# class WEBrick::HTTPServlet::AbstractServlet

`AbstractServlet` allows HTTP server modules to be reused across multiple servers and allows encapsulation of functionality.

By default a servlet will respond to GET, HEAD (through an alias to GET) and OPTIONS requests.

By default a new servlet is initialized for every request. A servlet instance can be reused by overriding `::get_instance` in the `AbstractServlet` subclass.

## A Simple Servlet¶ ↑

    class Simple < WEBrick::HTTPServlet::AbstractServlet
      def do_GET request, response
        status, content_type, body = do_stuff_with request

        response.status = status
        response['Content-Type'] = content_type
        response.body = body
      end

      def do_stuff_with request
        return 200, 'text/plain', 'you got a page'
      end
    end

This servlet can be mounted on a server at a given path:

    server.mount '/simple', Simple

## Servlet Configuration¶ ↑

Servlets can be configured via initialize. The first argument is the HTTP server the servlet is being initialized for.

    class Configurable < Simple
      def initialize server, color, size
        super server
        @color = color
        @size = size
      end

      def do_stuff_with request
        content = "<p " \
                  %q{style="color: #{@color}; font-size: #{@size}"} \
                  ">Hello, World!"

        return 200, "text/html", content
      end
    end

This servlet must be provided two arguments at mount time:

    server.mount '/configurable', Configurable, 'red', '2em'

### Public Class Methods

get_instance(server, *options) click to toggle source

Factory for servlet instances that will handle a request from `server` using `options` from the mount point. By default a new servlet instance is created for every call.

    # File lib/webrick/httpservlet/abstract.rb, line 83
    def self.get_instance(server, *options)
      self.new(server, *options)
    end

new(server, *options) click to toggle source

Initializes a new servlet for `server` using `options` which are stored as-is in +@options+. +@logger+ is also provided.

    # File lib/webrick/httpservlet/abstract.rb, line 91
    def initialize(server, *options)
      @server = @config = server
      @logger = @server[:Logger]
      @options = options
    end

### Public Instance Methods

do_GET(req, res) click to toggle source

Raises a NotFound exception

    # File lib/webrick/httpservlet/abstract.rb, line 115
    def do_GET(req, res)
      raise HTTPStatus::NotFound, "not found."
    end

do_HEAD(req, res) click to toggle source

Dispatches to `do_GET`

    # File lib/webrick/httpservlet/abstract.rb, line 122
    def do_HEAD(req, res)
      do_GET(req, res)
    end

do_OPTIONS(req, res) click to toggle source

Returns the allowed HTTP request methods

    # File lib/webrick/httpservlet/abstract.rb, line 129
    def do_OPTIONS(req, res)
      m = self.methods.grep(/\Ado_([A-Z]+)\z/) {$1}
      m.sort!
      res["allow"] = m.join(",")
    end

service(req, res) click to toggle source

Dispatches to a `do_` method based on `req` if such a method is available. (`do_GET` for a GET request). Raises a MethodNotAllowed exception if the method is not implemented.

    # File lib/webrick/httpservlet/abstract.rb, line 102
    def service(req, res)
      method_name = "do_" + req.request_method.gsub(/-/, "_")
      if respond_to?(method_name)
        __send__(method_name, req, res)
      else
        raise HTTPStatus::MethodNotAllowed,
              "unsupported method `#{req.request_method}'."
      end
    end

### Private Instance Methods

redirect_to_directory_uri(req, res) click to toggle source

Redirects to a path ending in /

    # File lib/webrick/httpservlet/abstract.rb, line 140
    def redirect_to_directory_uri(req, res)
      if req.path[-1] != ?/
        location = WEBrick::HTTPUtils.escape_path(req.path + "/")
        if req.query_string && req.query_string.bytesize > 0
          location << "?" << req.query_string
        end
        res.set_redirect(HTTPStatus::MovedPermanently, location)
      end
    end