1.创建Maven工程,pom.xml文件导入依赖
<dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>5.3.20</version> </dependency>
2.创建一个entity包,在包里面创建一个student类,
public class student { private String name; private Integer age; private Integer id;
}
3.然后生成get和set方法以及tostring方法
package org.example.entity; public class student { private String name; private Integer age; private Integer id; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } @java.lang.Override public java.lang.String toString() { return "student{" + "name=" + name + ", age=" + age + ", id=" + id + '}'; } }
4.我们可以通过lombok依赖快速自动生成get和set方法,先在pom.xml文件中引入lombok依赖
<dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>1.18.10</version> </dependency>
然后在类前注入@Data注解
会自动生成get和set等方法
如果只需要get方法就引入get注解
只需要set方法就引入setter注解
需要无参构造方法就引入NoArgsConstructor注解
需要有参构造方法就引入AllArgsConstructor注解
5.使用lombok必须提前在idea中安装插件
6.然后创建一个text包,创建一个text类,
package org.example.test; import org.example.entity.student; import java.lang.*; public class test { public static void main(String[] args) { student student = new student(); System.out.println(student); } }
7.运行后结果如下:
小结.以上方法是传统方式创建对象,手动创建对象,
Ioc方式
接下来我们用Ioc方式自动创建对象,开发者只需要取出对象即可
1.首先我们需要一个配置文件,在resources包里面创建spring.xml文件,在里面加上文件配置头文件,直接复制粘贴即可
<?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:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> ...<!--中间xml文件部分-->..... </beans>
2.IoC容器通过读取spring.xml配置文件,加载bean标签来创建对象
<bean id="student" class="org.example.entity.student"></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" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <bean id="student" class="org.example.entity.student"></bean> </beans>
3.调用API获取IoC容器中已经创建的对象
public class test { public static void main(String[] args) { ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml"); student student = (student) applicationContext.getBean("student"); System.out.println(student); } }