设计模式读书笔记之工厂方法模式(Factory method)

拿前面的简单工厂的例子作案例.把简单工厂改造成工厂方法.

//工厂接口package designpattern.factory.factorymethod;import designpattern.factory.*;public interface IFactory {public UserDao createUserDao();}//DB2Dao工厂 package designpattern.factory.factorymethod;import designpattern.factory.*;public class DB2DaoFactory implements IFactory{public UserDao createUserDao() {return new UserDB2Dao();}}//OracleDao工厂package designpattern.factory.factorymethod;import designpattern.factory.*;public class OracleDaoFactory implements IFactory{public UserDao createUserDao() {return new UserOracleDao();}}//test casepackage designpattern.factory.factorymethod;import designpattern.factory.*;public class Test {public static void main(String[] args) {IFactory f = new DB2DaoFactory();UserDao userDao = f.createUserDao();userDao.insert(new User());userDao.DeleteById("123456");}}

 

特点: 有一个工厂序列, 工厂序列中各个工厂负责创建具体的对象.

与简单工厂的区别: 工厂方法把对象的实例化推迟到子类中. 把选择权交给客户代码来做.