Filter的用法
public interface Filter { //初始化方法，整个生命周期中只实验一次。 //在init方法乐成(失败如抛非常等)实验完前，不能提供过滤服务。 //参数FilterConfig用于获取初始化参数 public void init(FilterConfig filterConfig) throws ServletException; //实验过滤使命的方法，参数FilterChain表现过滤器链，doFilter方法中只有实验chain.doFilter()后才气调用下一个过滤器的doFilter方法 //才气将哀求交经下一个Filter或Servlet实验 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException; //销毁方法，当移出服务时由web容器调用。整个生命周期中destroy方法只会实验一次 //destroy方法可用于开释持有的资源，如内存、文件句柄等 public void destroy();}
- Filter的接口界说包罗init、doFilter、destroy等接口。
@Componentpublic class TimeFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { System.out.println("time filter init"); } @Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { System.out.println("time filter start"); long startTime = System.currentTimeMillis(); filterChain.doFilter(servletRequest, servletResponse); long endTime = System.currentTimeMillis(); System.out.println("time filter consume " + (endTime - startTime) + " ms"); System.out.println("time filter end"); } @Override public void destroy() { System.out.println("time filter init"); }}
- 自界说 Filter对象须要实现Filter的接口并实现此中的方法。
Filter的初始化
public class StandardContext extends ContainerBase implements Context, NotificationEmitter { private HashMap<String, FilterDef> filterDefs = new HashMap<>(); private HashMap<String, ApplicationFilterConfig> filterConfigs = new HashMap<>(); @Override protected synchronized void startInternal() throws LifecycleException { // 省略其他代码 if (ok) { if (!filterStart()) { log.error(sm.getString("standardContext.filterFail")); ok = false; } } } public boolean filterStart() { boolean ok = true; synchronized (filterConfigs) { filterConfigs.clear(); // 遍历filterDefs的map初始化Filter对象 for (Entry<String,FilterDef> entry : filterDefs.entrySet()) { String name = entry.getKey(); try { ApplicationFilterConfig filterConfig = new ApplicationFilterConfig(this, entry.getValue()); filterConfigs.put(name, filterConfig); } catch (Throwable t) { ok = false; } } } return ok; }}
- StandardContext#filterStart负责遍历filterDefs并创建ApplicationFilterConfig对象。
- ApplicationFilterConfig是包罗 Filter 实例的对象，FilterDef是包罗的过滤器的界说。
- StandardContext的filterDefs生存 Filter 的界说，filterConfigs生存 Filter 的实例包装对象ApplicationFilterConfig。
Filter核心类界说
public class FilterDef implements Serializable { private static final long serialVersionUID = 1L; private static final StringManager sm = StringManager.getManager(Constants.PACKAGE_NAME); private String description = null; private String displayName = null; private transient Filter filter = null; private String filterClass = null; private String filterName = null; private String largeIcon = null; private final Map<String, String> parameters = new HashMap<>(); private String smallIcon = null; private String asyncSupported = null;}
- FilterDef是Filter的界说类，filterClass表现过滤器的界说类。
public final class ApplicationFilterConfig implements FilterConfig, Serializable { private static final long serialVersionUID = 1L; static final StringManager sm = StringManager.getManager(Constants.Package); private static final List<String> emptyString = Collections.emptyList(); private final transient Context context; private transient Filter filter = null; private final FilterDef filterDef; private transient InstanceManager instanceManager; private ObjectName oname; ApplicationFilterConfig(Context context, FilterDef filterDef) throws ClassCastException, ClassNotFoundException, IllegalAccessException, InstantiationException, ServletException, InvocationTargetException, NamingException, IllegalArgumentException, NoSuchMethodException, SecurityException { super(); this.context = context; this.filterDef = filterDef; if (filterDef.getFilter() == null) { getFilter(); } else { this.filter = filterDef.getFilter(); getInstanceManager().newInstance(filter); initFilter(); } } Filter getFilter() throws ClassCastException, ClassNotFoundException, IllegalAccessException, InstantiationException, ServletException, InvocationTargetException, NamingException, IllegalArgumentException, NoSuchMethodException, SecurityException { if (this.filter != null) return (this.filter); // 创建 并初始化 Filter 对象 String filterClass = filterDef.getFilterClass(); this.filter = (Filter) getInstanceManager().newInstance(filterClass); initFilter(); return (this.filter); } private void initFilter() throws ServletException { if (context instanceof StandardContext && context.getSwallowOutput()) { try { SystemLogHandler.startCapture(); filter.init(this); } finally { String capturedlog = SystemLogHandler.stopCapture(); if (capturedlog != null && capturedlog.length() > 0) { getServletContext().log(capturedlog); } } } else { filter.init(this); } registerJMX(); }}
- ApplicationFilterConfig的创建过程就是通过实例化FilterDef的 filterClass的类并调用 Filter 的 init 方法初始化 Filter 对象。
- initFilter方法负责初始化 Filter 对象，也就是调用 filter 的 init 方法。
- ApplicationFilterConfig的filter字段生存实例话后的 Filter 实例。
FilterDef的加载
FilterDef 的泉源须要如果是 web.xml 界说那么就从 webxml 中获取，如果是springboot 工程，就通过ApplicationContextFacade范例举行获取。
public class ContextConfig implements LifecycleListener { private void configureContext(WebXml webxml) { // 省略相干代码 for (FilterDef filter : webxml.getFilters().values()) { if (filter.getAsyncSupported() == null) { filter.setAsyncSupported("false"); } context.addFilterDef(filter); } }}
- 通过webxml.getFilters()获取过滤器的FilterDef并添加到StandardContext对象当中。
- 上述方式一样平常在 spring MVC 项目在 web.xml 设置过滤器的时间使用。
public class ApplicationContextFacade implements org.apache.catalina.servlet4preview.ServletContext { @Override public FilterRegistration.Dynamic addFilter(String filterName, Filter filter) { if (SecurityUtil.isPackageProtectionEnabled()) { return (FilterRegistration.Dynamic) doPrivileged("addFilter", new Class[]{String.class, Filter.class}, new Object[]{filterName, filter}); } else { return context.addFilter(filterName, filter); } }}public class ApplicationContext implements org.apache.catalina.servlet4preview.ServletContext { private FilterRegistration.Dynamic addFilter(String filterName, String filterClass, Filter filter) throws IllegalStateException { FilterDef filterDef = context.findFilterDef(filterName); // context是StandardContext对象 if (filterDef == null) { filterDef = new FilterDef(); filterDef.setFilterName(filterName); context.addFilterDef(filterDef); } else { if (filterDef.getFilterName() != null && filterDef.getFilterClass() != null) { return null; } } if (filter == null) { filterDef.setFilterClass(filterClass); } else { filterDef.setFilterClass(filter.getClass().getName()); filterDef.setFilter(filter); } return new ApplicationFilterRegistration(filterDef, context); }}
- 通过ApplicationContextFacade的addFilter方法并终极调用ApplicationContext的addFilter方法将过滤器的FilterDef并添加到StandardContext对象当中。
- 是上述方式一样平常在springboot 工程中的加载过程。
Filter的加载流程
- Filter的界说的加载序次如上图所示，包罗分析 web.xml 文件天生 FilterDef并生存到 StandardContext 当中，遍历 StandardContext 的 FilterDef 天生ApplicationFilterConfig并生存到StandardContext当中。
- StandardContext负责生存核心的FilterDef和ApplicationFilterConfig。
Filter实验
Filter团体流程
final class StandardWrapperValve extends ValveBase { @Override public final void invoke(Request request, Response response) throws IOException, ServletException { // 省略相干代码 ApplicationFilterChain filterChain = ApplicationFilterFactory.createFilterChain(request, wrapper, servlet); try { if ((servlet != null) && (filterChain != null)) { if (context.getSwallowOutput()) { try { SystemLogHandler.startCapture(); if (request.isAsyncDispatching()) { request.getAsyncContextInternal().doInternalDispatch(); } else { filterChain.doFilter(request.getRequest(), response.getResponse()); } } finally { } } else { if (request.isAsyncDispatching()) { request.getAsyncContextInternal().doInternalDispatch(); } else { filterChain.doFilter (request.getRequest(), response.getResponse()); } } } } catch (Throwable e) { } // Release the filter chain (if any) for this request if (filterChain != null) { filterChain.release(); } }}
- Filter 实验流程在StandardWrapperValve#invoke 方法当中，核心流程包罗创建 Filter 调用链和实验 Filter 调用链。
- ApplicationFilterFactory.createFilterChain负责创建调用链对象ApplicationFilterChain。
- filterChain.doFilter负责实验 Filter 调用链。
filterChain的构建
public final class ApplicationFilterChain implements FilterChain { public static final int INCREMENT = 10; private ApplicationFilterConfig[] filters = new ApplicationFilterConfig[0]; private int pos = 0; private int n = 0; private Servlet servlet = null; private boolean servletSupportsAsync = false; private static final StringManager sm = StringManager.getManager(Constants.Package); void addFilter(ApplicationFilterConfig filterConfig) { for(ApplicationFilterConfig filter:filters) if(filter==filterConfig) return; if (n == filters.length) { ApplicationFilterConfig[] newFilters = new ApplicationFilterConfig[n + INCREMENT]; System.arraycopy(filters, 0, newFilters, 0, n); filters = newFilters; } filters[n++] = filterConfig; }}
- ApplicationFilterChain的内部维护ApplicationFilterConfig[] filters来生存 Filter 对象。
public final class ApplicationFilterFactory { public static ApplicationFilterChain createFilterChain(ServletRequest request, Wrapper wrapper, Servlet servlet) { ApplicationFilterChain filterChain = null; if (request instanceof Request) { Request req = (Request) request; if (Globals.IS_SECURITY_ENABLED) { filterChain = new ApplicationFilterChain(); } else { filterChain = (ApplicationFilterChain) req.getFilterChain(); if (filterChain == null) { filterChain = new ApplicationFilterChain(); req.setFilterChain(filterChain); } } } else { filterChain = new ApplicationFilterChain(); } filterChain.setServlet(servlet); filterChain.setServletSupportsAsync(wrapper.isAsyncSupported()); // 通过StandardContext#findFilterMaps获取全部的Filter对象 StandardContext context = (StandardContext) wrapper.getParent(); FilterMap filterMaps[] = context.findFilterMaps(); if ((filterMaps == null) || (filterMaps.length == 0)) return (filterChain); DispatcherType dispatcher = (DispatcherType) request.getAttribute(Globals.DISPATCHER_TYPE_ATTR); String requestPath = null; Object attribute = request.getAttribute(Globals.DISPATCHER_REQUEST_PATH_ATTR); if (attribute != null){ requestPath = attribute.toString(); } String servletName = wrapper.getName(); // 匹配路径 Add the relevant path-mapped filters to this filter chain for (int i = 0; i < filterMaps.length; i++) { if (!matchDispatcher(filterMaps ,dispatcher)) { continue; } if (!matchFiltersURL(filterMaps, requestPath)) continue; // 通过StandardContext#findFilterConfig获取Filter对象 ApplicationFilterConfig filterConfig = (ApplicationFilterConfig) context.findFilterConfig(filterMaps.getFilterName()); if (filterConfig == null) { continue; } filterChain.addFilter(filterConfig); } // 匹配servlet的名字 Add filters that match on servlet name second for (int i = 0; i < filterMaps.length; i++) { if (!matchDispatcher(filterMaps ,dispatcher)) { continue; } if (!matchFiltersServlet(filterMaps, servletName)) continue; ApplicationFilterConfig filterConfig = (ApplicationFilterConfig) context.findFilterConfig(filterMaps.getFilterName()); if (filterConfig == null) { // FIXME - log configuration problem continue; } filterChain.addFilter(filterConfig); } // Return the completed filter chain return filterChain; }}
- 获取StandardContext的FilterMap[] 对象，遍历FilterMap[]后举行规则匹配，匹配后通过 StandardContext 获取ApplicationFilterConfig对象添加到ApplicationFilterChain当中。
- StandardContext自己维护的ApplicationFilterConfig的加载流程已经分析，须要相识FilterMap的加载过程。
Filter 实验流程
public final class ApplicationFilterChain implements FilterChain { public static final int INCREMENT = 10; private ApplicationFilterConfig[] filters = new ApplicationFilterConfig[0]; private int pos = 0; private int n = 0; private Servlet servlet = null; private boolean servletSupportsAsync = false; private static final StringManager sm = StringManager.getManager(Constants.Package); @Override public void doFilter(ServletRequest request, ServletResponse response) throws IOException, ServletException { if( Globals.IS_SECURITY_ENABLED ) { // 省略相干代码 } else { internalDoFilter(request,response); } } private void internalDoFilter(ServletRequest request, ServletResponse response) throws IOException, ServletException { if (pos < n) { ApplicationFilterConfig filterConfig = filters[pos++]; try { Filter filter = filterConfig.getFilter(); if( Globals.IS_SECURITY_ENABLED ) { // 省略相干代码 } else { filter.doFilter(request, response, this); } } catch (IOException | ServletException | RuntimeException e) { } catch (Throwable e) { } return; } try { if ((request instanceof HttpServletRequest) && (response instanceof HttpServletResponse) && Globals.IS_SECURITY_ENABLED ) { // 省略相干代码 } else { servlet.service(request, response); } } catch (IOException | ServletException | RuntimeException e) { } catch (Throwable e) { } finally { } }}
- ApplicationFilterChain#internalDoFilter负责 Filter 调用链的实验，内部通过维护 Filter 的对象数组filters和下标pos依次实验 Filter。
FilterMap先容
/** * 来看下这个类的官方表明： * Web应用程序的过滤器映射的表现形式，如摆设描述符中<filter-mapping>元素中的所示 * 每个过滤器映射都必须包罗过滤器名称以及URL模式或servlet名称 * 比方以下设置： * <filter-mapping> * <filter-name>MyFilter</filter-name> * <url-pattern>/my</url-pattern> * </filter-mapping> * * 说白了，这个FilterMap就是封装了设置信息中<filter-mapping>标签中的元素 * 此中还包罗了两个重点属性：过滤器名、过滤器对应过滤的url */public class FilterMap extends XmlEncodingBase implements Serializable { private boolean matchAllUrlPatterns = false; private boolean matchAllServletNames = false; // serverlet的名字，对应多个 private String[] servletNames = new String[0]; // 过滤器名，对应的是<filter-name>中的内容 private String filterName = null; // 过滤url，对应的是<url-pattern>中的内容（可设置多个<filter-mapping>匹配差异的url，因此是数组形式） private String[] urlPatterns = new String[0]; }
- FilterMap的核心字段包罗匹配的 Url格式，对应的 Filter 对象的filterName等。
FilterMap的加载
public class ContextConfig implements LifecycleListener { private void configureContext(WebXml webxml) { // 省略相干代码 for (FilterMap filterMap : webxml.getFilterMappings()) { context.addFilterMap(filterMap); } }}
- 通过webxml.getFilterMappings()获取过滤器的filterMap并添加到StandardContext中。
- 上述方式一样平常在 spring MVC 项目在 web.xml 设置过滤器的时间使用。
public class ApplicationFilterRegistration implements FilterRegistration.Dynamic { private static final StringManager sm = StringManager.getManager(Constants.Package); private final FilterDef filterDef; private final Context context; public ApplicationFilterRegistration(FilterDef filterDef, Context context) { this.filterDef = filterDef; this.context = context; } @Override public void addMappingForServletNames( EnumSet<DispatcherType> dispatcherTypes, boolean isMatchAfter, String... servletNames) { FilterMap filterMap = new FilterMap(); filterMap.setFilterName(filterDef.getFilterName()); if (dispatcherTypes != null) { for (DispatcherType dispatcherType : dispatcherTypes) { filterMap.setDispatcher(dispatcherType.name()); } } if (servletNames != null) { for (String servletName : servletNames) { filterMap.addServletName(servletName); } if (isMatchAfter) { context.addFilterMap(filterMap); } else { context.addFilterMapBefore(filterMap); } } } @Override public void addMappingForUrlPatterns( EnumSet<DispatcherType> dispatcherTypes, boolean isMatchAfter, String... urlPatterns) { FilterMap filterMap = new FilterMap(); filterMap.setFilterName(filterDef.getFilterName()); if (dispatcherTypes != null) { for (DispatcherType dispatcherType : dispatcherTypes) { filterMap.setDispatcher(dispatcherType.name()); } } if (urlPatterns != null) { for (String urlPattern : urlPatterns) { filterMap.addURLPattern(urlPattern); } if (isMatchAfter) { context.addFilterMap(filterMap); } else { context.addFilterMapBefore(filterMap); } } }}
- addMappingForServletNames和addMappingForUrlPatterns负责获取过滤器的filterMap并添加到StandardContext中。
- 上述方式一样平常在 spring boot 工程中加载FilterMap使用。
Filter实验流程图
- 通过分析 web.xml 文件天生 FilterMap并生存到 StandardContext 当中。
- ApplicationFilterChaiFactory 负责创建 Filter 对象 ApplicationFilterChain，然后遍历FilterMap s并添加符合的 Filter 包装对象 ApplicationFilterConfig。
- 实验ApplicationFilterChain的doFilter方法调用过滤器。
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