JavaWeb网上图书商城完整项目--day02-27.查询所有分类功能之Servlet和Service层

我们在上面实现了数据库层的代码，现在我们来实现业务层和Servlet层的代码：
业务层的代码如下：

package com.weiyuan.goods.category.service;

import java.sql.SQLException;
import java.util.List;

import com.weiyuan.goods.category.dao.CategoryDao;
import com.weiyuan.goods.category.domain.Category;

public class CategoryService {

    private CategoryDao dao = new CategoryDao();
    
    public  List<Category> findAll(){
        try {
            return dao.findAll();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            throw new RuntimeException(e.getMessage());
        }
    }
}

我们来看看Servlet层的代码：

package com.weiyuan.goods.category.web.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.weiyuan.goods.category.domain.Category;
import com.weiyuan.goods.category.service.CategoryService;

import cn.itcast.servlet.BaseServlet;

/**
 * Servlet implementation class CategoryServlet
 */
@WebServlet("/CategoryServlet")
public class CategoryServlet extends BaseServlet {
    private static final long serialVersionUID = 1L;

    private CategoryService service = new CategoryService();
    
    public String findAll(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
         List<Category> parents = service.findAll();
         request.setAttribute("parents", parents);
         //重定向到left.jsp页面
        return"f:/jsps/left.jsp";
    }

}