我们应该怎样看待框架

      翻了翻老帖子，看到Robbin当年下站贴说实现同样需求对比Java代码和RoR代码（http://www.iteye.com/topic/57075?page=1），我始终搞不明白为什么说ActiveRecord是充血模型，而将DAO和Domain分开就不是了，对于我的那个封装JDBC（见原帖），我又把Hibernate和Spring加进来，进一步模仿了一下RoR，先看测试：

     public void testEmployeeExtendsBase(){

              //按ID查询
		Employee e=new Employee();
		e=(Employee) e.findById(43442l);
		System.out.println(e.getFullName());

              //查询
		Employee e2=new Employee();
		e2.setFullName("张三");
		String effectiveDateProperty = "effectiveDate";
		Date lo = getSwitchDate("2005-01-03");
		Date hi = getSwitchDate("2010-09-02");
		Criterion effectiveDateRange = Restrictions.between(
				effectiveDateProperty, lo, hi);
		/* 仿效RoR代码：
	    def processing_tasks  
	      find :all, :conditions => ["start_time <= ? AND end_time is null", Time.now]  
	    end  */
		List<Employee> employees=(List<Employee>)e2.find_All(effectiveDateRange);
		for(Employee emp:employees){
			System.out.println("员工编号："+emp.getId()+"|| 员工姓名："+emp.getFullName());
		}
	}

   再看Employee代码

@Entity
@Table(name = "Employee")
public class Employee extends Base{
	@Id
	 
	private Long id;
 
	private String fullName;
 
	private Date effectiveDate;

	private Department department;

	public Long getId() {
		return id;
	}

	public void setId(Long id) {
		this.id = id;
	}

	public String getFullName() {
		return fullName;
	}

	public void setFullName(String fullName) {
		this.fullName = fullName;
	}

	public Date getEffectiveDate() {
		return effectiveDate;
	}

	public void setEffectiveDate(Date effectiveDate) {
		this.effectiveDate = effectiveDate;
	}

	public Department getDepartment() {
		return department;
	}

	public void setDepartment(Department department) {
		this.department = department;
	}
}

   我和firebody的实现不太一样（http://www.iteye.com/topic/65406），Base继承了泛型DAO，并且动态注入子类，和SessionFactory，而SessionFactory由Spring初始化。

   我的find_all是个多态方法，可以放入Criterion... criterion，HQL，并且内部基于一个QBE+QBC的查询，并且这个QBE是经过扩展的，它支持关联关系。

   如果POJO或者实体类可以强制继承某个基类了，如本文的Base，我们又回到了EJB时代，独立测试的领域模型不见了。

   从来都没有人说过一定要一个Service配一个DAO，一个DAO配一个Entity，这完全取决于你的需要，然后采取的不同模式！

              //按ID查询
		Employee e=new Employee();
		e=(Employee) e.findById(43442l);
		System.out.println(e.getFullName());

              //查询
		Employee e2=new Employee();
		e2.setFullName("张三");
		String effectiveDateProperty = "effectiveDate";
		Date lo = getSwitchDate("2005-01-03");
		Date hi = getSwitchDate("2010-09-02");
		Criterion effectiveDateRange = Restrictions.between(
				effectiveDateProperty, lo, hi);
		/* 仿效RoR代码：
	    def processing_tasks  
	      find :all, :conditions => ["start_time <= ? AND end_time is null", Time.now]  
	    end  */
		List<Employee> employees=(List<Employee>)e2.find_All(effectiveDateRange);
		for(Employee emp:employees){
			System.out.println("员工编号："+emp.getId()+"|| 员工姓名："+emp.getFullName());
		}
	}

@Entity
@Table(name = "Employee")
public class Employee extends Base{
	@Id
	 
	private Long id;
 
	private String fullName;
 
	private Date effectiveDate;

	private Department department;

	public Long getId() {
		return id;
	}

	public void setId(Long id) {
		this.id = id;
	}

	public String getFullName() {
		return fullName;
	}

	public void setFullName(String fullName) {
		this.fullName = fullName;
	}

	public Date getEffectiveDate() {
		return effectiveDate;
	}

	public void setEffectiveDate(Date effectiveDate) {
		this.effectiveDate = effectiveDate;
	}

	public Department getDepartment() {
		return department;
	}

	public void setDepartment(Department department) {
		this.department = department;
	}
}

其实之前pojos in action一直标榜spring框架的"非侵入性",即框架之上开发的业务对象与框架本身松耦合,可跑在本地自动化测试环境里,但是这样的"非侵入性并不好实现,因为pojo本身除了属性还有方法,有些方法比如find,涉及到系统中最小化的业务单元,以及通过仓库访问数据库的操作,在这些具有简单业务性的操作上难免会有框架级别支撑的服务类或者工具,比如

public Emplyee { // 没继承base

    // 属性

   ...

   public find(){

       // 框架提供的静态工具

       StringUtil.....

   }

}

除非所有这些工具都是由构造子注入注入进来,否则也无法跑在脱离框架环境的自动化测试机中,保持pojo不继承基础类只是实现pojo独立的第一步

              //按ID查询
		Employee e=new Employee();
		e=(Employee) e.findById(43442l);
		System.out.println(e.getFullName());

              //查询
		Employee e2=new Employee();
		e2.setFullName("张三");
		String effectiveDateProperty = "effectiveDate";
		Date lo = getSwitchDate("2005-01-03");
		Date hi = getSwitchDate("2010-09-02");
		Criterion effectiveDateRange = Restrictions.between(
				effectiveDateProperty, lo, hi);
		/* 仿效RoR代码：
	    def processing_tasks  
	      find :all, :conditions => ["start_time <= ? AND end_time is null", Time.now]  
	    end  */
		List<Employee> employees=(List<Employee>)e2.find_All(effectiveDateRange);
		for(Employee emp:employees){
			System.out.println("员工编号："+emp.getId()+"|| 员工姓名："+emp.getFullName());
		}
	}

@Entity
@Table(name = "Employee")
public class Employee extends Base{
	@Id
	 
	private Long id;
 
	private String fullName;
 
	private Date effectiveDate;

	private Department department;

	public Long getId() {
		return id;
	}

	public void setId(Long id) {
		this.id = id;
	}

	public String getFullName() {
		return fullName;
	}

	public void setFullName(String fullName) {
		this.fullName = fullName;
	}

	public Date getEffectiveDate() {
		return effectiveDate;
	}

	public void setEffectiveDate(Date effectiveDate) {
		this.effectiveDate = effectiveDate;
	}

	public Department getDepartment() {
		return department;
	}

	public void setDepartment(Department department) {
		this.department = department;
	}
}

所有的对于其他服务的调用都依赖于接口而非类，然后做Mock。

并且我认为，你的事务范围是很重要的，然后做好关联，如果你的对象和另一个对象是关联关系，那用get方法拿过来，就不要在方法里面再调用dao查找了，除非另外那个是一个服务。