开始之前:本文满满的图片。请大家在阅读之前准备好流量，以防爆表。哈哈。第一次写IOC的文章，希望大家多多支持，谢谢。
本文主要针对ClasspathXmlApplicationContext(还有与之类似的FileSystemXml...)的整体初始化流程做讲解。如有疑问可以加QQ群: 77174608 来讨论。
主题开始:
读源码准备的环境:
maven, logback基础知识, Spring 相关使用经验。
进入正文: 首先开始pom.xml
<properties>
<spring.version>4.3.14.RELEASE</spring.version>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.springframework/spring-asm -->
<!-- 注意，这里是第一个坑，在高版本的spring中是不需要手动引入该依赖了，如果引入则会抛出 java.lang.IncompatibleClassChangeError: class org.springframework.core.type.classreading.ClassMetadataReadingVisitor has interface org.springframework.asm.ClassVisitor as super class 异常 -->
<!--<dependency>-->
<!--<groupId>org.springframework</groupId>-->
<!--<artifactId>spring-asm</artifactId>-->
<!--<version>3.1.4.RELEASE</version>-->
<!--</dependency>-->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
<version>1.7.21</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.1.7</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
<exclusions>
<exclusion>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-expression</artifactId>
<version>${spring.version}</version>
</dependency>
</dependencies>
logback配置:
<appender name="console" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{HH:mm:ss.SSS} %contextName [%thread] %-5level %logger{36} - %msg%n
</pattern>
</encoder>
</appender>
<logger name="org.springframework" additivity="false" level="debug">
<appender-ref ref="console"/>
</logger>
我这里使用了自动扫包，所以beans.xml配置为:
<context:annotation-config/> <context:component-scan base-package="com.autorun.spring.demo"/>
ok, 环境已经基本已经搞定，我们开始写基本类
package com.autorun.spring.demo.beans;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
/**
* @author Autorun
* Created by Autorun on 2018/3/4.
*/
@Component
public class A {
@Autowired
private B b;
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
A a = (A) o;
return b != null ? b.equals(a.b) : a.b == null;
}
@Override
public int hashCode() {
return b != null ? b.hashCode() : 0;
}
@Override
public String toString() {
return "A{" +
", b=" + b +
'}';
}
}
package com.autorun.spring.demo.beans;
import org.springframework.stereotype.Component;
/**
* @author Autorun
* Created by Autorun on 2018/3/4.
*/
@Component
public class B {
}
然后创建主类(当然, 目前spring还是主要用于web开发,有用过springboot的童鞋应该对这种玩法有所了解。不再赘述):
public class Application {
public static void main(String[] args) {
ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("beans-parent.xml");
ctx.setDisplayName("parent");
/// ctx.start();
A a = ctx.getBean(A.class);
System.out.println(a);
B b = ctx.getBean(B.class);
System.out.println(b);
}
以上就是环境准备篇。毕竟基础。下一篇将正式开始源码拆解。 前几篇文章会粗略的走一遍加载，目的是让大家熟悉一下整体流程。之后会对每个组件进行讲解。谢谢大家支持
