minte9
LearnRemember   SPRING





Rest Service

Simple RESTful web service with Spring on port 9090. Use start.spring.io to create a web project. 
 
/src/main/java/com/example/
    DemoApp.java
    DemoRestController.java
    DemoQuote.java

Pom 

 
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-devtools</artifactId>
    <scope>runtime</scope>
    <optional>true</optional>
</dependency>

Demo Application 

 
/**
 * REST SERVICE - Application
 * *
 * The service will handle GET requests.
 * For endpoin /quote will return JSON response.
 */

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApp {
    public static void main(String[] args) {
        SpringApplication.run(DemoApp.class, args);
    }
}

Rest Controller 

 
/**
 * REST CONTROLLER - quote mapping
 * 
 * mvn package
 * mvn spring-boot:run
 * curl http://localhost:9090/quote/1 
 *      {"id":1,"content":"Spring Boot apps easy."}
 * 
 * java -jar .\target\rest_service-0.0.1.jar
 * curl http://localhost:9090/quote/2
 *      {"id":2,"content":"Spring Boot deploy everywhere."}
 */

package com.example;

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DemoRestController {
    
    @GetMapping("/")
    public String quote() {
        return "Welcome!";
    }

    @GetMapping("/quote/{id}")
    public DemoQuote getQuote(@PathVariable Integer id) {

        List<DemoQuote> quotes = Arrays.asList(
            new DemoQuote(1, "Spring Boot apps easy."),
            new DemoQuote(2, "Spring Boot deploy everywhere.")
        );

        return quotes
                .stream()
                .filter(x -> x.getId() == id)
                .collect(Collectors.toList())
                .get(0);
    }
}

Quote Model 

 
/**
 * Quote - Model 
 */

package com.example;

public class DemoQuote {
    private final Integer id;
    private final String content;

    public DemoQuote(Integer id, String content) {
        this.id = id;
        this.content = content;
    }

    public int getId() {
        return id;
    }

    public String getContent() {
        return content;
    }
}

Port

Use a different port from 8080 (default). src/main/resources/application.properties 
 
server.port=9090

Run 

 
mvn clean package

mvn spring-boot:run
curl http://localhost:9090/quote/1 
{"id":1,"content":"Spring Boot apps easy."}

java -jar .\target\rest_service-0.0.1.jar
curl http://localhost:9090/quote/2
{"id":2,"content":"Spring Boot deploy everywhere."}

Rest Client

Rest Controller with /client_request_quote on port 9091 resources/application.properties 
 
server.port=9091

Client Controller 

 
/**
 * REST CLIENT
 * 
 * Service:
 * The service is already running on port 9090
 * curl http://localhost:9090/quote/1
 *      {"id":1,"content":"Spring Boot apps easy."}
 * 
 * Client:
 * curl http://localhost:9091/client/quote/1
 *      {"id":1,"content":"Spring Boot apps easy."}
 * 
 * curl http://localhost:9091/client/quote/2
 *      {"id":2,"content":"Spring Boot deploy everywhere."}
 */
package com.example;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class DemoRestClientController {
    
    @GetMapping("/client/quote/{id}")
    public Object client_request_quote(@PathVariable Integer id) {
        RestTemplate rt = new RestTemplate();  // Browser

        Object quote = rt.getForObject("http://localhost:9090/quote/" + id, Object.class);
        return quote;
    }
}

Run 

 
cd rest_client/
mvn package
mvn spring-boot:run

curl http://localhost:9091/client/quote/1
    {"id":1,"content":"Spring Boot apps easy."}

curl http://localhost:9091/client/quote/2
    {"id":2,"content":"Spring Boot deploy everywhere."}




References: