Briefly describe the default-lazy-init='true' configuration in java configuration

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There is a default-lazy-init="true" configuration on the root node in the spring configuration:

1, Spring's default-lazy-init parameter

This parameter indicates delayed loading, that is, the annotated bean will not be instantiated when the project is started unless starting the project Need to use, uninstantiated annotationObjectThe call is only injected when the program actually accesses the call

When spring starts, the default-lazy-init parameter defaults to false and will be loaded by default. The entire object instance graph, from initialization ACTION configuration, to service configuration, to dao configuration, to database connection, transactions, etc. This can reduce the load on the web server during runtime, but it is undoubtedly an extremely inefficient setting for developers.

spring provides the default-lazy-init attribute, its configuration form is as follows, in applicationContext.xml:

< beans default-lazy-init ="true" >
　　....... 
</beans>

In actual development, the default-lazy-init attribute can be set to true, which can greatly reduce the project startup time

2. The lazy-init and abstract attributes in Spring

1. lazy-init

<beans> 
   <bean id="service1" type="bean路径" lazy-init="true"/> 
   <bean id="service2" type="bean路径" lazy-init="false"> 
       <property name="service1" ref="service1"/> 
   </bean> 
</beans>

For the above two beans, one lazy-init attribute is true and the other is false. What is the difference?

When the IoC container starts, service2 will be instantiated, but service1 will not; but when the container instantiates service2, service1 is also instantiated. Why, because service2 needs it. In other words, for lazy-init="true" beans, the bean will not be instantiated when the IoC container starts. It will only be instantiated when the container needs to use it. Lazy-init is beneficial to container efficiency, and you can ignore unnecessary beans.

At the same time, we can use the lazy-init attribute in the corresponding bean for a specific module. lazy-init has a higher priority than default-lazy-init.

Spring annotations can be annotated on the class name using the @Lazy(false) annotation tag, which is equivalent to configuring the lazy-init attribute in the bean

2, abstract

<bean id="baseTxService" class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean" abstract="true"> 
</bean>

When bean abstract="true", the bean will not be instantiated

This is just to save startup time during the development process and deploy it to the actual environment , there is no need to set default-lazy-init to true. After all, it is not a common thing to deploy into the actual environment. Starting it for 1 minute each time is not a big problem, and it can improve server efficiency.

Of course, not all beans can set default-lazy-init to true. Lazy-init cannot be used for scheduler beans

[Related recommendations]

1 . Java Free Video Tutorial

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