Spring中有5种bean的范围： |
5 types of bean scopes supported :
- singleton – Return a single bean instance per Spring IoC container 这个范围也是默认的
- prototype – Return a new bean instance each time when requested
- request – Return a single bean instance per HTTP request. *
- session – Return a single bean instance per HTTP session. *
- globalSession – Return a single bean instance per global HTTP session. *
P.S * means only valid in the context of a web-aware Spring ApplicationContext
我们看个关于singleton and prototype.的例子：
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public class CustomerService
{ String message;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
} |
1. Singleton example
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<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-2.5.xsd">
<bean id="customerService"
class="com.mkyong.customer.services.CustomerService" />
</beans> |
运行：
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public class App
{ public static void main( String[] args )
{
ApplicationContext context =
new ClassPathXmlApplicationContext(new String[] {"Spring-Customer.xml"});
CustomerService custA = (CustomerService)context.getBean("customerService");
custA.setMessage("Message by custA");
System.out.println("Message : " + custA.getMessage());
//retrieve it again
CustomerService custB = (CustomerService)context.getBean("customerService");
System.out.println("Message : " + custB.getMessage());
}
} |
输出为：
Message : Message by custA Message : Message by custA
2. Prototype example
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<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-2.5.xsd">
<bean id="customerService" class="com.mkyong.customer.services.CustomerService"
scope="prototype"/>
</beans>
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运行输出为：
Message : Message by custA Message : null
也可以使用注解来做这些事情：
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package com.mkyong.customer.services;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Service;
@Service@Scope("prototype")
public class CustomerService
{ String message;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
} |
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<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-2.5.xsd">
<context:component-scan base-package="com.mkyong.customer" />
</beans> |
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本文转自被遗忘的博客园博客，原文链接：http://www.cnblogs.com/rollenholt/archive/2012/12/27/2835109.html，如需转载请自行联系原作者