How Do You Register Custom Filters in Spring Boot Using FilterRegistrationBean?

Adding a Filter Class in Spring Boot

Spring Boot offers various ways to register filters in web applications. For custom filters, the FilterRegistrationBean bean is commonly used.

Using FilterRegistrationBean

To add a custom filter using FilterRegistrationBean, follow these steps:

1. Create a new bean in your @Configuration class:

   <code class="java">@Bean
   public FilterRegistrationBean filterRegistration() {
   
    FilterRegistrationBean registration = new FilterRegistrationBean();
    registration.setFilter(customFilter());
    registration.addUrlPatterns("/url/*");
    registration.setName("customFilter");
    registration.setOrder(1);
    return registration;
   }</code>

2. Define the actual filter implementation:

   <code class="java">public class CustomFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // Initialization logic here
    }
   
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        // Filter logic here
        filterChain.doFilter(servletRequest, servletResponse);
    }
   
    @Override
    public void destroy() {
        // Destroy logic here
    }
   }</code>

3. Customize the filter configuration as needed, such as:

   • addInitParameter for initializing filter parameters
   • addUrlPatterns to specify URL patterns to apply the filter to
   • setName for assigning a unique name to the filter
   • setOrder to determine the order in which filters are executed

Additional Considerations

• Test the above approach with Spring Boot version 1.2.3 or later.
• Use the init-params tag in the @Bean annotation to set init parameters for the filter.
• Note that Spring Boot 2.0 has a more concise syntax for setting up these filters using the WebFilter interface.

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