Spring实例化对象方式①.构造器实例化（无参数构造器,与构造器的访问权限无关），最标准，使用最多。

最新推荐文章于 2024-12-18 23:57:14 发布

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本文通过Employee类演示了两种实例化方式：直接new和Spring容器管理。对比了传统实例化和Spring管理的区别，展示了如何在Spring中配置Bean并从容器获取实例。

Employee.java：

package text.spring._05_instance.constructor;

/**
 * Created by Administrator on 2019/9/2.
 */
public class Employee {
    public Employee(){
        System.out.println("构造函数的实例化方式");
    }
}

App.java：

package text.spring._05_instance.constructor;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

/**
 * Created by Administrator on 2019/9/2.
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration
public class App {
    @Autowired
    private ApplicationContext context;

    @Test
    public void testOld(){
        Employee em=new Employee();
        System.out.println(em);
    }

    @Test
    public void testSpring() throws Exception {
        Employee employee = context.getBean(Employee.class);
        System.out.println(employee);
    }
}

App-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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="employee" class="text.spring._05_instance.constructor.Employee">

    </bean>
</beans>