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Spring MVC 4 handles requests mapping
with RequestMappingHandlerMapping and RequestMappingHandlerAdapter beans (that's the "out-of-the-box" configuration that comes with your springmvc application).
But you may want to use a request Router for your application:
- Route Configuration is centralized in one place (you don't need to look into your controllers anymore)
- URL Refactoring is easier
- Many web frameworks use that system (Rails, PlayFramework and many others)
- Handles routes priority
Define your application routes like this!
GET /user/? userController.listAll
GET /user/{<[0-9]+>id} userController.showUser
DELETE /user/{<[0-9]+>id} userController.deleteUser
POST /user/add/? userController.createUser
Warning: this project is currently tested on Spring 4.0.x, should work on 3.2.x but is not compatible with Spring 3.0.x.
Your project needs these dependencies (Hint: the new "Bill of materials") is really handy:
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-framework-bom</artifactId>
<version>4.0.2.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
...
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
</dependency>
...
<dependency>
<groupId>org.resthub</groupId>
<artifactId>springmvc-router</artifactId>
<version>1.2.0</version>
</dependency>
...
</dependencies>
If you want to use SNAPSHOTs, add oss.sonatype.org as a repository.
<repositories>
<repository>
<id>sonatype.oss.snapshots</id>
<name>Sonatype OSS Snapshot Repository</name>
<url>http://oss.sonatype.org/content/repositories/snapshots</url>
<releases>
<enabled>false</enabled>
</releases>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
</repositories>
In your *-servlet.xml file, add the following beans:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<!--
Enable bean declaration by annotations, update base package according to your project
-->
<context:annotation-config/>
<!--
Package to scan for Controllers.
All Controllers with @Controller annotation are loaded as such.
-->
<context:component-scan base-package="com.example.yourproject.controllers" />
<!--
Choose HandlerMapping.
RouterHandlerMapping loads routes configuration from a file.
Router adapted from Play! Framework.
@see http://www.playframework.org/documentation/1.2.4/routes#syntax
for route configuration syntax.
Example:
GET /home PageController.showPage(id:'home')
GET /page/{id} PageController.showPage
-->
<bean id="handlerMapping"
class="org.resthub.web.springmvc.router.RouterHandlerMapping">
<property name="routeFiles">
<list>
<value>routes.conf</value>
<!--
Router will *append* routes declared in additional files
<value>addroutes.conf</value>
-->
</list>
</property>
<!--
Uncomment the following configuration line
if you want routes to be dynamically reloaded when
route files are modified.
Can be a good idea in dev mode, not so much in production!
-->
<!-- <property name="autoReloadEnabled" value="true" /> -->
</bean>
</beans>
Or you can achieve the same thing with a Javaconfig class like this:
@Configuration
@ComponentScan(basePackages = "com.example.yourproject.controllers")
// You should not use the @EnableWebMvc annotation
public class WebAppConfig extends RouterConfigurationSupport {
@Override
public List<String> listRouteFiles() {
List<String> routeFiles = new ArrayList<String>();
routeFiles.add("routes.conf");
return routeFiles;
}
}
The example above will load the configuration file using Spring ResourceLoader - so create a new file in your project src/main/resources/routes.conf.
The router maps HTTP request to a specific action (i.e. a public method of a Controller class handling requests).
Controllers can use Spring MVC annotations and conventions - only the @RequestMapping annotation is useless.
@Controller
public class HelloController {
public void simpleAction() {
}
public @ResponseBody String sayHelloTo(@PathVariable(value = "name") String name) {
return "Hello "+name+" !";
}
}
Warning: in the route configuration file, Controller names are case sensitive, and should always start with a lower case letter.
# this is a comment
GET /simpleaction helloController.simpleAction
GET /hello/{<[a-zA-Z]+>name} helloController.sayHelloTo
For more details on routes syntax, check out the PlayFramework documentation.
Routing requests to actions is one thing. But refactoring routes can be a real pain if all your URLs are hard coded in your template views. Reverse routing is the solution.
Example route file:
GET /user/? userController.listAll
GET /user/{<[0-9]+>id} userController.showUser
DELETE /user/{<[0-9]+>id} userController.deleteUser
POST /user/add/? userController.createUser
Reverse routing in your Java class:
import org.resthub.web.springmvc.router.Router;
public class MyClass {
public void myMethod() {
ActionDefinition action = Router.reverse("userController.listAll");
// logs "/user/"
logger.info(action.url);
HashMap<String, Object> args = new HashMap<String, Object>();
args.put("id",42L);
ActionDefinition otherAction = Router.reverse("userController.showUser", args);
// logs "/user/42"
logger.info(otherAction.url);
}
}
First, add the RouteDirective to your Velocity Engine configuration:
<!--
Configure your Velocity Template engine.
Add the custom directive to the engine.
-->
<bean id="velocityConfig"
class="org.springframework.web.servlet.view.velocity.VelocityConfigurer">
<property name="resourceLoaderPath" value="classpath:velocity" />
<property name="preferFileSystemAccess" value="false"/>
<property name="velocityProperties">
<props>
<prop key="userdirective">org.resthub.web.springmvc.view.velocity.RouteDirective</prop>
</props>
</property>
</bean>
Then use the #route directive within your .vm file:
<a href="#route("userController.listAll")">List all users</a>
<a href="#route("userController.showUser(id:'42')")">Show user 42</a>
In your Spring MVC context add the following:
<mvc:interceptors>
<bean class="org.resthub.web.springmvc.view.freemarker.RouterModelAttribute"/>
</mvc:interceptors>
This will inject a model attribute called "route" to every model. The attribute name can be modified by setting the property "attributeName".
<mvc:interceptors>
<bean class="org.resthub.web.springmvc.view.freemarker.RouterModelAttribute">
<property name="attributeName" value="myAttributeName"/>
</bean>
</mvc:interceptors>
Then use the Router instance within your .ftl files:
<a href="${route.reverse('userController.listAll')}">List all users</a>
<#assign params = {"id":42}/>
<a href="${route.reverse('userController.showUser', params)}">Show user 42</a>
In your JSP, declare the taglib:
<%@ taglib prefix="route" uri="/springmvc-router" %>
Then use the reverse method to generate URLs:
<a href="<route:reverse action="userController.listAll" />">List all users</a>
Dynamic parameters can also be used:
<a href="<route:reverse action="userController.showUser" userId="42" />">Show user 42</a>
SpringMVC Router has its own LinkBuilder implementation to work with Spring HATEOAS.
springmvc-router-ide is a Maven plugin to generate template files that assist IDEs in autocompleting reverse routing with this project.
This project can be used as an addon to RESThub framework.