spring BeanFactoryPostProcessor分析，带实例

女爷i 2022-10-22 07:43 182阅读 0赞

## 1：分析 ##

该接口是spring提供给我们的另一个扩展点，用于在解析配置信息为BeanDefinition之后在生成bean之前，加入一个允许我们修改BeanDefinition的点，接口定义如下：

// 是只有一个方法的函数接口
    @FunctionalInterface
    public interface BeanFactoryPostProcessor { 
    	// 我们可以通过该方法来修改beandefinition，从而达到修改最终bean的效果
    	void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException;
    
    }

另外关于beandefinition可以参考[这里][Link 1]。

## 2：实例 ##

### 2.1：说明 ###

实现修改属性的自定义占位符，从而设置属性值为最终值。

### 2.2：测试的bean ###

public class MyBeanFactoryProcessorTestBean { 
        private String name;
    
        public String getName() { 
            return name;
        }
    
        public void setName(String name) { 
            this.name = name;
        }
    
        @Override
        public String toString() { 
            return JSON.toJSONString(this);
        }
    }

### 2.3：自定义BeanFactoryPostProcessor ###

public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor { 
    
        @Override
        public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { 
            // 如果beanName是myBeanFactoryProcessorTestBean，则替换
            // name属性的{nameToBeReplaced}占位符为张三的歌
            String[] beanNames = beanFactory.getBeanDefinitionNames();
            for (String beanName : beanNames) { 
                BeanDefinition beanDefinition
                        = beanFactory.getBeanDefinition(beanName);
                //this.printBeanDef(beanName, beanDefinition);
                if ("myBeanFactoryProcessorTestBean".equalsIgnoreCase(beanName)) { 
                    MutablePropertyValues propertyValues = beanDefinition.getPropertyValues();
                    String propertyName = "name";
                    PropertyValue namePv = propertyValues.getPropertyValue(propertyName);
                    String nameValAfterReplace
                            = ((TypedStringValue)namePv.getValue()).getValue().replace("{nameToBeReplaced}", "张三的歌");
                    propertyValues.addPropertyValue(propertyName, nameValAfterReplace);
                }
            }
        }
    }

### 2.4：xml ###

<?xml version="1.0" encoding="UTF-8"?>
    <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.xsd">
        <bean id="beanFactoryPostProcessor" class="yudaosourcecode.studyhelp.MyBeanFactoryPostProcessor"/>
    
        <bean id="myBeanFactoryProcessorTestBean" class="yudaosourcecode.studyhelp.MyBeanFactoryProcessorTestBean">
            <property name="name" value="姓名是{nameToBeReplaced}"/>
        </bean>
    </beans>

注意配置的name的值为`姓名是{nameToBeReplaced}`，我们会替换`{nameToBeReplaced}`为真实的值。

### 2.5：测试 ###

@Test
    publicvoid testmybeanfactorypostprocessor() { 
        ClassPathXmlApplicationContext ac
                = new ClassPathXmlApplicationContext("testmybeanfactorypostprocessor.xml");
        MyBeanFactoryProcessorTestBean myBeanFactoryProcessorTestBean = ac.getBean("myBeanFactoryProcessorTestBean",
                MyBeanFactoryProcessorTestBean.class);
        System.out.println("myBeanFactoryProcessorTestBean is: " +
                myBeanFactoryProcessorTestBean);
    }

运行：

myBeanFactoryProcessorTestBean is: {"name":"姓名是张三的歌"}
    
    Process finished with exit code 0

[Link 1]: https://blog.csdn.net/wang0907/article/details/114495131