Spring Boot 教程：服务组件

【注】本文译自： https://www.tutorialspoint.co...

  服务组件是包含 @Service 注解的类文件。这些类文件可用在与 @RestController 类文件所不同的层来编写业务逻辑。创建服务组件类文件如下所示：

public interface ProductService {
}

  以 @Service 注解实现接口的类如下所示：

@Service
public class ProductServiceImpl implements ProductService {
}

  回顾以前的教程中，我们使用产品服务 API(s) 来存储、获取、更新和删除产品。我们在 @RestController 类文件自身中编写业务逻辑。现在我们要把业务逻辑代码从控制器移到服务组件。
  你可以创建一个接口，包含增加、编辑、获取和删除方法，示例代码如下：

package com.tutorialspoint.demo.service;

import java.util.Collection;
import com.tutorialspoint.demo.model.Product;

public interface ProductService {
   public abstract void createProduct(Product product);
   public abstract void updateProduct(String id, Product product);
   public abstract void deleteProduct(String id);
   public abstract Collection<Product> getProducts();
}

  以下代码将让你创建一个以 @Service 注解来实现 ProductService 接口的类，用以编写存储、获取、删除和更新产品。

package com.tutorialspoint.demo.service;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import org.springframework.stereotype.Service;
import com.tutorialspoint.demo.model.Product;

@Service
public class ProductServiceImpl implements ProductService {
   private static Map<String, Product> productRepo = new HashMap<>();
   static {
      Product honey = new Product();
      honey.setId("1");
      honey.setName("Honey");
      productRepo.put(honey.getId(), honey);

      Product almond = new Product();
      almond.setId("2");
      almond.setName("Almond");
      productRepo.put(almond.getId(), almond);
   }
   @Override
   public void createProduct(Product product) {
      productRepo.put(product.getId(), product);
   }
   @Override
   public void updateProduct(String id, Product product) {
      productRepo.remove(id);
      product.setId(id);
      productRepo.put(id, product);
   }
   @Override
   public void deleteProduct(String id) {
      productRepo.remove(id);

   }
   @Override
   public Collection<Product> getProducts() {
      return productRepo.values();
   }
}

  以里的代码展示了 Rest Controller 类文件，我们用 @Autowired 来自动注入 ProductService 接口并调用其方法。

package com.tutorialspoint.demo.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PathVariable;
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.RestController;

import com.tutorialspoint.demo.model.Product;
import com.tutorialspoint.demo.service.ProductService;

@RestController
public class ProductServiceController {
   @Autowired
   ProductService productService;

   @RequestMapping(value = "/products")
   public ResponseEntity<Object> getProduct() {
      return new ResponseEntity<>(productService.getProducts(), HttpStatus.OK);
   }
   @RequestMapping(value = "/products/{id}", method = RequestMethod.PUT)
   public ResponseEntity<Object> 
      updateProduct(@PathVariable("id") String id, @RequestBody Product product) {
      
      productService.updateProduct(id, product);
      return new ResponseEntity<>("Product is updated successsfully", HttpStatus.OK);
   }
   @RequestMapping(value = "/products/{id}", method = RequestMethod.DELETE)
   public ResponseEntity<Object> delete(@PathVariable("id") String id) {
      productService.deleteProduct(id);
      return new ResponseEntity<>("Product is deleted successsfully", HttpStatus.OK);
   }
   @RequestMapping(value = "/products", method = RequestMethod.POST)
   public ResponseEntity<Object> createProduct(@RequestBody Product product) {
      productService.createProduct(product);
      return new ResponseEntity<>("Product is created successfully", HttpStatus.CREATED);
   }
}

  POJO class – Product.java 代码在此：

package com.tutorialspoint.demo.model;

public class Product {
   private String id;
   private String name;

   public String getId() {
      return id;
   }
   public void setId(String id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
}

  主 Spring Boot 应用如下：

package com.tutorialspoint.demo;

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

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

  Maven build – pom.xml 代码如下所示：

<?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>com.tutorialspoint</groupId>
   <artifactId>demo</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <packaging>jar</packaging>
   <name>demo</name>
   <description>Demo project for Spring Boot</description>

   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>1.5.8.RELEASE</version>
      <relativePath/> 
   </parent>

   <properties>
      <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
      <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
      <java.version>1.8</java.version>
   </properties>

   <dependencies>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-web</artifactId>
      </dependency>

      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-test</artifactId>
         <scope>test</scope>
      </dependency>
   </dependencies>

   <build>
      <plugins>
         <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
         </plugin>
      </plugins>
   </build>

</project>

  Gradle Build – build.gradle 代码如下：

buildscript {
   ext {
      springBootVersion = '1.5.8.RELEASE'
   }
   repositories {
      mavenCentral()
   }
   dependencies {
      classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
   }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'

group = 'com.tutorialspoint'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8

repositories {
   mavenCentral()
}
dependencies {
   compile('org.springframework.boot:spring-boot-starter-web')
   testCompile('org.springframework.boot:spring-boot-starter-test')
}

  现在你可以使用 Maven 或 Gradle 命令创建可执行 executable JAR 文件并运行 Spring Boot 应用了：
  Maven 命令如下：

mvn clean install

  在 “BUILD SUCCESS” 之后，你可以在 target 目录下找到 JAR 文件。
  Gradle 可以使用以下命令：

gradle clean build

  在 “BUILD SUCCESSFUL” 之后，你可以在 build/libs 目录下找到 JAR 文件。
  现在，使用以下命令运行 JAR 文件：

java –jar <JARFILE>

  应用将在 Tomcat 8080 端口启动，如下图所示：

  现在在 POSTMAN 应用中输入以下 URL，可以看到下图所示的输出：
GET API URL 为： http://localhost:8080/products

POST API URL 为： http://localhost:8080/products

PUT API URL 为： http://localhost:8080/products/3

DELETE API URL 为： http://localhost:8080/products/3