JAVA抽象工厂设计模式：Abstract Factory

wangking717 写道

抽象工厂模式：
提供一个创建一系列相关活相互依赖对象的接口，而无需指定他们具体的类。

 

举2个例子：

1.BOSS要求提供JDBC，Hibernate，Ibatis等多套数据库操作解决方案，能够无成本地在这三个解决方案间切换。

2.系统的产品有多于一个的产品族，而系统只消费其中某一族的产品（Unix&Windows）

　　Button--->UnixButton/WinButton

　　Text----->UnixText/WinText

　　Unix产品族和Windows产品族，不会同时使用。

　　Factory--->UnixFactory/WinFactory

 

看类图吧：

BOOK产品：

 

public interface IBookDAO {

	public void drop();
	public void save();
	public void copy();
	
}


public class MySQLBookDAO implements IBookDAO {

	public void copy() {
		System.out.println("copy book using the MySQL...");
	}

	public void drop() {
		System.out.println("drop book using the MySQL...");
	}

	public void save() {
		System.out.println("save book using the MySQL...");
	}

}


public class SQLServerBookDAO implements IBookDAO {

	public void copy() {
		System.out.println("copy book using the sqlserver...");
	}

	public void drop() {
		System.out.println("drop book using the sqlserver...");
	}

	public void save() {
		System.out.println("save book using the sqlserver...");
	}

}

 

USER产品：

 

public interface IUserDAO {

	public void save();
	public void delete();
	public void get();
	
}

public class MySQLUserDAO implements IUserDAO {

	public void delete() {
		System.out.println("delete user using the MySQL...");
	}

	public void get() {
		System.out.println("get user using the MySQL...");
	}

	public void save() {
		System.out.println("save user using the MySQL...");
	}

}

public class SQLServerUserDAO implements IUserDAO {

	public void delete() {
		System.out.println("delete user using the sqlserver...");
	}

	public void get() {
		System.out.println("get user using the sqlserver...");
	}

	public void save() {
		System.out.println("save user using the sqlserver...");
	}

}

 

FACTORY:

 

public interface IFactory {

	public IUserDAO getUserDAO();
	public IBookDAO getBookDAO();
	
}

public class MySQLFactory implements IFactory {

	public IBookDAO getBookDAO() {
		return new MySQLBookDAO();
	}

	public IUserDAO getUserDAO() {
		return new MySQLUserDAO();
	}

}

public class SQLServerFactory implements IFactory {

	public IBookDAO getBookDAO() {
		return new SQLServerBookDAO();
	}

	public IUserDAO getUserDAO() {
		return new SQLServerUserDAO();
	}

}

 

TEST:

 

public class Test {

	public static void main(String[] args) {
		
		IFactory factory = new SQLServerFactory();
		factory.getUserDAO().delete();
		factory.getBookDAO().copy();
		
	}
	
}

 

但是这里也有一个不好的地方，如果我在系统的各个地方都IFactory factory = new ...的话，假设new了100处，以后要换为MYSQLFactory的话，就得改100处地方。。所以可以抽象工厂+简单工厂来解耦。

 

抽象工厂的简单工厂类：

 

public class AbstractFactory {
	
	private static final String DB = "mysql";
	
	public static IFactory getDataAcessFactory(){
		IFactory factory = null;
		if("mysql".equals(DB)){
			factory = new MySQLFactory();
		}else if("sqlserver".equals(DB)){
			factory = new SQLServerFactory();
		}else{
			throw new RuntimeException("No DB logic matched in the abstract factory.");
		}
		return factory;
	}
	
}

 

客户端测试：

 

public class Test2 {

	public static void main(String[] args) {
		
		IFactory factory = AbstractFactory.getDataAcessFactory();
		factory.getUserDAO().delete();
		factory.getBookDAO().copy();
		
	}
	
}