Java interview questions summarized from many years of development experience - (8)

1. Several injection methods of Spring

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Annotation injection, setter injection, constructor injection

2. How Spring implements transaction management

Programmatic transaction management: embed transaction management code into business methods to control transaction submission and Rollback, in programmatic transactions, requires additional transaction management code included in each business operation.

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Declarative transaction management: implemented using spring aop interceptor.

3. The principles of Spring IOC and AOP

IOC is mainly a container that helps us create objects and manage beans. Its inversion of control means giving the power to create objects to the ioc container (spring container) ), when starting spring, load the xml and other configuration files into the ioc container. The ioc then creates a registration information table for management, and then turns it into a bean through the registry, and puts the bean into the spring container bean buffer pool (hashMap implementation), and then Use beans to fetch directly from the cache pool.

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Remember: spring's configuration file is used to describe bean relationships, and uses the reflection function to establish bean dependencies.

The bottom layer of Spring AOP is a dynamic proxy. The dynamic proxy is divided into jdk proxy and cglib proxy. The jdk proxy requires that the proxy class must have a parent class interface. It mainly implements the InvocationHandler interface and implements it through the Proxy and InvocationHandler interfaces. The invoke method passes in parameters including interface objects and interface methods, and then creates a proxy object through reflection (two parameters need to be passed in, one is an instance of the current calling class, and the other is an instance that implements InvocationHandler and passes in the interface).

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