在开始本文之前请确保安装好 Redis 和 Node.js 以及 Node.js 的 Redis 扩展 —— node_redis
首先创建一个新文件夹并新建文本文件 app.js 文件内容如下：
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()); }); }
当连接到 Redis 后会调用 runSample 函数并设置一个值，紧接着便读出该值，运行的结果如下：
OK Hello World
我们也可以使用 EXPIRE 命令来设置对象的失效时间，代码如下：
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: 上述使用的定时器只是为了演示 EXPIRE 命令，你必须在 Node.js 项目中谨慎使用定时器。
运行上述程序的输出结果是：
Reply: OK I live: Hello World I live: Hello World I live: Hello World I expired
接下来我们检查一个值在失效之前存留了多长时间：
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); }
运行结果：
Reply: OK I live: Hello World I live for this long yet: 2 I live: Hello World I live for this long yet: 1 I live: Hello World I live for this long yet: 0 I expired
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