spring - 如何使用注释覆盖 xml 中定义的 spring bean？

Question

我有一个现有的 bean overrideBean定义于 spring.xml我想使用注释覆盖它。我尝试了以下方法来覆盖 bean:

@Configuration
@ImportResource({"/spring.xml"})
public class Main {

    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(DdwMain.class);

        Object o = context.getBean("overrideBean");
        // o should be null but it is not
    }

    @Bean(name="overrideBean")
    public OverrideBean overrideBean() {
        return null;
    }

}

使用上面的代码，来自 spring.xml 的 bean config 总是由 context.getBean 实例化和返回称呼。

bean 可以通过在 @ImportResource 中包含另一个 XML 配置文件来覆盖。但是我更愿意找到使用注释的解决方案会更干净。

Answer 1

我正在使用通过 xml 配置的旧应用程序(spring 3.1.1)，但我需要调整一些配置以进行测试，而不会偏离生产配置太远。我的方法是使用 BeanPostProcessor。

package myapp.test;

import javax.servlet.ServletContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.ImportResource;
import org.springframework.mock.web.MockServletContext;
import org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer;

import myapp.spring.config.ComplexSpringConfiguration;

/**
 * Closely resembles production configuration for testing
 * @author jim
 */
@Configuration
@ImportResource("file:src/main/webapp/WEB-INF/spring-servlet.xml")
@Import(ComplexSpringConfiguration.class)
public class TestConfig {
    final Logger logger = LoggerFactory.getLogger(getClass());

    static {
        System.setProperty("env.test", "system");
    }

    //Override templateLoaderPath with something amenable to testing
    @Bean
    public BeanPostProcessor beanPostProcessor(){
        return new BeanPostProcessor(){
            @Override
            public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException  {
                //Override templateLoaderPath with something amenable to testing
                if(beanName.equals("freemarkerConfig")) {
                    logger.debug("overriding bean with name:" + beanName);
                    FreeMarkerConfigurer fc = new FreeMarkerConfigurer();
                    fc.setTemplateLoaderPath("file:src/main/webapp/WEB-INF/freemarker");
                    bean = fc;
                }
                return bean;
            }

            @Override
            public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
                return bean;
           }  
       };
    }

    @Bean
    public ServletContext servletContext(){
        MockServletContext mockContext = new MockServletContext();
        mockContext.setContextPath("/myapp");
        return mockContext;
    }
}