
(21 answers)
Closed 6 years ago.
I was able to use RestTemplate and autowire it. However I want to move my rest template related part of code into another class as follows:
public class Bridge {
private final String BASE_URL = "http://localhost:8080/u";
#Autowired
RestTemplate restTemplate;
public void addW() {
Map<String, String> x = new HashMap<String, String>();
W c = restTemplate.getForObject(BASE_URL + "/device/yeni", W.class, x);
System.out.println("Here!");
}
}
And at another class I call it:
...
Bridge wb = new Bridge();
wb.addW();
...
I am new to Spring and Dependency Injection terms. My restTemplate variable is null and throws an exception. What can I do it how to solve it(I don't know is it related to I use new keyword)?
Using Bridge wb = new Bridge() does not work with dependency injection. Your restTemplate is not injected, because wb in not managed by Spring.
You have to make your Bridge a Spring bean itself, e.g. by annotation:
#Service
public class Bridge {
// ...
}
or by bean declaration:
<bean id="bridge" class="Bridge"/>
Just to add further to Jeha's correct answer.
Currently, by doing
Bridge wb = new Bridge();
Means that, that object instance is not "Spring Managed" - I.e. Spring does not know anything about it. So how can it inject a dependency it knows nothing about.
So as Jeha said. Add the #Service annotation or specify it in your application context xml config file (Or if you are using Spring 3 you #Configuration object)
Then when the Spring context starts up, there will be a Singleton (default behavior) instance of the Bridge.class in the BeanFactory. Either inject that into your other Spring-Managed objects, or pull it out manually e.g.
Bridge wb = (Bridge) applicationContext.getBean("bridge"); // Name comes from the default of the class
Now it will have the dependencies wired in.
If you want to use new operator and still all dependency injected, then rather than making this a spring component (by annotating this with #Service), make it a #Configurable class.
This way even object is instantiated by new operator dependencies will be injected.
Few configuration is also required. A detailed explanation and sample project is here.
http://spring-framework-interoperability.blogspot.in/2012/07/spring-managed-components.html
tl;dr: how to enable spring's ResourceUrlEncodingFilter for spring boot Error pages?
(Question written while using spring boot 1.3.7.RELEASE and Spring Framework/MVC 4.2.4.RELEASE)
Some background: We have a fairly standard spring boot/spring webmvc project using Thymeleaf as the view layer. We have the out-of-the-box spring boot Resource Chain enabled to serve static assets.
Our thymeleaf views have standard url-encoding syntax in them such as <script th:src="#{/js/some-page.js}"></script>. This relies on Spring's org.springframework.web.servlet.resource.ResourceUrlEncodingFilter to transform the url into an appropriately-versioned url such as /v1.6/js/some-page.js.
Our error handling is done by:
setting server.error.whitelabel.enabled=false
subclassing spring boot's default BasicErrorController to override public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response)
relying on our already-configured thymeleaf view resolvers to render our custom error page
The problem is: the ResourceUrlEncodingFilter isn't applying on our error pages. I assume it's a lack of the filter being registered for ERROR dispatched requests, but it's not obvious to me: a) how to customize this in spring boot; and b) why this wasn't done by default.
Update 1:
The issue seems to be with a combination of OncePerRequestFilter and the ERROR dispatcher. Namely:
ResouceUrlEncodingFilter does not bind to the ERROR dispatcher by default. While overriding this is messy it's not impossible, but doesn't help due to:
OncePerRequestFilter (parent of ResourceUrlEncodingFilter) sets an attribute on the Request indicating it's been applied so as to not re-apply. It then wraps the response object. However, when an ERROR is dispatched, the wrapped response is not used and the filter does not re-wrap due to the request attribute still being present.
Worse still, the logic for customizing boolean hasAlreadyFilteredAttribute is not overridable by request. OncePerRequestFilter's doFilter() method is final, and getAlreadyFilteredAttributeName() (the extension point) does not have access to the current request object to get the dispatcher.
I feel like I must be missing something; it seems impossible to use versioned resources on a 404 page in spring boot.
Update 2: A working but messy solution
This is the best I've been able to come up with, which still seems awfully messy:
public abstract class OncePerErrorRequestFilter extends OncePerRequestFilter {
#Override
protected String getAlreadyFilteredAttributeName() {
return super.getAlreadyFilteredAttributeName() + ".ERROR";
}
#Override
protected boolean shouldNotFilterErrorDispatch() {
return false;
}
}
public class ErrorPageCapableResourceUrlEncodingFilter extends OncePerErrorRequestFilter {
// everything in here is a perfect copy-paste of ResourceUrlEncodingFilter since the internal ResourceUrlEncodingResponseWrapper is private
}
// register the error-supporting version if the whitelabel error page has been disabled ... could/should use a dedicated property for this
#Configuration
#AutoConfigureAfter(WebMvcAutoConfiguration.class)
#ConditionalOnClass(OncePerErrorRequestFilter.class)
#ConditionalOnWebApplication
#ConditionalOnEnabledResourceChain
#ConditionalOnProperty(prefix = "server.error.whitelabel", name = "enabled", havingValue="false", matchIfMissing = false)
public static class ThymeleafResourceUrlEncodingFilterErrorConfiguration {
#Bean
public FilterRegistrationBean errorPageResourceUrlEncodingFilterRegistration() {
FilterRegistrationBean reg = new FilterRegistrationBean();
reg.setFilter(new ErrorPageCapableResourceUrlEncodingFilter());
reg.setDispatcherTypes(DispatcherType.ERROR);
return reg;
}
}
Better solutions?
This has been reported in spring-projects/spring-boot#7348 and a fix is on its way.
It seems you've made an extensive analysis of the issue; too bad you didn't report this issue earlier. Next time, please consider raising those on the Spring Boot tracker.
Thanks!
I'm creating a Spring Starter project and need to get all classes which are marked with a custom annotation. The annotated class is not a spring bean.
My current solution is to use the ClassPathScanningCandidateComponentProvider to find the required classes.
ClassPathScanningCandidateComponentProvider scanner =
new ClassPathScanningCandidateComponentProvider(false);
scanner.addIncludeFilter(new AnnotationTypeFilter(CustomAnnotation.class));
candidates = scanner.findCandidateComponents("THE MISSING PACKAGE NAME");
The problem is that I'm currently provide an empty package String so that all packages/classes are scanned which slows the startup down.
I need to access the packages which are scanned by Spring to avoid the scanning of all packages and classes.
Is there a way to retrieve all packages programmatically which are scanned by Spring or is there an alternative solution to retrieve custom annotated classes which are not Spring beans.
Greets
One solution without the need to make a full classpath scan is to use the AutowiredAnnotationBeanPostProcessor:
private List<Class<?>> candidates = new ArrayList<>();
#Override
public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
if(beanClass.isAnnotationPresent(YourAnnotation.class)){
candiates.add(beanClass));
System.out.println(beanClass);
return new Object();
}
}
#Bean
public CandiateHolder candidates() {
return new CandidateHolder(candidates);
}
You can check if the bean class which should be instantiated has the required annotation. If its the case you add the class to a property to expose it later as a bean. Instead of returning null you have to return an instance of a new Object. The returned object can be used to wrap the class in a proxy. Cause I don't need an instance I will return a simple new object. Its maybe a dirty hack but it works.
I have to use this kind of hack cause an instantiation of the needed object will result in an runtime error cause it has to be instantiated in the framework I use.