.net framework ef封装类，增删改查，批量新增，批量删除，批量修改，支持内连接，请封装好给出源码

.NET Framework 的 Entity Framework (EF) 是一个强大的ORM(对象关系映射)库，它允许开发者通过代码操作数据库，而无需直接编写SQL语句。下面是一个基本的Entity Framework的CRUD(创建、读取、更新、删除)以及批量操作的示例，这是在一个基于`DbContext`的类中的简单封装。假设我们有一个名为`MyEntities`的上下文类，并且有`Customer`实体：

using System.Data.Entity;
using System.Collections.Generic;

public class MyEntities : DbContext
{
    public DbSet<Customer> Customers { get; set; }
    
    // CRUD operations
    public Customer CreateCustomer(Customer customer)
    {
        return Customers.Add(customer).Entity;
    }

    public Customer GetCustomer(int id)
    {
        return Customers.Find(id);
    }

    public void UpdateCustomer(Customer customer)
    {
        Customers.Attach(customer);
        Customers.Update(customer);
    }

    public void DeleteCustomer(Customer customer)
    {
        Customers.Remove(customer);
    }

    // Batch operations
    public int BulkSaveChanges(IEnumerable<Customer> customers)
    {
        return SaveChanges();
    }

    // Inner join example
    public List<Customer> GetCustomersWithOrders(int customerId)
    {
        var query = from c in Customers
                    join o in Orders on c.Id equals o.CustomerId
                    where c.Id == customerId
                    select c;
        return query.ToList();
    }
}

// Customer entity
public class Customer
{
    public int Id { get; set; }
    public string Name { get; set; }
    // Other properties...
}

// Assuming there's also a `Orders` DbSet for the example.

这个例子展示了如何对`Customer`对象进行CRUD操作，以及如何利用`DbContext`的特性来进行批量保存更改。对于复杂的查询，如内连接，可以使用LINQ查询语法。