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## org.apache.struts2.interceptor
Class TokenInterceptor

    java.lang.Object
      com.opensymphony.xwork2.interceptor.AbstractInterceptor
          com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
              org.apache.struts2.interceptor.TokenInterceptor

All Implemented Interfaces:
  Interceptor, Serializable

Direct Known Subclasses:
  TokenSessionStoreInterceptor

    public class TokenInterceptor

extends MethodFilterInterceptor

Ensures that only one request per token is processed. This interceptor can make sure that back buttons and double clicks don't cause un-intended side affects. For example, you can use this to prevent careless users who might double click on a "checkout" button at an online store. This interceptor uses a fairly primitive technique for when an invalid token is found: it returns the result invalid.token, which can be mapped in your action configuration. A more complex implementation, `TokenSessionStoreInterceptor`, can provide much better logic for when invalid tokens are found.

Note: To set a token in your form, you should use the token tag. This tag is required and must be used in the forms that submit to actions protected by this interceptor. Any request that does not provide a token (using the token tag) will be processed as a request with an invalid token.

Internationalization Note: The following key could be used to internationalized the action errors generated by this token interceptor

- struts.messages.invalid.token

NOTE: As this method extends off MethodFilterInterceptor, it is capable of deciding if it is applicable only to selective methods in the action class. See `MethodFilterInterceptor` for more info.

Interceptor parameters:

- None

Extending the interceptor:

While not very common for users to extend, this interceptor is extended by the `TokenSessionStoreInterceptor`. The `handleInvalidToken(com.opensymphony.xwork2.ActionInvocation)` and `handleValidToken(com.opensymphony.xwork2.ActionInvocation)` methods are protected and available for more interesting logic, such as done with the token session interceptor.

Example code:

     <action name="someAction" class="com.examples.SomeAction">
         <interceptor-ref name="token"/>
         <interceptor-ref name="basicStack"/>
         <result name="success">good_result.ftl</result>
     </action>

     <-- In this case, myMethod of the action class will not
            get checked for invalidity of token -->
     <action name="someAction" class="com.examples.SomeAction">
         <interceptor-ref name="token">
            <param name="excludeMethods">myMethod</param>
         </interceptor-ref name="token"/>
         <interceptor-ref name="basicStack"/>
         <result name="success">good_result.ftl</result>
     </action>

See Also:
  `TokenSessionStoreInterceptor`, `TokenHelper`, Serialized Form

Field Summary
`static String` | `INVALID_TOKEN_CODE`
`private static long` | `serialVersionUID`

Fields inherited from class com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
`excludeMethods, includeMethods, log`

Constructor Summary
`TokenInterceptor()`

Method Summary
`protected String` | `doIntercept(ActionInvocation invocation)` Subclasses must override to implement the interceptor logic.
`protected String` | `handleInvalidToken(ActionInvocation invocation)` Determines what to do if an invalida token is provided.
`protected String` | `handleValidToken(ActionInvocation invocation)` Called when a valid token is found.

Methods inherited from class com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
`applyInterceptor, getExcludeMethodsSet, getIncludeMethodsSet, intercept, setExcludeMethods, setIncludeMethods`

Methods inherited from class com.opensymphony.xwork2.interceptor.AbstractInterceptor
`destroy, init`

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

Field Detail

### serialVersionUID

    private static final long serialVersionUID

See Also:
  Constant Field Values

### INVALID_TOKEN_CODE

    public static final String INVALID_TOKEN_CODE

See Also:
  Constant Field Values

Constructor Detail

### TokenInterceptor

    public TokenInterceptor()

Method Detail

### doIntercept

    protected String doIntercept(ActionInvocation invocation)
                          throws Exception

  Description copied from class: `MethodFilterInterceptor`
  Subclasses must override to implement the interceptor logic.

  Specified by:
    `doIntercept` in class `MethodFilterInterceptor`
  Parameters:
    `invocation` - the action invocation
  Returns:
    the result of invocation
  Throws:
    `Exception`
  See Also:
    `MethodFilterInterceptor.doIntercept(com.opensymphony.xwork2.ActionInvocation)`

### handleInvalidToken

    protected String handleInvalidToken(ActionInvocation invocation)
                                 throws Exception

  Determines what to do if an invalida token is provided. If the action implements `ValidationAware`

  Parameters:
    `invocation` - the action invocation where the invalid token failed
  Returns:
    the return code to indicate should be processed
  Throws:
    `Exception` - when any unexpected error occurs.

### handleValidToken

    protected String handleValidToken(ActionInvocation invocation)
                               throws Exception

  Called when a valid token is found. This method invokes the action by can be changed to do something more interesting.

  Parameters:
    `invocation` - the action invocation
  Throws:
    `Exception` - when any unexpected error occurs.

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