// Test empty pattern
        urlFilter.addInclude("");
        urlFilter.addExclude("");

        // Test single character pattern
        urlFilter.addInclude(".");
        urlFilter.addExclude("*");

        // Test patterns with only special characters
        urlFilter.addInclude("^$");
        urlFilter.addExclude(".*");

        // Should handle boundary conditions gracefully

        crawler.crawlerContext.setMaxAccessCount(maxCount);
        crawler.crawlerContext.setNumOfThread(numOfThread);
        crawler.urlFilter.addInclude(url + ".*");
        crawler.urlFilter.addExclude(url + "/dir1/.*");
        final String sessionId = crawler.execute();
        assertEquals(maxCount, dataService.getCount(sessionId));
        dataService.delete(sessionId);
    }

        crawler.crawlerContext.setMaxAccessCount(maxCount);
        crawler.crawlerContext.setNumOfThread(numOfThread);
        crawler.urlFilter.addInclude(url + ".*");
        crawler.urlFilter.addExclude(url + "/dir1/.*");
        final String sessionId = crawler.execute();
        assertEquals(maxCount, dataService.getCount(sessionId));
        dataService.delete(sessionId);
    }

```

### URL Filtering

```java
// Include patterns
crawler.urlFilter.addInclude("https://example.com/.*");
crawler.urlFilter.addInclude(".*\\.pdf$");

// Exclude patterns  
crawler.urlFilter.addExclude(".*\\.js$");
crawler.urlFilter.addExclude(".*login.*");
```

## Supported Protocols and Formats

### Protocols

     * @param regexp The regular expression for the include filter.
     */
    public void addIncludeFilter(final String regexp) {
        if (StringUtil.isNotBlank(regexp)) {
            urlFilter.addInclude(regexp);
        }
    }

    /**
     * Adds an exclude filter for URLs.
     * URLs matching this regular expression will not be crawled.
     * @param regexp The regular expression for the exclude filter.

        @Override
        public void init(String sessionId) {
        }

        @Override
        public void addInclude(String urlPattern) {
        }

        @Override
        public void addExclude(String urlPattern) {
        }

        @Override
        public boolean match(String url) {
            return true;
        }

        @Override