WhitelistUrlFilter (Alpine 1.9.2 API)

java.lang.Object
- alpine.filters.WhitelistUrlFilter

All Implemented Interfaces:

javax.servlet.Filter
```
public final class WhitelistUrlFilter
extends Object
implements javax.servlet.Filter
```
WhitelistUrlFilter is a configurable Servlet Filter that can prevent access to specific URLs. The filter will ignore access to all URLs that are not specifically whitelisted. Ignored URLs result in a HTTP 404 response. The filter may be used when specific files or directories should not be accessible. In the case of executable WARs, use of this filter is highly recommended since executable WARs must meet the requirements of both JAR and WAR files, thus placing compiled classes and their package structure inside the document webroot. Sample usage:
```
 <filter>
   <filter-name>WhitelistUrlFilter</filter-name>
   <filter-class>alpine.filters.WhitelistUrlFilter</filter-class>
   <init-param>
     <param-name>allowUrls</param-name>
     <param-value>/images,/css</param-value>
   </init-param>
 </filter>

 <filter-mapping>
   <filter-name>WhitelistUrlFilter</filter-name>
   <url-pattern>/*</url-pattern>
 </filter-mapping>

 
```
Optionally, the forwardTo parameter can be specified to instruct the WhitelistUrlFilter to forward the request to a URL of another Servlet, JSP, or HTML file should the originally requested URL not be whitelisted. This may be necessary in some Single Page Applications (SPA).
Since:

1.0.0

Author:

Steve Springett

Constructor Summary

Constructors
Constructor Description

WhitelistUrlFilter()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`destroy()`
`void`	`doFilter(javax.servlet.ServletRequest request, javax.servlet.ServletResponse response, javax.servlet.FilterChain chain)`	Check for allowed URLs being requested.
`void`	`init(javax.servlet.FilterConfig filterConfig)`	Initialize "allowUrls" parameter from web.xml.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - WhitelistUrlFilter
```
public WhitelistUrlFilter()
```
- Method Detail
  - init
```
public void init(javax.servlet.FilterConfig filterConfig)
```
    Initialize "allowUrls" parameter from web.xml.
    
    Specified by:
    
    init in interface javax.servlet.Filter
    
    Parameters:
    
    filterConfig - A filter configuration object used by a servlet container to pass information to a filter during initialization.
  - doFilter
```
public void doFilter(javax.servlet.ServletRequest request,
                     javax.servlet.ServletResponse response,
                     javax.servlet.FilterChain chain)
              throws IOException,
                     javax.servlet.ServletException
```
    Check for allowed URLs being requested.
    
    Specified by:
    
    doFilter in interface javax.servlet.Filter
    
    Parameters:
    
    request - The request object.
    
    response - The response object.
    
    chain - Refers to the FilterChain object to pass control to the next Filter.
    
    Throws:
    
    IOException - a IOException
    
    javax.servlet.ServletException - a ServletException
  - destroy
```
public void destroy()
```
    Specified by:
    
    destroy in interface javax.servlet.Filter