SpringBoot : How to create a Filter in Spring Boot Application

Points To Remember

• Implement the class Filter.
• Add @Configuration annotation to the class to register it as a filter bean.
• Call method 
• filterChain.doFilter(resquest,response) to continue the request flow
• Call method sendError to send error,

  ((HttpServletResponse)response).sendError(HttpServletResponse.SC_BAD_REQUEST);

• Call method sendRedirect to redirect request to error handler

  ((HttpServletResponse)response).sendRedirect("/errorUrl");

How to create a Filter in Spring Boot Application

IN order to make a filter, we have create a class SecurityFilter

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1. package com.ekiras.filter;  
2.   
3. import org.springframework.core.Ordered;  
4. import org.springframework.core.annotation.Order;  
5. import org.springframework.stereotype.Component;  
6.   
7. import javax.servlet.*;  
8. import javax.servlet.http.HttpServletResponse;  
9. import java.io.IOException;  
10.   
11. /** 
12.  * @author ekansh 
13.  */  
14. @Component  
15. @Order(Ordered.HIGHEST_PRECEDENCE)  
16. public class SecurityFilter implements Filter {  
17.   
18.     private static final boolean CONDITION = true;  
19.   
20.     @Override  
21.     public void init(FilterConfig filterConfig) throws ServletException {  
22.   
23.     }  
24.   
25.     @Override  
26.     public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {  
27.         if(CONDITION==true)  
28.             chain.doFilter(request,response);  
29.         else{  
30.             ((HttpServletResponse)response).setStatus(HttpServletResponse.SC_BAD_REQUEST);  
31.         }  
32.   
33.     }  
34.   
35.     @Override  
36.     public void destroy() {  
37.   
38.     }  
39. }  

package com.ekiras.filter; import org.springframework.core.Ordered; import org.springframework.core.annotation.Order; import org.springframework.stereotype.Component; import javax.servlet.*; import javax.servlet.http.HttpServletResponse; import java.io.IOException; /** * @author ekansh */ @Component @Order(Ordered.HIGHEST_PRECEDENCE) public class SecurityFilter implements Filter { private static final boolean CONDITION = true; @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { if(CONDITION==true) chain.doFilter(request,response); else{ ((HttpServletResponse)response).setStatus(HttpServletResponse.SC_BAD_REQUEST); } } @Override public void destroy() { } }

This is how you can create the filter and register it in the Spring Boot Application.