1 在 spring 里面通过配置文件创建对象
2 bean 实例化三种方式实现
第一种、使用类的无参数构造创建(重点)
(1) xml 文件 bean1.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”>
- <!–ioc 入门–>
- <bean id=“user” class=“com.liuyanzhao.ioc.User”></bean>
- </beans>
(2) User 类
- package com.liuyanzhao.ioc;
- public class User {
- public void add() {
- System.out.println(“add……….”);
- }
- }
(3)测试类 TestIOC 类
- package com.liuyanzhao.ioc;
- import org.junit.Test;
- import org.springframework.context.ApplicationContext;
- import org.springframework.context.support.ClassPathXmlApplicationContext;
- public class TestIOC {
- @Test
- public void testUser() {
- //1、加载Spring配置文件,根据创建对象
- ApplicationContext context =
- new ClassPathXmlApplicationContext(“bean1.xml”);
- //2、得到配置创建的对象
- User user = (User) context.getBean(“user”);
- System.out.println(user);
- }
- }
第二种 、使用静态工厂创建(了解)
(1)xml 文件 bean1.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”>
- <!–使用静态工厂创建对象–>
- <bean id=“bean2” class=“com.liuyanzhao.bean.Bean2Factory” factory-method=“getBean2”></bean>
- </beans>
(2)Bean2 类
- package com.liuyanzhao.bean;
- public class Bean2 {
- public void add() {
- System.out.println(“bean2………”);
- }
- }
(3)Bean2Factory 类
- package com.liuyanzhao.bean;
- public class Bean2Factory {
- //静态方法,返回 Bean2 对象
- public static Bean2 getBean2() {
- return new Bean2();
- }
- }
(4) 测试类 TestIOC 类
- package com.liuyanzhao.bean;
- import org.junit.Test;
- import org.springframework.context.ApplicationContext;
- import org.springframework.context.support.ClassPathXmlApplicationContext;
- public class TestIOC {
- @Test
- public void testUser() {
- //1、加载Spring配置文件,根据创建对象
- ApplicationContext context =
- new ClassPathXmlApplicationContext(“bean1.xml”);
- //2、得到配置创建的对象
- Bean2 bean2 = (Bean2) context.getBean(“bean2”);
- System.out.println(bean2);
- }
- }
第三种、使用实例工厂创建(了解)
(1)xml 文件
- <?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”>
- <!–使用实例工厂创建对象–>
- <!–创建工厂对象–>
- <bean id=“bean3Factory” class=“com.liuyanzhao.bean.Bean3Factory”></bean>
- <bean id=“bean3” factory-bean=“bean3Factory” factory-method=“getBean3” ></bean>
- </beans>
(2) Bean3 类
- package com.liuyanzhao.bean;
- public class Bean3 {
- public void add() {
- System.out.println(“bean3………”);
- }
- }
(3)Bean3Factory 类
- package com.liuyanzhao.bean;
- public class Bean3Factory {
- //普通方法,返回 Bean3 对象
- public Bean3 getBean3() {
- return new Bean3();
- }
- }
(4)测试类 TestIOC 类
- package com.liuyanzhao.bean;
- import org.junit.Test;
- import org.springframework.context.ApplicationContext;
- import org.springframework.context.support.ClassPathXmlApplicationContext;
- public class TestIOC {
- @Test
- public void testUser() {
- //1、加载Spring配置文件,根据创建对象
- ApplicationContext context =
- new ClassPathXmlApplicationContext(“bean1.xml”);
- //2、得到配置创建的对象
- Bean3 bean3 = (Bean3) context.getBean(“bean3”);
- System.out.println(bean3);
- }
- }