Spring中bean的范围

5 types of bean scopes supported :

1. singleton – Return a single bean instance per Spring IoC container 这个范围也是默认的
2. prototype – Return a new bean instance each time when requested
3. request – Return a single bean instance per HTTP request. *
4. session – Return a single bean instance per HTTP session. *
5. 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 >

　　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>

转载于:https://www.cnblogs.com/youngdream-ppj/archive/2013/04/02/2996708.html