Lua http socket評估

Question

我使用lua 5.1和luaSocket 2.0.2-4從Web服務器檢索頁面。我首先檢查服務器是否正在響應，然後將Web服務器響應分配給lua變量。

local mysocket = require("socket.http") 
if mysocket.request(URL) == nil then 
    print('The server is unreachable on:\n'..URL) 
    return 
end 
local response, httpCode, header = mysocket.request(URL) 

一切正常，但請求被執行兩次。我不知道如果我可以做喜歡的事（這並不明顯工作）：

local mysocket = require("socket.http") 
if (local response, httpCode, header = mysocket.request(URL)) == nil then 
    print('The server is unreachable on:\n'..URL) 
    return 
end 

Answer 1

是的，是這樣的：

local mysocket = require("socket.http") 
local response, httpCode, header = mysocket.request(URL) 

if response == nil then 
    print('The server is unreachable on:\n'..URL) 
    return 
end 

-- here you do your stuff that's supposed to happen when request worked 

請求將只發送一次，和功能將退出，如果它失敗。

Answer 2

更好的是，當請求失敗，第二復位的原因是：

在故障的情況下，該函數返回nil後跟一個錯誤消息。

（從the documentation for http.request）

所以，你可以直接從插座的嘴打印問題：

local http = require("socket.http") 
local response, httpCode, header = http.request(URL) 

if response == nil then 
    -- the httpCode variable contains the error message instead 
    print(httpCode) 
    return 
end 

-- here you do your stuff that's supposed to happen when request worked