如何使用Java Spring Boot 创建一个微服务项目 二？

如何使用Java Spring Boot 创建一个微服务项目 二？

上一篇我们已经链接了 如何使用Java Spring Boot 创建一个微服务项目 一？这一篇我们接着实现第二部分

微服务2：货币兑换样本服务

这也是一个maven项目

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 
							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/> 
	</parent>
	<groupId>com.gfg.microservices</groupId>
	<artifactId>currency-conversion-sample-service</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>currency-conversion-servicce</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>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-actuator</artifactId>
		</dependency>
		<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>

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

主要重要的java文件

CurrencyConversionSampleServiceApplication.java

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

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

CurrencyConversionSampleBean.java

import java.math.BigDecimal;

public class CurrencyConversionSampleBean {
	// We need to set all the fields that is going to
	// received in response
	private Long id;
	private String from;
	private String to;
	private BigDecimal ConversionMultiple;
	private BigDecimal quantity;
	private BigDecimal totalCalculatedAmount;
	private int port;

	// default constructor
	public CurrencyConversionSampleBean() {}

	// creating constructor
	public CurrencyConversionSampleBean(
		Long id, String from, String to,
		BigDecimal conversionMultiple, BigDecimal quantity,
		BigDecimal totalCalculatedAmount, int port)
	{
		super();
		this.id = id;
		this.from = from;
		this.to = to;
		ConversionMultiple = conversionMultiple;
		this.quantity = quantity;
		this.totalCalculatedAmount = totalCalculatedAmount;
		this.port = port;
	}

	// creating setters and getters
	public Long getId() { return id; }

	public void setId(Long id) { this.id = id; }

	public String getFrom() { return from; }

	public void setFrom(String from) { this.from = from; }

	public String getTo() { return to; }

	public void setTo(String to) { this.to = to; }

	public BigDecimal getConversionMultiple()
	{
		return ConversionMultiple;
	}

	public void
	setConversionMultiple(BigDecimal conversionMultiple)
	{
		ConversionMultiple = conversionMultiple;
	}

	public BigDecimal getQuantity() { return quantity; }

	public void setQuantity(BigDecimal quantity)
	{
		this.quantity = quantity;
	}

	public BigDecimal getTotalCalculatedAmount()
	{
		return totalCalculatedAmount;
	}

	public void setTotalCalculatedAmount(
		BigDecimal totalCalculatedAmount)
	{
		this.totalCalculatedAmount = totalCalculatedAmount;
	}

	public int getPort() { return port; }

	public void setPort(int port) { this.port = port; }
}

CurrencyConversionSampleController.java

package com.gfg.microservices.currencyconversionservice;

import java.math.BigDecimal;
import java.util.HashMap;
import java.util.Map;
import org.springframework.http.ResponseEntity;
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 CurrencyConversionSampleController {
	@GetMapping(
		"/currency-converter-sample/fromCurrency/{fromCurrency}/toCurrency/{toCurrency}/quantity/{quantity}")
	
	public CurrencyConversionSampleBean
	convertCurrency(@PathVariable String fromCurrency,
					@PathVariable String toCurrency,
					@PathVariable BigDecimal quantity)
	{

		// setting variables to currency exchange service
		Map<String, String> uriVariables = new HashMap<>();
		// urlParams should match properly
		uriVariables.put("fromCurrency", fromCurrency);
		uriVariables.put("toCurrency", toCurrency);
		// 调用货币兑换示例服务
// http://localhost:8000/currency-exchange-sample/fromCurrency/{fromCurrency}/toCurrency/{toCurrency}
// 是从第一部分调用的服务。它的响应已经接收，并通过 CurrencyConversionSampleBean 我们获取了结果回来
		ResponseEntity<CurrencyConversionSampleBean>
			responseEntity
			= new RestTemplate().getForEntity(
				"http://localhost:8000/currency-exchange-sample/fromCurrency/{fromCurrency}/toCurrency/{toCurrency}",
				CurrencyConversionSampleBean.class,
				uriVariables);
		CurrencyConversionSampleBean response
			= responseEntity.getBody();
		// 创建一个新的响应Bean并获取响应，将其放入Bean中。因此，输出Bean应包含从响应接收到的所有字段。
		return new CurrencyConversionSampleBean(
			response.getId(), fromCurrency, toCurrency,
			response.getConversionMultiple(), quantity,
			quantity.multiply(
				response.getConversionMultiple()),
			response.getPort());
	}
}

也就是说这个项目是在端口8100上启动的。现在我们可以执行以下URLS

http://localhost:8100/currency-converter-sample/fromCurrency/USD/toCurrency/INR/quantity/1000

当这个服务被调用时，它会依次调用。

假设：

currency-exchange-sample 正在端口 8000 中运行，并产生所需的响应

http://localhost:8000/currency-exchange-sample/fromCurrency/USD/toCurrency/INR

然后逻辑写成

ResponseEntity<CurrencyConversionSampleBean>respnotallow=new RestTemplate().getForEntity("http://localhost:8000/currency-exchange-sample/fromCurrency/{fromCurrency}/toCurrency/{toCurrency}",CurrencyConversionSampleBean.class, uriVariables);
        CurrencyConversionSampleBean response=responseEntity.getBody();  
        // 创建一个新的响应 bean 并获取响应并将其放入 Bean 中
        // 因此输出 bean 应该具有从响应接收到的所有字段
        返回新的CurrencyConversionSampleBean（response.getId（），fromCurrency，toCurrency，response.getConversionMultiple（），数量，quantity.multiply（response.getConversionMultiple（）），response.getPort（））;

我们看到totalCalculatedAmount 为78 * 1000，即78000。我们从第一个URL 中获取“conversionMultiple”，并将其与此处的数量值相乘。非常理想的是，我们不需要将交换服务逻辑引入到该应用程序中，即第 1 部分项目可以分开，第 2 部分项目可以在此处调用第 1 部分 URL。因此微服务可以单独运行，其他服务可以使用它们。其余可检查的网址

例子1

http://localhost:8100/currency-converter-sample/fromCurrency/EUR/toCurrency/INR/quantity/5000

这会依次调用

http://localhost:8000/currency-exchange-sample/fromCurrency/EUR/toCurrency/INR

输出

例子2

http://localhost:8100/currency-converter-sample/fromCurrency/AUD/toCurrency/INR/quantity/2000

这会依次调用

http://localhost:8000/currency-exchange-sample/fromCurrency/AUD/toCurrency/INR

输出