Spring MVC 学习笔记1：Spring 框架

使用Spring，程序几乎可以将所有重要对象的创建工作交给Spring，并配置如何注入不同对象间的依赖。
Spring支持XML或注释两种配置方式。加载一个包含beans信息的XML文件内容的方式一般有两种：
1）从类路径中加载；2）从文件系统中加载

从类路径中创建一个bean实例

现在假设config1.xml文件中的bean信息如下：

<bean name = "product" class = "app01a.bean.Product"/>

类路径加载XML并获取bean对象：

org.springframework.context.ApplicationContext context = new ClassPathXmlApplicationContext(new String[] {"config1.xml"});Product product1 = context.getBean("product", Product.class); //查询id为product且类型为Product的bean对象。product1.setName("cup");System.out.println("product1: " + product1.getName());

从文件系统加载bean实例

ApplicationContext context = new FileSystemXmlApplicationContext("config1.xml");Product product = context.getBean("product", Product.class);product1.setName("cup");System.out.println("product1: " + product1.getName());

通过工厂方法创建一个bean实例

现在假设config1.xml文件中的bean信息如下：

<bean id = "calendar" class = "java.util.Calendar" factory-method = "getInstance"/>

ApplicationContext context = new ClassPathXmlApplicationContext(new String[] {"config1.xml"});Calendar calendar = context.getBean("calendar", Calendar.class);

设置bean对象参数的方式

假设calendar的属性有year、month和day组成。
方法一：

<bean id = "calendar" class = "java.util.Calendar" factory-method = "getInstance"/>    <property name = “year” value = "2016"/>    <property name = “month” value = "9"/>    <property name = “day” value = "13"/></bean>

方法二：通过构造器来设置：

<bean id = "calendar" class = "java.util.Calendar" factory-method = "getInstance"/>    <constructor-arg name = “year” value = "2016"/>    <constructor-arg name = “month” value = "9"/>    <constructor-arg name = “day” value = "13"/></bean>

通过构造器方式来完成依赖注入

假设现在有两个JavaBean类。分别是Employee和Address。那么Employee类是依赖于Address的。
此时可通过构造器的方式来来完成依赖注入：

<bean id = "employee" class = "alex.bean.Employee" factory-method = "getInstance"/>    <constructor-arg name = “name” value = "alex"/>    <constructor-arg name = “address” ref = "address"/></bean><bean id = "address" class = "alex.bean.Address" factory-method = "getInstance"/>    <constructor-arg name = “city” value = "suzhpu"/>    <constructor-arg name = “street” value = "shizi road"/>    <constructor-arg name = “line” value = "333"/></bean>