package com.how2java.tmall.pojo;
import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Transient;
 
@Entity
@Table(name = "category")
public class Category {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    @Column(name = "id")	
    int id;
    
    String name;
    
    @Transient
	List<Product> products;
    @Transient
	List<List<Product>> productsByRow;    
    
	public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
	@Override
	public String toString() {
		return "Category [id=" + id + ", name=" + name + "]";
	}
	public List<Product> getProducts() {
		return products;
	}
	public void setProducts(List<Product> products) {
		this.products = products;
	}
	public List<List<Product>> getProductsByRow() {
		return productsByRow;
	}
	public void setProductsByRow(List<List<Product>> productsByRow) {
		this.productsByRow = productsByRow;
	}

}

package com.how2java.tmall.service;

import java.util.List;

import com.how2java.tmall.pojo.Category;

public interface ProductService extends BaseService {
	public void fill(List<Category> categorys);
	public void fill(Category category);
	public void fillByRow(List<Category> categorys);
}

package com.how2java.tmall.service.impl;

import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.how2java.tmall.pojo.Category;
import com.how2java.tmall.pojo.Product;
import com.how2java.tmall.service.ProductImageService;
import com.how2java.tmall.service.ProductService;

@Service
public class ProductServiceImpl  extends BaseServiceImpl implements ProductService {

	@Autowired
	ProductImageService productImageService;
	
	public void fill(List<Category> categorys) {
		for (Category category : categorys) {
			fill(category);
		}
	}

	@Override
	public void fillByRow(List<Category> categorys) {
		int productNumberEachRow = 8;
		for (Category category : categorys) {
			List<Product> products =  category.getProducts();
			List<List<Product>> productsByRow =  new ArrayList<>();
			for (int i = 0; i < products.size(); i+=productNumberEachRow) {
				int size = i+productNumberEachRow;
				size= size>products.size()?products.size():size;
				List<Product> productsOfEachRow =products.subList(i, size);
				productsByRow.add(productsOfEachRow);
			}
			
			category.setProductsByRow(productsByRow);
		}
	}
	
	@Override
	public void fill(Category category) {
		List<Product> products= listByParent(category);
		
		for (Product product : products) 
			productImageService.setFirstProdutImage(product);
		
		category.setProducts(products);
		
	}	
}

package com.how2java.tmall.action;

import org.apache.struts2.convention.annotation.Action;

public class ForeAction extends Action4Result {
	
	@Action("forehome")
	public String home() {
		categorys = categoryService.list();
		productService.fill(categorys);
		productService.fillByRow(categorys);
		return "home.jsp";
	}
}