分类:
spring
一、
作用:提高bean的加载数度,将没有加载到bean里面的类通过自定义导入器可以加载到bean
用法:
案例、
1.1、加载单个类的bean
1.2、
1.3、
2.1、加载多个类的bean
2.2、
SpringConfig配置类就不用改了
3.1、
3.2、
代码:
package com.itheima.config.selector; import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.ImportSelector; import org.springframework.core.io.support.PropertiesLoaderUtils; import org.springframework.core.type.AnnotationMetadata; import org.springframework.core.type.filter.AspectJTypeFilter; import org.springframework.core.type.filter.TypeFilter; import java.io.IOException; import java.util.HashSet; import java.util.Map; import java.util.Properties; import java.util.Set; public class CustomerImportSelector implements ImportSelector { private String expression; public CustomerImportSelector(){ try { //初始化时指定加载的properties文件名 Properties loadAllProperties = PropertiesLoaderUtils.loadAllProperties("import.properties"); //设定加载的属性名 expression = loadAllProperties.getProperty("path"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } @Override public String[] selectImports(AnnotationMetadata importingClassMetadata) { //1.定义扫描包的名称 String[] basePackages = null; //2.判断有@Import注解的类上是否有@ComponentScan注解 if (importingClassMetadata.hasAnnotation(ComponentScan.class.getName())) { //3.取出@ComponentScan注解的属性 Map<String, Object> annotationAttributes = importingClassMetadata.getAnnotationAttributes(ComponentScan.class.getName()); //4.取出属性名称为basePackages属性的值 basePackages = (String[]) annotationAttributes.get("basePackages"); } //5.判断是否有此属性(如果没有ComponentScan注解则属性值为null,如果有ComponentScan注解,则basePackages默认为空数组) if (basePackages == null || basePackages.length == 0) { String basePackage = null; try { //6.取出包含@Import注解类的包名 basePackage = Class.forName(importingClassMetadata.getClassName()).getPackage().getName(); } catch (ClassNotFoundException e) { e.printStackTrace(); } //7.存入数组中 basePackages = new String[] {basePackage}; } //8.创建类路径扫描器 ClassPathScanningCandidateComponentProvider scanner = new ClassPathScanningCandidateComponentProvider(false); //9.创建类型过滤器(此处使用切入点表达式类型过滤器) TypeFilter typeFilter = new AspectJTypeFilter(expression,this.getClass().getClassLoader()); //10.给扫描器加入类型过滤器 scanner.addIncludeFilter(typeFilter); //11.创建存放全限定类名的集合 Set<String> classes = new HashSet<>(); //12.填充集合数据 for (String basePackage : basePackages) { scanner.findCandidateComponents(basePackage).forEach(beanDefinition -> classes.add(beanDefinition.getBeanClassName())); } //13.按照规则返回 return classes.toArray(new String[classes.size()]); } }
3.3、
二、自定义注册器
案例、
1、properties文件
2、创建类实现接口
代码:
//package config.registrar; import org.springframework.beans.factory.support.BeanDefinitionRegistry; import org.springframework.context.annotation.ClassPathBeanDefinitionScanner; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.ImportBeanDefinitionRegistrar; import org.springframework.core.io.support.PropertiesLoaderUtils; import org.springframework.core.type.AnnotationMetadata; import org.springframework.core.type.filter.AspectJTypeFilter; import org.springframework.core.type.filter.TypeFilter; import java.io.IOException; import java.util.Map; import java.util.Properties; public class CustomeImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar { private String expression; public CustomeImportBeanDefinitionRegistrar(){ try { //初始化时指定加载的properties文件名 Properties loadAllProperties = PropertiesLoaderUtils.loadAllProperties("import.properties"); //设定加载的属性名 expression = loadAllProperties.getProperty("path"); } catch (IOException e) { e.printStackTrace(); } } @Override public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) { //1.定义扫描包的名称 String[] basePackages = null; //2.判断有@Import注解的类上是否有@ComponentScan注解 if (importingClassMetadata.hasAnnotation(ComponentScan.class.getName())) { //3.取出@ComponentScan注解的属性 Map<String, Object> annotationAttributes = importingClassMetadata.getAnnotationAttributes(ComponentScan.class.getName()); //4.取出属性名称为basePackages属性的值 basePackages = (String[]) annotationAttributes.get("basePackages"); } //5.判断是否有此属性(如果没有ComponentScan注解则属性值为null,如果有ComponentScan注解,则basePackages默认为空数组) if (basePackages == null || basePackages.length == 0) { String basePackage = null; try { //6.取出包含@Import注解类的包名 basePackage = Class.forName(importingClassMetadata.getClassName()).getPackage().getName(); } catch (ClassNotFoundException e) { e.printStackTrace(); } //7.存入数组中 basePackages = new String[] {basePackage}; } //8.创建类路径扫描器 ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(registry, false); //9.创建类型过滤器(此处使用切入点表达式类型过滤器) TypeFilter typeFilter = new AspectJTypeFilter(expression,this.getClass().getClassLoader()); //10.给扫描器加入类型过滤器 scanner.addIncludeFilter(typeFilter); //11.扫描指定包 scanner.scan(basePackages); } }
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