Spring-web开发

java项目下，可以通过 new ClassPathXmlApplicationContext("ApplicationContext.xml");

web项目下，需通过监听器 Listener,初始化xml文件，否则就需要在大部分类中new ,容易内存溢出

   

   

• <?xml version="1.0" encoding="UTF-8"?>
• <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
•     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
•     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
•     <display-name>web 02</display-name>
•     <welcome-file-list>
•         <welcome-file>index.jsp</welcome-file>
•     </welcome-file-list>
•     
•     <context-param>
•         <param-name>contextConfigLocation</param-name>
•         <!-- classpath代表类路径src，如是不写classpath则会直接去web-INF去找 -->
•         <param-value>classpath:applicationContext.xml</param-value>
•     </context-param>
•     <listener>
•         <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
•     </listener>
• </web-app>

   

spring针对web开发的几种方式

例如一个考勤项目

   

1、三层架构，DB >> student\class >> servcice >>servlet

配置文件：applicationContext-Student.xml

applicationContext-service.xml

applicationContext-servlet.xml

   

   

   

2、按功能模块呀模块划分，DB >> student（包括service/servlet） \ class

配置文件：applicationContext-Student.xml

applicationContext-class.xml

   

加载多个配置文件

1、推荐方式

   

•     <context-param>
•             <param-name>contextConfigLocation</param-name>
•             <!-- classpath代表类路径src -->
•             <param-value>
•                 <!--classpath:applicationContext-student.xml
•   classpath:applicationContext-class.xml
•  classpath:applicationContext-teacher.xmlà

     

•                 <!--通配符加载à
• classpath:applicationContext-*.xml
•             </param-value>
•         </context-param>
•         <listener>
•             <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
•         </listener>

   

2\ 不推荐此类方法

Web.xml文件只需加载主配置文件，将其他附属配置文件用<import resource=""/>单个或者群居加入

   

•     <?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">
•     <import resource="applicationContext-student.xml"/>
•     <import resource="applicationContext-class.xml"/>
•     <import resource="applicationContext-teacher.xml"/>
•     <import resource="applicationContext-*.xml"/>
•     
•     </beans>

   

   

Spring-web + servlet

   

web.xml配置监听器:目的是tomcat启动时自动初始化applicationContext.xml文件（IOC容器）

   

•         <context-param>
•             <param-name>contextConfigLocation</param-name>
•             <!-- classpath代表类路径src -->
•             <param-value>
•                 <!-- classpath:applicationContext-student.xml
                  classpath:applicationContext-class.xml
                  classpath:applicationContext-teacher.xml -->
•                 classpath:applicationContext.xml
•             </param-value>
•         </context-param>
•         <listener>
•             <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
• </listener>

   

//因为servlet和spring ioc是2个单独的容器，项目启动会自动初始化IOC容器。

//但是请求时有时servlet容器，所以还需在servlet容器中访问一次IOC容器。只需拿到最后的值。

   

1.      @Override
2.         public void init() throws ServletException {
3.             //一种方式
4. //ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml")
5.   //web开发常用方式
6.   ApplicationContext context = WebApplicationContextUtils.getWebApplicationContext(this.getServletContext());
7.             ss = (StudentService) context.getBean("studentService");
8.        }