内容简介:DelegatingFilterProxy这个东西太熟悉了,在类似shiro和springsecurity的权限认证框架都有见到它的身影,但又陌生,印象似乎只停留在DelegatingFilterProxy把servlet 容器中的filter同spring容器中的bean关联起来,交由spring容器管理。DelegatingFilterProxy代理类把filter和IOC容器进行了结合在一起,从spring上下文寻找要代理的过滤类,执行初始化,过滤和销毁过程。下面结合springsecurity就翻翻
DelegatingFilterProxy这个东西太熟悉了,在类似shiro和springsecurity的权限认证框架都有见到它的身影,但又陌生,印象似乎只停留在DelegatingFilterProxy把servlet 容器中的filter同spring容器中的bean关联起来,交由spring容器管理。DelegatingFilterProxy代理类把filter和IOC容器进行了结合在一起,从spring上下文寻找要代理的过滤类,执行初始化,过滤和销毁过程。下面结合springsecurity就翻翻源码:
获取filter配置参数
DelegatingFilterProxy
继承了 GenericFilterBean
,父类实现了一堆接口:
public abstract class GenericFilterBean implements Filter, BeanNameAware, EnvironmentAware, EnvironmentCapable, ServletContextAware, InitializingBean, DisposableBean 复制代码
- BeanNameAware //返回当前的beanName
- EnvironmentAware//读取配置文件
- EnvironmentCapable//检查接受了BeanFactory接口的框架方法
- ServletContextAware//获取ServletContext
- InitializingBean//初始化bean对象
- DisposableBean //销毁bean
父类中 init
方法将过滤器的参数配置传递给代理对象 源码如下:
public final void init(FilterConfig filterConfig) throws ServletException { Assert.notNull(filterConfig, "FilterConfig must not be null"); this.filterConfig = filterConfig; PropertyValues pvs = new GenericFilterBean.FilterConfigPropertyValues(filterConfig, this.requiredProperties); if (!pvs.isEmpty()) { try { BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this); ResourceLoader resourceLoader = new ServletContextResourceLoader(filterConfig.getServletContext()); Environment env = this.environment; if (env == null) { env = new StandardServletEnvironment(); } bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader, (PropertyResolver)env)); this.initBeanWrapper(bw); bw.setPropertyValues(pvs, true); } catch (BeansException var6) { String msg = "Failed to set bean properties on filter '" + filterConfig.getFilterName() + "': " + var6.getMessage(); this.logger.error(msg, var6); throw new NestedServletException(msg, var6); } } 复制代码
bean对象初始化
获取目标对象的name。
protected void initFilterBean() throws ServletException { synchronized(this.delegateMonitor) { if (this.delegate == null) { if (this.targetBeanName == null) { this.targetBeanName = this.getFilterName(); } WebApplicationContext wac = this.findWebApplicationContext(); if (wac != null) { this.delegate = this.initDelegate(wac); } } } } 复制代码
初始化代理对象
在web.xml文件中配置的 org.springframework.web.context.ContextLoaderListener
实现加载Sping的上下文环境 (由XmlWebApplicationContent来装载)。
通过initDelegate(wac)得到代理过滤器
protected Filter initDelegate(WebApplicationContext wac) throws ServletException { String targetBeanName = this.getTargetBeanName(); Assert.state(targetBeanName != null, "No target bean name set"); Filter delegate = (Filter)wac.getBean(targetBeanName, Filter.class); if (this.isTargetFilterLifecycle()) { delegate.init(this.getFilterConfig()); } return delegate; } 复制代码
代理执行过滤方法
在执行过滤方法之前,通过 invokeDelegate
调用delegate执行过滤方法
protected void invokeDelegate(Filter delegate, ServletRequest request, ServletResponse response, FilterChain filterChain) throws ServletException, IOException { delegate.doFilter(request, response, filterChain); } 复制代码
过滤方法
public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws ServletException, IOException { Filter delegateToUse = this.delegate; if (delegateToUse == null) { synchronized(this.delegateMonitor) { delegateToUse = this.delegate; if (delegateToUse == null) { WebApplicationContext wac = this.findWebApplicationContext(); if (wac == null) { throw new IllegalStateException("No WebApplicationContext found: no ContextLoaderListener or DispatcherServlet registered?"); } delegateToUse = this.initDelegate(wac); } this.delegate = delegateToUse; } } 复制代码
以上所述就是小编给大家介绍的《代理过滤器》,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对 码农网 的支持!
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