03_Spring Bean 工厂方式实例化

待我称王封你为后i 2022-12-29 06:40 205阅读 0赞

# Spring 工厂方式实例化Bean #

## 静态工厂方式实例化 ##

UserFactory类

public class UserFactory { 
    	public static User newInstance(String name) { 
    		return new User(name);
    	}
    }

user类

public class User { 
    	private String name;
    	
    	public User(String name) { 
    		this.name = name;
    	}
    	public String getName() { 
    		return name;
    	}
    	public void setName(String name) { 
    		this.name = name;
    	}
    		
    }

xml

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
       <bean id="user" class="cn.lingyiwin.factory.UserFactory" factory-method="newInstance">
       		<constructor-arg index="0" value="静态工程创建bean"/>
       </bean>
    </beans>

执行结果：

public class TestUser { 
    	public static void main(String[] args) { 
    		ApplicationContext act =new ClassPathXmlApplicationContext("config/spring.xml");
    		User user = (User)act.getBean("user");
    		System.out.println(user);
    		System.out.println(user.getName());
    	}
    }
    cn.lingyiwin.bean.User@56ac3a89
    静态工程创建bean

## 实例工厂方式bean实例化 ##

UserDynamicFactory 类

public class UserDynamicFactory { 
    	public static User newInstance(String name) { 
    		return new User(name);
    	}
    }

xml

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
       <bean id ="userFactory" class="cn.lingyiwin.factory.UserDynamicFactory"/>
       <bean id="user" factory-bean="userFactory" factory-method="newInstance">
       		<constructor-arg index="0" value="动态工程创建bean"/>
       </bean>
    </beans>

执行结果报错了：

Error creating bean with name 'user' defined in class path resource [config/spring.xml]: 
    No matching factory method found: factory bean 'userFactory'; factory method 
    'newInstance(String)'. Check that a method with the specified name and 
    arguments exists and that it is non-static.
    工厂中方法newInstance 不能是静态的

。

修改UserDynamicFactory 类

public class UserDynamicFactory { 
    	public  User newInstance(String name) { 
    		return new User(name);
    	}
    }

执行结果：

cn.lingyiwin.bean.User@56ac3a89
    动态工程创建bean