Spring

Spring helps development teams everywhere build simple, portable, fast and flexible JVM-based systems and applications.

REST service

spring.io/guides/gs/rest-service/

Structure

.
|-- pom.xml
|-- src
|   `-- main
|       `-- java
|           `-- hello
|               |-- Application.java
|               |-- Greeting.java
|               `-- GreetingController.java
`-- target
    |-- classes
    |   `-- hello
    |       |-- Application.class
    |       |-- Greeting.class
    |       `-- GreetingController.class
    |-- generated-sources
    |   `-- annotations
    |-- gs-rest-service-0.1.0.jar
    |-- gs-rest-service-0.1.0.jar.original
    `-- maven-archiver
        `-- pom.properties

Steps

• mkdir -p /tmp/greetingSpring
• mkdir -p /tmp/greetingSpring/src/main/java/hello
• mkdir -p /tmp/greetingSpring/target
• cd /tmp/greetingSpring

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.springframework</groupId>
  <artifactId>gs-rest-service</artifactId>
  <version>0.1.0</version>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.1.5.RELEASE</version>
  </parent>
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
  </dependencies>
<properties>
<start-class>hello.Application</start-class>
</properties>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
</plugin>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-releases</id>
<url>http://repo.spring.io/libs-release</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-releases</id>
<url>http://repo.spring.io/libs-release</url>
</pluginRepository>
</pluginRepositories>
</project>

src/main/java/hello/Application.java

   1 package hello;
   2 
   3 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
   4 import org.springframework.boot.SpringApplication;
   5 import org.springframework.context.annotation.ComponentScan;
   6 
   7 @ComponentScan
   8 @EnableAutoConfiguration
   9 public class Application {
  10 
  11     public static void main(String[] args) {
  12         SpringApplication.run(Application.class, args);
  13     }
  14 }

src/main/java/hello/Greeting.java

   1 package hello;
   2 
   3 public class Greeting {
   4 
   5     private final long id;
   6     private final String content;
   7 
   8     public Greeting(long id, String content) {
   9         this.id = id;
  10         this.content = content;
  11     }
  12 
  13     public long getId() {
  14         return id;
  15     }
  16 
  17     public String getContent() {
  18         return content;
  19     }
  20 }

src/main/java/hello/GreetingController.java

   1 package hello;
   2 
   3 import java.util.concurrent.atomic.AtomicLong;
   4 import org.springframework.web.bind.annotation.RequestMapping;
   5 import org.springframework.web.bind.annotation.RequestParam;
   6 import org.springframework.web.bind.annotation.RestController;
   7 
   8 @RestController
   9 public class GreetingController {
  10 
  11     private static final String template = "Hello, %s!";
  12     private final AtomicLong counter = new AtomicLong();
  13 
  14     @RequestMapping("/greeting")
  15     public Greeting greeting(@RequestParam(value="name", required=false, defaultValue="World") String name) {
  16         return new Greeting(counter.incrementAndGet(),
  17                             String.format(template, name));
  18     }
  19 }

Build with

• mvn clean compile package

Run with:

• jar -tf target/gs-rest-service-0.1.0.jar # check JAR contents
• java -jar target/gs-rest-service-0.1.0.jar

• open URL http://localhost:8080/greeting