使用ngx_lua模組(http://wiki.nginx.org/HttpLuaModule)：

local request_method = ngx.var.request_method
local args = nil
local param = nil
local param2 = nil


--獲取引數的值
if "GET" == request_method then
    args = ngx.req.get_uri_args()
elseif "POST" == request_method then
    ngx.req.read_body()
    args = ngx.req.get_post_args()
end

param = args["param"]
param2 = args["param2"]
 

升級版(能處理content-type=multipart/form-data的表單)：

local function explode ( _str,seperator )
	local pos, arr = 0, {}
		for st, sp in function() return string.find( _str, seperator, pos, true ) end do
			table.insert( arr, string.sub( _str, pos, st-1 ) )
			pos = sp + 1
		end
	table.insert( arr, string.sub( _str, pos ) )
	return arr
end
local args = {}
local file_args = {}
local is_have_file_param = false
local function init_form_args()
        local receive_headers = ngx.req.get_headers()
	local request_method = ngx.var.request_method


	if "GET" == request_method then
		args = ngx.req.get_uri_args()
	elseif "POST" == request_method then
		ngx.req.read_body()
		if string.sub(receive_headers["content-type"],1,20) == "multipart/form-data;" then--判斷是否是multipart/form-data型別的表單
			is_have_file_param = true
			content_type = receive_headers["content-type"]
			body_data = ngx.req.get_body_data()--body_data可是符合http協議的請求體，不是普通的字串

                        --請求體的size大於nginx配置裡的client_body_buffer_size，則會導致請求體被緩衝到磁碟臨時檔案裡，client_body_buffer_size預設是8k或者16k
			if not body_data then
				local datafile = ngx.req.get_body_file()
				if not datafile then
					error_code = 1
					error_msg = "no request body found"
				else
					local fh, err = io.open(datafile, "r")
					if not fh then
						error_code = 2
						error_msg = "failed to open " .. tostring(datafile) .. "for reading: " .. tostring(err)
					else
						fh:seek("set")
						body_data = fh:read("*a")
						fh:close()
						if body_data == "" then
							error_code = 3
							error_msg = "request body is empty"
						end
					end
				end
			end


			local new_body_data = {}
			--確保取到請求體的資料
			if not error_code then
				local boundary = "--" .. string.sub(receive_headers["content-type"],31)
				local body_data_table = explode(tostring(body_data),boundary)


				local first_string = table.remove(body_data_table,1)
				local last_string = table.remove(body_data_table)


				for i,v in ipairs(body_data_table) do
					local start_pos,end_pos,capture,capture2 = string.find(v,'Content%-Disposition: form%-data; name="(.+)"; filename="(.*)"')
					if not start_pos then--普通引數
						local t = explode(v,"\r\n\r\n")
						local temp_param_name = string.sub(t[1],41,-2)
						local temp_param_value = string.sub(t[2],1,-3)
						args[temp_param_name] = temp_param_value
					else--檔案型別的引數，capture是引數名稱，capture2是檔名
						file_args[capture] = capture2
						table.insert(new_body_data,v)
					end
				end
				table.insert(new_body_data,1,first_string)
				table.insert(new_body_data,last_string)
				--去掉app_key,app_secret等幾個引數，把業務級別的引數傳給內部的API
				body_data = table.concat(new_body_data,boundary)--body_data可是符合http協議的請求體，不是普通的字串
			end
		else
			args = ngx.req.get_post_args()
		end
	end
end