filter（二） filter中<url-pattern>的匹配规则(转)

下面的代码摘自tomcat源码，用来匹配<filter-mapping>中的<url-pattern>，相信比文字更容易理解：
java 代码

/**
     * Return <code>true</code> if the context-relative request path
     * matches the requirements of the specified filter mapping;
     * otherwise, return <code>null</code>.
     *
     * @param filterMap Filter mapping being checked
     * @param requestPath Context-relative request path of this request
     */
    private boolean matchFiltersURL(FilterMap filterMap, String requestPath) {

        if (requestPath == null)
            return (false);

        // Match on context relative request path
        String testPath = filterMap.getURLPattern();
        if (testPath == null)
            return (false);

        // Case 1 - Exact Match
        if (testPath.equals(requestPath))
            return (true);

        // Case 2 - Path Match ("/.../*")
        if (testPath.equals("/*"))
            return (true);
        if (testPath.endsWith("/*")) {
            if (testPath.regionMatches(0, requestPath, 0,
                                       testPath.length() - 2)) {
                if (requestPath.length() == (testPath.length() - 2)) {
                    return (true);
                } else if ('/' == requestPath.charAt(testPath.length() - 2)) {
                    return (true);
                }
            }
            return (false);
        }

        // Case 3 - Extension Match
        if (testPath.startsWith("*.")) {
            int slash = requestPath.lastIndexOf('/');
            int period = requestPath.lastIndexOf('.');
            if ((slash >= 0) && (period > slash)
                && (period != requestPath.length() - 1)
                && ((requestPath.length() - period)
                    == (testPath.length() - 1))) {
                return (testPath.regionMatches(2, requestPath, period + 1,
                                               testPath.length() - 2));
            }
        }

        // Case 4 - "Default" Match
        return (false); // NOTE - Not relevant for selecting filters

    }