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抽象工厂模式：创建一些列相关或者互相依赖的对象的接口，而无需指定他们具体的类，
1、创建工厂Factory：
package patterns.design.factory;
import java.io.InputStream;
import java.util.Properties;
public class DaoFactory {
// 单例
private DaoFactory(){
try {
// 读配置文件获得实现类 类名
Properties props = new Properties();
InputStream in = DaoFactory.class.getClassLoader()
.getResourceAsStream("dao.properties");
props.load(in);
this.employeeDaoClassname = props.getProperty("employeeDaoClassname");
} catch (Exception e) {
throw new ExceptionInInitializerError(e);
}
}
private static DaoFactory instance = new DaoFactory();
public static DaoFactory newDaoFactory() {
return instance;
}
private String employeeDaoClassname;
// 提供方法返回实例对象dao
public EmployeeDao newEmplyeeDao() {
try {
// 反射创建对象
EmployeeDao employeeDao = (EmployeeDao) Class.forName(
this.employeeDaoClassname).newInstance();
return employeeDao;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
2.在service中调用工厂类创建对象
1 package patterns.design.factory; 2 3 import java.util.List; 4 5 6 public class BusinessService { 7 8 // service 的方法取决于功能 9 private EmployeeDao employeeDao; 10 11 public BusinessService() { 12 // 自己创建对象 13 // 调用 工厂类获得一个dao对象 14 this.employeeDao = DaoFactory.newDaoFactory().newEmplyeeDao(); 15 } 16 17 18 //查看所有员工 19 public List getAllEmployees() { 20 return employeeDao.getAll(); 21 } 22 23 24 }
3.dao.properties
employeeDaoClassname=patterns.design.factory.EmployeeDaoImpl
4.EmployeeDao.java
1 package patterns.design.factory; 2 import java.util.List; 3 public interface EmployeeDao { 4 public List getAll(); 5 }
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原文地址：http://www.cnblogs.com/zhangshiwen/p/4349232.html
