Spring

Spring

IOC / AOP

​ Ioc—Inversion of Control，即“控制反转”，不是什么技术，而是一种设计思想。在Java开发中，Ioc意味着将你设计好的对象交给容器控制，而不是传统的在你的对象内部直接控制。如何理解好Ioc呢？理解好Ioc的关键是要明确“谁控制谁，控制什么，为何是反转（有反转就应该有正转了），哪些方面反转了”，那我们来深入分析一下：

●谁控制谁，控制什么：传统Java SE程序设计，我们直接在对象内部通过new进行创建对象，是程序主动去创建依赖对象；而IoC是有专门一个容器来创建这些对象，即由Ioc容器来控制对 象的创建；谁控制谁？当然是IoC 容器控制了对象；控制什么？那就是主要控制了外部资源获取（不只是对象包括比如文件等）。

●为何是反转，哪些方面反转了：有反转就有正转，传统应用程序是由我们自己在对象中主动控制去直接获取依赖对象，也就是正转；而反转则是由容器来帮忙创建及注入依赖对象；为何是反转？因为由容器帮我们查找及注入依赖对象，对象只是被动的接受依赖对象，所以是反转；哪些方面反转了？依赖对象的获取被反转了。

HelloSpring

package com.yrz.pojo;public class Hello {    private String str;    public String getStr() { return str;    }    public void setStr(String str) { this.str = str;    }    @Override    public String toString() { return "Hello{" +  "str='" + str + '\'' +  '}';    }}

<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd">    <bean id="hello" class="com.yrz.pojo.Hello"> <property name="str" value="YRZ"/>    </bean></beans>

import com.yrz.pojo.Hello;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class MyTest {    public static void main(String[] args) { //获取spring的上下文对象 ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml"); Hello hello = (Hello) context.getBean("hello"); System.out.println(hello.toString());    }    }

IOC创建对象的方式

package com.yrz.pojo;public class User {    private String name;    public User(String name){ this.name = name;    }    public String getName() { return name;    }    public void setName(String name) { this.name = name;    }    public void show() { System.out.println("name="+name);    }}

构造器注入

<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd">    <bean id="user" class="com.yrz.pojo.User">  <constructor-arg index="0" value="yrz"/>    </bean>    <bean id="user" class="com.yrz.pojo.User">  <constructor-arg type="java.lang.String" value="yrz"/>    </bean>    <bean id="user" class="com.yrz.pojo.User">  <constructor-arg name="name" value="yrz"/>    </bean></beans>

import com.yrz.pojo.User;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test {    public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml"); User user = (User) context.getBean("user"); user.show();    }}

依赖注入之–Set注入（重点）

<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:util="http://www.springframework.org/schema/util"xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/util https://www.springframework.org/schema/util/spring-util.xsd">    <bean id="address" class="com.yrz.pojo.Address"> <property name="address" value="上海"></property>    </bean>    <bean id="student" class="com.yrz.pojo.Student">  <property name="name" value="yrz"></property>  <property name="address" ref="address"></property>  <property name="books">     <array>  <value>红楼梦</value>  <value>西游记</value>  <value>三国演义</value>  <value>水浒传</value>     </array> </property>  <property name="hobbys">     <list>  <value>听歌</value>  <value>打游戏</value>  <value>看电影</value>     </list> </property>  <property name="card">     <map>  <entry key="身份证" value="6531"></entry>  <entry key="学生证" value="1998"></entry>     </map> </property>  <property name="game">     <set><value>LOL</value><value>COC</value>     </set> </property>  <property name="wife">     <null></null> </property>  <property name="info">     <props>  <prop key="学号">132456</prop>  <prop key="性别">男</prop>  <prop key="名字">Y</prop>     </props> </property></bean></beans>

注解自动装配

package com.yrz.pojo;import org.springframework.beans.factory.annotation.Autowired;public class People {    private String name;    @Autowired    private Cat cat;    @Autowired    private Dog dog;    public String getName() { return name;    }    public void setName(String name) { this.name = name;    }    public Cat getCat() { return cat;    }    public void setCat(Cat cat) { this.cat = cat;    }    public Dog getDog() { return dog;    }    public void setDog(Dog dog) { this.dog = dog;    }    @Override    public String toString() { return "People{" +  "name='" + name + '\'' +  ", cat=" + cat +  ", dog=" + dog +  '}';    }}

<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 https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd    <context:annotation-config/>    <bean id="cat" class="com.yrz.pojo.Cat"></bean>    <bean id="dog" class="com.yrz.pojo.Dog"></bean>    <bean id="people" class="com.yrz.pojo.People"></bean></beans>

import com.yrz.pojo.People;import org.junit.Test;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class MyTest { @Test public void test1(){     ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");     People people = context.getBean("people", People.class);     people.getCat().shout();     people.getDog().shout(); }    }

在xml中开启注解的支持

<context:component-scan base-package="com.yrz.pojo"/><context:annotation-config/>

@Autowired:自动装配先通过类型，再通过名字

@Resource：自动装配先通过名字，再通过类型

@Qualifier：使用@Qualifier(value="")去配置@Autowired的使用

@Component(“user”)：// 相当于配置文件中

–dao【@Repository】

–service【@Service】

–controller【@Controller】【@RestController】-- 不走视图层，返回字符串

@Scope：作用域

@Configuration：代表这是一个配置类，和beans.xml一样

@Bean：作用于方法上，相当于bean标签，id是方法名，class是返回值

@ComponentScan：扫描Component

@Aspect：标志这个类是一个切面

package com.yrz.pojo;import org.springframework.beans.factory.annotation.Value;import org.springframework.context.annotation.Scope;import org.springframework.stereotype.Component;//相当于配置文件中 @Component//作用域@Scope("prototype")public class User {    public String name;    //相当于     @Value("YRZ")    public void setName(String name) { this.name = name;    }}

静态代理模式

UserService

package com.yrz.demo02;public interface UserService {    public void add();    public void delete();    public void update();    public void query();}

UserServiceImpl

package com.yrz.demo02;public class UserServiceImpl implements UserService{    public void add() { System.out.println("add");    }    public void delete() { System.out.println("delete");    }    public void update() { System.out.println("update");    }    public void query() { System.out.println("query");    }}

UserServiceProxy

package com.yrz.demo02;public class UserServiceProxy implements UserService{    private UserServiceImpl userService;    public void setUserService(UserServiceImpl userService) { this.userService = userService;    }    public void add() { log("add"); userService.add();    }    public void delete() { log("delete"); userService.delete();    }    public void update() { log("update"); userService.update();    }    public void query() { log("query"); userService.query();    }    public void log(String msg){ System.out.println("[Debug]使用了"+msg+"方法");    }}

Client

package com.yrz.demo02;public class Client {    public Client() {    }    public static void main(String[] args) { UserServiceImpl userService = new UserServiceImpl(); UserServiceProxy proxy = new UserServiceProxy(); proxy.setUserService(userService); proxy.add();    }}

动态代理模式

• 基于接口–JDK动态代理

了解两个类：

• Proxy–代理
• InvocationHandler–调用处理程序

ProxyInvocationHandler

package com.yrz.demo04;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;public class ProxyInvocationHandler implements InvocationHandler {    //被代理的接口    private Object target;    public void setTarget(Object target) { this.target = target;    } //生成得到代理类    public Object getProxy(){ return Proxy.newProxyInstance(this.getClass().getClassLoader()  ,target.getClass().getInterfaces(),this);    }    //处理代理实例，并返回结果    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { log(method.getName()); Object result = method.invoke(target, args); return result;    }    public void log(String msg){ System.out.println("使用了"+msg+"方法");    }}

Client

package com.yrz.demo04;import com.yrz.demo02.UserService;import com.yrz.demo02.UserServiceImpl;public class Client {    public static void main(String[] args) { //真实角色 UserServiceImpl userService = new UserServiceImpl(); //代理角色，不存在 ProxyInvocationHandler pih = new ProxyInvocationHandler(); pih.setTarget(userService);//设置要代理的对象 //动态生成代理类 UserService proxy = (UserService) pih.getProxy(); proxy.delete();    }}

AOP实现方式一

使用原生Spring API接口（主要是Spring API接口实现）

package com.yrz.service;public class UserServiceImpl implements UserService{    public void add() { System.out.println("增");    }    public void delete() { System.out.println("删");    }    public void update() { System.out.println("改");    }    public void select() { System.out.println("查");    }}

package com.yrz.service;import org.springframework.aop.MethodBeforeAdvice;import java.lang.reflect.Method;public class Log implements MethodBeforeAdvice {    //method:要执行的目标对象方法    //args:参数    //target:目标    public void before(Method method, Object[] args, Object target) throws Throwable { System.out.println(target.getClass().getName()+"的"+method.getName()+"方法被执行了");    }}

package com.yrz.service;import org.springframework.aop.AfterReturningAdvice;import java.lang.reflect.Method;public class AfterLog implements AfterReturningAdvice {    public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable { System.out.println("执行了"+method.getName()+"方法，返回值结果为："+returnValue);    }}

<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"xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd"> <bean id="userService" class="com.yrz.service.UserServiceImpl"></bean>    <bean id="log" class="com.yrz.service.Log"></bean>    <bean id="afterLog" class="com.yrz.service.AfterLog"></bean>    <aop:config>     <aop:pointcut id="pointcut" expression="execution(* com.yrz.service.UserServiceImpl.*(..))"/>     <aop:advisor advice-ref="log" pointcut-ref="pointcut"></aop:advisor> <aop:advisor advice-ref="afterLog" pointcut-ref="pointcut"></aop:advisor>    </aop:config></beans>

import com.yrz.service.UserService;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class MyTest {    public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); UserService userService = (UserService) context.getBean("userService"); userService.add();    }}

AOP实现方式二

使用自定义类来实现AOP（主要是切面定义）

package com.yrz.diy;public class DiyPointCut {    public void before(){ System.out.println("========方法执行前========");    }    public void after(){ System.out.println("========方法执行后========");    }}

<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"xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">    <bean id="userService" class="com.yrz.service.UserServiceImpl"></bean>    <bean id="log" class="com.yrz.service.Log"></bean>    <bean id="afterLog" class="com.yrz.service.AfterLog"></bean>    <bean id="diy" class="com.yrz.diy.DiyPointCut"></bean>    <aop:config>  <aop:aspect ref="diy">          <aop:pointcut id="point" expression="execution(* com.yrz.service.UserServiceImpl.*(..))"/>     <aop:before method="before" pointcut-ref="point"></aop:before>     <aop:after method="after" pointcut-ref="point"></aop:after> </aop:aspect>    </aop:config></beans>

AOP实现方式三

注解实现AOP

package com.yrz.diy;import org.aspectj.lang.annotation.After;import org.aspectj.lang.annotation.Aspect;import org.aspectj.lang.annotation.Before;@Aspect //标注这个类是一个切面public class AnnotationPointCut {    @Before("execution(* com.yrz.service.UserServiceImpl.*(..))")    public void before(){ System.out.println("执行前");    }    @After("execution(* com.yrz.service.UserServiceImpl.*(..))")    public void after(){ System.out.println("执行后");    }}

<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"xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">    <bean id="userService" class="com.yrz.service.UserServiceImpl"></bean>    <bean id="log" class="com.yrz.service.Log"></bean>    <bean id="afterLog" class="com.yrz.service.AfterLog"></bean>        <bean id="annotationPointCut" class="com.yrz.diy.AnnotationPointCut"></bean>        <aop:aspectj-autoproxy></aop:aspectj-autoproxy></beans>