Spring4.0学习笔记(1) —— 基础知识
1、基本定义
IOC: 其思想是反转资源获取的方向，传统的资源查找方式要求组件向容器发起请求查找资源，作为回应，容器适时的返回资源，而应用了
IOC之后，容器主动将资源推送给它所管理的组件，组件索要做的只是选择一种合适的方式接受资源，这种行为也被称为查找的被动形式。
DI: IOC 的另一种表述方式，即组件以一些预定好的方式(例如Action中属性的setter方法)接受来自容器的资源注入
2、原理
3、Bean的配置
Bean：通过全类名(反射)、通过工厂方法(静态工厂方法&实例工厂方法)、FactoryBean
IOC容器:BeanFactory& ApplicationContext 概述
依赖注入的方式：属性注入、构造器注入
3.1、IOC容器的实现
Spring提供了两种类型的IOC容器
BeanFactory : IOC容器的基本实现，面向Spring本身。
ApplicationContext : 提供了 更多的高级特性，是BeanFactory的子接口,面向开发者。
主要实现类 {ClassPathXmlApplicationContext : 从类路径下加载文件，FileSystemXmlApplicationContext : 从文件系统中加载配置文件}
//1、创建spring 的 ioc 容器,配置文件在类路径下 ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml"); //2、ioc 容器中获取 Bean实例,利用id 定位到IOC容器中的bean HelloWorld helloWorld = (HelloWorld)ctx.getBean("helloWorld");
<bean id="helloWorld" class="com.spring.beans.HelloWorld"> <property name="name" value="spring"></property> </bean>
3.2、依赖注入的方式
3.2.1 属性注入<property>
通过setter方法注入Bean的属性值或者依赖的对象
3.2.2 构造器注入<constructor-arg>
通过构造方法注入Bean的属性值或依赖的对象，保证了Bean实例在实例化后就可以使用<constructor-arg>
4、bean属性值详解
4.1、出现特殊字符时:
<constructor-arg> <value><![CDATA[<Audi>]]></value> </constructor-arg>
4.2、ref 建立bean之间的引用关系 :
<bean id="car_ref" class="com.spring.beans.Car"> <constructor-arg> <value><![CDATA[<Audi>]]></value> </constructor-arg> <constructor-arg value="ShangHai"></constructor-arg> <constructor-arg value="300000"></constructor-arg> </bean> <bean id="person" class="com.spring.beans.Person"> <property name="name" value="Tom"></property> <property name="age" value="24"></property> <property name="car" ref="car_ref"></property> </bean>
4.3、内部bean，无法被外部bean引用
<bean id="person" class="com.spring.beans.Person"> <property name="name" value="Tom"></property> <property name="age" value="24"></property> <property name="car"> <bean class="com.spring.beans.Car"> <constructor-arg value="Ford"></constructor-arg> <constructor-arg value="ChangAn"></constructor-arg> <constructor-arg value="20000"></constructor-arg> </bean> </property> </bean>
4.4、null值和级联属性
null值
<bean id="person2" class="com.spring.beans.Person"> <constructor-arg value="jerry"></constructor-arg> <constructor-arg value="23"></constructor-arg> <constructor-arg><null/></constructor-arg> </bean>
级联属性
<bean id="car_ref" class="com.spring.beans.Car">
<constructor-arg> <value><![CDATA[<Audi>]]></value> </constructor-arg> <constructor-arg value="ShangHai"></constructor-arg> <constructor-arg value="300000"></constructor-arg> </bean> <bean id="person2" class="com.spring.beans.Person"> <constructor-arg value="jerry"></constructor-arg> <constructor-arg value="23"></constructor-arg> <constructor-arg ref="car_ref"></constructor-arg>
//必须在bean文件中，定义maxSpeed的set方法【属性注入！】
<property name="car.maxSpeed"></property> </bean>
集合属性
<bean id="car_ref" class="com.spring.beans.collections.Car"> <constructor-arg> <value><![CDATA[<Audi>]]></value> </constructor-arg> <constructor-arg value="ShangHai"></constructor-arg> <constructor-arg value="300000"></constructor-arg> </bean> <bean id="car2_ref" class="com.spring.beans.collections.Car"> <constructor-arg value="Ford"></constructor-arg> <constructor-arg value="beijing"></constructor-arg> <constructor-arg value="20000"></constructor-arg> </bean> <bean id="car3_ref" class="com.spring.beans.collections.Car"> <constructor-arg value="Honda"></constructor-arg> <constructor-arg value="beijing"></constructor-arg> <constructor-arg value="120000"></constructor-arg> </bean> <!-- 测试如何配置集合属性 --> <bean id="testCollections" class="com.spring.beans.collections.Person" > <property name="name" value="Mike"></property> <property name="age" value="27"></property> <property name="cars"> <list> <ref bean="car_ref"></ref> <ref bean="car2_ref"></ref> <ref bean="car3_ref"></ref> </list> </property> </bean>
package com.spring.beans.collections; import java.util.List; public class Person { private String name; private int age; private List<Car> cars; public Person(String name, int age, List<Car> cars) { super(); this.name = name; this.age = age; this.cars = cars; } @Override public String toString() { return "Person [age=" + age + ", cars=" + getCarStr(cars) + ", name=" + name + "]"; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public Person() { } public List<Car> getCars() { return cars; } public void setCars(List<Car> cars) { this.cars = cars; } //获取汽车 public String getCarStr(List<Car> cars) { StringBuffer sb = new StringBuffer(); sb.append("["); for(Car car :cars){ sb.append("brand: "+car.getBrand()+ "corp:"+ car.getCorp() +"maxSpeed:" +car.getMaxSpeed()+"price:"+car.getPrice()+"\n"); } sb.append("]"); return sb.toString(); } }
package com.spring.beans.collections; public class Car { private String brand; private String corp; private String price; private String maxSpeed; //通过构造器注入 public Car(String brand, String corp, String price) { super(); this.brand = brand; this.corp = corp; this.price = price; } public String getBrand() { return brand; } public void setBrand(String brand) { this.brand = brand; } public String getCorp() { return corp; } public void setCorp(String corp) { this.corp = corp; } public String getPrice() { return price; } public void setPrice(String price) { this.price = price; } public String getMaxSpeed() { return maxSpeed; } public void setMaxSpeed(String maxSpeed) { this.maxSpeed = maxSpeed; } }
集合属性-2 【map】
<bean id="testMap" class="com.spring.beans.collections.newPerson"> <property name="name" value="java"></property> <property name="age" value="30"></property> <property name="cars"> <map> <entry key="A1" value-ref="car_ref"></entry> <entry key="A2" value-ref="car2_ref"></entry> <entry key="A3" value-ref="car3_ref"></entry> </map> </property> </bean>
集合属性-3【properties】
<bean id="dataSource" class="com.spring.beans.collections.DataSource"> <property name="properties"> <props> <prop key="user">root</prop> <prop key="password">root</prop> <prop key="jdbcUrl">jdbc:mysql:///test</prop> <prop key="driverClass">com.mysql.jdbc.drivce</prop> </props> </property> </bean>
p标签
<bean id="person5" class="com.spring.beans.collections.Person" p:name="queen" p:age="30" p:cars-ref="cars"> </bean>
配置单例的集合bean
<!-- 配置单例的集合bean,以供多个bean进行引用，需要导入util命名空间 --> <util:list id="cars"> <ref bean="car_ref"></ref> <ref bean="car2_ref"></ref> <ref bean="car3_ref"></ref> </util:list> <bean id="person4" class="com.spring.beans.collections.Person"> <property name="name" value="jack"></property> <property name="age" value="30"></property> <property name="cars" ref="cars"></property> </bean>
