spring boot微服务-第三部分：创建货币兑换服务

货币兑换服务

货币兑换服务（Currency Conversion Service CCS）能计算出将一定数量的货币转化为另一种货币的数量。它使用汇率服务（Forex Service，Fs，上一节介绍的服务）得到汇率。因此CCS是一个消费服务.

访问这个服务的请求和返回结果如下所示：

get请求：http://localhost:8100/currencyconverter/from/EUR/to/INR/quantity/10000

{
  id: 10002,
  from: "EUR",
  to: "INR",
  conversionMultiple: 75,
  quantity: 10000,
  totalCalculatedAmount: 750000,
  port: 8000,
}

上述请求是10000元欧元可以转换为多少卢比（750000卢比）。通信过程如下图所示

image.png

代码

创建bean
用于返回结果

public class CurrencyConversionBean {
  private Long id;
  private String from;
  private String to;
  private BigDecimal conversionMultiple;
  private BigDecimal quantity;
  private BigDecimal totalCalculatedAmount;
  private int port;

  public CurrencyConversionBean() {

  }

  public CurrencyConversionBean(Long id, String from, String to, BigDecimal conversionMultiple, BigDecimal quantity,
      BigDecimal totalCalculatedAmount, int port) {
    super();
    this.id = id;
    this.from = from;
    this.to = to;
    this.conversionMultiple = conversionMultiple;
    this.quantity = quantity;
    this.totalCalculatedAmount = totalCalculatedAmount;
    this.port = port;
  }

使用RestTemplate创建Rest客户端
调用FS服务并且处理返回的结果

@RestController
public class CurrencyConversionController {

  private Logger logger = LoggerFactory.getLogger(this.getClass());

  @GetMapping("/currency-converter/from/{from}/to/{to}/quantity/{quantity}")
  public CurrencyConversionBean convertCurrency(@PathVariable String from, @PathVariable String to,
      @PathVariable BigDecimal quantity) {

    Map<String, String> uriVariables = new HashMap<>();
    uriVariables.put("from", from);
    uriVariables.put("to", to);

    ResponseEntity<CurrencyConversionBean> responseEntity = new RestTemplate().getForEntity(
        "http://localhost:8000/currency-exchange/from/{from}/to/{to}", CurrencyConversionBean.class,
        uriVariables);

    CurrencyConversionBean response = responseEntity.getBody();

    return new CurrencyConversionBean(response.getId(), from, to, response.getConversionMultiple(), quantity,
        quantity.multiply(response.getConversionMultiple()), response.getPort());
  }

配置文件
application.properties

spring.application.name=currency-conversion-service
server.port=8100

测试
get请求：
http://localhost:8100/currency converter/from/EUR/to/INR/quantity/10000
返回：

{
  id: 10002,
  from: "EUR",
  to: "INR",
  conversionMultiple: 75,
  quantity: 10000,
  totalCalculatedAmount: 750000,
  port: 8000,
}

改进

创建代理(feign proxy)
调用Rest Api而不直接使用URL的方式

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.cloud.netflix.ribbon.RibbonClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@FeignClient(name="forex-service" url="localhost:8000")
public interface CurrencyExchangeServiceProxy {
  @GetMapping("/currency-exchange/from/{from}/to/{to}")
  public CurrencyConversionBean retrieveExchangeValue
    (@PathVariable("from") String from, @PathVariable("to") String to);
}

说明

@FeignClient(name="forex-service" url="localhost:800")
声明这是一个代理，name指示代理的服务名称，url是代理的URL
@GetMapping("/currency-exchange/from/{from}/to/{to}")
服务的URI

在控制器中使用代理

@Autowired
  private CurrencyExchangeServiceProxy proxy;

  @GetMapping("/currency-converter-feign/from/{from}/to/{to}/quantity/{quantity}")
  public CurrencyConversionBean convertCurrencyFeign(@PathVariable String from, @PathVariable String to,
      @PathVariable BigDecimal quantity) {

    CurrencyConversionBean response = proxy.retrieveExchangeValue(from, to);

    logger.info("{}", response);

    return new CurrencyConversionBean(response.getId(), from, to, response.getConversionMultiple(), quantity,
        quantity.multiply(response.getConversionMultiple()), response.getPort());
  }

开启代理功能

@SpringBootApplication
@EnableFeignClients("com.zhg.springboot.microservice.example.currencyconversion")
@EnableDiscoveryClient
public class SpringBootMicroserviceCurrencyConversionApplication {

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

对微服务进行测试，使用代理的方式
get请求：
http://localhost:8100/currency-converter feign/from/EUR/to/INR/quantity/10000
返回

{
  id: 10002,
  from: "EUR",
  to: "INR",
  conversionMultiple: 75,
  quantity: 10000,
  totalCalculatedAmount: 750000,
  port: 8000,
}

完整代码

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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.zhg.springboot.microservice.example.currency-conversion</groupId>
  <artifactId>spring-boot-microservice-currency-conversion</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>spring-boot-microservice-currency-conversion</name>
  <description>Microservices with Spring Boot and Spring Cloud - Currency Conversion Service</description>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.0.RELEASE</version>
    <relativePath /> <!-- lookup parent from repository -->
  </parent>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
    <spring-cloud.version>Finchley.M8</spring-cloud.version>
  </properties>

  <dependencies>

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

    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-devtools</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </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-snapshots</id>
      <name>Spring Snapshots</name>
      <url>https://repo.spring.io/snapshot</url>
      <snapshots>
        <enabled>true</enabled>
      </snapshots>
    </repository>
    <repository>
      <id>spring-milestones</id>
      <name>Spring Milestones</name>
      <url>https://repo.spring.io/milestone</url>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
    </repository>
  </repositories>

  <pluginRepositories>
    <pluginRepository>
      <id>spring-snapshots</id>
      <name>Spring Snapshots</name>
      <url>https://repo.spring.io/snapshot</url>
      <snapshots>
        <enabled>true</enabled>
      </snapshots>
    </pluginRepository>
    <pluginRepository>
      <id>spring-milestones</id>
      <name>Spring Milestones</name>
      <url>https://repo.spring.io/milestone</url>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
    </pluginRepository>
  </pluginRepositories>


</project>

CurrencyConversionBean.java

package com.zhg.springboot.microservice.example.currencyconversion;
import java.math.BigDecimal;

public class CurrencyConversionBean {
  private Long id;
  private String from;
  private String to;
  private BigDecimal conversionMultiple;
  private BigDecimal quantity;
  private BigDecimal totalCalculatedAmount;
  private int port;

  public CurrencyConversionBean() {

  }

  public CurrencyConversionBean(Long id, String from, String to, BigDecimal conversionMultiple, BigDecimal quantity,
      BigDecimal totalCalculatedAmount, int port) {
    super();
    this.id = id;
    this.from = from;
    this.to = to;
    this.conversionMultiple = conversionMultiple;
    this.quantity = quantity;
    this.totalCalculatedAmount = totalCalculatedAmount;
    this.port = port;
  }

  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) {
    this.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;
  }

}

CurrencyConversionController.java

package com.zhg.springboot.microservice.example.currencyconversion;

import java.math.BigDecimal;
import java.util.HashMap;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
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 CurrencyConversionController {

  private Logger logger = LoggerFactory.getLogger(this.getClass());

  @Autowired
  private CurrencyExchangeServiceProxy proxy;

  @GetMapping("/currency-converter/from/{from}/to/{to}/quantity/{quantity}")
  public CurrencyConversionBean convertCurrency(@PathVariable String from, @PathVariable String to,
      @PathVariable BigDecimal quantity) {

    Map<String, String> uriVariables = new HashMap<>();
    uriVariables.put("from", from);
    uriVariables.put("to", to);

    ResponseEntity<CurrencyConversionBean> responseEntity = new RestTemplate().getForEntity(
        "http://localhost:8000/currency-exchange/from/{from}/to/{to}", CurrencyConversionBean.class,
        uriVariables);

    CurrencyConversionBean response = responseEntity.getBody();

    return new CurrencyConversionBean(response.getId(), from, to, response.getConversionMultiple(), quantity,
        quantity.multiply(response.getConversionMultiple()), response.getPort());
  }

  @GetMapping("/currency-converter-feign/from/{from}/to/{to}/quantity/{quantity}")
  public CurrencyConversionBean convertCurrencyFeign(@PathVariable String from, @PathVariable String to,
      @PathVariable BigDecimal quantity) {

    CurrencyConversionBean response = proxy.retrieveExchangeValue(from, to);

    logger.info("{}", response);

    return new CurrencyConversionBean(response.getId(), from, to, response.getConversionMultiple(), quantity,
        quantity.multiply(response.getConversionMultiple()), response.getPort());
  }

}

CurrencyExchangeServiceProxy.java

package com.zhg.springboot.microservice.example.currencyconversion;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.cloud.netflix.ribbon.RibbonClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@FeignClient(name="forex-service" url="localhost:8000")
public interface CurrencyExchangeServiceProxy {
  @GetMapping("/currency-exchange/from/{from}/to/{to}")
  public CurrencyConversionBean retrieveExchangeValue
    (@PathVariable("from") String from, @PathVariable("to") String to);
}

SpringBootMicroserviceCurrencyConversionApplication.java

package com.zhg.springboot.microservice.example.currencyconversion;

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

@SpringBootApplication
@EnableFeignClients("com.in28minutes.springboot.microservice.example.currencyconversion")
public class SpringBootMicroserviceCurrencyConversionApplication {

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

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spring boot微服务-第三部分：创建货币兑换服务

货币兑换服务

代码

改进

完整代码

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