Java中转换器设计模式深入讲解

public abstract class Converter < T, C > {

 private final Function < T,
 C > fromDto;
 private final Function < C,
 T > fromEntity;

 /**
  * @param fromDto
  *   Function that converts given dto entity into the domain
  *   entity.
  * @param fromEntity
  *   Function that converts given domain entity into the dto
  *   entity.
  */
 public Converter(final Function < T, C > fromDto, final Function < C, T > fromEntity) {
  this.fromDto = fromDto;
  this.fromEntity = fromEntity;
 }

 /**
  * @param customerDto
  *   DTO entity
  * @return The domain representation - the result of the converting function
  *   application on dto entity.
  */
 public final C convertFromDto(final T customerDto) {
  return fromDto.apply(customerDto);
 }

 /**
  * @param customer
  *   domain entity
  * @return The DTO representation - the result of the converting function
  *   application on domain entity.
  */
 public final T convertFromEntity(final C customer) {
  return fromEntity.apply(customer);
 }

 /**
  * @param dtoCustomers
  *   collection of DTO entities
  * @return List of domain representation of provided entities retrieved by
  *   mapping each of them with the conversion function
  */
 public final List < C > createFromDtos(final Collection < T > dtoCustomers) {
  return dtoCustomers.stream().map(this::convertFromDto).collect(Collectors.toList());
 }

 /**
  * @param customers
  *   collection of domain entities
  * @return List of domain representation of provided entities retrieved by
  *   mapping each of them with the conversion function
  */
 public final List < T > createFromEntities(final Collection < C > customers) {
  return customers.stream().map(this::convertFromEntity).collect(Collectors.toList());
 }
}

public class CustomerConverter extends Converter<CustomerDto, Customer> {

 public CustomerConverter() {
 super(customerDto -> new Customer(customerDto.getCustomerId(), customerDto.getCustomerName(),
 customerDto.getCustomerLastName(), customerDto.isStatus()),
 customer -> new CustomerDto(customer.getCustomerId(), customer.getCustomerName(),
  customer.getCustomerLastName(), customer.isStatus()));

 }

}

public class CustomerDto {
 private String customerId;
 private String customerName;
 private String customerLastName;
 private boolean status;
 public CustomerDto(String customerId, String customerName, String customerLastName, boolean status) {
  super();
  this.customerId = customerId;
  this.customerName = customerName;
  this.customerLastName = customerLastName;
  this.status = status;
 }
 public String getCustomerId() {
  return customerId;
 }
 public void setCustomerId(String customerId) {
  this.customerId = customerId;
 }
 public String getCustomerName() {
  return customerName;
 }
 public void setCustomerName(String customerName) {
  this.customerName = customerName;
 }
 public String getCustomerLastName() {
  return customerLastName;
 }
 public void setCustomerLastName(String customerLastName) {
  this.customerLastName = customerLastName;
 }
 public boolean isStatus() {
  return status;
 }
 public void setStatus(boolean status) {
  this.status = status;
 }

}

public class Customer {
 private String customerId;
 private String customerName;
 private String customerLastName;
 private boolean status;
 public Customer(String customerId, String customerName, String customerLastName, boolean status) {
  super();
  this.customerId = customerId;
  this.customerName = customerName;
  this.customerLastName = customerLastName;
  this.status = status;
 }
 public String getCustomerId() {
  return customerId;
 }
 public void setCustomerId(String customerId) {
  this.customerId = customerId;
 }
 public String getCustomerName() {
  return customerName;
 }
 public void setCustomerName(String customerName) {
  this.customerName = customerName;
 }
 public String getCustomerLastName() {
  return customerLastName;
 }
 public void setCustomerLastName(String customerLastName) {
  this.customerLastName = customerLastName;
 }
 public boolean isStatus() {
  return status;
 }
 public void setStatus(boolean status) {
  this.status = status;
 }
}

public class Client {
 /**
  * Program entry point
  *
  * @param args command line args
  */
 public static void main(String[] args) {
  Converter < CustomerDto, Customer > CustomerConverter = new CustomerConverter();

  CustomerDto dtoCustomer = new CustomerDto("100", "Ramesh", "Fadatare", true);
  Customer Customer = CustomerConverter.convertFromDto(dtoCustomer);
  System.out.println("Entity converted from DTO:" + Customer);

  List < Customer > customers = new ArrayList < > ();
  customers.add(new Customer("100", "Ramesh1", "Fadatare", true));
  customers.add(new Customer("200", "Ramesh2", "Fadatare", true));
  customers.add(new Customer("300", "Ramesh3", "Fadatare", true));

  customers.forEach(System.out::println);

  customers.forEach((customer) - > System.out.println(customer.getCustomerId()));

  System.out.println("DTO entities converted from domain:");
  List < CustomerDto > dtoEntities = CustomerConverter.createFromEntities(customers);
  dtoEntities.forEach(System.out::println);
  dtoEntities.forEach((customer) - > System.out.println(customer.getCustomerId()));

 }
}