Nginx+Lua 积累

1、解析16进制编码的中文参数

local encodeStr = "%E6%B0%94"
local decodeStr = "";
for i = 2, #encodeStr - 1, 3 do
    local num = encodeStr:sub(i, i + 1);
    num = tonumber(num, 16);
    decodeStr = decodeStr .. string.char(num);
end
ngx.say(decodeStr)

2、类似replace

local str = "a1b1c1d"
local result = string.gsub(str,"1","2")   --将1替换成2

local str = "A1B1C1"
local result = string.gsub(str,"1","0",2)    --输出的结果为：A0B0C1

3、直连mysql

local mysql = require "resty.mysql"
local db = mysql:new()
db:connect{
    host = "10.10.3.218",
    port = 3306,
    database = "test_db",
    user = "root",
    password = "123456",
    max_packet_size = 1024*1024
}
local result = db:query("SELECT ID,NAME FROM TABLE")
ngx.say(result[1]["ID"])
ngx.say(result[1]["NAME"])

4、直接Redis

local redis = require "resty.redis"
local cache = redis.new()
cache.connect(cache,"10.10.3.208", "6379")
local result = cache:get("key")

5、使用管道

local redis = require "resty.redis"
local cache = redis.new()
cache.connect(cache,"10.10.3.208", "6379")
cache:init_pipeline()
for i=1,10 do
    cache:get("key")
end
local res = cache:commit_pipeline()
for j=1,#res do
    ngx.say(res[j])
end

6、计算一共有多少页

local totalPage = math.floor((totalRow+pageSize-1)/pageSize)

 7、Lua Table 多字段排序

--排列顺序优先级从高到低依次为：
--第一：等级由高到低；
--第二：稀有度由高到低；
--第三：伙伴ID从高到低。
local function sort_(a, b)
    local r
    local al = tonumber(a.level)
    local bl = tonumber(b.level)
    local aq = tonumber(a.data.quality)
    local bq = tonumber(b.data.quality)
    local aid = tonumber(a.pid)
    local bid = tonumber(b.pid)
    if  al == bl then
        if aq == bq then
            r = aid > bid
        else
            r = aq > bq
        end 
    else
        r = al > bl
    end
    return r
end

table.sort(tableName,sort_)

 8、四舍五入小数点保留2位

local function keepTwoDecimalPlaces(decimal)
        decimal = math.floor((decimal * 100)+0.5)*0.01       
        return  decimal 
end

ngx.say(keepTwoDecimalPlaces(1.369))