can get access_token for weixin

lib/weixin_authorize.rb

+require "rest-client"
 require "weixin_authorize/version"
 require "weixin_authorize/client"
 

lib/weixin_authorize/client.rb

+# encoding: utf-8
+
 module WeixinAuthorize
 
   class Client
-    attr_accessor :app_id, :app_secret
+    attr_accessor :app_id, :app_secret, :expired_at # Time.now + expires_in
 
     attr_accessor :access_token
 
-    def initialize(&block)
-      instance_eval(&block)
+    def initialize(app_id="", app_secret="", expired_at=nil)
+      @app_id     = app_id
+      @app_secret = app_secret
+      @expired_at = (expired_at.to_i || Time.now.to_i)
+      yield self if block_given?
+    end
+
+    # return token
+    def get_access_token
+      # 如果当前token过期时间小于现在的时间，则重新获取一次
+      if @expired_at < Time.now.to_i
+        authenticate
+      end
+      @access_token
+    end
+
+    # authenticate access_token
+    def authenticate
+      hash_infos        = JSON.parse(RestClient.get(authenticate_url))
+      self.access_token = hash_infos["access_token"]
+      self.expired_at   = Time.now.to_i + hash_infos["expires_in"]
     end
 
+    private
+
+      def authenticate_url
+        "#{endpoint}/token?grant_type=client_credential&appid=#{app_id}&secret=#{app_secret}"
+      end
+
+      def endpoint
+        "https://api.weixin.qq.com/cgi-bin"
+      end
+
   end
 end

spec/fetch_access_token_spec.rb

@@ -2,8 +2,20 @@ require "spec_helper"
 
 describe WeixinAuthorize::Client do
   describe "#get access_token" do
-    it "returns a access_token value" do
-      expect($client.app_id).not_to eq("ss")
+    it "return a access_token nil value before authenticate" do
+      expect($client.access_token).to eq(nil)
+    end
+
+    it "return access_token after authenticate" do
+      $client.authenticate
+      expect($client.access_token).not_to eq(nil)
+    end
+
+    it "return the same access_token in the same thing twice" do
+      access_token_1 = $client.get_access_token
+      sleep 5
+      access_token_2 = $client.get_access_token
+      expect(access_token_1).to eq(access_token_2)
     end
   end
 end