Fix Java XSS Filter Null Issue

If your Java XSS filter returns null, it could be due to the filter not being properly configured or having incomplete rules. Here are some possible solutions:

1. Check the configuration of the filters: Verify that the initialization and configuration of the filters are correct, including setting filter rules and the order of the filters.
2. Check filtering rules: Ensure that the rules for the filter include filtering of HTML tags, JavaScript code, and special characters. You can use a pre-made XSS filter library or create custom filtering rules.
3. Check the input data: Make sure the input data is not empty and meets the expected format. Empty or incorrect data input could lead to the filter reporting as empty.
4. Debugging filters: adding log outputs or debugging information in the filters can help locate the problem. Debugging allows you to view the processing logic of the filters and identify the reasons for the null reports.
5. Update the filter: If you are using a filter provided by a third-party library or framework, try updating to the latest version as it may fix some known issues.

In conclusion, carefully examining the configuration and rules of the filter, ensuring that input data is correct and adding debugging information can help solve the issue of Java XSS filter reporting as empty. If the issue persists, it is recommended to review the source code of the filter or seek assistance from the developer of the filter.