Interface Handler

All Known Subinterfaces:
Filter
All Known Implementing Classes:
AclSwitchHandler, AsteriskAGIHandler, AsteriskHandler, BasicAuthHandler, CacheManager, CgiHandler, ChainHandler, ChainSawHandler, ChownHandler, ConfigFileHandler, CookieFilter, CookieSessionHandler, CopyContentFilter, DefaultFileHandler, DeferredHandler, DelayHandler, DialogHandler, DigestAuthHandler, DirectoryHandler, DirectoryTemplate, DynamicConfigHandler, ExecFilter, ExprPropsHandler, FileHandler, FilterHandler, GenericProxyHandler, HistoryFilter, HomeDirHandler, JunkBusterHandler, LogHandler, MD5Filter, MultiHostHandler, MultipartSetTemplate, MultiProxyHandler, NotFoundHandler, PlainFilter, PollHandler, PropertiesCacheManager, PropertiesHandler, ProxyHandler, ProxyPropertiesHandler, PublishHandler, PushHandler, PutHandler, ReFilter, ReflectHandler, ReplaceFilter, RePollHandler, ResourceHandler, ResourceLimitHandler, RestartHandler, RestartingMultiHostHandler, RestrictClientHandler, RolesHandler, SessionFilter, SetTemplate, SimpleSessionHandler, SMTPHandler, StunnelHandler, SubstPropsHandler, SunNetAuthHandler, SunProxy, SupplyHandler, TemplateFilter, TemplateHandler, UrlMapFilter, UrlMapperHandler, UrlSessionFilter, VirtualHostHandler
public interface Handler
The interface for writing HTTP handlers. Provides basic functionality to accept HTTP requests and dispatch to methods that handle the request.

The init(Server, String) method is called before this Handler processes the first HTTP request, to allow it to prepare itself, such as by allocating any resources needed for the lifetime of the server.

The respond(Request) method is called to handle an HTTP request. This method, and all methods it calls must be thread-safe since they may handle HTTP requests from multiple sockets concurrently. However, each concurrent request gets its own individual Request object.

Any instance variables should be initialized in the init(Server, String), and only referenced, but not set in the respond(Request) method. If any state needs to be retained, it should be done either by associating it with the Request object, or using the session manager. Class statics should be avoided, as it is possible, and even common to run multiple unrelated Brazil servers in the same JVM. As above, the session manager should be used instead.

Version:
2.3
Author:
Stephen Uhler (stephen.uhler@sun.com), Colin Stevens (colin.stevens@sun.com)

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    init(Server server, String prefix)
    Initializes the handler.
    boolean
    respond(Request request)
    Responds to an HTTP request.

  • Method Details

    • init

      boolean init(Server server, String prefix)
      Initializes the handler.
      Parameters:
      server - The HTTP server that created this Handler. Typical Handlers will use Server.props to obtain run-time configuration information.
      prefix - The handlers name. The string this Handler may prepend to all of the keys that it uses to extract configuration information from Server.props. This is set (by the Server and ChainHandler) to help avoid configuration parameter namespace collisions.
      Returns:
      true if this Handler initialized successfully, false otherwise. If false is returned, this Handler should not be used.

    • respond

      boolean respond(Request request) throws IOException
      Responds to an HTTP request.
      Parameters:
      request - The Request object that represents the HTTP request.
      Returns:
      true if the request was handled. A request was handled if a response was supplied to the client, typically by calling Request.sendResponse() or Request.sendError.
      Throws:
      IOException - if there was an I/O error while sending the response to the client. Typically, in that case, the Server will (try to) send an error message to the client and then close the client's connection.

      The IOException should not be used to silently ignore problems such as being unable to access some server-side resource (for example getting a FileNotFoundException due to not being able to open a file). In that case, the Handler's duty is to turn that IOException into a HTTP response indicating, in this case, that a file could not be found.