这篇文章主要介绍了Springboot自动装配实现过程代码实例,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下
创建一个简单的项目：
4.0.0 spring-boot-starter-parentorg.springframework.boot2.1.12.RELEASEcom.xiazhidemo1.0-SNAPSHOT org.springframework.bootspring-boot-starter-web org.springframework.bootspring-boot-starter-test
首先创建自定义注解：
package com.xiazhi.demo.annotation; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; /** * MyComponent 作用于类上，表示这是一个组件，于component，service注解作用相同 * @author zhaoshuai */ @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) public @interface MyComponent { }
package com.xiazhi.demo.annotation; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; /** * 作用于字段上，自动装配的注解，与autowired注解作用相同 * @author zhaoshuai */ @Target(ElementType.FIELD) @Retention(RetentionPolicy.RUNTIME) public @interface Reference { }
然后写配置类：
package com.xiazhi.demo.config; import com.xiazhi.demo.annotation.MyComponent; import org.springframework.beans.factory.support.BeanDefinitionRegistry; import org.springframework.context.ResourceLoaderAware; import org.springframework.context.annotation.ClassPathBeanDefinitionScanner; import org.springframework.context.annotation.ImportBeanDefinitionRegistrar; import org.springframework.core.io.ResourceLoader; import org.springframework.core.type.AnnotationMetadata; import org.springframework.core.type.filter.AnnotationTypeFilter; /** * @author ZhaoShuai * @company lihfinance.com * @date Create in 2020/3/21 **/ public class ComponentAutoConfiguration implements ImportBeanDefinitionRegistrar, ResourceLoaderAware { private ResourceLoader resourceLoader; @Override public void registerBeanDefinitions(AnnotationMetadata annotationMetadata, BeanDefinitionRegistry beanDefinitionRegistry) { String className = annotationMetadata.getClassName(); String basePackages = className.substring(0, className.lastIndexOf(".")); ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(beanDefinitionRegistry, false); scanner.addIncludeFilter(new AnnotationTypeFilter(MyComponent.class)); scanner.scan(basePackages); scanner.setResourceLoader(resourceLoader); } @Override public void setResourceLoader(ResourceLoader resourceLoader) { this.resourceLoader = resourceLoader; } }
上面是配置扫描指定包下被MyComponent注解标注的类并注册为spring的bean，bean注册成功后，下面来源gaodai$ma#com搞$代*码网就是属性的注入了
package com.xiazhi.demo.config; import com.xiazhi.demo.annotation.MyComponent; import com.xiazhi.demo.annotation.Reference; import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.BeanPostProcessor; import org.springframework.boot.SpringBootConfiguration; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import org.springframework.context.annotation.Bean; import org.springframework.util.ReflectionUtils; import java.lang.reflect.Field; /** * @author ZhaoShuai * @company lihfinance.com * @date Create in 2020/3/21 **/ @SpringBootConfiguration public class Configuration implements ApplicationContextAware { private ApplicationContext applicationContext; @Bean public BeanPostProcessor beanPostProcessor() { return new BeanPostProcessor() { /** * @company lihfinance.com * @author create by ZhaoShuai in 2020/3/21 * 在bean注册前会被调用 * @param [bean, beanName] * @return java.lang.Object **/ @Override public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { return bean; } /** * @company lihfinance.com * @author create by ZhaoShuai in 2020/3/21 * 在bean注册后会被加载，本次在bean注册成功后注入属性值 * @param [bean, beanName] * @return java.lang.Object **/ @Override public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { Class clazz = bean.getClass(); if (!clazz.isAnnotationPresent(MyComponent.class)) { return bean; } Field[] fields = clazz.getDeclaredFields(); for (Field field : fields) { if (!field.isAnnotationPresent(Reference.class)) { continue; } Class type = field.getType(); Object obj = applicationContext.getBean(type); ReflectionUtils.makeAccessible(field); ReflectionUtils.setField(field, bean, obj); } return bean; } }; } @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { this.applicationContext = applicationContext; } }
下面开始使用注解来看看
package com.xiazhi.demo.service; import com.xiazhi.demo.annotation.MyComponent; import javax.annotation.PostConstruct; /** * @author ZhaoShuai * @company lihfinance.com * @date Create in 2020/3/21 **/ @MyComponent public class MyService { @PostConstruct public void init() { System.out.println("hello world"); } public void test() { System.out.println("测试案例"); } }
package com.xiazhi.demo.service; import com.xiazhi.demo.annotation.MyComponent; import com.xiazhi.demo.annotation.Reference; /** * @author ZhaoShuai * @company lihfinance.com * @date Create in 2020/3/21 **/ @MyComponent public class MyConsumer { @Reference private MyService myService; public void aaa() { myService.test(); } }
启动类要引入配置文件：
import注解引入配置文件。
编写测试类测试：
@SpringBootTest(classes = ApplicationRun.class) @RunWith(SpringRunner.class) public class TestDemo { @Autowired public MyConsumer myConsumer; @Test public void fun1() { myConsumer.aaa(); } }
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转载请注明原文链接：Springboot自动装配实现过程代码实例
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