首页 > 软件编程 > java > Spring底层机制环境搭建

Spring底层机制环境搭建全过程

2024-12-09 10:50:31 作者：S-X-S

本文介绍了如何创建和使用Spring框架,包括模块创建、依赖引入、环境搭建、Bean的生命周期管理、AOP编程以及代码托管,通过实际操作和代码示例,详细讲解了Spring的核心概念和功能

Spring底层机制环境搭建

1.模块创建和依赖引入

聚合模块，下面有一个myspring

查看父模块是否管理了子模块

myspring模块引入基本包

<dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>5.3.8</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aspects</artifactId>
        <version>5.3.8</version>
    </dependency>
</dependencies>

2.进行环境搭建

目录概览

UserController.java

package com.sunxiansheng.myspring.component;

import org.springframework.stereotype.Component;

/**
 * Description: 就是一个Controller组件
 * @Author sun
 * @Create 2024/8/4 13:53
 * @Version 1.0
 */
@Component
public class UserController {
}

UserService.java

package com.sunxiansheng.myspring.component;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

/**
 * Description: 一个Service组件
 * @Author sun
 * @Create 2024/8/4 13:54
 * @Version 1.0
 */
@Component
public class UserService {

    /**
     * 依赖注入UserDao
     */
    @Autowired
    private UserDao userDao;

    public void add() {
        System.out.println("UserService 调用了UserDao的add方法");
        userDao.add();
    }

}

UserDao.java

package com.sunxiansheng.myspring.component;

import org.springframework.stereotype.Component;

/**
 * Description: 一个Dao组件
 * @Author sun
 * @Create 2024/8/4 13:53
 * @Version 1.0
 */
@Component
public class UserDao {

    public void add() {
        System.out.println("UserDao add...");
    }

}

AppMain.java

package com.sunxiansheng.myspring;

import com.sunxiansheng.myspring.component.UserController;
import com.sunxiansheng.myspring.component.UserDao;
import com.sunxiansheng.myspring.component.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * Description: 启动类
 * @Author sun
 * @Create 2024/8/4 13:59
 * @Version 1.0
 */
public class AppMain {

    public static void main(String[] args) {
        // 从类路径下加载beans.xml配置文件
        ApplicationContext ioc = new ClassPathXmlApplicationContext("beans.xml");
        // 从容器中获取UserController对象，这里获取两次，看是否是同一个对象
        UserController userController1 = (UserController) ioc.getBean("userController");
        UserController userController2 = (UserController) ioc.getBean("userController");
        System.out.println("userController1 == userController2 ? " + (userController1 == userController2));
        // 从容器中获取UserService对象
        UserService userService = (UserService) ioc.getBean("userService");
        System.out.println("userService = " + userService);
        // 从容器中获取UserDao对象
        UserDao userDao = (UserDao) ioc.getBean("userDao");
        System.out.println("userDao = " + userDao);
    }

}

beans.xml

<?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 https://www.springframework.org/schema/context/spring-context.xsd">

    <!-- 配置自动扫描的包 -->
    <context:component-scan base-package="com.sunxiansheng.myspring.component"/>

</beans>

测试

配置UserController.java为多例的，然后测试

UserService调用add方法，然后测试

引入Bean后置处理器

1.位置

2.MyBeanPostProcessor.java

package com.sunxiansheng.myspring.process;

import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component;

/**
 * Description: Bean的后置处理器
 * @Author sun
 * @Create 2024/8/4 14:19
 * @Version 1.0
 */
@Component // 将这个类加入到容器中
public class MyBeanPostProcessor implements BeanPostProcessor {

    /**
     * 在每个Bean的初始化方法之前执行
     * @param bean
     * @param beanName
     * @return
     */
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) {
        // 这里可以提前对bean进行一些处理
        System.out.println("postProcessBeforeInitialization..."+beanName+"=>"+bean.getClass());
        return bean;
    }

    /**
     * 在每个Bean的初始化方法之后执行
     * @param bean
     * @param beanName
     * @return
     */
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) {
        System.out.println("postProcessAfterInitialization..."+beanName+"=>"+bean.getClass());
        return bean;
    }

}

3.UserService.java 设置初始化方法

4.beans.xml配置扫描

5.测试

6.注意事项

bean的后置处理器在初始化方法调用前后执行
触发时机为单例的第一次getBean和多例的每次getBean，也就是，每个Bean都会经过Bean的后置处理器处理

引入AOP

1.目录

2.SmartAnimal.java

package com.sunxiansheng.myspring.aop;

/**
 * Description: SmartAnimal
 * @Author sun
 * @Create 2024/8/4 14:51
 * @Version 1.0
 */
public interface SmartAnimal {

    public float getSum(float a, float b);

    public float getSub(float a, float b);

}

3.SmartDog.java

package com.sunxiansheng.myspring.aop;

import org.springframework.stereotype.Component;

/**
 * Description: SmartDog
 * @Author sun
 * @Create 2024/8/4 14:51
 * @Version 1.0
 */
@Component // 交给Spring容器管理
public class SmartDog implements SmartAnimal {

    @Override
    public float getSum(float a, float b) {
        System.out.println("SmartDog...getSum...res=" + (a + b));
        return a + b;
    }

    @Override
    public float getSub(float a, float b) {
        System.out.println("SmartDog...getSub...res=" + (a - b));
        return a - b;
    }
}

4.SmartAnimalAspect.java

package com.sunxiansheng.myspring.aop;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.Signature;
import org.aspectj.lang.annotation.*;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.stereotype.Component;

import java.util.Arrays;

/**
 * Description: 切面类
 * @Author sun
 * @Create 2024/8/4 14:53
 * @Version 1.0
 */
@Component // 交给Spring容器管理
@Aspect // 标注这是一个切面类
public class SmartAnimalAspect {

    /**
     * @param joinPoint 保存了要切入的方法的信息
     * @Before 前置通知
     * execution（。。。） 切入表达式，表明要切入的方法，格式：格式：访问修饰符+返回类型 全类名 方法名（参数类型）
     */
    @Before(value = "execution(public float com.sunxiansheng.myspring.aop.SmartDog.getSub(float, float))")
    public void before(JoinPoint joinPoint) {
        // 获取方法签名
        Signature signature = joinPoint.getSignature();
        System.out.println("方法执行开始-日志-方法名-" + signature.getName()
                + "-参数" + Arrays.asList(joinPoint.getArgs()));
        // 还可以获取目标对象，这样就可以反射进行任何操作了
        SmartDog target = (SmartDog) joinPoint.getTarget();
        System.out.println("目标对象-" + target.getClass());
    }

    /**
     * @param joinPoint 保存了要切入的方法的信息
     * @AfterReturning 返回通知
     */
    @AfterReturning(value = "execution(public float com.sunxiansheng.myspring.aop.SmartDog.getSub(float, float))")
    public void afterReturning(JoinPoint joinPoint) {
        Signature signature = joinPoint.getSignature();
        System.out.println("方法执行正常结束-日志-方法名-" + signature.getName());
    }

    /**
     * @param joinPoint
     * @AfterThrowing 异常通知
     */
    @AfterThrowing(value = "execution(public float com.sunxiansheng.myspring.aop.SmartDog.getSub(float, float))")
    public void throwing(JoinPoint joinPoint) {
        Signature signature = joinPoint.getSignature();
        System.out.println("方法出现异常-日志-方法名-" + signature.getName());
    }

    /**
     * @param joinPoint
     * @After 后置通知
     */
    @After(value = "execution(public float com.sunxiansheng.myspring.aop.SmartDog.getSub(float, float))")
    public void after(JoinPoint joinPoint) {
        Signature signature = joinPoint.getSignature();
        System.out.println("方法最终执行完毕-日志-方法名-" + signature.getName());
    }

    /**
     * 环绕通知
     * @param joinPoint
     * @return
     * @throws Throwable
     */
    @Around("execution(public float com.sunxiansheng.myspring.aop.SmartDog.getSub(float, float))")
    public Object logMethodExecution(ProceedingJoinPoint joinPoint) throws Throwable {
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();

        // 获取方法信息
        String methodName = signature.getMethod().getName();
        String className = signature.getDeclaringType().getSimpleName();

        System.out.println("环绕通知 method " + className + "." + methodName);

        // 获取目标对象
        Object targetObject = joinPoint.getTarget();
        // 环绕通知获取目标对象
        System.out.println("环绕通知获取目标对象：" + targetObject);

        try {
            // 前置通知：环绕通知获取参数
            System.out.println("环绕通知获取参数：" + Arrays.asList(joinPoint.getArgs()));
            Object result = joinPoint.proceed();  // 执行目标方法
            // 返回通知：环绕通知获取结果
            System.out.println("环绕通知获取结果：" + result);
            return result;
        } catch (Exception e) {
            // 异常通知
            throw e;
        } finally {
            // 最终通知
            System.out.println("环绕通知 method " + className + "." + methodName);
        }
    }

}

5.beans.xml开启aop注解并扫描aop包