Develop Microservice with SpringMVC

Concept Description

ServiceComb supports Spring MVC remark and allows you to develop microservices in Spring MVC mode.

Development Example

• Step 1 Import dependencies into your maven project:

    <dependencyManagement>
     <dependencies>
       <dependency>
         <groupId>org.apache.servicecomb</groupId>
         <artifactId>java-chassis-dependencies</artifactId>
         <version>1.0.0-m1</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>
     </dependencies>
    </dependencyManagement>
    <dependencies>
      <!--transport can optional import through endpoint setting in microservice.yaml, we import both rest and highway as example-->
      <dependency>
        <groupId>org.apache.servicecomb</groupId>
        <artifactId>transport-rest-vertx</artifactId>
      </dependency>
      <dependency>
        <groupId>org.apache.servicecomb</groupId>
        <artifactId>transport-highway</artifactId>
      </dependency>
      <dependency>
        <groupId>org.apache.servicecomb</groupId>
        <artifactId>provider-springmvc</artifactId>
      </dependency>
      <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
      </dependency>
    </dependencies>
  

• Step 2 Implement the services. Spring MVC is used to describe the development of service code. The implementation of the Hello service is as follow:

   import javax.ws.rs.core.MediaType;
   import org.springframework.web.bind.annotation.RequestBody;
   import org.springframework.web.bind.annotation.RequestMapping;
   import org.springframework.web.bind.annotation.RequestMethod;
   import org.springframework.web.bind.annotation.RequestParam;
   import org.apache.servicecomb.samples.common.schema.models.Person;
  
   @RequestMapping(path = "/springmvchello", produces = MediaType.APPLICATION_JSON)
   public class SpringmvcHelloImpl {
     @RequestMapping(path = "/sayhi", method = RequestMethod.POST)
     public String sayHi(@RequestParam(name = "name") String name) {
   　  return "Hello " + name;
     }
  
     @RequestMapping(path = "/sayhello", method = RequestMethod.POST)
     public String sayHello(@RequestBody Person person) {
   　  return "Hello person " + person.getName();
   　}
   }
  

  Note: PLEASE MAKE SURE TO MARK @RequestMapping ON YOUR PRODUCER(SpringmvcHelloImpl), OR THE PATH AND METHOD OF PUBLISHED WILL BE INCORRECT!

  In this sample the Path of sayHi is /springmvchello/sayhi, and the Path of sayHello is /springmvchello/sayhello, if you wish them /sayhi and /sayhello, please change the setting of @RequestMapping on the SpringmvcHelloImpl to @RequestMapping("/").

• Step 3 Release the service. Add @RestSchema as the annotation of the service implementation class and specify schemaId, which indicates that the implementation is released as a schema of the current microservice. The code is as follows:

   import org.apache.servicecomb.provider.rest.common.RestSchema;
   // other code omitted
   @RestSchema(schemaId = "springmvcHello")
   public class SpringmvcHelloImpl {
     // other code omitted
   }
  

  Create the springmvcHello.bean.xml file(the file name format is *.bean.xml) in the resources/META-INF/spring directory and configure base-package that performs scanning. The content of the file is as follows:

   <?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 classpath:org/springframework/beans/factory/xml/spring-beans-3.0.xsd
          http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">
  
       <context:component-scan base-package="org.apache.servicecomb.samples.springmvc.provider"/>
   </beans>
  

• Step 4 Add service definition file:

  Add microservice.yaml file into resources folder of your project.

• Step 5 Add Main class:

   import org.apache.servicecomb.foundation.common.utils.BeanUtils;
   import org.apache.servicecomb.foundation.common.utils.Log4jUtils;
  
   public class Application {
     public static void main(String[] args) throws Exception {
        //initializing log, loading bean(including its parameters), and registering service, more detail can be found here : https://docs.servicecomb.io/java-chassis/zh_CN/build-provider/bootup.html
        Log4jUtils.init();
        BeanUtils.init();
     }
   }
  

Involved APIs

Currently, the Spring MVC development mode supports the following annotations in the org.springframework.web.bind.annotation package. For details about how to use the annotations, see Spring MVC official documentation。

Remarks	Location	Description
RequestMapping	schema/operation	Data of path, method or produces is allowed. By default, an operation inherits produces from a schema.
GetMapping	schema/operation	Data of path or produces is allowed. By default, an operation inherits produces from a schema.
PutMapping	schema/operation	Data of path or produces is allowed, an operation inherits produces from a schema.
PostMapping	schema/operation	Data of path or produces is allowed, an operation inherits produces from a schema.
DeleteMapping	schema/operation	Data of path or produces is allowed, an operation inherits produces from a schema.
PatchMapping	schema/operation	Data of path or produces is allowed, an operation inherits produces from a schema.
PathVariable	parameter	Obtain parameters from path.
RequestParam	parameter	Obtain parameters from query.
RequestHeader	parameter	Obtain parameters from header.
RequestBody	parameter	Obtain parameters from body. Each operation can have only one body parameter.