title: Do filter action before spring security login-processing-url (/j_spring_security_check)
body: <p>I use a spring security form, which looks like : </p>
  
  <pre><code>         &lt;form-login login-page="/login.jsp" 
                  default-target-url="/user/main.html"
                  authentication-failure-url="/login.jsp?error=loginfail" 
                  login-processing-url="/j_spring_security_check"/&gt;
  </code></pre>
  
  <p>I want to do some action before user login. If I create a filter : </p>
  
  <pre><code>&lt;filter-mapping&gt;
      &lt;filter-name&gt;tenantFilter&lt;/filter-name&gt;
      &lt;url-pattern&gt;/j_spring_security_check&lt;/url-pattern&gt;
  &lt;/filter-mapping&gt;
  </code></pre>
  
  <p>It looks like I cannot catch the before login action. Does anyone have some idea?</p>