Spring框架之IOC介紹講解
一、對spring的理解
spring是一個開源框架,它由Rod Johnson 創(chuàng)建。它是為了解決企業(yè)應(yīng)用開發(fā)的復(fù)雜性而創(chuàng)建的。
目的:解決企業(yè)應(yīng)用開發(fā)的復(fù)雜性
功能:使用基本的JavaBean代替EJB,并提供了更多的企業(yè)應(yīng)用功能
范圍:任何Java應(yīng)用
簡單來說,Spring是一個輕量級的控制反轉(zhuǎn)(IoC)和面向切面(AOP)的容器框架。
二、spring中ioc的特點
建一個maven項目
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> <!-- 將當(dāng)前項目所用的jar包依賴版本定義在外部目的在于所有jar 包版本進行統(tǒng)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、導(dǎo)入spring依賴 --> <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控制反轉(zhuǎn)
建一個com.yzp.biz的包
UserBiz
package com.yzp.biz; /** * 用戶業(yè)務(wù)類 * @author yzp * */ public interface UserBiz { void list(); }
建一個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("查詢用戶數(shù)據(jù)。。按照年齡排序。"); } }
UserBizImpl2
package com.yzp.biz.impl; import com.yzp.biz.UserBiz; public class UserBizImpl2 implements UserBiz{ @Override public void list() { System.out.println("查詢用戶數(shù)據(jù)。。按照入職時間排序。"); } }
建一個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(); } }
常規(guī)做法即運用spring之前的處理方法
需求:
同時在用戶模塊,訂單模塊拿到所有的用戶數(shù)據(jù)
需求變更1:
同時在用戶模塊,訂單模塊拿到所有的用戶數(shù)據(jù),并且要求用戶數(shù)據(jù)是通過年齡排序的
對應(yīng)策略:修改UserBiz中l(wèi)ist方法,添加排序功能
需求變更2:
同時在用戶模塊,訂單模塊拿到所有的用戶數(shù)據(jù),并且要求用戶數(shù)據(jù)是通過注冊時間排序的
對應(yīng)策略,修改UserBiz中l(wèi)ist方法,添加排序功能,按照時間點排序
總結(jié):
最原始:頻繁修改業(yè)務(wù)層biz的代碼
多實現(xiàn):凡是涉及到用戶業(yè)務(wù)層調(diào)用的地方,都需要修改代碼
將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:一定要在有網(wǎng)絡(luò)的情況下進行,否則約束不生效
IOC的主要作用管理整個項目的Javabean:依靠依賴注入、控制反轉(zhuǎn)的特點進行管理
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的主要作用管理整個項目的Javabean:依靠依賴注入、控制反轉(zhuǎn)的特點進行管理 --> <!-- <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; } }
建一個com.yzp.ioc的包
在里面建一個Demo1的類
建模,打印com.yzp.biz.impl.UserBizImpl2中的語句
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(); } }
運行結(jié)果:
可見 能拿到
總結(jié)
1.對spring框架的配置文件進行建模,建模之后spring-context.xml中所有的Javabean信息
都會加載進spring容器的上下文中
2.上下文中就包含了spring-context.xml 所有對象
測試orderaction也拿到相同結(jié)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的主要作用管理整個項目的Javabean:依靠依賴注入、控制反轉(zhuǎn)的特點進行管理 --> <!-- <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.對spring框架的配置文件進行建模,建模之后spring-context.xml中所有的Javabean信息 * 都會加載進spring容器的上下文中 * 2.上下文中就包含了spring-context.xml 所有對象 * @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(); } }
結(jié)果:
若是要按年齡排序,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的主要作用管理整個項目的Javabean:依靠依賴注入、控制反轉(zhuǎn)的特點進行管理 --> <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注入依賴
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的主要作用管理整個項目的Javabean:依靠依賴注入、控制反轉(zhuǎn)的特點進行管理 --> <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>籃球</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.對spring框架的配置文件進行建模,建模之后spring-context.xml中所有的Javabean信息 * 都會加載進spring容器的上下文中 * 2.上下文中就包含了spring-context.xml 所有對象 * @author yzp * * IOC特點(控制反轉(zhuǎn)):將創(chuàng)建對象的權(quán)利反轉(zhuǎn)給spring容器來完成 * * */ 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(); } }
結(jié)果;
方式② 構(gòu)造注入
OrderAction
package com.yzp.web; import java.util.List; import com.yzp.biz.UserBiz; import com.yzp.biz.impl.UserBizImpl1; /** * 依賴注入的三種方式: * 1.set注入 * 2.構(gòu)造注入 * 3.自動裝配 * 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的主要作用管理整個項目的Javabean:依靠依賴注入、控制反轉(zhuǎn)的特點進行管理 --> <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>籃球</value> <value>足球</value> <value>唱歌</value> </list> </property> </bean> <!-- 構(gòu)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>籃球1</value> <value>足球1</value> <value>唱歌1</value> </list> </constructor-arg> </bean> </beans>
運行結(jié)果:
方式③ 自動裝配
將set和構(gòu)造的注入 注釋
byType不報錯 byName報錯
自動裝配
default-autowire="byName"
byName:是通過spring管理的bean對象的ID進行查找,如果找不到,則注入失敗,反之成功
byType:是通過spring管理的bean對象的接口實現(xiàn)類進行查找,如果沒有或者2個以上,則注入失敗,反之成功
三、spring與web容器的整合
分析:
spring與web容器的整合原理
why:建模的過程是十分耗時的
解決問題:
1.建模必不可少
2.建模只保障只執(zhí)行一次
3.建模后期望在每一個servlet都能夠拿到spring的上下文對象ClassPathXmlApplicationContext
how:
1.監(jiān)聽器的初始化方法 只執(zhí)行一次
2.spring的上下文要存放在Tomcat上下文中
建一個包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("初始化執(zhí)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"); //將spring的上下文保存在Tomcat上下文中 servletContext.setAttribute("springContext", context); } }
在com.yzp.ioc中建一個類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與web容器的整合原理 * why:建模的過程是十分耗時的 * 解決問題: * 1.建模必不可少 * 2.建模只保障只執(zhí)行一次 * 3.建模后期望在每一個servlet都能夠拿到spring的上下文對象ClassPathXmlApplicationContext * how: * 1.監(jiān)聽器的初始化方法 只執(zhí)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的主要作用管理整個項目的Javabean:依靠依賴注入、控制反轉(zhuǎn)的特點進行管理 --> <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>籃球</value> <value>足球</value> <value>唱歌</value> </list> </property> </bean> <!-- 構(gòu)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>籃球1</value> <value>足球1</value> <value>唱歌1</value> </list> </constructor-arg> </bean> <!-- 自動裝配 --> </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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