Spring核心机制

1 Spring IoC 和 AOP

Spring 框架Java开发的行业标准

Spring 全家桶

Web：Spring Web MVC/Spring MVC、Spring Web Flux

持久层: Spring Data/ Spring DataJPA、Spring Data Redis、Spring Data MongoDB

安全校验: Spring Security

构建工程脚手架:Spring Boot

微服务:Spring Cloud

IoC是Spring全家桶各个功能模块的基础，创建对象的容器。

AOP也是以loC为基础，AOP是面向切面编程，抽象化的面向对象

1、打印日志

2、事务

3、权限处理

1.1 IoC

控制反转，将对象的创建进行反转，常规情况下，对象都是开发者手动创建的，使用loC开发者不再需要创建对象，而是由loC容器根据需求自动创建项目所需要的对象。

不用IoC：所有对象开发者自己创建

使用IoC：对象不用开发者创建，而是交给Spring框架来完成

1.pom.xml

<dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.2.12.RELEASE</version>
</dependency>

引入IoC的环境下

基于XML和基于注解

基于XML：开发者把需要的对象在XML中进行配置，Spring框架读取这个配置文件，根据配置文件的内容来创建对象

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:context="http://www.springframework.org/schema/context"xmlns:aop="http://www.springframework.org/schema/aop"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:tx="http://www.springframework.org/schema/beans"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsdhttp://www.springframework.org/schema/beanshttp://www.springframework.org/schema/tx/spring-tx.xsd"><bean class="nuc.edu.springdemo.DataConfig" id="config"><property name="driverName" value="Driver"></property><property name="url" value="loaclhost:8080"></property><property name="username" value="root"></property><property name="password" value="654321"></property></bean>
</beans>

package nuc.edu.springdemo;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test {public static void main(String[] args) {//        DataConfig dataConfig = new DataConfig();
//        dataConfig.setDriverName("Driver");
//        dataConfig.setUrl("localhost:3306/dbname");
//        dataConfig.setUsername("root");
//        dataConfig.setPassword("123456");ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");System.out.println(context.getBean("config"));}
}

基于注解

1、配置类

package nuc.edu.springdemo.configuration;import nuc.edu.springdemo.DataConfig;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;@Configuration
public class BeanConfiguration {@Bean(value = "config")public DataConfig dataConfig() {DataConfig dataConfig = new DataConfig();dataConfig.setDriverName("Driver");dataConfig.setUrl("localhost:3306/dbname");dataConfig.setUsername("root");dataConfig.setPassword("123456");return dataConfig;}
}

package nuc.edu.springdemo;import nuc.edu.springdemo.configuration.BeanConfiguration;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test {public static void main(String[] args) {//        DataConfig dataConfig = new DataConfig();
//        dataConfig.setDriverName("Driver");
//        dataConfig.setUrl("localhost:3306/dbname");
//        dataConfig.setUsername("root");
//        dataConfig.setPassword("123456");ApplicationContext context = new AnnotationConfigApplicationContext(BeanConfiguration.class);
System.out.println(context.getBean(DataConfig.class));
System.out.println(context.getBean("config"));

当配置类存在多个时，直接使用包名

ApplicationContext context = new AnnotationConfigApplicationContext("nuc.edu.springdemo.configuration");

2、扫包+注解

更简单的方式，不再需要依赖于XML或者配置类，而是直接将bean的创建交给目标类，在目标类添加注解来创建

package nuc.edu.springdemo.ioc;import lombok.Data;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;@Data
@Component
public class DataConfig {@Value("localhost:3306")private String url;@Value("Driver")private String driverName;@Value("root")private String username;@Value("654123")private String password;}

ApplicationContext context = new AnnotationConfigApplicationContext("nuc.edu.springdemo.ioc");
System.out.println(context.getBean(DataConfig.class));

自动创建对象，完成依赖注入

package nuc.edu.springdemo.ioc;import lombok.Data;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;@Data
@Component
public class GlobalConfig {@Value("8080")private String port;@Value("/")private String path;@Autowiredprivate DataConfig dataConfig;
}

@Autowired 通过类型进行注入，如果需要通过名称取值，通过@Qualifier注解完成名称的映射

package nuc.edu.springdemo.ioc;import lombok.Data;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;@Data
@Component
public class GlobalConfig {@Value("8080")private String port;@Value("/")private String path;@Autowired@Qualifier("config")private DataConfig dataConfig;
}

package nuc.edu.springdemo.ioc;import lombok.Data;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;@Data
@Component("config")
public class DataConfig {@Value("localhost:3306")private String url;@Value("Driver")private String driverName;@Value("root")private String username;@Value("654123")private String password;
}

1.2AOP

面向切面编程，是一种抽象化的面向对象编程，对面向对象编程的补充，底层使用动态代理机制来实现

打印日志

业务代码和打印日志耦合起来

package nuc.edu.springdemo.aop;public class CalImpl implements Cal {@Overridepublic int add(int num1, int num2) {System.out.println("add方法的参数是[" + num1 + "," + num2 + "]");int result = num1 + num2;System.out.println("add方法的结果是" + result);return result;}@Overridepublic int sub(int num1, int num2) {System.out.println("sub方法的参数是[" + num1 + "," + num2 + "]");int result = num1 - num2;System.out.println("sub方法的结果是" + result);return result;}@Overridepublic int mul(int num1, int num2) {System.out.println("mul方法的参数是[" + num1 + "," + num2 + "]");int result = num1 * num2;System.out.println("mul方法的结果是" + result);return result;}@Overridepublic int div(int num1, int num2) {System.out.println("div方法的参数是[" + num1 + "," + num2 + "]");int result = num1 / num2;System.out.println("div方法的结果是" + result);return result;}
}

计算器方法中，日志和业务混合在一起，AOP要做的就是将日志代码全部抽象出去统一进行处理，计算器方法中只保留核心的业务代码。

做到核心业务和非业务代码的解耦合

1、创建切面类

package nuc.edu.springdemo.aop;import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.stereotype.Component;import java.util.Arrays;@Component
@Aspect
public class LoggerAspect {@Before("execution(public int nuc.edu.springdemo.aop.CalImpl.*(..))")public void before(JoinPoint joinPoint){String name = joinPoint.getSignature().getName();System.out.println(name+"方法的参数是"+ Arrays.toString(joinPoint.getArgs()));}@AfterReturning(value = "execution(public int nuc.edu.springdemo.aop.CalImpl.*(..))",returning = "result")public void afterReturning(JoinPoint joinPoint,Object result){String name = joinPoint.getSignature().getName();System.out.println(name+"方法的结果是"+ result);}
}

2、实现类添加@Component注解

package nuc.edu.springdemo.aop;import org.springframework.stereotype.Component;@Component
public class CalImpl implements Cal {@Overridepublic int add(int num1, int num2) {int result = num1 + num2;return result;}@Overridepublic int sub(int num1, int num2) {int result = num1 - num2;return result;}@Overridepublic int mul(int num1, int num2) {int result = num1 * num2;return result;}@Overridepublic int div(int num1, int num2) {int result = num1 / num2;return result;}
}

3、配置自动扫包，开启自动生产代理对象

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:context="http://www.springframework.org/schema/context"xmlns:aop="http://www.springframework.org/schema/aop"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:tx="http://www.springframework.org/schema/beans"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/aophttp://www.springframework.org/schema/aop/spring-aop.xsdhttp://www.springframework.org/schema/beanshttp://www.springframework.org/schema/tx/spring-tx.xsd"><!--自动扫包--><context:component-scan base-package="nuc.edu.springdemo.aop"></context:component-scan><!--开启自动生成代理--><aop:aspectj-autoproxy></aop:aspectj-autoproxy></beans>

4、使用

package nuc.edu.springdemo.aop;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test {public static void main(String[] args) {ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");Cal bean = context.getBean(Cal.class);System.out.println(bean.add(9, 8));System.out.println(bean.sub(9, 8));System.out.println(bean.mul(9, 8));System.out.println(bean.div(9, 8));}
}