Learn more about IOC and AOP

This is the sixth day of my participation in the First Challenge 2022. For details: First Challenge 2022.

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6. IOC object creation method

6.1 Create by using the no-argument constructor

User.java

package com.spring.pojo; /** * @projectName: Spring5study * @package: com.spring. Pojo * @classname: User * @author: Zhang Shengrui * @date: 2022/1/23 22:00 * @version: 1.0 */ public class User {private String name; Public User() {system.out.println (" User entity class calls no-argument constructor "); } public void setName(String name) { this.name = name; } public void show() { System.out.println("name=" + name); }}Copy the code

bean.xml

<? The XML version = "1.0" encoding = "utf-8"? > <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 http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="user" class="com.spring.pojo.User"> <property name="name" value="changzhang"/> </bean> </beans>Copy the code

The test class

import com.spring.pojo.User; import org.junit.jupiter.api.Test; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; /** * @projectName: Spring5study * @package: PACKAGE_NAME * @classname: MyTest * @author: Zhang Shenggrui * @date: 2022/1/23 22:01 * @Version: Public class MyTest {@test public void Test (){ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml"); User = (user) context.getBean("user"); user = (user) context.getbean ("user"); // Call the object's method.user.show (); }}Copy the code

The results

As it turns out, the User object was already initialized with no-argument construction before the show method was called!

6.2 Create by the parameter constructor

UserT.java

package com.spring.pojo; /** * @projectName: Spring5study * @package: com.spring. Pojo * @classname: UserT * @author: Zhang Shengrui * @date: 2022/1/23 22:06 * @version: 1.0 */ public class UserT {private String name; public UserT(String name) { this.name = name; } public void setName(String name) { this.name = name; } public void show(){ System.out.println("name="+ name ); }}Copy the code

bean.xml

The first is based on the index parameter

<? The XML version = "1.0" encoding = "utf-8"? > <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 http://www.springframework.org/schema/beans/spring-beans.xsd"> <! <bean id="userT" class="com.spring.pojo. userT" > <! Constructor ="0" value="changzhang"/> </bean> </beans>Copy the code

The second is based on the parameter name

<? The XML version = "1.0" encoding = "utf-8"? > <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 http://www.springframework.org/schema/beans/spring-beans.xsd"> <! Bean id="userT" class="com.kuang.pojo. userT" > <! <constructor-arg name="name" value="changzhang"Copy the code

The third is based on the parameter type

<? The XML version = "1.0" encoding = "utf-8"? > <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 http://www.springframework.org/schema/beans/spring-beans.xsd"> <! Class ="com.spring.pojo. userT" > <constructor-arg type=" java.lang.string" value="changzhang"/> </bean> </beans>Copy the code

The test class

import com.spring.pojo.User; import org.junit.jupiter.api.Test; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; /** * @projectName: Spring5study * @package: PACKAGE_NAME * @classname: MyTest * @author: Zhang Shenggrui * @date: 2022/1/23 22:01 * @Version: Public class MyTest {@test public void testT() {ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml"); UserT user = (UserT) context.getBean("userT"); user.show(); }}Copy the code

The results

Conclusion: When the configuration file is loaded. All managed objects are already initialized!

Spring5demo: Spring Clocking learning (github.com)

After the language

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