春季–豆工厂
当我们谈论 spring 时，最重要的事情是依赖注入，这是可能的，因为 spring 实际上是一个容器，表现得像一个 Beans 的工厂。就像 BeanFactory 接口是最简单的容器，它提供了一种高级配置机制来实例化、配置和管理 beans 的生命周期。Beans 是运行时由 Spring IoC 容器配置的 java 对象。BeanFactory 表示一个基本的 IoC 容器，它是 ApplicationContext 的父接口。 BeanFactory 使用 Beans 及其依赖元数据在运行时创建和配置它们。BeanFactory 基于配置文件(XML)在 bean 之间加载 bean 定义和依赖关系，或者可以在需要时使用 Java Configuration 直接返回 bean。还有其他类型的配置文件，如 LDAP、RDMS、属性文件等。BeanFactory 不支持基于注释的配置，而 ApplicationContext 支持。
让我们先了解一下 bean 工厂的一些方法，然后再开始实现，如下表所示:
| 【方法】 | 描述 | | --- | --- | | 包含 Bean(字符串名称) | Does this Bean factory contain Bean definitions or externally registered singletons with a given name? | | Getalias (string name) | Returns the alias of the given bean name, if any. | | getBean(类必需类型) | Returns the Bean instance (if any) that uniquely matches the given object type. | | getBean(类所需类型，对象…参数) | Returns an instance of the specified Bean, which can be shared or independent. | | [getBean (string name) | Returns an instance of the specified Bean, which can be shared or independent. | | getBean(字符串名称,类所需类型) | Returns an instance of the specified Bean, which can be shared or independent. | | 字符串名称，对象…参数 | Returns an instance of the specified Bean, which can be shared or independent. | | getbean 提供程序(类必需类型) | Returns the provider of the bean, allowing lazy on-demand retrieval of instances, including availability and uniqueness options. | | getBeanProvider(resolvableType 必需类型) | Returns the provider of the bean, allowing delayed on-demand retrieval of instances, including availability and uniqueness options. | | Gets the type (string name) | Determines the type of bean with the given name. | | getType(■⑴{ fnsimheibord 1 sh ad1 pos(200，288)}你好，-什么 allowfactorybeainit) | Determines the type of bean with the given name. | | Is rototype (string name) | Is this bean a prototype? That is to say, will getBean(java.lang.String) always return independent instances? | | 是单例(字符串名称) | Is this bean a shared singleton? That is to say, will getBean(java.lang.String) always return the same instance? | | isTypeMatch（字符串名称，类 typeToMatch） | Checks whether the bean with the given name matches the specified type. | | istype match(■⑴{ fnsimheibord 1 sh ad1 pos(200，288)}你好，解析 typeto match) | Checks whether the bean with the given name matches the specified type. |程序:
- 使用 start.spring.io 创建一个 Spring 项目。
- 创建 POJO 类。
- 在bean-工厂-演示. xml 文件中配置学生 bean。
- 将其写入应用程序类。
实施:
第一步: Bean 定义:创建一个 Student POJO 类。
// Java Program where we are creating a POJO class
// POJO class
public class Student {
// Member variables
private String name;
private String age;
// Constructor 1
public Student() {
}
// Constructor 2
public Student(String name, String age) {
this.name = name;
this.age = age;
}
// Method inside POJO class
@Override
public String toString() {
// Print student clas attributes
return "Student{" + "name='" + name + '\'' + ", age='" + age + '\'' + '}';
}
}
第二步: XML Bean 配置:在Bean-factory-demo . XML文件中配置学生 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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="student" class = "com.gfg.demo.domain.Student">
<constructor-arg name="name" value="Tina"/>
<constructor-arg name="age" value="21"/>
</bean>
</beans>
第三步:主类
// Application class
@SpringBootApplication
// Main class
public class DemoApplication {
// Main driver method
public static void main(String[] args) {
// Creating object in a spring container (Beans)
BeanFactory factory = new ClassPathXmlApplicationContext("bean-factory-demo.xml");
Student student = (Student) factory.getBean("student");
System.out.println(student);
}
}
输出:
Student{name='Tina', age='21'}
注意:XmlBeanFactory 类已弃用。
版权属于：月萌API www.moonapi.com，转载请注明出处
