add a spring factories loader source code analysis instructions

ipipman · ipipman · commit fd6dd07615dc · 2021-06-05T22:44:35.000+08:00
diff --git a/springboot-source-code-analysis/(3)工厂加载机制解析.md b/springboot-source-code-analysis/(3)工厂加载机制解析.md
@@ -0,0 +1,39 @@
+ ## 工厂加载机制解析
+
+### SpringFactoriesLoader 介绍
+
+> org.springframework.core.io.support.SpringFactoriesLoader
+
+```java
+/**
+ * General purpose factory loading mechanism for internal use within the framework.
+ *
+ * <p>{@code SpringFactoriesLoader} {@linkplain #loadFactories loads} and instantiates
+ * factories of a given type from {@value #FACTORIES_RESOURCE_LOCATION} files which
+ * may be present in multiple JAR files in the classpath. The {@code spring.factories}
+ * file must be in {@link Properties} format, where the key is the fully qualified
+ * name of the interface or abstract class, and the value is a comma-separated list of
+ * implementation class names. For example:
+ *
+ * <pre class="code">example.MyService=example.MyServiceImpl1,example.MyServiceImpl2</pre>
+ *
+ * where {@code example.MyService} is the name of the interface, and {@code MyServiceImpl1}
+ * and {@code MyServiceImpl2} are two implementations.
+ *
+ * @author Arjen Poutsma
+ * @author Juergen Hoeller
+ * @author Sam Brannen
+ * @since 3.2
+ */
+public final class SpringFactoriesLoader {
+```
+
+- 框架内部使用的通用工厂加载机制
+- 从classpath 下多个jar包特定的位置读取文件并初始化类
+- 文件内容必须是kv形式，即properties类型
+- key是全限定名（抽象类｜接口）、value是实现，多个实现用逗号分隔
+
+
+
+
+
