How to Minify Dynamic HTML Responses in Spring Framework?

What are the best practices for minifying dynamic HTML responses in a Spring application?

// Example of a Spring filter for minifying HTML
public class HtmlMinificationFilter extends GenericFilterBean {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        CharResponseWrapper wrapper = new CharResponseWrapper((HttpServletResponse) response);
        chain.doFilter(request, wrapper);
        String minifiedHtml = minify(wrapper.toString());
        response.getWriter().write(minifiedHtml);
    }
    private String minify(String html) {
        return html.replaceAll("\s+", " ").replaceAll("<!--.*?-->", "").trim();
    }
}

Minifying dynamic HTML in a Spring application improves load times and reduces bandwidth usage by removing unnecessary whitespace and comments. This can be crucial for optimizing web performance.

@Bean
public FilterRegistrationBean<HtmlMinificationFilter> loggingFilter(){
    FilterRegistrationBean<HtmlMinificationFilter> registrationBean = new FilterRegistrationBean<>();
    registrationBean.setFilter(new HtmlMinificationFilter());
    registrationBean.addUrlPatterns("/*");
    return registrationBean;
}

Causes

• Excessive whitespace
• HTML comments
• Unoptimized resource loading

Solutions

• Implement an HTML minification filter in your Spring application.
• Utilize existing libraries like JSoup for HTML manipulation.
• Consider using Spring Boot filters to streamline the process.

Mistake: Not handling character encoding during minification.

Solution: Ensure that the character encoding is set correctly in the response.

Mistake: Ignoring JavaScript and CSS minification.

Solution: Combine HTML minification with tools like Terser or CSSNano for a full optimization.