No mapping found for HTTP request - spring

I am back with working in Springs. I used to work in Springs but blindly, didn't understand much. I used to get a lot of errors, very basic ones, and I am getting them again.
My problem is that, I don't know how the configuration of the Spring-MVC work.
What happens when I run the project from my STS?
I am working on the spring template project in STS.
I am getting this when I run the project.
WARN : org.springframework.web.servlet.PageNotFound - No mapping found for HTTP request with URI [/common/] in DispatcherServlet with name 'appServlet'
I am totally fed up and broken.
Just 2 months of break from work, I am back at the starting block.
I don't want to post my code and make the question specific.
I want an answer that explains the way in which the server executes a spring project. Right from the running of an application(basic hello world application) to the display of the home page.
This will be helpful for all the beginners.
I tried searching for such an explanation in the net but I didn't get any proper explanation, but got a lot of basic samples. Those samples are easy to understand but are not explaining the way in which the server goes about.
Note: I am looking for an answer that explains the Springs concept. From the running of an application to the display of a home page. What all happens in this process? Where does the server start with? How does it go about?

Here is the flow initially servlet container loads the web.xml file.In web.xml we will specify that all the requests are handled by the spring FrontController that is DispatcherServlet.
We include it by adding the following code
<servlet>
<servlet-name>dispatcher</servlet-name>
<servletclass>org.springframework.web.servlet.DispatcherServlet</servletclass>
<load-on-startup>2</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>*.htm</url-pattern>
</servlet-mapping>
Here it indicate if the url request is of *.htm it is handled by dispatcherServlet then dispatcherServlet load dispatcher-servlet.xml . Where we need to mention the mapping to controller by writing the specific url request such as
<bean name="/insert.htm" class="com.controller.MyController"></bean>
So in bean we mention that for request of /insert.htm it tells the servlet to look in the mentioned class.You need use the Annotation of #RequestMapping above the method for ex
#RequestMapping("/insert.htm")
public ModelAndView insert(HttpServletRequest req,Student student)
{
String name=req.getParameter("name");
int id=Integer.parseInt(req.getParameter("id"));
student.setId(id);
return new ModelAndView("display","Student",student);//It returns a view named display with modelclass name as `Student` and model object student
}
So when a Request url of /insert.htm appears it executes the above method it returns a ModelAndView object nothing but an view.It again goes to dispatcher-servlet.xml and looks for view Resolver the normal code that is to be added is
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver"
p:prefix="/WEB-INF/jsp/"
p:suffix=".jsp" />
So from this it gets the logical view name and appends the prefix and suffix to it .Finally it displays the content in the view.so it looks for display in view resolver prefixes and suffixes the things and finally returns /WEB-INF/jsp/display.jsp .Which displays the jsp content

You are mapping your Spring servlet only for requests that end with .htm. The request for the root of your application does not end with .htm and so, it does not get picked up by Spring. Edit your web.xml as follows, in order to use Spring for all requests:
<servlet-mapping>
<servlet-name>appServlet</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>
Then, use this as the controller:
package com.mkyong.common;
#Controller
public class HomeController {
#RequestMapping(value = "/", method = RequestMethod.GET)
public ModelAndView helloWorld() {
ModelAndView model = new ModelAndView("index");
model.addObject("msg", "hello world");
return model;
}
}
The controller intercepts the requests for the context root of the application, adds the msg attribute to the model and redirects to the index view.
So, you need to add the index.jsp file in the /WEB-INF/views/ directory. Inside your jsp, you will be able to use the value of the msg attribute.

From what every you have posted you do no have a request mapping for the url /common/.
You will have to create another request mapping function like the one below in your controller class and create a view file also.
#RequestMapping(value = "/common/", method = RequestMethod.GET)
public ModelAndView common(HttpServletRequest request,
HttpServletResponse response) {
ModelAndView model = new ModelAndView("common");
model.addObject("msg", "hello world");
return model;
}

Related

spring-mvc : issue in accessing url pattern configured in web.xml

I have tested like default, extension, path(start with '/' and end with '/*') these three are working fine but exact match url pattern '/test' showing 404 error.Please refer this is my exact code in web.xml file for configuring dispatcher servlet.
<servlet>
<servlet-name>frontController</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>frontController</servlet-name>
<url-pattern>/test</url-pattern>
</servlet-mapping>
For this url on address bar :http://localhost:8086/MVCFirstApp/test/sugar
I am getting error - 404 page not found for exact match url pattern only.
Please help me out from this, thanks in advance.
Please check few steps before reading the solutions
+ do you have proper controller to handle the requested request(url pattern)
+ do you have proper view returned by the controller
+ and is the base package scanned for controller (annotations)
It would be more convenient if you share the controller code too. But with what I understand with your statement you can try this
add URL patters as
/test/*
Let me explain what this does it will send all the request which comes tru URL /test/ to dispatcher servlet . For example /test/sugar or /test/abc/def/ghi anything, in more simple words any request with URL /test/* is sent to dispatcher servlet which matches and return the proper controller with help of handler mapping .
And make sure you have added the mapping for /test/sugar or /test with proper view in controller . Or if you want sugar to be your value then use #Pathvariable in your controller.

Spring MVC 404 even though URL is mapped

I've been trying to setup a Spring MVC controller but when I try to make a GET request, I get a 404 error.
I created a working test example here: https://github.com/Jardo-51/zk-spring-mvc-test
When I run the application on Tomcat and try to make a GET request to: http://localhost:8080/zk-spring-mvc-test/api/v0/foo, I get a 404 error and the logs say:
WARNING: No mapping found for HTTP request with URI [/zk-spring-mvc-test/api/v0/foo] in DispatcherServlet with name 'dispatcher-api'`
I've been trying to fix it according to this answer, and found out that the controller is mapped correctly because the logs on startup say:
INFO: Mapped "{[/zk-spring-mvc-test/api/v0/foo],methods=[GET]}" onto public org.springframework.http.ResponseEntity<java.lang.String> com.jardoapps.zkspringmvctest.controllers.FooController.method()
The app uses ZK framework which needs its own servlets so maybe there is a conflict with the DispatcherServlet. Please see my example app for more details (it contains only the necessary code).
Here is the web.xlm (Spring context and MVC config are at the top).
Here is the controller class.
Simply replace #RequestMapping("zk-spring-mvc-test/api/v0/foo") with #RequestMapping("/v0/foo") in your FooController class.
The reason is that the path that you specify into the #RequestMapping annotation is the part of the request's URL beyond the part that called the servlet.
You defined DispatcherServlet's mapping as:
<servlet-mapping>
<servlet-name>dispatcher-api</servlet-name>
<url-pattern>/api/*</url-pattern>
</servlet-mapping>
So we have zk-spring-mvc-test that is the context root (this is deploy dependent), /api/ that calls the Spring DispatcherServlet, and finally /v0/foo that should be mapped by your controller:
#RestController
#RequestMapping("/v0/foo")
public class FooController {
#RequestMapping(method = RequestMethod.GET)
public ResponseEntity<String> method() {
return ResponseEntity.ok().body("OK");
}
}
You can see Spring MVC configure url-pattern for further information.

Spring MVC how are exceptions handled when no request mapping?

What happens when all of the request mappings in the controller do not match the incoming request? I was using the exceptionhandler catching Exception.class but that did not seem to catch it? Can anyone explain?
According to documentation #ExceptionHandler deal with unexpected exceptions that occur during controller execution. In the case when incoming request do not match any request mapping, controller method even will not be executed.
Spring-MVC based on Servlet technology. All incoming requests will be processed by DispatcherServlet (that registered in web.xml). DispatcherServlet looks for handlers which can process current request. If no appropriate handler will be found (i.e. no appropriate mapped controller's method will be found), DispatcherServlet initiates 404 error.
When an error occurs, the web container(Tomcat or any other servlet container) generates a default page containing exception message. But you can also specify that the container should return a specific error page for a given exception. For process this error manually you should add into web.xml new error-page element, that will allow you map error code to url:
...
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<error-page>
<error-code>404</error-code>
<location>/page-not-found</location>
</error-page>
...
Because location will be processed by Spring-MVC as usual request you can create controller to handle this request:
#Controller
public class ExceptionController{
#RequestMapping("/page-not-found")
public ModelAndView pageNotFound(){
return new ModelAndView("page-not-found");
}
}
Now just create view with name page-not-found.jsp and show exception info as you wish.

Spring Batch Admin Home Page

Is there a way to change what should be home page for spring batch admin webapp?
I tried various solutions and nothing helps. What bothers me is that RequestMapping(value = { "/", "/home" }) is bidden to HomeController inside spring-batch-resources project, and I can't override that mapping.
I didn't know what would be necessary, I first tried redefining index.jsp page to farward to "/myHomePage" instead of "/home" that is by default. No result.
I tried defining my own controller to have same RequestMapping(value = "/"). No result. Ambiguous mappings exception.
I tried extending and overriding method from HomeController in my own controller, also without result, also ambiguous mappings exception.
I even added
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
NO RESULT!
I don't care much about "/home" mapping I just want to override "/" mapping, or to forward it to my page, or something like that. Is there a way?
P.S. I can't change HomeController implementation, since it is spring-batch-resources dependency for spring-batch-admin-sample...
Explanation for the answer I've given in comments, requested by #kap
It's been a long time since I worked on this, and I don't have the code available now, but as I can remember:
In one of the definitions for the application-context in XML files in resources (sorry I forgot which one) you need to add something like
<mvc:interceptor>
<mvc:mapping path="/"/>
<bean class="blabla.MyInterceptor" />
</mvc:interceptor>
and then create class MyInterceptor that implements HandlerInterceptor which will redirect the request. There are 3 methods you can use to override the behavior
preHandle
postHandle
afterCompletion
and I think that I used postHandle to implement code for redirect to my custom homepage. You can google for tutorials on redirection of requests using Spring interceptors to see how to implement that.
this worked for me:
adding this to web.xml
<servlet-mapping>
<servlet-name>Batch Servlet</servlet-name>
<url-pattern>/batch/*</url-pattern>
</servlet-mapping>
and adding this part on my own index page
<body>
<div class="pageHeader" id="pageHeader" style="height: 100px;"></div>
<p>Batch job admin</p>
</body>

getting the HTTP URL from inside a JAX-RS resource

From inside my JAX-RS (Jersey) resource I need to get the base URL of the Jersey Servlet that's "publishing" that resource. I tried injecting ServletContext as described here, and then doing a:
return servletContext.getResource("/").toString();
to get the "base" URL of the Jersey Servlet for this resource.
However the above code returns a value like:
jndi:/localhost/jax-rs-tomcat-test/
where I was expecting something more like:
http://localhost:8080/jax-rs-tomcat-test/jax-rs
Where "jax-rs" is what I have in my web.xml:
<servlet-mapping>
<servlet-name>jersey-servlet</servlet-name>
<url-pattern>/jax-rs/*</url-pattern>
</servlet-mapping>
That is, there are four "differences": (a) protocol, (b) single instead of double slash after the protocol, (c) port number and (d) missing URL pattern for triggering the Jersey servlet. So, how do I get:
the base http:// URL of the Jersey servlet
the full URL that triggered a particular #GET or #POST annotated method ?
You're looking for UriInfo. Inject it into your resource using #Context:
#Context
private UriInfo uriInfo;
and then you can call getBaseUri() method:
uriInfo.getBaseUri();

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