在Node.js應用中讀寫Redis資料庫的簡單方法_node.js

 在開始本文之前請確保安裝好 Redis 和 Node.js 以及 Node.js 的 Redis 擴充 —— node_redis

首先建立一個新檔案夾並建立文字檔 app.js 檔案內容如下：
 

var redis = require("redis")  , client = redis.createClient(); client.on("error", function (err) {  console.log("Error " + err);}); client.on("connect", runSample); function runSample() {  // Set a value  client.set("string key", "Hello World", function (err, reply) {    console.log(reply.toString());  });  // Get a value  client.get("string key", function (err, reply) {    console.log(reply.toString());  });}

當串連到 Redis 後會調用 runSample 函數並設定一個值，緊接著便讀出該值，啟動並執行結果如下：
 

OKHello World

我們也可以使用 EXPIRE 命令來設定對象的失效時間，代碼如下：
 

var redis = require('redis')  , client = redis.createClient(); client.on('error', function (err) {  console.log('Error ' + err);}); client.on('connect', runSample); function runSample() {  // Set a value with an expiration  client.set('string key', 'Hello World', redis.print);  // Expire in 3 seconds  client.expire('string key', 3);   // This timer is only to demo the TTL  // Runs every second until the timeout  // occurs on the value  var myTimer = setInterval(function() {    client.get('string key', function (err, reply) {      if(reply) {        console.log('I live: ' + reply.toString());      } else {        clearTimeout(myTimer);        console.log('I expired');        client.quit();      }    });  }, 1000);}

注意: 上述使用的定時器只是為了示範 EXPIRE 命令，你必須在 Node.js 項目中謹慎使用定時器。

運行上述程式的輸出結果是：

 

Reply: OKI live: Hello WorldI live: Hello WorldI live: Hello WorldI expired

接下來我們檢查一個值在失效之前存留了多長時間：
 

var redis = require('redis')  , client = redis.createClient(); client.on('error', function (err) {  console.log('Error ' + err);}); client.on('connect', runSample); function runSample() {  // Set a value  client.set('string key', 'Hello World', redis.print);  // Expire in 3 seconds  client.expire('string key', 3);   // This timer is only to demo the TTL  // Runs every second until the timeout  // occurs on the value  var myTimer = setInterval(function() {    client.get('string key', function (err, reply) {      if(reply) {        console.log('I live: ' + reply.toString());        client.ttl('string key', writeTTL);      } else {        clearTimeout(myTimer);        console.log('I expired');        client.quit();      }    });  }, 1000);} function writeTTL(err, data) {  console.log('I live for this long yet: ' + data);}

運行結果：
 

Reply: OKI live: Hello WorldI live for this long yet: 2I live: Hello WorldI live for this long yet: 1I live: Hello WorldI live for this long yet: 0I expired