@EnableAutoConfiguration
@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 {};
}
标注了@AutoConfigurationPackage，并且导入了AutoConfigurationImportSelector
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Import(AutoConfigurationPackages.Registrar.class)
public @interface AutoConfigurationPackage {
}
@AutoConfigurationPackage注解导入了AutoConfigurationPackages.Registrar。
下面来看看这两个导入类
1、AutoConfigurationPackages.Registrar这是一个内部类，外部类AutoConfigurationPackages是一个抽象类
static class Registrar implements ImportBeanDefinitionRegistrar, DeterminableImports {
@Override
public void registerBeanDefinitions(AnnotationMetadata metadata, BeanDefinitionRegistry registry) {
//注册
register(registry, new PackageImport(metadata).getPackageName());
}
//这个方法没有地方调用，暂不分析
@Override
public Set
1.1、注册
private final String packageName;
PackageImport(AnnotationMetadata metadata) {
this.packageName = ClassUtils.getPackageName(metadata.getClassName());
}
PackageImport也是一个内部类，构造方法中赋值了一个成员变量packageName。
public static String getPackageName(String fqClassName) {
Assert.notNull(fqClassName, "Class name must not be null");
int lastDotIndex = fqClassName.lastIndexOf(PACKAGE_SEPARATOR);
return (lastDotIndex != -1 ? fqClassName.substring(0, lastDotIndex) : "");
}
getPackageName方法中会根据@AutoConfigurationPackage标注类的全限定名，获取@AutoConfigurationPackage标注类的包名。
然后将@AutoConfigurationPackage标注类的包名赋值给PackageImport的成员变量packageName。
String getPackageName() {
return this.packageName;
}
getPackageName方法只是简单的将PackageImport#packageName返回。
然后调用外部类AutoConfigurationPackages的静态方法register
private static final String BEAN = AutoConfigurationPackages.class.getName();
public static void register(BeanDefinitionRegistry registry, String... packageNames) {
//已经注册过 BEAN 了，代表不是第一次调用AutoConfigurationPackages.Registrar
if (registry.containsBeanDefinition(BEAN)) {
BeanDefinition beanDefinition = registry.getBeanDefinition(BEAN);
ConstructorArgumentValues constructorArguments = beanDefinition.getConstructorArgumentValues();
//将这次调用AutoConfigurationPackages.Registrar，将标注@AutoConfigurationPackage 注解的类的包名添加到 BEAN 的参数中
constructorArguments.addIndexedArgumentValue(0, addBasePackages(constructorArguments, packageNames));
}
else {
//第一次调用AutoConfigurationPackages.Registrar，注册 BEAN
GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
beanDefinition.setBeanClass(BasePackages.class);
//获取BasePackages构造器的参数，是个 String... ，将packageNames放到数组第一个位置
beanDefinition.getConstructorArgumentValues().addIndexedArgumentValue(0, packageNames);
beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
registry.registerBeanDefinition(BEAN, beanDefinition);
}
}
1.1.1、注册AutoConfigurationPackages
static final class BasePackages {
private final List packages;
private boolean loggedBasePackageInfo;
BasePackages(String... names) {
List packages = new ArrayList<>();
for (String name : names) {
if (StringUtils.hasText(name)) {
packages.add(name);
}
}
this.packages = packages;
}
List get() {
if (!this.loggedBasePackageInfo) {
if (this.packages.isEmpty()) {
if (logger.isWarnEnabled()) {
...//只是输出日志
}
}
else {
if (logger.isDebugEnabled()) {
String packageNames = StringUtils.collectionToCommaDelimitedString(this.packages);
...//输出日志
}
}
this.loggedBasePackageInfo = true;
}
return this.packages;
}
}
注册时bean的名称是上面的 BEAN，bean的类为BasePackages。
1.1.2、已经注册过AutoConfigurationPackagesprivate static String[] addBasePackages(ConstructorArgumentValues constructorArguments, String[] packageNames) {
//取出BasePackages构造器的参数 String...
String[] existing = (String[]) constructorArguments.getIndexedArgumentValue(0, String[].class).getValue();
//创建新的集合，将原有的包名和现有的包名添加进去，用set去重，然后返回
Set merged = new LinkedHashSet<>();
merged.addAll(Arrays.asList(existing));
merged.addAll(Arrays.asList(packageNames));
return StringUtils.toStringArray(merged);
}
2、AutoConfigurationImportSelector
AutoConfigurationImportSelector实现了DeferredImportSelector，DeferredImportSelector实现了ImportSelector。
public String[] selectImports(AnnotationMetadata annotationMetadata) {
//不起用自动装配
if (!isEnabled(annotationMetadata)) {
return NO_IMPORTS;
}
//获得AutoConfiguration的注解元数据
AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader
.loadMetadata(this.beanClassLoader);
AutoConfigurationEntry autoConfigurationEntry = getAutoConfigurationEntry(autoConfigurationMetadata,
annotationMetadata);
return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());
}
protected AutoConfigurationEntry getAutoConfigurationEntry(AutoConfigurationMetadata autoConfigurationMetadata,
AnnotationMetadata annotationMetadata) {
if (!isEnabled(annotationMetadata)) {
return EMPTY_ENTRY;
}
//获取注解的属性
AnnotationAttributes attributes = getAttributes(annotationMetadata);
//获取实现EnableAutoConfiguration的类名集合
List configurations = getCandidateConfigurations(annotationMetadata, attributes);
//去重
configurations = removeDuplicates(configurations);
//获取要排除的类名
Set exclusions = getExclusions(annotationMetadata, attributes);
checkExcludedClasses(configurations, exclusions);
//排除
configurations.removeAll(exclusions);
//过滤
configurations = filter(configurations, autoConfigurationMetadata);
fireAutoConfigurationImportEvents(configurations, exclusions);
return new AutoConfigurationEntry(configurations, exclusions);
}
2.1、获取所有EnableAutoConfiguration实现类名
protected ListgetCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) { //利用spi获取实现了EnableAutoConfiguration的类名集合 List configurations = SpringFactoriesLoader.loadFactoryNames(getSpringFactoriesLoaderFactoryClass(), getBeanClassLoader()); Assert.notEmpty(configurations, "No auto configuration classes found in META-INF/spring.factories. If you " + "are using a custom packaging, make sure that file is correct."); return configurations; }
protected Class getSpringFactoriesLoaderFactoryClass() {
return EnableAutoConfiguration.class;
}
2.2、去重
protected final2.3、获取要排除的类名List removeDuplicates(List list) { return new ArrayList<>(new LinkedHashSet<>(list)); }
protected SetgetExclusions(AnnotationMetadata metadata, AnnotationAttributes attributes) { Set excluded = new LinkedHashSet<>(); excluded.addAll(asList(attributes, "exclude")); excluded.addAll(Arrays.asList(attributes.getStringArray("excludeName"))); excluded.addAll(getExcludeAutoConfigurationsProperty()); return excluded; }
private List2.4、过滤getExcludeAutoConfigurationsProperty() { if (getEnvironment() instanceof ConfigurableEnvironment) { Binder binder = Binder.get(getEnvironment()); return binder.bind(PROPERTY_NAME_AUTOCONFIGURE_EXCLUDE, String[].class).map(Arrays::asList) .orElse(Collections.emptyList()); } String[] excludes = getEnvironment().getProperty(PROPERTY_NAME_AUTOCONFIGURE_EXCLUDE, String[].class); return (excludes != null) ? Arrays.asList(excludes) : Collections.emptyList(); }
private Listfilter(List configurations, AutoConfigurationMetadata autoConfigurationMetadata) { long startTime = System.nanoTime(); String[] candidates = StringUtils.toStringArray(configurations); boolean[] skip = new boolean[candidates.length]; boolean skipped = false; for (AutoConfigurationImportFilter filter : getAutoConfigurationImportFilters()) { invokeAwareMethods(filter); boolean[] match = filter.match(candidates, autoConfigurationMetadata); for (int i = 0; i < match.length; i++) { if (!match[i]) { skip[i] = true; candidates[i] = null; skipped = true; } } } if (!skipped) { return configurations; } List result = new ArrayList<>(candidates.length); for (int i = 0; i < candidates.length; i++) { if (!skip[i]) { result.add(candidates[i]); } } if (logger.isTraceEnabled()) { int numberFiltered = configurations.size() - result.size(); logger.trace("Filtered " + numberFiltered + " auto configuration class in " + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime) + " ms"); } return new ArrayList<>(result); }
protected ListgetAutoConfigurationImportFilters() { return SpringFactoriesLoader.loadFactories(AutoConfigurationImportFilter.class, this.beanClassLoader); }
根据AutoConfigurationImportFilter的实现类过滤自动装配类
