40-综合实战：多对多映射

    将以上的结构转换为类结构，并且可以获取如下的信息：

• 获取一个用户访问的所有商品的详细信息；

• 获取一个商品被浏览过的全部的用户信息；

    对于此时的程序只需要去考虑实体表的设计即可，也就是说对于中间的访问记录信息表不要求你进行转换处理，之定义两个类即可。

范例：

class Member{
    private String mid;
    private String name;
    private Product products []; //多个商品
    public Member(String mid,String name){
        this.mid = mid;
        this.name = name;
    }
    public void setProducts(Product products[]){
        this.products = products;
    }
    public Product[] getProducts(){
        return this.products; 
    }
    // setter、getter、无参构造略
    public String getInfo(){
        return "【用户信息】mid = " + this.mid + "、name = " + this.name;
    }
}
class Product{
    private long pid;
    private String name;
    private double price;
    private Member members[];
    public Product(long pid,String name,double price){
        this.pid = pid;
        this.name = name;
        this.price = price;
    }
    //  setter、getter、无参构造略
    public void setMembers(Member members[]){
        this.members = members;
    }
    public Member[] getMembers(){
        return this.members;
    }
    public String getInfo(){
        return "【商品信息】pid =" + this.pid + "、name = " + this.name + "、price = " + this.price;
    }
}
public class JavaDemo{
    public static void main(String args[]){
        //第一步：根据结构设置对象数据
        Member memA = new Member("mldn","李四");
        Member memB = new Member("mldn","张三");
        Product proA = new Product(1L,"Java开发图书",79.8);
        Product proB = new Product(2L,"很高端大气的耳机",2399.0);
        Product proC = new Product(3L,"小米手机10",3999.0);
        memA.setProducts(new Product[]{proA,proB,proC});
        memB.setProducts(new Product[]{proA});
        proA.setMembers(new Member[]{memA,memB});
        proB.setMembers(new Member[]{memA});
        proC.setMembers(new Member[]{memA});
        //第二步：根据要求获取数据
        System.out.println("--------------根据用户查看浏览商品信息---------------");
        System.out.println(memA.getInfo());
        for(int x = 0;x<memA.getProducts().length; x++){
            System.out.println("\t|- " + memA.getProducts()[x].getInfo());
        }
        System.out.println("--------------查看商品被浏览的记录---------------");
        System.out.println(proA.getInfo());
        for(int x = 0; x < proA.getMembers().length; x++){
            System.out.println("\t|- " + proA.getMembers()[x].getInfo());
        }
    }   
}