2021-07-20

xml配置文件文件
如果用了xml方式获取了ctx，然后又是用的注解，需要在xml里面增加扫描，扫描对应包下面的注解
<context:component-scan base-package="com.example.Annotion"></context:component-scan>

        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("ApplicationContext.xml");
        UserService userService = (UserService) ctx.getBean("userService");
        userService.saveUser();

注解，如果用下面的方式获取ctx，不需要去配置扫描了

        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext("com.example.Annotion");
        UserService bean = ctx.getBean(UserServiceImpl.class);
        bean.saveUser();

@Autowired
@Qualifier("userDao")
===
@Resource("userDao")
相等的
autowired+Qualifier = resource

加载配置文件

<context:property-placeholder location="classpath:conn.properties"/><!-- 加载配置文件 -->
 
<!-- com.mchange.v2.c3p0.ComboPooledDataSource类在c3p0-0.9.5.1.jar包的com.mchange.v2.c3p0包中 -->
 <bean id="dataSource" class="${dataSource}"> <!-- 这些配置Spring在启动时会去conn.properties中找 -->
    <property name="driverClass" value="${driverClass}" />
    <property name="jdbcUrl" value="${jdbcUrl}" />
    <property name="user" value="${user}" />
    <property name="password" value="${password}" />
 </bean>

集成web

1. 首先导入坐标

 <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>5.2.16.RELEASE</version>
        </dependency>

2. 在web.xml中配置监听器, 当监听到servletContext创建的时候就会去加载配置文件.相当于应用一启动就加载了

<context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
    </context-param>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

3. 通过WebApplicationContextUtils(spring封装的工具类)来获取WebApplicationContext ,为applicationContext的子类

 ServletContext servletContext = request.getServletContext();
        WebApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(servletContext);