Spring入门案例创建流程

Spring详细创建流程如下

1）创建Maven工程

        打开idea主界面

        创建maven项目填写流程

                  new Project ===> Name ==> Language ===> Maven ===> JDK ===> GroupId ===> Create

        删除src

                Src ===> 鼠标右键===>Delete

                 创建module

                        鼠标右键spring-demo ===> new ===> Module

                module填写

                        new Module ===> Name ==> Language ==> Build System ===> Jdk ==>Create

 

2）导入依赖

<!--导入spring-context依赖--><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>6.1.12</version></dependency><!--导入测试依赖--><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.13.2</version><scope>test</scope></dependency>

        导入maven依赖

                spring01下的pom.xml文件

3）创建MySrping.config

        鼠标右击resourse文件 ===> new  ===> XML  ==> SpringConfig

<?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">

    
</beans>

4）创建Users类

/**
 * 自定义类
 */
public class Users {

    public void userInfo(){
        System.out.println("userInfo");
    }
}
 

5）编写MyConfig.xml文件的bean

<?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">

    <!-- id 定义bean的id  -->
    <!-- class (包名+类名) 即Users类所在的路径 -->
    <bean id="users" class="org.xiji.Users">

    </bean>
    
</beans>

6）手动创建Users类

import org.junit.Test;
import org.xiji.Users;

public class CreateUsersByHandTest {

    @Test
    public void createUsers(){
        System.out.println("通过手写创建");
        Users users = new Users();
        System.out.println(users);
        users.userInfo();
    }
}

测试结果

7）通过spring框架的ClassPathXmlApplicationContext 创建对象

        new ClassPathXmlApplicationContext("加载指定配置类") ==> 加载bean

import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.xiji.Users;public class CreateUsersBySpringTest {@Testpublic void test(){System.out.println("使用spring框架创建");//通过xml文件创建对象  == >  加载指定的配置类ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("MyConfig.xml");Users users = context.getBean("users", Users.class);System.out.println(users);users.userInfo();}
}

        图片详解

测试结果

8）通过反射创建对象

        反射创建对象流程

                通过java反射机制 Class.forName("类的全类名") ===> 获取构造器 ==》 实例化对象 ==》强转 ==》o.userInfo()

        反射创建对象代码如下

import org.junit.Test;
import org.xiji.Users;public class CreateBeanByReflectTest {/*** 反射创建* spring是通过反射创建类的*/@Testpublic void createBeanByReflect() throws Exception {System.out.println("通过反射创建");//通过类的全路径创建类Class aClass = Class.forName("org.xiji.Users");/*** 获取构造器，然后创建对象*/Users o = (Users) aClass.getDeclaredConstructor().newInstance();System.out.println(o);o.userInfo();}
}

测试结果