Day2 Spring初识

Posted 2020-10-25 扎心了，老铁

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Bean的实例化

bean实例化方式有3种：默认构造、静态工厂、实例工厂

默认构造

调用无参构造，属性+setter

User.java

package entity;

public class User {
    private int id;
    private String name;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + "]";
    }
    
    
}

ApplicatitonContext.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">

    <!-- 1.默认调用无参构造   属性+setter 
            name:真实赋值使用setter方法
            scope:作用域
    -->
     <bean id="user" class="entity.User">
        <property name="id" value="1"></property>
        <property name="name" value="zs"></property>
    </bean>  
    
    
    
</beans>

Test.java

package test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import entity.User;


public class Test {
    
    @org.junit.Test
    public void test() {
        ApplicationContext context = new ClassPathXmlApplicationContext("ApplicatitonContext.xml");
        User user = context.getBean("user",User.class);
        System.out.println(user);
    }
}

运行结果

二月 01, 2018 8:19:43 下午 org.springframework.context.support.AbstractApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@2a33fae0: startup date [Thu Feb 01 20:19:43 CST 2018]; root of context hierarchy
二月 01, 2018 8:19:44 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [ApplicatitonContext.xml]
User [id=1, name=zs]

调用有参构造属性+有参构造

User.java

package entity;

public class User {
    private int id;
    private String name;
    
    public User(int id, String name) {
        super();
        this.id = id;
        this.name = name;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + "]";
    } 
}

ApplicatitonContext.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">

    <!-- 2.调用有参构造      属性+有参构造
        constructor-arg:
            name:属性名称
            value:简单类型的值
            ref:引用
            
            index:参数的索引
            type:参数的类型
     -->
    <bean id="user" class="entity.User">
        <constructor-arg name="id" value="1"  ></constructor-arg>
        <constructor-arg name="name" value="lisi"></constructor-arg>
        
        <!-- <constructor-arg index="0" type="int"  value="1"></constructor-arg>
        <constructor-arg index="1" value="zs"></constructor-arg> -->
    </bean>
    
    
    
</beans>

Test.java

package test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import entity.User;


public class Test {
    
    @org.junit.Test
    public void test() {
        ApplicationContext context = new ClassPathXmlApplicationContext("ApplicatitonContext.xml");
        User user = context.getBean("user",User.class);
        System.out.println(user);
    }
}

运行结果

二月 01, 2018 8:23:39 下午 org.springframework.context.support.AbstractApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@2a33fae0: startup date [Thu Feb 01 20:23:39 CST 2018]; root of context hierarchy
二月 01, 2018 8:23:39 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [ApplicatitonContext.xml]
User [id=1, name=lisi]

静态工厂

User.java

package entity;

public class User {
    private int id;
    private String name;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + "]";
    }
    
    
}

View Code

StaticFactory.java

package factory;

import entity.User;

public class StaticFactory {
    
    public static User createUser() {
        return new User();
    }
}

View Code

ApplicatitonContext.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">

    <!-- 静态工厂  -->
    <bean id="user" class="factory.StaticFactory" factory-method="createUser"></bean>
    
    
</beans>

View Code

Test.java

package test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import entity.User;


public class Test {
    
    @org.junit.Test
    public void test() {
        ApplicationContext context = new ClassPathXmlApplicationContext("ApplicatitonContext.xml");
        User user = context.getBean("user",User.class);
        System.out.println(user);
    }
}

View Code

运行结果

二月 01, 2018 8:28:44 下午 org.springframework.context.support.AbstractApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@2a33fae0: startup date [Thu Feb 01 20:28:44 CST 2018]; root of context hierarchy
二月 01, 2018 8:28:44 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [ApplicatitonContext.xml]
User [id=0, name=null]

动态工厂

User.java

package entity;

public class User {
    private int id;
    private String name;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + "]";
    }
    
    
}

View Code

InstanceFactory.java

package factory;

import entity.User;

public class InstanceFactory {
    
    public User createUser(){
        return new User();
    }
}

View Code

ApplicatitonContext.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">

    <!-- 3.实例工厂 -->
    <bean id="factory" class="factory.InstanceFactory"></bean>
    <bean id="user" factory-bean="factory" factory-method="createUser"></bean>
    
    
</beans>

View Code

Test.java

package test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import entity.User;


public class Test {
    
    @org.junit.Test
    public void test() {
        ApplicationContext context = new ClassPathXmlApplicationContext("ApplicatitonContext.xml");
        User user = context.getBean("user",User.class);
        System.out.println(user);
    }
}

View Code

运行结果

二月 01, 2018 8:32:59 下午 org.springframework.context.support.AbstractApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@2a33fae0: startup date [Thu Feb 01 20:32:59 CST 2018]; root of context hierarchy
二月 01, 2018 8:32:59 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [ApplicatitonContext.xml]
User [id=0, name=null]

Bean的作用域

singleton:(单实例模式)spring容器只会存在一个共享的bean实例，并且所有针对该bean的请求只会返回同一个bean实例。
propertype(no-singleton):对每一次针对该bean的请求都会生成一个新的bean实例。相当于java中的new 操作。定义为propertype的bean其生命周期很长，不易回收，通常要额外的处理。
request:针对每一次的http请求都会产生一个新的bean实例，Bean仅在当前的http request范围内有效
session:针对每一次的http请求都会产生一个新的bean实例，Bean仅在当前的http session范围内有效

Bean的声明周期

图示说明

初始化方法和销毁方法

User.java

package entity;

public class User {
    private int id;
    private String name;
    
    public void init() {
        System.out.println("初始化");
    }
    
    public void destory() {
        System.out.println("销毁");
    }
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + "]";
    }
    
    
}

View Code

ApplicatitonContext.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">

    <!-- 1.默认调用无参构造   属性+setter 
            name:真实赋值使用setter方法
            scope:作用域
    -->
     <bean id="user" class="entity.User" init-method="init" destroy-method="destory">
        <property name="id" value="1"></property>
        <property name="name" value="zs"></property>
    </bean>  
    
</beans>

View Code

Test.java

package test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import entity.User;


public class Test {
    
    @org.junit.Test
    public void test() {
        ApplicationContext context = new ClassPathXmlApplicationContext("ApplicatitonContext.xml");
        User user = context.getBean("user",User.class);
        System.out.println(user);
        //容器关闭,必须使用单例默认,只有容器关闭之后才能调用destroy方法
        ((ClassPathXmlApplicationContext)context).close();
    }
}

View Code

运行结果

二月 01, 2018 8:44:32 下午 org.springframework.context.support.AbstractApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@2a33fae0: startup date [Thu Feb 01 20:44:32 CST 2018]; root of context hierarchy
二月 01, 2018 8:44:32 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [ApplicatitonContext.xml]
初始化
二月 01, 2018 8:44:32 下午 org.springframework.context.support.AbstractApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@2a33fae0: startup date [Thu Feb 01 20:44:32 CST 2018]; root of context hierarchy
User [id=1, name=zs]
销毁

生命周期管理

两个时机

Spring可以管理实例化bean之间以及销毁之前的行为

注入依赖关系之后：

使用init-method属性：通过指定init-method属性，确定某个方法应该在Bean依赖关系结束之后执行。这种方式无需要将代码与Spring的接口耦合在一起代码污染极小。通常在bean当中进行方法定义如init()方法，然后在配置文件Bean元素中加入init-method属性来实现这个过程。
实现InnitializingBean接口：这种方式无须指明init-method属性，当窗口依赖注入以后，会自动调用afterPropertiesSet方法，它和init-method执行效果一样，但这种方式属于侵入性的代码设计不推荐使用

销毁Bean之前：

destroy-method:用于在执行Bean销毁之前所执行的方法，这种方式和init-method一样无压需要代码与Spring的接口耦合在一起代码污染极小。在bean中加入destory-method属性和实现这个过程
实现DisposeableBean接口：无需要指明destory-method属性，当容器依赖注入以后，会自动调用destroty方法,属于侵入性代码设计不推荐使用

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