BeanPostProcessor Bean实例的初始化前后的自定义修改

BeanPostProcessor接口的行为方法

public interface BeanPostProcessor {

    /**
     * Apply this BeanPostProcessor to the given new bean instance <i>before</i> any bean
     * initialization callbacks (like InitializingBean's {@code afterPropertiesSet}
     * or a custom init-method). The bean will already be populated with property values.
     * The returned bean instance may be a wrapper around the original.
     * @param bean the new bean instance
     * @param beanName the name of the bean
     * @return the bean instance to use, either the original or a wrapped one; if
     * {@code null}, no subsequent BeanPostProcessors will be invoked
     * @throws org.springframework.beans.BeansException in case of errors
     * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet
     */
    Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException;

    /**
     * Apply this BeanPostProcessor to the given new bean instance <i>after</i> any bean
     * initialization callbacks (like InitializingBean's {@code afterPropertiesSet}
     * or a custom init-method). The bean will already be populated with property values.
     * The returned bean instance may be a wrapper around the original.
     * <p>In case of a FactoryBean, this callback will be invoked for both the FactoryBean
     * instance and the objects created by the FactoryBean (as of Spring 2.0). The
     * post-processor can decide whether to apply to either the FactoryBean or created
     * objects or both through corresponding {@code bean instanceof FactoryBean} checks.
     * <p>This callback will also be invoked after a short-circuiting triggered by a
     * {@link InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation} method,
     * in contrast to all other BeanPostProcessor callbacks.
     * @param bean the new bean instance
     * @param beanName the name of the bean
     * @return the bean instance to use, either the original or a wrapped one; if
     * {@code null}, no subsequent BeanPostProcessors will be invoked
     * @throws org.springframework.beans.BeansException in case of errors
     * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet
     * @see org.springframework.beans.factory.FactoryBean
     */
    Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException;

}

自定义的BeanPostProcessor

package com.wjz.spring;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;

import com.wjz.core.CustomInitializable;

public class CustomBeanPostProcessor implements BeanPostProcessor {

    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof CustomInitializable) {
            System.out.println("before init......");
            ((CustomInitializable) bean).init();
        }
        return bean;
    }

    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("after init......");
        return bean;
    }

}

自定义的修改

package com.wjz.core;

public abstract interface CustomInitializable {

    abstract void init();
}

package com.wjz.core;

public class Realm implements CustomInitializable {

    public void init() {
        System.out.println("init......");
    }

}

关于Shiro框架对于BeanPostProcessor的使用

LifecycleBeanPostProcessor

 

public Object postProcessBeforeInitialization(Object object, String name) throws BeansException {
        if (object instanceof Initializable) {
            try {
                if (log.isDebugEnabled()) {
                    log.debug("Initializing bean [" + name + "]...");
                }

                ((Initializable) object).init();
            } catch (Exception e) {
                throw new FatalBeanException("Error initializing bean [" + name + "]", e);
            }
        }
        return object;
    }


    /**
     * Does nothing - merely returns the object argument immediately.
     */
    public Object postProcessAfterInitialization(Object object, String name) throws BeansException {
        // Does nothing after initialization
        return object;
    }

public abstract interface org.apache.shiro.util.Initializable {
  
    public abstract void init() throws org.apache.shiro.ShiroException;

}

AuthenticatingRealm

public final void init() {
        //trigger obtaining the authorization cache if possible 如果可能，触发获得授权缓存
        getAvailableAuthenticationCache();
        onInit();
    }