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Overview of Spring IoC container
- The Spring container embodies the principle of IoC
- The Spring container is responsible for instantiating, configuring and assembling Beans by reading configuration metadata
- Configuration metadata can be described in XML, Java annotations or Java code
The Spring container will read the configuration file, place the object in the container, and automatically generate the object for you.
BeanFactory
To help you instantiate the objects you use, reflection technology is used.
BeanFactory is actually a factory model.
Examples in class...
ApplicationContext
It is a sub-interface of BeanFactory and has more functions than BeanFactory.
It's super.
There are four implementation classes. (Implementation of ApplicationContext)
- ClassPathXmlApplicationContext is
based on the configuration of the XML file, placed in the root directory of the file - FileSystemXmlApplicationContext
XML file is placed in the path of the operating system (C: / D: what) - XmlWebApplicationContext
based on WEB program configuration - AnnotationConfigApplicationContext
fully annotated
Superset = provide more things
Bean overview
Constructor instantiation
Project structure
Desk.java
package com;
public class Desk {
private static Desk desk;
public Desk() {
System.out.println("Desk构造方法");
}
public static Desk createInstance() {
System.out.println("createInstance");
if(desk==null)
desk = new Desk();
return desk;
}
}
Test.java
package com;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Test {
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
Desk desk = (Desk)ctx.getBean("Desk");
}
}
operation result
Static factory method instantiation
Modifications can be made on the basis of the instantiation of the construction method
Modify the Bean.xml file
<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-4.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
增加Factory-method属性即可
<bean id="Desk" class="com.Desk" factory-method="createInstance"/>
</beans>
Instance factory instantiation
Project structure
Chair.java
package com;
public class Chair {
public Chair() {
System.out.println("Chair无参数构造");
}
}
ChairFactory.java
package com;
public class ChairFactory {
public Chair create() {
return new Chair();
}
}
Desk.java
package com;
public class Desk {
private static Desk desk;
public Desk() {
System.out.println("Desk构造方法");
}
public static Desk createInstance() {
System.out.println("createInstance");
if(desk==null)
desk = new Desk();
return desk;
}
}
Test.java
package com;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Test {
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
Chair chair=(Chair)ctx.getBean("Chair");
}
}
Beans.xml
<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-4.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
<bean id="Desk" class="com.Desk" factory-method="createInstance"/>
<bean id="ChairFactory" class="com.ChairFactory"></bean>
<!-- factory-bean的属性值是上面的id值，不是类名 -->
<!-- factory-methid的属性值是工厂类的方法名 -->
<bean id="Chair" factory-bean="ChairFactory" factory-method="create"></bean>
</beans>
operation result
Bean's life cycle
Implement Aware interface and use custom method configuration
Is the systematic method and the user-defined method
Project structure
BeanLife.java
package com;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
//实现接口
public class BeanLife implements ApplicationContextAware, InitializingBean, DisposableBean{
private ApplicationContext ctx;
private String name;
public void setName(String name) {
this.name = name;
System.out.println("setName属性的赋值");
}
public BeanLife() {
System.out.println("BeanLife的无参构造方法");
}
public void show() {
System.out.println(name);
}
@Override
public void setApplicationContext(ApplicationContext arg0) throws BeansException {
ctx = arg0;//让自己的类可以用传来的ApplicationContext参数
System.out.println("applicationAware");
}
@Override
public void destroy() throws Exception {
System.out.println("destroy");
}
@Override
public void afterPropertiesSet() throws Exception {
System.out.println("afterPropertiesSet");
}
public void init1() {
System.out.println("init1");
}
public void destroy1() {
System.out.println("destroy1");
}
}
Test.java
package com;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Test {
public static void main(String[] args) {
// ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
// BeanLife bl = (BeanLife)ctx.getBean("BeanLife");
// bl.show();
ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
BeanLife bl = (BeanLife)ctx.getBean("BeanLife");
bl.show();
ctx.close();//关闭的方法在实现类里面，不再容器里面
}
}
Beans.xml
<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-4.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
<bean id="BeanLife" class="com.BeanLife" init-method="init1" destroy-method="destroy1">
<property name="name" value="ZhangSan"></property>
</bean>
</beans>
operation result
Configure using annotations
Compared with the above, only the bean properties in the Bean.xml file are deleted, replaced by annotations, and some annotations are added to the BeanFactory
Project structure
BeanLife
package com;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
//实现接口
@Component("BeanLife")
public class BeanLife implements ApplicationContextAware, InitializingBean, DisposableBean{
private ApplicationContext ctx;
private String name;
public void setName(String name) {
this.name = name;
System.out.println("setName属性的赋值");
}
public BeanLife() {
System.out.println("BeanLife的无参构造方法");
}
public void show() {
System.out.println(name);
}
@Override
public void setApplicationContext(ApplicationContext arg0) throws BeansException {
ctx = arg0;//让自己的类可以用传来的ApplicationContext参数
System.out.println("applicationAware");
}
@Override
public void destroy() throws Exception {
System.out.println("destroy");
}
@Override
public void afterPropertiesSet() throws Exception {
System.out.println("afterPropertiesSet");
}
@PostConstruct
public void init1() {
System.out.println("init1");
}
@PreDestroy
public void destroy1() {
System.out.println("destroy1");
}
}
Beans.xml
<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-4.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
<context:annotation-config />
<context:component-scan base-package="com">
</context:component-scan>
</beans>
Bean scope
Configure singleton properties
