I'm having trouble with Spring MVC RequestMapping and I'm hoping someone can give me advice on how to proceed.
I'm working on a server that will be accessed by a legacy client. The client sends simple requests (see below) but cannot be changed in any way to accommodate the new server.
The client sends gets or posts of the form /dbintf?command=GETINFO,acctNum=111
The server is called dbintf and it returns a simple text response.
I would like to create a Spring controller for each command and annotate a single controller method with
a params mapping that is based on the command parameter. So the mapping in the GETINFOController would be:
#RequestMapping(params="command=GETINFO")
public String serviceRequest(....
However, I cannot get this to work. Here are some details of the service.
The servlet mapping in web.xml:
<servlet-mapping>
<servlet-name>dbintf</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
The annotation scanning directives in intf-servlet.xml
<context:component-scan base-package="com.intf.controller" />
<bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping"/>
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"/>
I have been trying various combinations of things to try to get this scheme to work and I'll boil this
trial-and-error work down to two examples:
This does not work. The response is: "The requested resource () is not available."
#RequestMapping( params="command=GETINFO")
public class TESTController {
#RequestMapping( method = RequestMethod.GET)
public String serviceRequest
If I change the url to add another level: /dbintf/test?command=GETINFO,acctNum=111
it works if I add a URL pattern to the handler method annotation.
#RequestMapping( params="command=GETINFO")
public class TESTController {
#RequestMapping( value="/test",method = RequestMethod.GET)
public String serviceRequest
This makes me think that params mapping alone will not work. It appears that a URL
pattern must be part of any mapping scheme. For my case however, there is no
URL pattern available since the the client request URL is fixed as: dbintf?.....
My question: is it possible to use parameter based mapping alone and not
in conjunction with a pattern? If so, what am I missing?
Thanks in advance for any help or advice,
beeky
I don't see in your config where you are mapping your controllers to "/dbintf"? You've got your DispatcherServlet (assuming that "dbintf" servlet is your DispatcherServlet) mapped to just "/", not "/dbintf". Are you deploying your webapp so that it's available at "/dbintf" relative to your container's "/"? I guess what I'm trying to get at is that you may just need to add some config to your #RequestMapping's:
#RequestMapping(value="/dbintf", params="command=GETINFO")
Related
I have a problem while use Spring MVC:
I wrote a Controller, a method named
#RequestMapping("/{moduleName}/{subModuleName}")
public ModelAndView getModuleContent(#PathVariable String moduleName, #PathVariable String subModuleName) {
...},
now the problem is, when I access a static resource, for example:
http://www.mytomcat:8080/images/testpng
it would mapping that controller, but I don't want this, how can I resolve the conflict?
Try to specify regex pattern for path vars:
#RequestMapping(value = "/{year:\\d+}/{month:\\d+}/**", method = RequestMethod.GET)
This helps spring to avoid conflicts with <mvc:resources/> mapped to path like /images/**. If your path variable can contain all except 'images' you can try regex like this: (?!images).
configure following accordingly.
<mvc:resources mapping="/resources/**" location="/public-resources/"/>
You may configure resource handlers for resource folders such as /images.
It should help, because mapping of these handlers would be more specific than /{moduleName}/{subModuleName}, therefore resource handlers should take precedence.
In struts2 why is a Filter is used as a controller instead of ActionServlet?
What is the advantage of using a Filter over ActionServlet?
As per Struts2 Budi Karnival struts2 book, There is one distinct advantage of using a filter over a servlet as a controller. With a filter you can conveniently choose to serve all the resources in your application, including static ones.
With a servlet, your controller only handles access to the dynamic part of the application. Note that the url-pattern element in the web.xml file in the previous application is
<servlet>
<servlet-name>Controller</servlet-name>
<servlet-class>...</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Controller</servlet-name>
<url-pattern>*.action</url-pattern>
</servlet-mapping>
With such a setting, requests for static resources are not handled by the servlet controller, but by the container. You wouldn't want to handle static resources in your servlet controller because that would mean extra work.
A filter is different. A filter can opt to let through requests for static contents. To pass on a request, call the filterChain.doFilter method in the filter's doFilter method.
Consequently, employing a filter as the controller allows you to block all requests to the application, including request for static contents. You will then have the following setting in your deployment descriptor:
<filter>
<filter-name>filterDispatcher</filter-name>
<filter-class>...</filter-class>
</filter>
<filter-mapping>
<filter-name>filterDispatcher</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
Advantage of this filter : One thing for sure, you can easily protect your static files from curious eyes.
The following code will send an error message if a user tries to view a JavaScript file:
public void doFilter(ServletRequest request, ServletResponse response,FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse res = (HttpServletResponse) response;
String uri = req.getRequestURI();
if (uri.indexOf("/css/") != -1 && req.getHeader("referer") == null) {
res.sendError(HttpServletResponse.SC_FORBIDDEN);
} else {
// handle this request
}
}
It will not protect your code from the most determined people, but users can no longer type in the URL of your static file to view it. By the same token, you can protect your images so that no one can link to them at your expense.
Another advantage :
The introduction of Interceptors in Struts2 framework.It not just reduce our coding effort,but helps us write any code which we would have used filters for coding and necessary change in the web.xml as opposed to Struts1.So now any code that fits better in Filter can now moved to interceptors( which is more controllable than filters), all configuration can be controlled in struts.xml file, no need to touch the web.xml file
We generally Use a Filter when we want to filter and/or modify requests based on specific conditions.
For S2 to work it needs to perform certain reprocessing and modification work in order for a successful execution of your request while on other hands we use Servlet when we want to control, preprocess and/or post-process requests.
For controlling request S2 use Servlet under the hood but being hidden away to make the overall application structure more clean and easy to use.
This is what we have for Filters in The Java EE 6 Tutorial.
A filter is an object that can transform the header and content (or both) of a request or response. Filters differ from web components in that filters usually do not themselves create a response. Instead, a filter provides functionality that can be “attached” to any kind of web resource. Consequently, a filter should not have any dependencies on a web resource for which it is acting as a filter; this way, it can be composed with more than one type of web resource.
I use filenames in my REST API (example: GET http://xxx/api/myImage.jpg)
problem is #PathVariable dropped ".jpg".
this problems already asked few times in here and answered. but not worked to me.
so I searched then found at the
https://jira.springsource.org/browse/SPR-6524
"... is simply not supposed to be combined with manual DefaultAnnotationHandlerMapping instances; this is designed as an either-or choice at present, quite similar to and ."
"mvc namespace are make simplifed configurations".
Real question is mvc what does do? and changed?
I found my self these things..
intercepter configuration changed. (mvc namspace required in bean configuation)
useDefaultSuffixPattern is not working.
adds JSON message converter. if jackson library is available
#PathVariable arguments are auto added to model
Any others?
Thanks in advance!
The mvc:annotationDriven tag essentially sets you your Spring context to allow for dispatching requests to Controllers.
The tag will configure two beans DefaultAnnotationHandlerMapping and AnnotationMethodHandlerAdapter.
You can find more information from the spring documents:
http://static.springsource.org/spring/docs/current/spring-framework-reference/html/mvc.html
Before I provide certain points let me clear up the answer provided by Roy is not accurate. You don't have to provide mvc:annotation-driven tag to instantiate default beans. This tag can be used Spring 3.0+ to enable new feature introduced from Spring 3.0
(Do not use it if you want backward compatibility, especially if you are using old controller based classes like MultiActionController, SimpleFormController)
Now lets come to what this tag actually does -
Prior to Spring 3.1 default beans used where
DefaultAnnotationHandlerMapping
AnnotationMethodHandlerAdapter
AnnotationMethodHandlerExceptionResolver
These are deprecated in Spring 3.1 and if you use above mentioned tag it will be replaced by -
RequestMappingHandlerMapping
RequestMappingHandlerAdapter
ExceptionHandlerExceptionResolver
DefaultAnnotationHandlerMapping decided which controller to use and the AnnotationMethodHandlerAdapter selected the actual method that handled the request. RequestMappingHandlerMapping does both the tasks. Therefore the request is directly mapped right to the method.
There are other infrastructure beans that are instantiated by these tag (chained in addition to defaults) like - MappedInterceptor, ConfigurableWebBindingInitializer, SessionFlashManager, ContentNegociationManager etc. I am not going to explain these :) as they each are long answers themselves, so google it for more info.
PS : And yes Spring 3.1+ automatically expose #PathVariables to the model. Also you have mvc:interceptors tag. But I think it is not related to <mvc:annotation-driven />. I would highly recommend read - http://spring.io/blog/2009/12/21/mvc-simplifications-in-spring-3-0/
To enable MVC Java config add the annotation #EnableWebMvc to one of your #Configuration classes:
#Configuration
#EnableWebMvc
public class WebConfig {
}
To achieve the same in XML use the
mvc:annotation-driven
element in your DispatcherServlet context (or in your root context if you have no DispatcherServlet context defined):
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<mvc:annotation-driven/>
</beans>
The above registers a RequestMappingHandlerMapping, a RequestMappingHandlerAdapter, and an ExceptionHandlerExceptionResolver (among others) in support of processing requests with annotated controller methods using annotations such as #RequestMapping, #ExceptionHandler, and others.
For details refer the below link :
http://docs.spring.io/spring/docs/current/spring-framework-reference/html/mvc.html#mvc-config
mvc:annotation-driven tag do extra work from context:component-scan tag
The tag registers the Handler Mapping and Handler Adapter required to dispatch requests to your #Controllers:
tag helps registering the following components.
DefaultAnnotationHandlerMapping - This is a HandlerMapping implementation which maps the HTTP requests to the handler methods defined using the #RequestMapping annotation.
AnnotationMethodHandlerAdapter - It is responsible for scanning the controllers to identify methods (and parameters) annotated with #MVC annotations. It scans and caches handler methods annotated with #RequestMapping. Also handles the #RequestParam, #ModelAttribute, #SessionAttributes and #InitBinder annotations.
ConfigurableWebBindingInitializer - The initializer for the Web Data Binder. Helps in declaratively configuring the Web Binder with validators, conversion services, property editors, etc.
LocalValidatorFactoryBean - Implements the validator interface and enables JSR303 validation. This is injected into ConfigurableWebBindingInitializer.
FormattingConversionServiceFactoryBean - A conversion factory that returns conversion services for basic objects like date and numbers. This factory is again injected into ConfigurableWebBindingInitializer.
Message Converters
ByteArrayHttpMessageConverter - A HTTP request message converter that reads a HTTP message body and returns a byte stream. It can also read a byte stream and construct a response body. Used for receiving and sending documents like PDF, XLS, etc.
StringHttpMessageConverter - A HTTP request message converter that reads a plain text request body and binds it to a String object. And vice-versa with response.
FormHttpMessageConverter - A HTTP request message converter that reads a form encoded request body and binds it to a form Binding object.
SourceHttpMessageConverter - A HTTP request converter that converts a XML message body to/from Binding Object.
If we do not use mvc:annotation-driven tag then we have to do register these components manually in xml file in order to use them , which results in too much extra work.
This feels like a basic question, but I haven't had much luck Googling.
My app connects to an SMTP server and sends mail through it. I need this SMTP server to be configurable based on which environment the app is deployed to.
How can I specify the specify the SMTP server name in my web.xml config file and access it from my Spring MVC 3.0 controller?
The controller does not extend or implement anything. It is completely annotation driven with #Controller and #RequestMapping. From what I have seen online, people access context-params via the servlet API. Being annotation driven, I do not have access to the servlet object.
I solved this.
Make your controller implement ServletContextAware, which requires a method called
setServletContext(ServletContext servletContext)
Spring MVC will inject the servlet context into this method if your controller is ServletContextAware.
Create a private variable on your controller to store the servletController that is injected into the above method. You can now use servletContext just as you would if you were using a regular servlet.
hth.
Adding an instance of Servletcontext and autowiring it worked for me
#Controller
public MyController {
// other instances relevant to your requirement
#Autowired
private ServletContext sCtx;
//other methods relevant to your requirement
}
I suppose following also should work:
void action(final HttpServletRequest request) {
final paramValue = request.getSession().getServletContext().getInitParameter("paramName");
...
}
The familiar code:
<servlet-mapping>
<servlet-name>main</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>main</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
My understanding is that /* maps to http://host:port/context/*.
How about /? It sure doesn't map to http://host:port/context root only. In fact, it will accept http://host:port/context/hello, but reject http://host:port/context/hello.jsp.
Can anyone explain how is http://host:port/context/hello mapped?
<url-pattern>/*</url-pattern>
The /* on a servlet overrides all other servlets, including all servlets provided by the servletcontainer such as the default servlet and the JSP servlet. Whatever request you fire, it will end up in that servlet. This is thus a bad URL pattern for servlets. Usually, you'd like to use /* on a Filter only. It is able to let the request continue to any of the servlets listening on a more specific URL pattern by calling FilterChain#doFilter().
<url-pattern>/</url-pattern>
The / doesn't override any other servlet. It only replaces the servletcontainer's built in default servlet for all requests which doesn't match any other registered servlet. This is normally only invoked on static resources (CSS/JS/image/etc) and directory listings. The servletcontainer's built in default servlet is also capable of dealing with HTTP cache requests, media (audio/video) streaming and file download resumes. Usually, you don't want to override the default servlet as you would otherwise have to take care of all its tasks, which is not exactly trivial (JSF utility library OmniFaces has an open source example). This is thus also a bad URL pattern for servlets. As to why JSP pages doesn't hit this servlet, it's because the servletcontainer's built in JSP servlet will be invoked, which is already by default mapped on the more specific URL pattern *.jsp.
<url-pattern></url-pattern>
Then there's also the empty string URL pattern . This will be invoked when the context root is requested. This is different from the <welcome-file> approach that it isn't invoked when any subfolder is requested. This is most likely the URL pattern you're actually looking for in case you want a "home page servlet". I only have to admit that I'd intuitively expect the empty string URL pattern and the slash URL pattern / be defined exactly the other way round, so I can understand that a lot of starters got confused on this. But it is what it is.
Front Controller
In case you actually intend to have a front controller servlet, then you'd best map it on a more specific URL pattern like *.html, *.do, /pages/*, /app/*, etc. You can hide away the front controller URL pattern and cover static resources on a common URL pattern like /resources/*, /static/*, etc with help of a servlet filter. See also How to prevent static resources from being handled by front controller servlet which is mapped on /*. Noted should be that Spring MVC has a built in static resource servlet, so that's why you could map its front controller on / if you configure a common URL pattern for static resources in Spring. See also How to handle static content in Spring MVC?
I'd like to supplement BalusC's answer with the mapping rules and an example.
Mapping rules from Servlet 2.5 specification:
Map exact URL
Map wildcard paths
Map extensions
Map to the default servlet
In our example, there're three servlets. / is the default servlet installed by us. Tomcat installs two servlets to serve jsp and jspx. So to map http://host:port/context/hello
No exact URL servlets installed, next.
No wildcard paths servlets installed, next.
Doesn't match any extensions, next.
Map to the default servlet, return.
To map http://host:port/context/hello.jsp
No exact URL servlets installed, next.
No wildcard paths servlets installed, next.
Found extension servlet, return.
Perhaps you need to know how urls are mapped too, since I suffered 404 for hours. There are two kinds of handlers handling requests. BeanNameUrlHandlerMapping and SimpleUrlHandlerMapping. When we defined a servlet-mapping, we are using SimpleUrlHandlerMapping. One thing we need to know is these two handlers share a common property called alwaysUseFullPath which defaults to false.
false here means Spring will not use the full path to mapp a url to a controller. What does it mean? It means when you define a servlet-mapping:
<servlet-mapping>
<servlet-name>viewServlet</servlet-name>
<url-pattern>/perfix/*</url-pattern>
</servlet-mapping>
the handler will actually use the * part to find the controller. For example, the following controller will face a 404 error when you request it using /perfix/api/feature/doSomething
#Controller()
#RequestMapping("/perfix/api/feature")
public class MyController {
#RequestMapping(value = "/doSomething", method = RequestMethod.GET)
#ResponseBody
public String doSomething(HttpServletRequest request) {
....
}
}
It is a perfect match, right? But why 404. As mentioned before, default value of alwaysUseFullPath is false, which means in your request, only /api/feature/doSomething is used to find a corresponding Controller, but there is no Controller cares about that path. You need to either change your url to /perfix/perfix/api/feature/doSomething or remove perfix from MyController base #RequestingMapping.
I think Candy's answer is mostly correct. There is one small part I think otherwise.
To map host:port/context/hello.jsp
No exact URL servlets installed, next.
Found wildcard paths servlets, return.
I believe that why "/*" does not match host:port/context/hello because it treats "/hello" as a path instead of a file (since it does not have an extension).
The essential difference between /* and / is that a servlet with mapping /* will be selected before any servlet with an extension mapping (like *.html), while a servlet with mapping / will be selected only after extension mappings are considered (and will be used for any request which doesn't match anything else---it is the "default servlet").
In particular, a /* mapping will always be selected before a / mapping. Having either prevents any requests from reaching the container's own default servlet.
Either will be selected only after servlet mappings which are exact matches (like /foo/bar) and those which are path mappings longer than /* (like /foo/*). Note that the empty string mapping is an exact match for the context root (http://host:port/context/).
See Chapter 12 of the Java Servlet Specification, available in version 3.1 at http://download.oracle.com/otndocs/jcp/servlet-3_1-fr-eval-spec/index.html.