ConditionalOnClass

参考文章 blog.csdn.net/swordcenter…

只看FeignAutoConfiguration

asSourceClass

SourceClass asSourceClass(@Nullable String className, Predicate<String> filter) throws IOException {
   if (className == null || filter.test(className)) {
      return this.objectSourceClass;
   }
   if (className.startsWith("java")) {
      // Never use ASM for core java types
      try {
         return new SourceClass(ClassUtils.forName(className, this.resourceLoader.getClassLoader()));
      }
      catch (ClassNotFoundException ex) {
         throw new NestedIOException("Failed to load class [" + className + "]", ex);
      }
   }
   return new SourceClass(this.metadataReaderFactory.getMetadataReader(className));
}

排序后一个个处理

org.springframework.cloud.openfeign.FeignAutoConfiguration里的所有内部类

先处理类本身

这里用反射判断是否存在，存在返回true，不存在返回false

判断第一个内部类的，org.springframework.cloud.openfeign.FeignAutoConfiguration$HttpClient5FeignConfiguration

@ConditionalOnClass(ApacheHttp5Client.class)

找出上一步中ConditionalOnClass的全包，feign.hc5.ApacheHttp5Client

通过反正调用失败，返回false