在应用中,当我们进行集成测试或者单元测试的时候,有些中间件因为涉及到了外部请求,所以想把测试拉起来,显得比较困难,但是由于spring中,我们可以对bean进行替换,所以这个事儿变得简单了。

我们需要基于BeanDefinitionRegistryPostProcessor 和 PriorityOrdered两个类,来对bean进行处理:

package org.tiny.upgrade.plugin.mock.mockbiz.mockbiz;//package com.jd.migration.service.replace;

import com.alibaba.fastjson.JSON;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.core.Ordered;
import org.springframework.core.PriorityOrdered;
import org.springframework.stereotype.Component;

//@Component
public class BeanReplace implements BeanDefinitionRegistryPostProcessor, PriorityOrdered {

    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) throws BeansException {
       System.out.println(JSON.toJSONString("xxxx"+beanDefinitionRegistry));
        for (String beanDefinitionName : beanDefinitionRegistry.getBeanDefinitionNames()) {
            String beanName = "redisClient";
            if(beanDefinitionName.equals(beanName)){
                //移除原有bean
                beanDefinitionRegistry.removeBeanDefinition(beanName);
                System.out.println("注册新的mock beanName:"+beanName);
                RootBeanDefinition beanDefinition = (RootBeanDefinition) BeanDefinitionBuilder.rootBeanDefinition(BeanFactory.class)
                        .setFactoryMethod("mock")
                        .addConstructorArgValue(loadClass("org.tiny.cli.Cluster", beanDefinitionRegistry))
                        .setLazyInit(false)
                        .setScope(BeanDefinition.SCOPE_SINGLETON)
                        .getBeanDefinition();
                beanDefinition.setTargetType(loadClass("org.tiny.cli.Cluster", beanDefinitionRegistry));
                //注入mock的bean
                beanDefinitionRegistry.registerBeanDefinition(beanName, beanDefinition);
            }
        }
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {

    }

    @Override
    public int getOrder() {
        return Ordered.LOWEST_PRECEDENCE - 10000;
    }


    public Class loadClass(String className, BeanDefinitionRegistry beanDefinitionRegistry) throws RuntimeException {
        ConfigurableBeanFactory cbf = (ConfigurableBeanFactory) beanDefinitionRegistry;
        Class clazz = tryLoadClass(cbf.getBeanClassLoader(), className);
        if (clazz != null) {
            return clazz;
        }
        return tryLoadClass(cbf.getTempClassLoader(), className);
    }

    private Class tryLoadClass(ClassLoader classLoader, String interfaceClassName) {
        try {
            return classLoader.loadClass(interfaceClassName);
        } catch (ClassNotFoundException e) {
            // 忽略
        }
        return null;
    }
}

从上面流程中,我们可以看到,我们先是移除了已经注册好的bean,之后创建了一个新的mock bean,并注册到spring的bean容器中。

由于这里面,我们用到了工厂方法:.setFactoryMethod("mock"), 所以我们需要定义一个工厂类:

public class BeanFactory {

    public static <T> T mock(Class<T> clazz) {
        System.out.println("创建mock的clazz:" + clazz.getName());
        return Mockito.mock(clazz);
    }


    public static Object original(Object obj) {
        System.out.println("创建mock的对象:" + obj.getClass().getName());
        return obj;
    }

}

跑起项目,可以看到bean被替换了。

posted on 2021-10-19 16:42  程序诗人  阅读(26)  评论(0编辑  收藏  举报