public  void destroy() 
{
		Filter delegateToUse = null;
		synchronized (this.delegateMonitor) {
			delegateToUse = this.delegate;
		}
		if (delegateToUse != null) {
			destroyDelegate(delegateToUse);
		}
}

 protected  void destroyDelegate(Filter delegate) 
{
		if (isTargetFilterLifecycle()) {
			delegate.destroy();
		}
}

Destroy the Filter delegate. Default implementation simply calls Filter.destroy on it.

 public  void doFilter(ServletRequest request,
    ServletResponse response,
    FilterChain filterChain) throws IOException, ServletException 
{
		// Lazily initialize the delegate if necessary.
		Filter delegateToUse = null;
		synchronized (this.delegateMonitor) {
			if (this.delegate == null) {
				WebApplicationContext wac = findWebApplicationContext();
				if (wac == null) {
					throw new IllegalStateException("No WebApplicationContext found: no ContextLoaderListener registered?");
				}
				this.delegate = initDelegate(wac);
			}
			delegateToUse = this.delegate;
		}
		// Let the delegate perform the actual doFilter operation.
		invokeDelegate(delegateToUse, request, response, filterChain);
}

 protected WebApplicationContext findWebApplicationContext() 
{
		String attrName = getContextAttribute();
		if (attrName != null) {
			return WebApplicationContextUtils.getWebApplicationContext(getServletContext(), attrName);
		}
		else {
			return WebApplicationContextUtils.getWebApplicationContext(getServletContext());
		}
}

Retrieve a WebApplicationContext from the ServletContext attribute with the configured name . The WebApplicationContext must have already been loaded and stored in the ServletContext before this filter gets initialized (or invoked).

Subclasses may override this method to provide a different WebApplicationContext retrieval strategy.

 public String getContextAttribute() 
{
		return this.contextAttribute;
}

Return the name of the ServletContext attribute which should be used to retrieve the WebApplicationContext from which to load the delegate Filter bean.

 protected String getTargetBeanName() 
{
		return this.targetBeanName;
}

Return the name of the target bean in the Spring application context.

 protected Filter initDelegate(WebApplicationContext wac) throws ServletException 
{
		Filter delegate = (Filter) wac.getBean(getTargetBeanName(), Filter.class);
		if (isTargetFilterLifecycle()) {
			delegate.init(getFilterConfig());
		}
		return delegate;
}

Initialize the Filter delegate, defined as bean the given Spring application context.

Default implementation fetches the bean from the application context and calls the standard Filter.init method on it, passing in the FilterConfig of this Filter proxy.

 protected  void initFilterBean() throws ServletException 
{
		// If no target bean name specified, use filter name.
		if (this.targetBeanName == null) {
			this.targetBeanName = getFilterName();
		}
		// Fetch Spring root application context and initialize the delegate early,
		// if possible. If the root application context will be started after this
		// filter proxy, we'll have to resort to lazy initialization.
		synchronized (this.delegateMonitor) {
			WebApplicationContext wac = findWebApplicationContext();
			if (wac != null) {
				this.delegate = initDelegate(wac);
			}
		}
}

 protected  void invokeDelegate(Filter delegate,
    ServletRequest request,
    ServletResponse response,
    FilterChain filterChain) throws IOException, ServletException 
{
		delegate.doFilter(request, response, filterChain);
}

Actually invoke the delegate Filter with the given request and response.

 protected boolean isTargetFilterLifecycle() 
{
		return this.targetFilterLifecycle;
}

Return whether to invoke the Filter.init and Filter.destroy lifecycle methods on the target bean.

 public  void setContextAttribute(String contextAttribute) 
{
	                         	 
		this.contextAttribute = contextAttribute;
}

Set the name of the ServletContext attribute which should be used to retrieve the WebApplicationContext from which to load the delegate Filter bean.

 public  void setTargetBeanName(String targetBeanName) 
{
		this.targetBeanName = targetBeanName;
}

Set the name of the target bean in the Spring application context. The target bean must implement the standard Servlet 2.3 Filter interface.

By default, the filter-name as specified for the DelegatingFilterProxy in web.xml will be used.

 public  void setTargetFilterLifecycle(boolean targetFilterLifecycle) 
{
		this.targetFilterLifecycle = targetFilterLifecycle;
}

Set whether to invoke the Filter.init and Filter.destroy lifecycle methods on the target bean.

Default is "false"; target beans usually rely on the Spring application context for managing their lifecycle. Setting this flag to "true" means that the servlet container will control the lifecycle of the target Filter, with this proxy delegating the corresponding calls.