Spring框架之IOC介绍讲解

目录

一、对spring的理解

二、spring中ioc的特点

2.1控制反转

2.2注入依赖

方式① set注入

方式② 构造注入

方式③ 自动装配

三、spring与web容器的整合

一、对spring的理解

spring是一个开源框架,它由Rod Johnson 创建。它是为了解决企业应用开发的复杂性而创建的。

目的:解决企业应用开发的复杂性

功能:使用基本的JavaBean代替EJB,并提供了更多的企业应用功能

范围:任何Java应用

简单来说,Spring是一个轻量级的控制反转(IoC)和面向切面(AOP)的容器框架。

二、spring中ioc的特点

建一个maven项目

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.yzp</groupId> <artifactId>T280_spring</artifactId> <packaging>war</packaging> <version>0.0.1-SNAPSHOT</version> <name>T280_spring Maven Webapp</name> <url>http://maven.apache.org</url> <!-- 将当前项目所用的jar包依赖版本定义在外部目的在于所有jar 包版本进行统一管理--> <properties> <spring.version>5.0.1.RELEASE</spring.version> <javax.servlet.version>4.0.0</javax.servlet.version> <junit.version>4.12</junit.version> </properties> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <!-- 2、导入spring依赖 --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aspects</artifactId> <version>${spring.version}</version> </dependency> <!-- 5.1、junit --> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>${junit.version}</version> <scope>test</scope> </dependency> <!-- 5.2、servlet --> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>${javax.servlet.version}</version> <scope>provided</scope> </dependency> </dependencies> <build> <finalName>T280_spring</finalName> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.7.0</version> <configuration> <source>1.8</source> <target>1.8</target> <encoding>UTF-8</encoding> </configuration> </plugin> </plugins> </build> </project>

web.xml

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1"> <display-name>Archetype Created Web Application</display-name> </web-app> 2.1控制反转

建一个com.yzp.biz的包

UserBiz

package com.yzp.biz; /** * 用户业务类 * @author yzp * */ public interface UserBiz { void list(); }

建一个com.yzp.biz.impl的包

UserBizImpl1

package com.yzp.biz.impl; import com.yzp.biz.UserBiz; public class UserBizImpl1 implements UserBiz{ @Override public void list() { System.out.println("查询用户数据。。按照年龄排序。"); } }

UserBizImpl2

package com.yzp.biz.impl; import com.yzp.biz.UserBiz; public class UserBizImpl2 implements UserBiz{ @Override public void list() { System.out.println("查询用户数据。。按照入职时间排序。"); } }

建一个com.yzp.web的包

OrderAction

package com.yzp.web; import com.yzp.biz.UserBiz; import com.yzp.biz.impl.UserBizImpl1; public class OrderAction { private UserBiz userBiz = new UserBizImpl1(); public void list() { userBiz.list(); } }

UserAction

package com.yzp.web; import com.yzp.biz.UserBiz; import com.yzp.biz.impl.UserBizImpl1; public class UserAction { private UserBiz userBiz = new UserBizImpl1(); public void list() { userBiz.list(); } }

常规做法即运用spring之前的处理方法

需求:
同时在用户模块,订单模块拿到所有的用户数据
需求变更1:
同时在用户模块,订单模块拿到所有的用户数据,并且要求用户数据是通过年龄排序的
对应策略:修改UserBiz中list方法,添加排序功能
需求变更2:
同时在用户模块,订单模块拿到所有的用户数据,并且要求用户数据是通过注册时间排序的
对应策略,修改UserBiz中list方法,添加排序功能,按照时间点排序

总结:
最原始:频繁修改业务层biz的代码
多实现:凡是涉及到用户业务层调用的地方,都需要修改代码

将spring的配置文件加入

spring-context.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: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/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"> </beans>

注意:一定要在有网络的情况下进行,否则约束不生效

IOC的主要作用管理整个项目的Javabean:依靠依赖注入、控制反转的特点进行管理

spring-context.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: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/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"> <!-- IOC的主要作用管理整个项目的Javabean:依靠依赖注入、控制反转的特点进行管理 --> <!-- <bean class="com.yzp.biz.impl.UserBizImpl1" id="userBiz1"></bean> --> <bean class="com.yzp.biz.impl.UserBizImpl2" id="userBiz2"></bean> <bean class="com.yzp.web.UserAction" id="userAction"> <property name="userBiz" ref="userBiz2"></property> </bean> <bean class="com.yzp.web.OrderAction" id="orderAction"></bean> </beans>

UserAction

package com.yzp.web; import com.yzp.biz.UserBiz; import com.yzp.biz.impl.UserBizImpl1; public class UserAction { //private UserBiz userBiz = new UserBizImpl1(); private UserBiz userBiz; public void list() { userBiz.list(); } public UserBiz getUserBiz() { return userBiz; } public void setUserBiz(UserBiz userBiz) { this.userBiz = userBiz; } }

建一个com.yzp.ioc的包

在里面建一个Demo1的类

建模,打印com.yzp.biz.impl.UserBizImpl2中的语句

package com.yzp.ioc; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.yzp.web.UserAction; public class Demo1 { @SuppressWarnings("resource") public static void main(String[] args) { //建模 ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("/spring-context.xml"); UserAction userAction = (UserAction) context.getBean("userAction"); userAction.list(); } }

运行结果:

可见 能拿到

 总结

1.对spring框架的配置文件进行建模,建模之后spring-context.xml中所有的Javabean信息
 都会加载进spring容器的上下文中
2.上下文中就包含了spring-context.xml 所有对象

测试orderaction也拿到相同结果,配置和orderaction都如useraction一致修改

package com.yzp.web; import com.yzp.biz.UserBiz; import com.yzp.biz.impl.UserBizImpl1; public class OrderAction { //private UserBiz userBiz = new UserBizImpl1(); private UserBiz userBiz; public void list() { userBiz.list(); } public UserBiz getUserBiz() { return userBiz; } public void setUserBiz(UserBiz userBiz) { this.userBiz = userBiz; } } <?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: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/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"> <!-- IOC的主要作用管理整个项目的Javabean:依靠依赖注入、控制反转的特点进行管理 --> <!-- <bean class="com.yzp.biz.impl.UserBizImpl1" id="userBiz1"></bean> --> <bean class="com.yzp.biz.impl.UserBizImpl2" id="userBiz2"></bean> <bean class="com.yzp.web.UserAction" id="userAction"> <property name="userBiz" ref="userBiz2"></property> </bean> <bean class="com.yzp.web.OrderAction" id="orderAction"> <property name="userBiz" ref="userBiz2"></property> </bean> </beans> package com.yzp.ioc; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.yzp.web.OrderAction; import com.yzp.web.UserAction; /** * 1.对spring框架的配置文件进行建模,建模之后spring-context.xml中所有的Javabean信息 * 都会加载进spring容器的上下文中 * 2.上下文中就包含了spring-context.xml 所有对象 * @author yzp * */ public class Demo1 { @SuppressWarnings("resource") public static void main(String[] args) { //建模 ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("/spring-context.xml"); UserAction userAction = (UserAction) context.getBean("userAction"); userAction.list(); OrderAction orderAction = (OrderAction) context.getBean("orderAction"); orderAction.list(); } }

结果:

若是要按年龄排序,就只需要修改配置文件就OK了

<?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: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/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"> <!-- IOC的主要作用管理整个项目的Javabean:依靠依赖注入、控制反转的特点进行管理 --> <bean class="com.yzp.biz.impl.UserBizImpl1" id="userBiz2"></bean> <bean class="com.yzp.web.UserAction" id="userAction"> <property name="userBiz" ref="userBiz2"></property> </bean> <bean class="com.yzp.web.OrderAction" id="orderAction"> <property name="userBiz" ref="userBiz2"></property> </bean> </beans>

2.2注入依赖 方式① set注入

UserAction

package com.yzp.web; import java.util.List; import com.yzp.biz.UserBiz; import com.yzp.biz.impl.UserBizImpl1; public class UserAction { //private UserBiz userBiz = new UserBizImpl1(); private UserBiz userBiz; public UserBiz getUserBiz() { return userBiz; } public void setUserBiz(UserBiz userBiz) { this.userBiz = userBiz; } private String name; private int age; private List<String> hobby; public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public List<String> getHobby() { return hobby; } public void setHobby(List<String> hobby) { this.hobby = hobby; } public void list() { System.out.println(name); System.out.println(age); System.out.println(hobby); userBiz.list(); } } <?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: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/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"> <!-- IOC的主要作用管理整个项目的Javabean:依靠依赖注入、控制反转的特点进行管理 --> <bean class="com.yzp.biz.impl.UserBizImpl1" id="userBiz2"></bean> <bean class="com.yzp.web.UserAction" id="userAction"> <property name="userBiz" ref="userBiz2"></property> <!--set注入 --> <property name="age" value="22"></property> <property name="name" value="cdl"></property> <property name="hobby"> <list> <value>篮球</value> <value>足球</value> <value>唱歌</value> </list> </property> </bean> <bean class="com.yzp.web.OrderAction" id="orderAction"> <property name="userBiz" ref="userBiz2"></property> </bean> </beans> package com.yzp.ioc; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.yzp.web.OrderAction; import com.yzp.web.UserAction; /** * 1.对spring框架的配置文件进行建模,建模之后spring-context.xml中所有的Javabean信息 * 都会加载进spring容器的上下文中 * 2.上下文中就包含了spring-context.xml 所有对象 * @author yzp * * IOC特点(控制反转):将创建对象的权利反转给spring容器来完成 * * */ public class Demo1 { @SuppressWarnings("resource") public static void main(String[] args) { //建模 ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("/spring-context.xml"); UserAction userAction = (UserAction) context.getBean("userAction"); userAction.list(); OrderAction orderAction = (OrderAction) context.getBean("orderAction"); orderAction.list(); } }

结果;

方式② 构造注入

OrderAction

package com.yzp.web; import java.util.List; import com.yzp.biz.UserBiz; import com.yzp.biz.impl.UserBizImpl1; /** * 依赖注入的三种方式: * 1.set注入 * 2.构造注入 * 3.自动装配 * byName * byType * @author yzp * */ public class OrderAction { //private UserBiz userBiz = new UserBizImpl1(); private UserBiz userBiz; public UserBiz getUserBiz() { return userBiz; } public void setUserBiz(UserBiz userBiz) { this.userBiz = userBiz; } private String name; private int age; private List<String> hobby; public OrderAction(String name, int age, List<String> hobby) { super(); this.name = name; this.age = age; this.hobby = hobby; } public OrderAction() { super(); // TODO Auto-generated constructor stub } public void list() { System.out.println(name); System.out.println(age); System.out.println(hobby); userBiz.list(); } } <?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: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/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"> <!-- IOC的主要作用管理整个项目的Javabean:依靠依赖注入、控制反转的特点进行管理 --> <bean class="com.yzp.biz.impl.UserBizImpl1" id="userBiz2"></bean> <!--set注入 --> <bean class="com.yzp.web.UserAction" id="userAction"> <property name="userBiz" ref="userBiz2"></property> <property name="age" value="22"></property> <property name="name" value="cdl"></property> <property name="hobby"> <list> <value>篮球</value> <value>足球</value> <value>唱歌</value> </list> </property> </bean> <!-- 构造注入 --> <bean class="com.yzp.web.OrderAction" id="orderAction"> <property name="userBiz" ref="userBiz2"></property> <constructor-arg name="name" value="yzp"></constructor-arg> <constructor-arg name="age" value="23"></constructor-arg> <constructor-arg name="hobby"> <list> <value>篮球1</value> <value>足球1</value> <value>唱歌1</value> </list> </constructor-arg> </bean> </beans>

运行结果:

方式③ 自动装配

将set和构造的注入 注释

byType不报错 byName报错

自动装配
 default-autowire="byName" 
 byName:是通过spring管理的bean对象的ID进行查找,如果找不到,则注入失败,反之成功
 byType:是通过spring管理的bean对象的接口实现类进行查找,如果没有或者2个以上,则注入失败,反之成功

三、spring与web容器的整合

分析:

spring与web容器的整合原理
    why:建模的过程是十分耗时的
  解决问题:
 1.建模必不可少
 2.建模只保障只执行一次
 3.建模后期望在每一个servlet都能够拿到spring的上下文对象ClassPathXmlApplicationContext
   how:
  1.监听器的初始化方法 只执行一次
  2.spring的上下文要存放在Tomcat上下文中

建一个包com.yzp.ioc.listener

package com.yzp.ioc.listener; import javax.servlet.ServletContext; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; import org.springframework.context.support.ClassPathXmlApplicationContext; public class SpringLoadListener implements ServletContextListener{ @Override public void contextInitialized(ServletContextEvent sce) { System.out.println("初始化执行"); ServletContext servletContext = sce.getServletContext(); String springConfigLocation = servletContext.getInitParameter("springConfigLocation"); System.out.println(springConfigLocation+"..."); //拿到spring上下文 ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("/spring-context.xml"); //将spring的上下文保存在Tomcat上下文中 servletContext.setAttribute("springContext", context); } }

在com.yzp.ioc中建一个类DemoServlet

package com.yzp.ioc; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.yzp.web.UserAction; /** * spring与web容器的整合原理 * why:建模的过程是十分耗时的 * 解决问题: * 1.建模必不可少 * 2.建模只保障只执行一次 * 3.建模后期望在每一个servlet都能够拿到spring的上下文对象ClassPathXmlApplicationContext * how: * 1.监听器的初始化方法 只执行一次 * 2.spring的上下文要存放在Tomcat上下文中 * @author yzp * */ @WebServlet("/springDemo") public class DemoServlet extends HttpServlet{ @Override protected void service(HttpServletRequest arg0, HttpServletResponse arg1){ //ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("/spring-context.xml"); ClassPathXmlApplicationContext context = (ClassPathXmlApplicationContext) arg0.getServletContext().getAttribute("springContext"); UserAction userAction = (UserAction) context.getBean("userAction"); userAction.list(); } }

spring-context.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: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/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"> <!-- IOC的主要作用管理整个项目的Javabean:依靠依赖注入、控制反转的特点进行管理 --> <bean class="com.yzp.biz.impl.UserBizImpl1" id="userBiz"></bean> <bean class="com.yzp.biz.impl.UserBizImpl1" id="userBiz1"></bean> <!--set注入 --> <bean class="com.yzp.web.UserAction" id="userAction"> <property name="userBiz" ref="userBiz1"></property> <property name="age" value="22"></property> <property name="name" value="cdl"></property> <property name="hobby"> <list> <value>篮球</value> <value>足球</value> <value>唱歌</value> </list> </property> </bean> <!-- 构造注入 --> <bean class="com.yzp.web.OrderAction" id="orderAction"> <property name="userBiz" ref="userBiz1"></property> <constructor-arg name="name" value="yzp"></constructor-arg> <constructor-arg name="age" value="23"></constructor-arg> <constructor-arg name="hobby"> <list> <value>篮球1</value> <value>足球1</value> <value>唱歌1</value> </list> </constructor-arg> </bean> <!-- 自动装配 --> </beans>

web.xml

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1"> <display-name>Archetype Created Web Application</display-name> <context-param> <param-name>springConfigLocation</param-name> <param-value>/applicationContext.xml</param-value> </context-param> <listener> <listener-class>com.yzp.ioc.listener.SpringLoadListener</listener-class> </listener> </web-app>

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