func (self *HttpDownloader) downloadJson(p *robot.Page, req *robot.Request) *robot.Page {
	var err error
	p, destbody := self.downloadFile(p, req)
	if !p.IsSucc() {
		return p
	}

	var body []byte
	body = []byte(destbody)
	mtype := req.GetResponceType()
	if mtype == "jsonp" {
		tmpstr := goutils.JsonpToJson(destbody)
		body = []byte(tmpstr)
	}

	var r *simplejson.Json
	if r, err = simplejson.NewJson(body); err != nil {
		mlog.LogInst().LogError(string(body) + "\t" + err.Error())
		p.SetStatus(true, err.Error())
		return p
	}

	// json result
	p.SetBodyStr(string(body)).SetJson(r).SetStatus(false, "")

	return p
}

func (self *QueueScheduler) Push(requ *robot.Request) {
	self.locker.Lock()
	var key [md5.Size]byte
	if self.rm {
		key = md5.Sum([]byte(requ.GetUrl()))
		if _, ok := self.rmKey[key]; ok {
			self.locker.Unlock()
			return
		}
	}
	e := self.queue.PushBack(requ)
	if self.rm {
		self.rmKey[key] = e
	}
	self.locker.Unlock()
}

func (self *RedisScheduler) Push(requ *robot.Request) {
	self.locker.Lock()
	defer self.locker.Unlock()
	requJson, err := json.Marshal(requ)
	if err != nil {
		log.Println("RedisScheduler Push Error: " + err.Error())
		return
	}

	conn := self.redisPool.Get()
	defer conn.Close()

	if err != nil {
		log.Println("RedisScheduler Push Error: " + err.Error())
		return
	}
	if self.forbiddenDuplicateUrl {
		urlExist, err := conn.Do("HGET", self.urlList, requ.GetUrl())
		if err != nil {
			log.Println("RedisScheduler Push Error: " + err.Error())
			return
		}
		if urlExist != nil {
			return
		}
		conn.Do("MULTI")
		_, err = conn.Do("HSET", self.urlList, requ.GetUrl(), 1)
		if err != nil {
			log.Println("RedisScheduler Push Error: " + err.Error())
			conn.Do("DISCARD")
			return
		}
	}
	_, err = conn.Do("RPUSH", self.requestList, requJson)
	if err != nil {
		log.Println("RedisScheduler Push Error: " + err.Error())
		if self.forbiddenDuplicateUrl {
			conn.Do("DISCARD")
		}
		return
	}

	if self.forbiddenDuplicateUrl {
		conn.Do("EXEC")
	}
}

// choose a proxy server to excute http GET/method to download
func connectByHttpProxy(p *robot.Page, in_req *robot.Request) (*http.Response, error) {
	request, _ := http.NewRequest("GET", in_req.GetUrl(), nil)
	proxy, err := url.Parse(in_req.GetProxyHost())
	if err != nil {
		return nil, err
	}
	client := &http.Client{
		Transport: &http.Transport{
			Proxy: http.ProxyURL(proxy),
		},
	}
	resp, err := client.Do(request)
	if err != nil {
		return nil, err
	}
	return resp, nil

}

func (self *HttpDownloader) Download(req *robot.Request) *robot.Page {
	var mtype string
	var p = robot.NewPage(req)
	mtype = req.GetResponceType()
	switch mtype {
	case "html":
		return self.downloadHtml(p, req)
	case "json":
		fallthrough
	case "jsonp":
		return self.downloadJson(p, req)
	case "text":
		return self.downloadText(p, req)
	default:
		mlog.LogInst().LogError("error request type:" + mtype)
	}
	return p
}

// Download file and change the charset of page charset.
func (self *HttpDownloader) downloadFile(p *robot.Page, req *robot.Request) (*robot.Page, string) {
	var err error
	var urlstr string
	if urlstr = req.GetUrl(); len(urlstr) == 0 {
		mlog.LogInst().LogError("url is empty")
		p.SetStatus(true, "url is empty")
		return p, ""
	}

	var resp *http.Response

	if proxystr := req.GetProxyHost(); len(proxystr) != 0 {
		//using http proxy
		//fmt.Print("HttpProxy Enter ",proxystr,"\n")
		resp, err = connectByHttpProxy(p, req)
	} else {
		//normal http download
		//fmt.Print("Http Normal Enter \n",proxystr,"\n")
		resp, err = connectByHttp(p, req)
	}

	if err != nil {
		return p, ""
	}

	p.SetHeader(resp.Header)
	p.SetCookies(resp.Cookies())

	// get converter to utf-8
	var bodyStr string
	if resp.Header.Get("Content-Encoding") == "gzip" {
		bodyStr = self.changeCharsetEncodingAutoGzipSupport(resp.Header.Get("Content-Type"), resp.Body)
	} else {
		bodyStr = self.changeCharsetEncodingAuto(resp.Header.Get("Content-Type"), resp.Body)
	}
	//fmt.Printf("utf-8 body %v \r\n", bodyStr)
	defer resp.Body.Close()
	return p, bodyStr
}

// choose http GET/method to download
func connectByHttp(p *robot.Page, req *robot.Request) (*http.Response, error) {
	client := &http.Client{}

	httpreq, err := http.NewRequest(req.GetMethod(), req.GetUrl(), strings.NewReader(req.GetPostdata()))
	if header := req.GetHeader(); header != nil {
		httpreq.Header = req.GetHeader()
	}

	if cookies := req.GetCookies(); cookies != nil {
		for i := range cookies {
			httpreq.AddCookie(cookies[i])
		}
	}

	var resp *http.Response
	if resp, err = client.Do(httpreq); err != nil {
		if e, ok := err.(*url.Error); ok && e.Err != nil && e.Err.Error() == "normal" {
			//  normal
		} else {
			mlog.LogInst().LogError(err.Error())
			p.SetStatus(true, err.Error())
			//fmt.Printf("client do error %v \r\n", err)
			return nil, err
		}
	}

	return resp, nil
}