spring笔记-BeanDefinitionVisitor

BeanDefinitionVisitor, 遍历bean的各个属性用properties填充, BeanDefinitionVisitor会将替换的操作委托给内部的一个StringValueResolver来执行(PlaceholderResolvingStringValueResolver), 而这个StringValueResolver又会将操作委托给PropertyPlaceholderHelper, 这个helper(PropertyPlaceholderHelper)在实际执行的时候会执行内部的parseStringValue函数

使用BeanDefinitionVisitor的visitBeanDefinition方法来解析

···
protected void doProcessProperties(ConfigurableListableBeanFactory beanFactoryToProcess,
StringValueResolver valueResolver) {

    BeanDefinitionVisitor visitor = new BeanDefinitionVisitor(valueResolver);

    String[] beanNames = beanFactoryToProcess.getBeanDefinitionNames();
    for (String curName : beanNames) {
        // Check that we're not parsing our own bean definition,
        // to avoid failing on unresolvable placeholders in properties file locations.
        if (!(curName.equals(this.beanName) && beanFactoryToProcess.equals(this.beanFactory))) {
            BeanDefinition bd = beanFactoryToProcess.getBeanDefinition(curName);
            try {
                visitor.visitBeanDefinition(bd);
            }
            catch (Exception ex) {
                throw new BeanDefinitionStoreException(bd.getResourceDescription(), curName, ex.getMessage(), ex);
            }
        }
    }

    // New in Spring 2.5: resolve placeholders in alias target names and aliases as well.
    beanFactoryToProcess.resolveAliases(valueResolver);

    // New in Spring 3.0: resolve placeholders in embedded values such as annotation attributes.
    beanFactoryToProcess.addEmbeddedValueResolver(valueResolver);
}

···

解析之后BeanDefinition的占位符将会被替换掉