一.IOC简介
IOC inversion of controller（控制反转）
spring的控制反转：
- 是一种设计思想。
- 把对象的创建，初始化，销毁等工作交给spring ioc容器，由spring ioc容器控制对象的生命周期。
二.spring创建对象的三种方式
spring创建对象的三种方式参考
创建com.jp.domain包，存放JavaBean对象
package com.jp.domain;
public class Person {
public String name;
//无参构造
public Person(){}
//有参构造
public Person(String name){this.name=name;}
public void talk(){
System.out.println("讲话...");
}
}
applicationContext.xml，总的xml配置文件
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<!-- applicationContext.xml文件是主文件 -->
<!-- 导入applicationContext_helloworld.xml文件 -->
<import resource="com/jp/applicationContext_helloworld.xml"/>
<!-- 导入applicationContext_person.xml文件 -->
<import resource="com/jp/domain/applicationContext_person.xml"/>
</beans>
1.无参构造
applicationContext_person.xml配置文件
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<!-- 无参构造 -->
<bean id="p" class="com.jp.domain.Person"></bean>
</beans>
测试类Demo.java
package com.jp.domain;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Demo {
//方式1：spring通过默认的构造函数创建对象
@Test
public void test1(){
ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");
Object o = ac.getBean("p");
Person p=(Person)o;
System.out.println(p);
}
}
2.静态工厂
创建工厂类，BeanFactory.java
package com.jp.domain;
public class BeanFactory {
//静态工厂，不用创建对象，直接类名.方法使用
public static Person getInstance(){
return new Person();
}
}
applicationContext.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" xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<!-- 静态工厂 -->
<bean id="factory" class="com.jp.domain.BeanFactory" factory-method="getInstance"></bean>
</beans>
测试类Demo.java
package com.jp.domain;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Demo {
//方式2：spring通过静态工厂创建对象
@Test
public void test2(){
ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");
Person p = (Person)ac.getBean("factory");
System.out.println(p);
}
}
3.实例工厂
创建工厂类，BeanFactory.java
package com.jp.domain;
public class BeanFactory {
//实例化工厂，要先创建BeanFactory对象，才能调用这个方法
public Person getInstance(){
return new Person();
}
}
applicationContext.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" xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<!-- 实例工厂 -->
<!-- factory-bean要与上面的id值一样，下面的id值可以随便写 -->
<bean id="factory" class="com.jp.domain.BeanFactory"></bean>
<bean id="f" factory-bean="factory" factory-method="getInstance"></bean>
</beans>
测试类Demo.java
package com.jp.domain;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Demo {
//方式3：spring通过实例化工厂创建对象
@Test
public void test3(){
ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");
BeanFactory factory = (BeanFactory)ac.getBean("factory");
System.out.println(factory);
Person p =(Person)ac.getBean("f");
System.out.println(p);
}
}
三.Bean标签
1.bean标签的scope属性
Demo.java
package com.jp.scope;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.jp.domain.Person;
public class Demo {
@Test
public void test1(){
ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");
Person p1 = (Person) ac.getBean("p");
System.out.println(p1);
Person p2 = (Person) ac.getBean("p");
System.out.println(p2);
Person p3 = (Person) ac.getBean("p");
System.out.println(p3);
}
}
①.singleton
单例，scope属性的默认值。代表在spring ioc容器中只创建一个bean实例，每次都调用这一个对象。当使用单例时，对象中的List集合等存储容器放在成员位置会有线程安全问题，但可以放到某个函数中，即局部位置。
applicationContext_scope.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" xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="p" class="com.jp.domain.Person" scope="singleton"></bean>
</beans>
Demo.java的三个结果相同
②.prototype多例
多例，每次从spring ioc容器中获取时，都会返回一个新的bean实例。
<?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:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="p" class="com.jp.domain.Person" scope="prototype"></bean>
</beans>
Demo.java的三个结果不相同
③.request
用在web开发中，将bean对象request.setAttribute()存储到request作用域中
④.session
用在web开发中，将bean对象session.setAttribute()存储到session作用域中
2.bean创建生命周期
①.创建对象
spring容器通过默认的构造函数创建对象
②.调用初始化方法
init-method=“init”
③.调用工程方法
talk()
④.调用销毁方法
estory-method=“destory”
<?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:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="person" class="com.jp.domain.Person" lazy-init="true" init-method="init" destroy-method="destroy"></bean>
</beans>
package com.jp.domain;
public class Person {
public String name;
public Person(){
System.out.println("Person对象创建了...");
}
public Person(String name){
this.name=name;
}
public void talk(){
System.out.println("讲话...");
}
public void init(){
System.out.println("初始化方法...");
}
public void destroy(){
System.out.println("销毁方法...");
}
}
package com.jp.life;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.jp.domain.Person;
public class Demo {
@Test
public void test1(){
ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");
Person p=(Person)ac.getBean("person");
p.talk();
}
}
- lazy-init属性
lazy-init="false"或者"default"或者不写
spring容器一启动，对象就创建完毕（调用空的构造方法）
lazy-init=“true”
调用spring容器调用getBean方法时，对象才创建（调用空的构造方法）
- init-method=“Person对象中的初始化方法名”；
- destroy-method=“Person对象中的销毁方法名”；
