CODEWITHSUNDEEP
javaspringweb.xmlservlet-filters
amphibient
amphibient

Reputation: 31212

Spring injection in Filter implementation mapped in web.xml

web.xml:

<filter>
    <filter-name>myFilter</filter-name>
    <filter-class>com.mypackage.MyFilter</filter-class>
</filter>

<filter-mapping>
    <filter-name>myFilter</filter-name>
    <url-pattern>/myFilterPattern/*</url-pattern>
</filter-mapping>

MyFilter:

public class MyFilter implements Filter {

    @Autowired
    InjectedBean someInjectedBean;

However, when intercepting /myFilterPattern/* requests, someInjectedBean in MyFilter.doFilter(...) is still null, meaning it has not been injected. The same bean (InjectedBean) is injected fine in other context components that are not referenced in web.xml.

Is it because container filtering takes place outside the Spring context? Is there any way to have Spring injection in Filter implementation mapped in web.xml?

Upvotes: 0

Views: 5257

Answers (2)

SarangRN
SarangRN

Reputation: 140

One more solution if you are using spring security and extending the OncePerRequestFilter

@Component
public class CustomAuthorizationFilter extends OncePerRequestFilter{

    @Autowired
    ResourceConfig resourceConfig;

    public CustomAuthorizationFilter() {
            SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);
    }
//...your code

its important to pull the details from resourceConfig in doFilterInternal block only so you will get values else you may end up at null pointer exception.

Upvotes: 1

Praneeth Ramesh
Praneeth Ramesh

Reputation: 3554

Since Filter is not a spring bean(it is a web component) the injections won't work inside them. Springs wont inject inside web component.

use a DelegatingFilterProxy, this is a filter implementation that takes a springbean name as init param and delegates the filter request to that bean.

<filter>
  <filter-name>myFilter</filter-name>
  <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
  <init-param>
    <param-name>targetBeanName</param-name>
    <param-value>myFilterBean</param-value>
  </init-param>
</filter>

<filter-mapping>
  <filter-name>myFilter</filter-name>
  <url-pattern>/myFilterPattern/*</url-pattern>
</filter-mapping>

And create a Bean with name myFilterBean in your spring context.

public class MyFilter extends GenericFilterBean {

    @Autowired
    InjectedBean someInjectedBean;
 
    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
      FilterChain chain) throws IOException, ServletException {
        chain.doFilter(request, response);
    }
}

Upvotes: 4

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