spring快速上手

一、基础概念

1.使用spring后，被spring管理的类，不需要再new。

2.要想类被spring管理，则需要通过bean的方式，把类引入到spirng的配置文件中。

二、导入spring框架

导入spring依赖

    <properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target><spring.version>4.0.1.RELEASE</spring.version></properties><dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-tx</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.aspectj</groupId><artifactId>aspectjweaver</artifactId><version>1.9.2</version></dependency></dependencies>

在资源目录下创建spring-config.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:aop="http://www.springframework.org/schema/aop"xmlns:tx="http://www.springframework.org/schema/tx"xmlns:p="http://www.springframework.org/schema/p"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd"></beans>

三、第一个IOC

创建一个实体类User

// 省略了getset
public class User {private int uid;private String uname;private String upassword;
}

注册bean

    <bean id="zhangsan" class="com.pojo.User"><property name="uname" value="张三"/><property name="upassword" value="123"/></bean>

测试

public static void main(String[] args) {ApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");User user = (User) context.getBean("zhangsan");System.out.println(user.getUname());
}

四、第一个AOP

AOP的理解：

• 将复杂的需求分解出不同方面，将散布在系统中的“公共功能”“集中解决”
• 采用代理机制组装起来运行，在“不改变原程序”的基础上对代码段进行增强处理，增加新的功能

1、创建增强类

package com.advice;public class LoggerAdvice {public void before(){System.out.println("LoggerAdvice.before()");}
}

2、创建要切入的业务类

package com.service;public class UserService {public void login() {System.out.println("login");}
}

3、注册到spring中和配置切面

<bean id="userService" class="com.service.UserService"></bean><bean id="loggerAdvice" class="com.advice.LoggerAdvice"/><aop:config><aop:pointcut id="pointcut" expression="execution(* com.service.*.*(..))"/><aop:aspect ref="loggerAdvice"><aop:before method="before" pointcut-ref="pointcut"/></aop:aspect>
</aop:config>

五、IOC扩展

package com.printor;public interface Ink {public void show();
}

package com.printor;public class InkColor implements Ink{@Overridepublic void show() {System.out.println("彩色");}
}

package com.printor;public interface Paper {public void show();
}

package com.printor;public class PaperA4 implements Paper{@Overridepublic void show() {System.out.println("A4纸");}
}

package com.printor;public class PaperB5 implements Paper{@Overridepublic void show() {System.out.println("B5");}
}

package com.printor;public class HPPrintor {private Ink ink;private Paper paper;public void print(String content) {System.out.println("HP打印机打印内容：" + content);this.ink.show();this.paper.show();}public Ink getInk() {return ink;}public void setInk(Ink ink) {this.ink = ink;}public Paper getPaper() {return paper;}public void setPaper(Paper paper) {this.paper = paper;}
}

将以上的类，注册到spring中

    <bean id="inkColor" class="com.printor.InkColor"></bean><bean id="paperA4" class="com.printor.PaperA4"></bean><bean id="paperB5" class="com.printor.PaperB5"></bean><bean id="hpPrintor1" class="com.printor.HPPrintor"><property name="ink" ref="inkColor"/><property name="paper" ref="paperA4"/></bean><bean id="hpPrintor2" class="com.printor.HPPrintor"><property name="ink" ref="inkColor"/><property name="paper" ref="paperB5"/></bean>

通过注解实现

<context:component-scan base-package="com.printor"></context:component-scan>

InkColor、PaperA4、PaperB5、HPPrintor类上增加@Component注解

@Component
public class HpPrintor {@Autowiredprivate Ink ink;@Autowired@Qualifier("paperA4")private Paper paper;
}

六、AOP扩展

使用注解实现

    <context:component-scan base-package="com.service"></context:component-scan><aop:aspectj-autoproxy/>

package com.advice;import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.*;
import org.springframework.stereotype.Component;import java.util.Arrays;@Aspect
@Component
public class PrintAdvice {@Pointcut("execution(* com.service.*.*(..))")public void pointcut(){}@Before("pointcut()")public void before(JoinPoint joinPoint) {System.out.println("打印前");String target = joinPoint.getTarget().toString(); // 类String method = joinPoint.getSignature().getName(); // 方法String args = Arrays.toString(joinPoint.getArgs()); // 参数列表System.out.println(target);System.out.println(method);System.out.println(args);}@After("pointcut()")public void after() {System.out.println("打印后");}@AfterReturning(pointcut = "pointcut()",returning = "ret")public void afterReturning(JoinPoint joinPoint, Object ret) {System.out.println("打印成功");}@AfterThrowing(pointcut = "pointcut()",throwing = "e")public void afterThrowing(Exception e) {System.out.println("打印失败");}@Around("pointcut()")public Object around(ProceedingJoinPoint joinPoint) {System.out.println("打印中");Object result = null;try {// 执行目标方法result = joinPoint.proceed();// 返回通知逻辑System.out.println("After method execution, result: " + result);} catch (Exception e) {// 异常通知逻辑System.out.println("Exception occurred: " + e.getMessage());} catch (Throwable e) {e.printStackTrace();} finally {// 后置最终通知，无论是否发生异常都会执行System.out.println("Finally block executed");return result;}}
}