Java Spring Boot Microservices Sample Project

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

@SpringBootApplication
// It is equivalent to using @Configuration,
// @EnableAutoConfiguration and @ComponentScan with their
// default attributes:
public class CurrencyExchangeServiceSampleApplication {

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

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
// The @RestController annotation in Spring is essentially
// just a combination of
// @Controller and @ResponseBody. This annotation was added
// during Spring 4.0 to remove the redundancy of declaring
// the @ResponseBody annotation in your controller
public class CurrencyExchangeSampleController {
    @Autowired private Environment environment;

    @GetMapping(
        "/currency-exchange-sample/fromCurrency/{fromCurrency}/toCurrency/{toCurrency}")
    // where {fromCurrency} and {toCurrency} are path
    // variable
    // fromCurrency can be USD,EUR,AUD,INR and toCurrency
    // can be the opposite of any fromCurrency
    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;
    }
}

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;
    }
}

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);
    }
}

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; }
}

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;

// To invoke an external service, RestTemplate() constructor
// is used
@RestController
public class CurrencyConversionSampleController {
    @GetMapping(
        "/currency-converter-sample/fromCurrency/{fromCurrency}/toCurrency/{toCurrency}/quantity/{quantity}")
    // where {from} and {to} represents the
    // column
    // returns a bean back
    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);
        // calling the currency-exchange-sample-service
        // http://localhost:8000/currency-exchange-sample/fromCurrency/{fromCurrency}/toCurrency/{toCurrency}
        // is the service that got called from part 1. Its
        // response is received and via
        // CurrencyConversionSampleBean we are getting the
        // results back
        ResponseEntity<CurrencyConversionSampleBean>
            responseEntity
            = new RestTemplate().getForEntity(
                "http://localhost:8000/currency-exchange-sample/fromCurrency/{fromCurrency}/toCurrency/{toCurrency}",
                CurrencyConversionSampleBean.class,
                uriVariables);
        CurrencyConversionSampleBean response
            = responseEntity.getBody();
        // creating a new response bean and getting the
        // response back and taking it into Bean Hence the
        // output bean should have all the fields that is
        // received from the response
        return new CurrencyConversionSampleBean(
            response.getId(), fromCurrency, toCurrency,
            response.getConversionMultiple(), quantity,
            quantity.multiply(
                response.getConversionMultiple()),
            response.getPort());
    }
}