几个applicationcontext实现类

时间:2021-03-24 17:09:36

ClassPathXmlApplicationContext:类路径加载
FileSystemXmlApplicationContext:文件系统路径加载
AnnotationConfigApplicationContext:用于基于注解的配置
WebApplicationContext:专门为web应用准备的,从相对于Web根目录的路径中装载配置文件完成初始化。

ApplicationContext ac = new ClassPathXmlApplicationContext("com/zzm/context/beans.xml");//等同路径:"classpath:com/zzm/context/beans.xml"
ac.getBean("abc",abc.calss);//就可以获得bean了

ApplicationContext ac = new FileSystemXmlApplicationContext("com/zzm/context/beans.xml");//等同路径:"file:com/zzm/context/beans.xml"
ac.getBean("abc",abc.calss);//就可以获得bean了

加载多个配置文件:

ApplicationContext ac = new ClassPathXmlApplicationContext(new String[]{"conf/beans1.xml","conf.beans2.xml"});

对于基于注解的,如:

@Coniguration
public class Beans{
@Bean(name="man")
public Man newMan(){
Man man = new Man();
man.setName("小明");
}

ApplicationContext ac = new AnnotationConfigApplicationContext(Beans.class);
Man man = ac.getBean("man",Man.class);

WebApplicationContext初始化需要ServletContext事例,即必须先有Web容器才能完成启动工作,可在web.xml中配置自启动Servlet或定义Web容器监听器(ServletContextListener)。

通过Web容器监听器:

web.xml:
<!--指定配置文件-->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/zzm-service.xml</param-value>
<!--也可以类路径:classpath:com/zzm/service.xml 可指定多个用,隔开-->
</context-param>
<!--声明Web容器监听-->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

通过自启动的Servlet引导

<!--指定配置文件-->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/zzm-service.xml</param-value>
</context-param>
<!--声明自启动的Servlet容器>
<servlet>
<servlet-name>sprinfContextLoaderServlet</servlet-name>
<servlet-class>org.springframework.web.context.ContextLoaderServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>

WebApplicationContext Spring提供WebApplicationContextUtils通过该类的getWebApplicationContext(ServletContext sc)方法获取,即可从ServletContext中获取WebApplicationContext。
新增3作用域:request,session,global session
像Spring中用过滤器Filter,如过滤器中需要加载配置时可用WebApplicationContext来加载

public class ACLFilter implements Filter{

private ServletContext sc;
private ApplicationContext ctx;
private UserService userService;

/**
* 过滤器初始化
*/
public void init(FilterConfig cfg)
throws ServletException {

sc= cfg.getServletContext();//获取Spring容器
ctx=WebApplicationContextUtils.getWebApplicationContext(sc);//从容器中获取 UserService 对象
userService=ctx.getBean("userService",UserService.class);
}
public void doFilter(ServletRequest req, ServletResponse res,FilterChain chain)throws IOException, ServletException {
/**/
chain.doFilter(request, response);
}

public void destroy() {
}

}