Package org.apache.http.impl.client

Class ClientParamsStack

java.lang.Object
org.apache.http.params.AbstractHttpParams
org.apache.http.impl.client.ClientParamsStack
All Implemented Interfaces:
HttpParams
public class ClientParamsStack
extends AbstractHttpParams
Represents a stack of parameter collections. When retrieving a parameter, the stack is searched in a fixed order and the first match returned. Setting parameters via the stack is not supported. To minimize overhead, the stack has a fixed size and does not maintain an internal array. The supported stack entries, sorted by increasing priority, are:
  1. Application parameters: expected to be the same for all clients used by an application. These provide "global", that is application-wide, defaults.
  2. Client parameters: specific to an instance of HttpClient. These provide client specific defaults.
  3. Request parameters: specific to a single request execution. For overriding client and global defaults.
  4. Override parameters: specific to an instance of HttpClient. These can be used to set parameters that cannot be overridden on a per-request basis.
Each stack entry may be null. That is preferable over an empty params collection, since it avoids searching the empty collection when looking up parameters.
Version:
$Revision: 673450 $
Author:
Roland Weber

  • Field Details

    • applicationParams

      protected final HttpParams applicationParams
      The application parameter collection, or null.

    • clientParams

      protected final HttpParams clientParams
      The client parameter collection, or null.

    • requestParams

      protected final HttpParams requestParams
      The request parameter collection, or null.

    • overrideParams

      protected final HttpParams overrideParams
      The override parameter collection, or null.

  • Constructor Details

    • ClientParamsStack

      public ClientParamsStack​(HttpParams aparams, HttpParams cparams, HttpParams rparams, HttpParams oparams)
      Creates a new parameter stack from elements. The arguments will be stored as-is, there is no copying to prevent modification.
      Parameters:
      aparams - application parameters, or null
      cparams - client parameters, or null
      rparams - request parameters, or null
      oparams - override parameters, or null

    • ClientParamsStack

      public ClientParamsStack​(ClientParamsStack stack)
      Creates a copy of a parameter stack. The new stack will have the exact same entries as the argument stack. There is no copying of parameters.
      Parameters:
      stack - the stack to copy

    • ClientParamsStack

      public ClientParamsStack​(ClientParamsStack stack, HttpParams aparams, HttpParams cparams, HttpParams rparams, HttpParams oparams)
      Creates a modified copy of a parameter stack. The new stack will contain the explicitly passed elements. For elements where the explicit argument is null, the corresponding element from the argument stack is used. There is no copying of parameters.
      Parameters:
      stack - the stack to modify
      aparams - application parameters, or null
      cparams - client parameters, or null
      rparams - request parameters, or null
      oparams - override parameters, or null

  • Method Details

    • getApplicationParams

      public final HttpParams getApplicationParams()
      Obtains the application parameters of this stack.
      Returns:
      the application parameters, or null

    • getClientParams

      public final HttpParams getClientParams()
      Obtains the client parameters of this stack.
      Returns:
      the client parameters, or null

    • getRequestParams

      public final HttpParams getRequestParams()
      Obtains the request parameters of this stack.
      Returns:
      the request parameters, or null

    • getOverrideParams

      public final HttpParams getOverrideParams()
      Obtains the override parameters of this stack.
      Returns:
      the override parameters, or null

    • getParameter

      public Object getParameter​(String name)
      Obtains a parameter from this stack. See class comment for search order.
      Parameters:
      name - the name of the parameter to obtain
      Returns:
      the highest-priority value for that parameter, or null if it is not set anywhere in this stack
      See Also:
      HttpParams.setParameter(String, Object)

    • setParameter

      public HttpParams setParameter​(String name, Object value) throws UnsupportedOperationException
      Does not set a parameter. Parameter stacks are read-only. It is possible, though discouraged, to access and modify specific stack entries. Derived classes may change this behavior.
      Parameters:
      name - ignored
      value - ignored
      Returns:
      nothing
      Throws:
      UnsupportedOperationException - always

    • removeParameter

      public boolean removeParameter​(String name)
      Does not remove a parameter. Parameter stacks are read-only. It is possible, though discouraged, to access and modify specific stack entries. Derived classes may change this behavior.
      Parameters:
      name - ignored
      Returns:
      nothing
      Throws:
      UnsupportedOperationException - always

    • copy

      public HttpParams copy()
      Does not copy parameters. Parameter stacks are lightweight objects, expected to be instantiated as needed and to be used only in a very specific context. On top of that, they are read-only. The typical copy operation to prevent accidental modification of parameters passed by the application to a framework object is therefore pointless and disabled. Create a new stack if you really need a copy.
      Derived classes may change this behavior.
      Returns:
      this parameter stack