使用springboot自动配置源码解读

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@AutoConfigurationPackage
@Import({AutoConfigurationImportSelector.class})
public @interface EnableAutoConfiguration {
    String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration";

    Class<?>[] exclude() default {};

    String[] excludeName() default {};
}

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Import({Registrar.class})
public @interface AutoConfigurationPackage {
    String[] basePackages() default {};

    Class<?>[] basePackageClasses() default {};
}

PackageImports(AnnotationMetadata metadata) {
	// 获取包名
    AnnotationAttributes attributes = AnnotationAttributes.fromMap(metadata.getAnnotationAttributes(AutoConfigurationPackage.class.getName(), false));
    List<String> packageNames = new ArrayList(Arrays.asList(attributes.getStringArray("basePackages")));
    Class[] var4 = attributes.getClassArray("basePackageClasses");
    int var5 = var4.length;
	// 获取basePackageClasses属性的属性值，并且对于的包名放入packageNames列表中
    for(int var6 = 0; var6 < var5; ++var6) {
        Class<?> basePackageClass = var4[var6];
        packageNames.add(basePackageClass.getPackage().getName());
    }

    if (packageNames.isEmpty()) {
    // 如果packageNames为空，就将AutoConfigurationPackage注解标注的类所在的包名作为packageNames
        packageNames.add(ClassUtils.getPackageName(metadata.getClassName()));
    }

    this.packageNames = Collections.unmodifiableList(packageNames);
}

// 判断是否开启自动配置
if (!this.isEnabled(annotationMetadata)) {
    return EMPTY_ENTRY;
} else {
    // 获取注解属性
    AnnotationAttributes attributes = this.getAttributes(annotationMetadata);
    // 从 spring.factories 文件中获取自动配置类
    List<String> configurations = this.getCandidateConfigurations(annotationMetadata, attributes);
    // 去掉重复的自动配置类
    configurations = this.removeDuplicates(configurations);
    // 根据注解配置 排除自动配置类
    Set<String> exclusions = this.getExclusions(annotationMetadata, attributes);
    this.checkExcludedClasses(configurations, exclusions);
    configurations.removeAll(exclusions);
    configurations = this.getConfigurationClassFilter().filter(configurations);
    this.fireAutoConfigurationImportEvents(configurations, exclusions);
    return new AutoConfigurationImportSelector.AutoConfigurationEntry(configurations, exclusions);
}