Spring Framework - ConverterFactory Examples

package com.logicbig.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.converter.Converter;
import org.springframework.core.convert.converter.ConverterFactory;
import org.springframework.core.convert.support.DefaultConversionService;

import java.math.BigDecimal;
import java.util.Date;


public class CustomConverterFactoryExample {

    public static void main (String[] args) {

        AnnotationConfigApplicationContext context = new
                            AnnotationConfigApplicationContext(Config.class);

        MyBean myBean = context.getBean(MyBean.class);
        Entity entity = myBean.getEntity("1000", Order.class);
        System.out.println(entity);

        entity = myBean.getEntity("431", Customer.class);
        System.out.println(entity);
    }

    @Configuration
    public static class Config {

        @Bean
        public ConversionService conversionService () {
            DefaultConversionService service = new DefaultConversionService();
            service.addConverterFactory(new IdToEntityConverterFactory());
            return service;
        }

        @Bean
        public MyBean myBean () {
            return new MyBean();
        }
    }

    public static class MyBean {
        @Autowired
        private ConversionService service;

        public Entity getEntity (String entityId, Class<? extends Entity> type) {
            return service.convert(entityId, type);

        }
    }

    private static class IdToEntityConverterFactory implements
                        ConverterFactory<String, Entity> {

        @Override
        public <T extends Entity> Converter<String, T> getConverter (Class<T> targetType) {
            return new IdToEntityConverter<>(targetType);
        }
    }

    private static class IdToEntityConverter<T extends Entity> implements Converter<String, T> {

        private Class<T> targetType;

        public IdToEntityConverter (Class<T> targetType) {
            this.targetType = targetType;
        }

        @Override
        public T convert (String id) {
            return EntityService.getEntity(id, targetType);
        }
    }

    //just a test service
    private static class EntityService {

        public static <T extends Entity> T getEntity (String id,
                            Class<T> targetType) {
            if (targetType == Item.class) {
                return (T) findItemById(id);
            } else if (targetType == Order.class) {
                return (T) findOrderById(id);
            } else if (targetType == Customer.class) {
                return (T) findCustomerById(id);
            }
            return null;
        }

        private static Customer findCustomerById (String id) {
            return new Customer(id, "Mike");
        }

        private static Order findOrderById (String id) {
            return new Order(id, 400, new Date());

        }

        private static Item findItemById (String id) {
            return new Item(id, "some tiem", new BigDecimal(100));
        }
    }

    private abstract static class Entity {
        private final String id;

        public Entity (String id) {
            this.id = id;
        }

        public String getId () {
            return id;
        }
    }

    private static class Order extends Entity {
        private final int quantity;
        private final Date date;

        private Order (String id, int quantity, Date date) {
            super(id);
            this.quantity = quantity;
            this.date = date;
        }

        public int getQuantity () {
            return quantity;
        }

        public Date getDate () {
            return date;
        }

        @Override
        public String toString () {
            return "Order{" +
                                "quantity=" + quantity +
                                ", date=" + date +
                                '}';
        }
    }

    private static class Item extends Entity {
        private final String itemName;
        private final BigDecimal cost;

        public Item (String id, String itemName, BigDecimal cost) {
            super(id);
            this.itemName = itemName;
            this.cost = cost;
        }

        public String getItemName () {
            return itemName;
        }

        public BigDecimal getCost () {
            return cost;
        }

        @Override
        public String toString () {
            return "Item{" +
                                "itemName='" + itemName + '\'' +
                                ", cost=" + cost +
                                '}';
        }
    }

    private static class Customer extends Entity {
        private final String name;

        private Customer (String id, String name) {
            super(id);
            this.name = name;
        }

        public String getName () {
            return name;
        }

        @Override
        public String toString () {
            return "Customer{" +
                                "name='" + name + '\'' +
                                '}';
        }
    }
}

package com.logicbig.example;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class CustomConverterFactoryExample {

    public static void main(String[] args) {

        AnnotationConfigApplicationContext context = new
                AnnotationConfigApplicationContext(Config.class);

        ClientBean clientBean = context.getBean(ClientBean.class);
        Shape shape = clientBean.getShape("10", Circle.class);
        System.out.println(shape);

        shape = clientBean.getShape("4", Square.class);
        System.out.println(shape);
    }
}

package com.logicbig.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.convert.ConversionService;

public class ClientBean {
    @Autowired
    private ConversionService service;

    public Shape getShape(String shapeString, Class<? extends Shape> type) {
        return service.convert(shapeString, type);
    }
}

package com.logicbig.example;

public interface Shape {
}

package com.logicbig.example;

public class Circle implements Shape {
    private int radius;

    public Circle(int radius) {
        this.radius = radius;
    }

    public int getRadius() {
        return radius;
    }

    @Override
    public String toString() {
        return "Circle{" +
                "radius=" + radius +
                '}';
    }
}

package com.logicbig.example;

public class Square implements Shape{
  private int side;

    public Square(int side) {
        this.side = side;
    }

    public int getSide() {
        return side;
    }

    @Override
    public String toString() {
        return "Square{" +
                "side=" + side +
                '}';
    }
}

package com.logicbig.example;

import org.springframework.core.convert.converter.Converter;

public class ShapeConverter<T extends Shape> implements Converter<String, T> {

    private Class<T> targetType;

    public ShapeConverter(Class<T> targetType) {
        this.targetType = targetType;
    }

    @Override
    public T convert(String source) {
       if(targetType==Square.class){
           int side = Integer.parseInt(source);
           return (T) new Square(side);
       }else if(targetType==Circle.class){
           int radius = Integer.parseInt(source);
           return (T) new Circle(radius);
       }
        return null;
    }
}

package com.logicbig.example;

import org.springframework.core.convert.converter.Converter;
import org.springframework.core.convert.converter.ConverterFactory;

public class StringToShapeConverterFactory implements ConverterFactory<String, Shape> {

    @Override
    public <T extends Shape> Converter<String, T> getConverter(Class<T> targetType) {
        return new ShapeConverter<>(targetType);
    }
}

package com.logicbig.example;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.support.DefaultConversionService;

@Configuration
public class Config {

    @Bean
    public ConversionService conversionService() {
        DefaultConversionService service = new DefaultConversionService();
        //registering our custom ConverterFactory
        service.addConverterFactory(new StringToShapeConverterFactory());
        return service;
    }

    @Bean
    public ClientBean clientBean() {
        return new ClientBean();
    }
}