Membina Sistem Perkhidmatan Mikro Pertama Anda dengan Spring Boot: Panduan Pemula

pengenalan

Dalam panduan ini, kami akan menelusuri penciptaan sistem perkhidmatan mikro yang ringkas tetapi komprehensif menggunakan Spring Boot. Kami akan merangkumi asas perkhidmatan mikro, menyediakan persekitaran yang diperlukan dan melaksanakan dua perkhidmatan mikro: OrderService dan InventoryService. Selain itu, kami akan menyepadukan penemuan perkhidmatan menggunakan Eureka dan Gateway API untuk mengurus penghalaan antara perkhidmatan.

Apakah perkhidmatan Mikro?

Perkhidmatan mikro ialah gaya seni bina perisian di mana aplikasi dibina sebagai koleksi perkhidmatan kecil dan bebas yang berfungsi bersama. Setiap perkhidmatan adalah serba lengkap dan berkomunikasi dengan orang lain melalui API yang jelas, menjadikan sistem lebih fleksibel, berskala dan lebih mudah untuk diurus.

Seni Bina Sistem

Seni bina sistem kami akan terdiri daripada dua perkhidmatan mikro: OrderService dan InventoryService. OrderService akan menggunakan pangkalan data hubungan (MySQL) untuk menyimpan butiran pesanan, manakala InventoryService akan menggunakan pangkalan data NoSQL (MongoDB) untuk mengurus data inventori. Kami juga akan melaksanakan penemuan perkhidmatan dengan Eureka dan menggunakan Gerbang API untuk permintaan penghalaan.

Persediaan Projek

Sebelum kami bermula, pastikan anda telah memasang alatan berikut:

• IDE: IntelliJ IDEA (diutamakan) atau Eclipse
• JDK: Versi 17 atau lebih baru
• Alat Bina: Maven
• Pangkalan Data: MySQL dan MongoDB

Perkhidmatan mikro 1: Perkhidmatan Pesanan

Langkah 1: Mulakan Projek

1. Pergi ke Spring Initializr.
2. Isi butiran projek:
   • Projek: Projek Maven
   • Bahasa: Java
   • But Musim Bunga: 2.5.7 (atau versi yang serasi)
   • Kumpulan: com.ordersystem
   • Artifak: perkhidmatan pesanan
   • Nama: perkhidmatan pesanan
   • Nama pakej: com.ordersystem.orderservice
   • Pembungkusan: Balang
   • Jawa: 17
3. Tambah kebergantungan berikut:
   • Jaman Musim Bunga
   • Data Musim Bunga JPA
   • Pemandu MySQL
   • Lombok
4. Klik Jana untuk memuat turun projek. Ekstrak fail zip yang dimuat turun dan bukanya dalam IDE anda.

Langkah 2: Konfigurasi Aplikasi

Buka fail application.properties dalam src/main/resources dan tambahkan konfigurasi berikut:

spring.datasource.url=jdbc:mysql://localhost:3306/orderservice
spring.datasource.username=root
spring.datasource.password=yourpassword
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL8Dialect
server.port=8081

Langkah 3: Laksanakan Model

Buat kelas entiti Pesanan dalam src/main/java/com/ordersystem/orderservice/model/Order.java:

package com.ordersystem.orderservice.model;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.*;

@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name = "orders")
public class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String product;
    private int quantity;
    private double price;
}

Langkah 4: Buat Repositori

Buat antara muka OrderRepository dalam src/main/java/com/ordersystem/orderservice/repository/OrderRepository.java:

package com.ordersystem.orderservice.repository;

import com.ordersystem.orderservice.model.Order;
import org.springframework.data.jpa.repository.JpaRepository;

public interface OrderRepository extends JpaRepository<Order, Long> {
}

Langkah 5: Laksanakan Perkhidmatan

Buat kelas OrderService dalam src/main/java/com/ordersystem/orderservice/service/OrderService.java:

package com.ordersystem.orderservice.service;

import com.ordersystem.orderservice.model.Order;
import com.ordersystem.orderservice.repository.OrderRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class OrderService {
    @Autowired
    private OrderRepository orderRepository;

    public List<Order> getAllOrders() {
        return orderRepository.findAll();
    }

    public Order getOrderById(Long id) {
        return orderRepository.findById(id).orElse(null);
    }

    public Order createOrder(Order order) {
        return orderRepository.save(order);
    }

    public void deleteOrder(Long id) {
        orderRepository.deleteById(id);
    }
}

Langkah 6: Buat Pengawal

Buat kelas OrderController dalam src/main/java/com/ordersystem/orderservice/controller/OrderController.java:

package com.ordersystem.orderservice.controller;

import com.ordersystem.orderservice.model.Order;
import com.ordersystem.orderservice.service.OrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/api/orders")
public class OrderController {
    @Autowired
    private OrderService orderService;

    @GetMapping
    public List<Order> getAllOrders() {
        return orderService.getAllOrders();
    }

    @GetMapping("/{id}")
    public Order getOrderById(@PathVariable Long id) {
        return orderService.getOrderById(id);
    }

    @PostMapping
    public Order createOrder(@RequestBody Order order) {
        return orderService.createOrder(order);
    }

    @DeleteMapping("/{id}")
    public void deleteOrder(@PathVariable Long id) {
        orderService.deleteOrder(id);
    }
}

Perkhidmatan Mikro 2: Perkhidmatan Inventori

Langkah 1: Mulakan Projek

1. Pergi ke Spring Initializr.
2. Isi butiran projek:
   • Projek: Projek Maven
   • Bahasa: Java
   • But Musim Bunga: 2.5.7 (atau versi yang serasi)
   • Kumpulan: com.ordersystem
   • Artifak: perkhidmatan inventori
   • Nama: perkhidmatan inventori
   • Nama pakej: com.ordersystem.inventoryservice
   • Pembungkusan: Balang
   • Jawa: 17
3. Tambah kebergantungan berikut:
   • Jaman Musim Bunga
   • Data Spring MongoDB
   • Lombok
4. Klik Jana untuk memuat turun projek. Ekstrak fail zip yang dimuat turun dan bukanya dalam IDE anda.

Langkah 2: Konfigurasi Aplikasi

Buka fail application.properties dalam src/main/resources dan tambahkan konfigurasi berikut:

spring.data.mongodb.uri=mongodb://localhost:27017/inventoryservice
server.port=8082

Langkah 3: Laksanakan Model

Buat kelas entiti InventoryItem dalam src/main/java/com/ordersystem/inventoryservice/model/InventoryItem.java:

package com.ordersystem.inventoryservice.model;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

@Data
@AllArgsConstructor
@NoArgsConstructor
@Document(collection = "inventory")
public class InventoryItem {
    @Id
    private String id;
    private String product;
    private int quantity;
}

Langkah 4: Buat Repositori

Buat antara muka InventoryRepository dalam src/main/java/com/ordersystem/inventoryservice/repository/InventoryRepository.java:

package com.ordersystem.inventoryservice.repository;

import com.ordersystem.inventoryservice.model.InventoryItem;
import org.springframework.data.mongodb.repository.MongoRepository;

public interface InventoryRepository extends MongoRepository<InventoryItem, String> {
}

Step 5: Implement the Service

Create the InventoryService class in src/main/java/com/ordersystem/inventoryservice/service/InventoryService.java:

package com.ordersystem.inventoryservice.service;

import com.ordersystem.inventoryservice.model.InventoryItem;
import com.ordersystem.inventoryservice.repository.InventoryRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class InventoryService {
    @Autowired
    private InventoryRepository inventoryRepository;

    public List<InventoryItem> getAllItems() {
        return inventoryRepository.findAll();
    }

    public InventoryItem getItemById(String id) {
        return inventoryRepository.findById(id).orElse(null);
    }

    public InventoryItem createItem(InventoryItem item) {
        return inventoryRepository.save(item);
    }

    public void deleteItem(String id) {
        inventoryRepository.deleteById(id);
    }
}

Step 6: Create the Controller

Create the InventoryController class in src/main/java/com/ordersystem/inventoryservice/controller/InventoryController.java:

package com.ordersystem.inventoryservice.controller;

import com.ordersystem.inventoryservice.model.InventoryItem;
import com.ordersystem.inventoryservice.service.InventoryService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/api/inventory")
public class InventoryController {
    @Autowired
    private InventoryService inventoryService;

    @GetMapping
    public List<InventoryItem> getAllItems() {
        return inventoryService.getAllItems();
    }

    @GetMapping("/{id}")
    public InventoryItem getItemById(@PathVariable String id) {
        return inventoryService.getItemById(id);
    }

    @PostMapping
    public InventoryItem createItem(@RequestBody InventoryItem item) {
        return inventoryService.createItem(item);
    }

    @DeleteMapping("/{id}")
    public void deleteItem(@PathVariable String id) {
        inventoryService.delete

Item(id);
    }
}

Service Discovery with Eureka

Step 1: Initialize the Eureka Server

1. Go to Spring Initializr.
2. Fill in the project details:
   • Project: Maven Project
   • Language: Java
   • Spring Boot: 2.5.7 (or a compatible version)
   • Group: com.ordersystem
   • Artifact: eureka-server
   • Name: eureka-server
   • Package name: com.ordersystem.eurekaserver
   • Packaging: Jar
   • Java: 17
3. Add the Eureka Server dependency.
4. Click Generate to download the project. Extract the downloaded zip file and open it in your IDE.

Step 2: Configure the Eureka Server

Open the application.properties file in src/main/resources and add the following configuration:

server.port=8761
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false

Step 3: Enable Eureka Server

Annotate the main application class in src/main/java/com/ordersystem/eurekaserver/EurekaServerApplication.java with @EnableEurekaServer:

package com.ordersystem.eurekaserver;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

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

Integrate Services with Eureka

Add the Eureka client dependency to both OrderService and InventoryService:

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>

Add Eureka client configuration to the application.properties files:

Order Service:

eureka.client.service-url.defaultZone=http://localhost:8761/eureka/
spring.application.name=order-service

Inventory Service:

eureka.client.service-url.defaultZone=http://localhost:8761/eureka/
spring.application.name=inventory-service

API Gateway

Step 1: Initialize the API Gateway

1. Go to Spring Initializr.
2. Fill in the project details:
   • Project: Maven Project
   • Language: Java
   • Spring Boot: 2.5.7 (or a compatible version)
   • Group: com.ordersystem
   • Artifact: api-gateway
   • Name: api-gateway
   • Package name: com.ordersystem.apigateway
   • Packaging: Jar
   • Java: 17
3. Add the Gateway and Eureka Discovery Client dependencies.
4. Click Generate to download the project. Extract the downloaded zip file and open it in your IDE.

Step 2: Configure the API Gateway

Open the application.yml file in src/main/resources and add the following configuration:

server:
  port: 8080

spring:
  application:
    name: api-gateway
  cloud:
    gateway:
      routes:
        - id: order-service
          uri: lb://order-service
          predicates:
            - Path=/api/orders/**
        - id: inventory-service
          uri: lb://inventory-service
          predicates:
            - Path=/api/inventory/**

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/

Step 3: Enable Discovery Client

Annotate the main application class in src/main/java/com/ordersystem/apigateway/ApiGatewayApplication.java with @EnableDiscoveryClient:

package com.ordersystem.apigateway;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

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

Testing the Microservices

1. Start Eureka Server: Run the Eureka Server application.
2. Start Order Service: Run the Order Service application.
3. Start Inventory Service: Run the Inventory Service application.
4. Start API Gateway: Run the API Gateway application.

Use Postman or any other API client to test the endpoints through the API Gateway:

• Create Order: POST http://localhost:8080/api/orders
• Get Orders: GET http://localhost:8080/api/orders
• Create Inventory Item: POST http://localhost:8080/api/inventory
• Get Inventory Items: GET http://localhost:8080/api/inventory

Conclusion

In this guide, we've built a simple microservices system using Spring Boot. We created two microservices (OrderService and InventoryService), integrated service discovery with Eureka, and set up an API Gateway for routing requests. This architecture allows for scalable and maintainable microservices that can be easily extended in the future.

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