apisix 测试和训练GET请求（其中包含HEAD方法）

    function _M.access(conf, ctx)
    -- 引入resty的http请求模块
    local http = require("resty.http")
    -- 新建一个http请求
    local httpc = http.new()
    -- 负载均衡的节点列表
    local hosts = {}
    hosts["192.168.123.131:81"] = 1
    hosts["192.168.123.131:82"] = 1
    hosts["192.168.123.131:83"] = 1
    hosts["192.168.123.131:84"] = 1
    -- 发送一个http请求
    local resp, err = httpc:request_uri("http://192.168.123.119:82/send", {
        method = "GET",
        headers = {
            -- 设置发送的数据类型
            ["Content-Type"] = "application/j