如何使用Java Spring Boot 创建一个微服务项目一？
微服务现在更流行。它们可以用任何语言编写。在这篇文章中，让我们看看Spring Boot微服务。在本文中，我们看到一个基础项目currency-exchange-sample-service，它具有业务逻辑，并且可以在另一个项目 currency-conversion-sample-service 中调用
微服务1：货币兑换样本服务
项目结构
pom.xml
代码语言：javascript复制<?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
https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.gfg.microservices</groupId>
<artifactId>currency-exchange-sample-service</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>currency-exchange-sample-service</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Hoxton.RC2</spring-cloud.version>
</properties>
<dependencies>
<!-- Starter for building web, including RESTful,
applications using Spring MVC. -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-config</artifactId>
</dependency>
<!-- The spring-boot-devtools module can be included in any
project to provide additional development-time features -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<!-- H2 is an open-source lightweight Java database -->
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<!-- starter for using Spring Data JPA with Hibernate. -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
<version>2.1.3.RELEASE</version>
</dependency>
<!-- provides secured endpoints for monitoring
and managing your Spring Boot application -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
</repository>
</repositories>
</project>让我们看看重要的文件
CurrencyExchangeServiceSampleApplication.java
代码语言：javascript复制import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
// 这与使用 @Configuration、@EnableAutoConfiguration 和 @ComponentScan 以及它们的默认属性等效：
public class CurrencyExchangeServiceSampleApplication {
public static void main(String[] args)
{
SpringApplication.run(
CurrencyExchangeServiceSampleApplication.class,
args);
}
}CurrencyExchangeSampleController.java
代码语言：javascript复制import java.math.BigDecimal;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.core.env.Environment;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
@SpringBootApplication
@RestController
public class CurrencyExchangeSampleController {
@Autowired private Environment environment;
@GetMapping(
"/currency-exchange-sample/fromCurrency/{fromCurrency}/toCurrency/{toCurrency}")
public ExchangeValue
retrieveExchangeValue(@PathVariable String fromCurrency,
@PathVariable String toCurrency)
{
// Here we need to write all of our business logic
BigDecimal conversionMultiple = null;
ExchangeValue exchangeValue = new ExchangeValue();
if (fromCurrency != null && toCurrency != null) {
if (fromCurrency.equalsIgnoreCase("USD")
&& toCurrency.equalsIgnoreCase("INR")) {
conversionMultiple = BigDecimal.valueOf(78);
}
if (fromCurrency.equalsIgnoreCase("INR")
&& toCurrency.equalsIgnoreCase("USD")) {
conversionMultiple
= BigDecimal.valueOf(0.013);
}
if (fromCurrency.equalsIgnoreCase("EUR")
&& toCurrency.equalsIgnoreCase("INR")) {
conversionMultiple = BigDecimal.valueOf(82);
}
if (fromCurrency.equalsIgnoreCase("AUD")
&& toCurrency.equalsIgnoreCase("INR")) {
conversionMultiple = BigDecimal.valueOf(54);
}
}
// setting the port
exchangeValue = new ExchangeValue(
1000L, fromCurrency, toCurrency,
conversionMultiple);
exchangeValue.setPort(Integer.parseInt(
environment.getProperty("local.server.port")));
return exchangeValue;
}
}ExchangeValue.java
代码语言：javascript复制import java.math.BigDecimal;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
// @Entity annotation defines that a class can be mapped to
// a table
@Entity
// Representation of the table name
@Table(name = "Exchange_Value")
public class ExchangeValue {
// The @Id annotation is inherited from
// javax.persistence.Id, indicating the member field
// below is the primary key of the current entity
@Id @Column(name = "id") private Long id;
@Column(name = "currency_from")
private String fromCurrency;
@Column(name = "currency_to") private String toCurrency;
@Column(name = "conversion_multiple")
private BigDecimal conversionMultiple;
@Column(name = "port") private int port;
public ExchangeValue() {}
// generating constructor using fields
public ExchangeValue(Long id, String fromCurrency,
String toCurrency,
BigDecimal conversionMultiple)
{
super();
this.id = id;
this.fromCurrency = fromCurrency;
this.toCurrency = toCurrency;
this.conversionMultiple = conversionMultiple;
}
// generating getters
public int getPort() { return port; }
public void setPort(int port) { this.port = port; }
public Long getId() { return id; }
public String getFrom() { return fromCurrency; }
public String getTo() { return toCurrency; }
public BigDecimal getConversionMultiple()
{
return conversionMultiple;
}
}应用程序属性
代码语言：javascript复制spring.application.name=货币交换样本服务
server.port=8000 #端口号的表示。我们也可以在运行配置中设置不同的端口号
spring.jpa.show-sql=true #显示SQL
spring.h2.console.enabled=true
spring.datasource.platform=h2 #由于我们使用的是h2数据源
spring.datasource.url=jdbc:h2:mem:gfg## data.sql
代码语言：javascript复制insert into exchange_value(id,currency_from,currency_to,conversion_multiple,port)
values(10001,'USD', 'INR' ,65,0);
insert into exchange_value(id,currency_from,currency_to,conversion_multiple,port)
values(10002,'EUR', 'INR' ,82,0);
insert into exchange_value(id,currency_from,currency_to,conversion_multiple,port)
values(10003,'AUD', 'INR' ,53,0);默认情况下，它已设置为在端口 8000 上运行。我们可以创建另一个实例，并可以通过以下方式使项目在端口 8001 上运行
由于这是Spring Boot应用程序，因此它可以作为Java应用程序正常运行
如果我们设置在两个不同的端口上运行应用程序，我们将得到以下选项
让我们选择第一个。运行应用程序时，在控制台中，我们看到
从控制台中，我们可以看到它使用默认的Tomcat，并且项目运行在端口8080上。由于我们使用了3个插入脚本，因此会自动创建表并插入数据。我们可以做到以下几点
代码语言：javascript复制http://localhost:8000/currency-exchange-sample/fromCurrency/USD/toCurrency/INR
当这个URL被点击时，它将被重定向到控制器，fromCurrency被视为“USD”，toCurrency被视为“INR”
同样，我们可以执行以下 URL
代码语言：javascript复制http://localhost:8000/currency-exchange-sample/fromCurrency/EUR/toCurrency/INR
http://localhost:8000/currency-exchange-sample/fromCurrency/AUD/toCurrency/INR
因此，根据我们的业务需求，我们可以将业务逻辑添加到控制器文件中
