学步园

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

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.