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设计模式11：抽象工厂模式
阅读材料：http://baike.xsoftlab.net/view/209.html#3_2
抽象工程模式解决的问题：
当前有一套产品，称为A；另一套产品称为B。客户端代码需要在两套产品中切换。
抽象工厂模式相当于在简单工厂模式之上又抽象了一层，使得客户端代码在两套产品切换中比较方便。
但是抽象工厂模式还是会引发大量的改动。如果要减少改动，可以使用反射+简单工厂解决这个问题。
UML:
User相关代码：
package abstractfactory;
public abstract class IUser {
public abstract void select();
public abstract void insert();
}
package abstractfactory;
public class MySQLUser extends IUser {
@Override
public void select() {
System.out.println("MySQL select User");
}
@Override
public void insert() {
System.out.println("MySQL insert User");
}
}
package abstractfactory;
public class OracleUser extends IUser {
@Override
public void select() {
System.out.println("Oracle select User");
}
@Override
public void insert() {
System.out.println("Oracle insert User");
}
}
Department相关代码：
package abstractfactory;
public abstract class IDepartment {
public abstract void select();
public abstract void insert();
}
package abstractfactory;
public class MySQLDepartment extends IDepartment {
@Override
public void select() {
System.out.println("MySQL select Department");
}
@Override
public void insert() {
System.out.println("MySQL insert Department");
}
}
package abstractfactory;
public class OracleDepartment extends IDepartment {
@Override
public void select() {
System.out.println("Oracle select Department");
}
@Override
public void insert() {
System.out.println("Oracle insert Department");
}
}
DataBase类：
使用反射确定要实例化哪个子类，数据库类型存储在xml中。
package abstractfactory;
import java.io.IOException;
import javax.xml.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.SAXException;
public class DataBase {
private static String databaseName = null;
static{
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = null;
try {
builder = factory.newDocumentBuilder();
} catch (ParserConfigurationException e) {
e.printStackTrace();
}
Document document = null;
try {
document = builder.parse("src\\abstractfactory\\Settings.xml");
} catch (SAXException | IOException e) {
e.printStackTrace();
}
Element database = (Element) document.getDocumentElement();
databaseName = database.getAttribute("Name");
}
public static IUser getUserHandler()
throws InstantiationException,
IllegalAccessException,
ClassNotFoundException {
String classname = "abstractfactory." + databaseName + "User";
return (IUser) Class.forName(classname).newInstance();
}
public static IDepartment getDepartmentHandler()
throws InstantiationException,
IllegalAccessException,
ClassNotFoundException {
String classname = "abstractfactory." + databaseName + "Department";
return (IDepartment) Class.forName(classname).newInstance();
}
}
settings.xml
<?xml version="1.0" encoding="UTF-8"?><DataBase Name="Oracle"/>
Demo:
package abstractfactory;
public class AbstractFactoryDemo {
public static void main(String[] args) {
IUser user;
IDepartment department;
try {
user = DataBase.getUserHandler();
user.select();
user.insert();
department = DataBase.getDepartmentHandler();
department.select();
department.insert();
} catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
e.printStackTrace();
}
}
}
设计模式11：抽象工厂模式
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