Spring Extension (1)-BeanPostProcessor based Logger Inject

Scenario:
Log Wrapper: slf4j. Each class must pass

[Java]
Private static final Logger LOGGER = LoggerFactory. getLogger (ErrorHandler. class );

Private static final Logger LOGGER = LoggerFactory. getLogger (ErrorHandler. class); this non-intelligent hard coding method is used to generate a logger instance.

Optimization:

In the spring framework, each class is instantiated by spring ioc. The BeanPostProcessor interface can implement custom logic after the instance Initialization is complete.

Spring's Annotation-based initialization class implements the BeanPostProcessor interface. For example, @ Required & RequiredAnnotationBeanPostProcessor.

The following method is used to automate the initial Logger instance-Based on spring 2.5-3.x:

1. Define Annotation:
[Java]
/**
* Log Annotation for Logger Injection
**/
@ Retention (RetentionPolicy. RUNTIME)
@ Target (ElementType. FIELD)
@ Brief ented
Public @ interface Log {
String value () default "";
}

/**
* Log Annotation for Logger Injection
**/
@ Retention (RetentionPolicy. RUNTIME)
@ Target (ElementType. FIELD)
@ Brief ented
Public @ interface Log {
String value () default "";
}

2. Define the target class:

[Java]
@ Component
Public class LoggerDemo {
@ Log
Private Logger logger;
// Some methods
// Some properties
}

@ Component
Public class LoggerDemo {
@ Log
Private Logger logger;
// Some methods
// Some properties
}

 

3. Custom BeanPostProcessor

 

[Java]
/**
* Init the slf4j logger in each spring bean
*/
@ Component
Public class LoggerBeanPostProcessor implements BeanPostProcessor {
 
@ Override
Public Object postProcessBeforeInitialization (final Object bean, String beanName) throws BeansException {
ReflectionUtils. doWithFields (bean. getClass (), new FieldCallback () {// spring reflection utils
@ Override
Public void doWith (Field field) throws IllegalArgumentException, IllegalAccessException {
ReflectionUtils. makeAccessible (field );
 
If (field. getType (). equals (Logger. class) & field. isAnnotationPresent (Log. class) {// Log Annotation check
Log logAnnotation = field. getAnnotation (Log. class );
String loggerName = logAnnotation. value ();
Logger logger = null;
If (loggerName! = Null &&! LoggerName. equals ("")){
Logger = LoggerFactory. getLogger (loggerName );
} Else {
Logger = LoggerFactory. getLogger (bean. getClass ());
}
Field. set (bean, logger); // init value
}
}
});
Return bean;
}
 
@ Override
Public Object postProcessAfterInitialization (Object bean, String beanName) throws BeansException {
Return bean;
}
 
}
 
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