Spring component auto-Scan details and instance code, spring details

Spring component auto-Scan details and instance code, spring details

Detailed description of automatic Spring component scanning and instance code

Problem description

A system usually has thousands of components. If you need to manually add all components to the spring container for management, it is a huge project.

Solution

Spring provides the component scanning function. It can automatically scan, detect, and instantiate components with specific annotations from classpath. The basic annotation is @ Component, which identifies a Component managed by Spring. Other specific annotations include @ Repository, @ Service, and @ Controller, which respectively identify the components of the persistence layer, Service layer, and presentation layer.

Implementation Method

User. Java

package com.zzj.bean;  import javax.annotation.Resource;  import org.springframework.stereotype.Component; @Component public class User {   @Resource   private Car car;    public void startCar(){     car.start();   } } 

Car. java

package com.zzj.bean;  import org.springframework.stereotype.Component;  @Component public class Car {   public void start(){     System.out.println("starting car...");   } } 

XML configuration file

<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans"     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"     xmlns:context="http://www.springframework.org/schema/context"     xsi:schemaLocation="http://www.springframework.org/schema/beans        http://www.springframework.org/schema/beans/spring-beans.xsd       http://www.springframework.org/schema/context       http://www.springframework.org/schema/context/spring-context.xsd">           <context:component-scan base-package="com.zzj.bean"/> </beans> 

Note: after Spring's automatic scanning function is enabled, the automatic injection function is also enabled.

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