,将介绍如何利Javascript做为服务端脚本,通过Nodejs框架web开发。Nodejs框架是基于V8的引擎,是目前速度最快的Javascript引擎。chrome浏览器就基于V8,同时打开20-30个网页都很流畅。Nodejs标准的web开发框架Express,可以帮助我们迅速建立web站点,比起PHP的开发效率更高,而且学习曲线更低。非常适合小型网站,个性化网站,我们自己的Geek网站!!
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- 张丹(Conan), 程序员Java,R,PHP,Javascript
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前言
MySQL是一款常用的开源数据库产品,通常也是免费数据库的首选。查了一下NPM列表,发现Nodejs有13库可以访问MySQL,felixge/node-mysql似乎是最受关注项目,我也决定尝试用一下。
要注意名字,”felixge/node-mysql”非”node-mysql”,安装部分会介绍这个小插曲!
目录
- node-mysql介绍
- 建立MySQL测试库
- node-mysql安装
- node-mysql使用
1. node-mysql介绍
felixge/node-mysql是一个纯nodejs的用javascript实现的一个MySQL客户端程序。felixge/node-mysql封装了Nodejs对MySQL的基本操作,100% MIT公共许可证。
项目地址:https://github.com/felixge/node-mysql
2. 建立MySQL测试库
本地创建MySQL测试库:nodejs
~ mysql -uroot -pmysql> CREATE DATABASE nodejs;mysql> SHOW DATABASES;+--------------------+| Database |+--------------------+| information_schema || mysql || nodejs || performance_schema |+--------------------+4 rows in set (0.00 sec)mysql> GRANT ALL ON nodejs.* to nodejs@'%' IDENTIFIED BY 'nodejs';mysql> GRANT ALL ON nodejs.* to nodejs@localhost IDENTIFIED BY 'nodejs';
重新登陆MySQL
C:\Users\Administrator>mysql -unodejs -pEnter password: ******mysql> SHOW DATABASES;+--------------------+| Database |+--------------------+| information_schema || nodejs || test |+--------------------+3 rows in set (0.00 sec)mysql> USE nodejsDatabase changed
新建一个user表
CREATE TABLE t_user(id INT PRIMARY KEY AUTO_INCREMENT,name VARCHAR(16) NOT NULL ,create_date TIMESTAMP NULL DEFAULT now())ENGINE=InnoDB DEFAULT CHARSET=utf8;CREATE UNIQUE INDEX t_quiz_IDX_0 on t_user(name);mysql> SHOW TABLES;+------------------+| Tables_in_nodejs |+------------------+| t_user |+------------------+1 row in set (0.04 sec)
3. node-mysql安装
我的系统环境
- win7 64bit
- Nodejs:v0.10.5
- Npm:1.2.19
- MySQL:Server version: 5.6.11 MySQL Community Server (GPL)
创建工程:nodejs-node-mysql
~ D:\workspace\javascript>mkdir nodejs-node-mysql~ D:\workspace\javascript>cd nodejs-node-mysql~ D:\workspace\javascript\nodejs-node-mysql>npm install node-mysqlnode-mysql@0.2.0 node_modules\node-mysql├── better-js-class@0.1.2├── cps@0.1.7├── underscore@1.5.2└── mysql@2.0.0-alpha9 (require-all@0.0.3, bignumber.js@1.0.1)
这里有一个小插曲
安装“node-mysql”后,打开package.json文件发现,这个项目地址是
https://github.com/redblaze/node-mysql.git
从依赖关系可以看到,它依赖于mysql库,是对felixge/node-mysql的封装。
由于这个项目star是0,fork也是0. 所以,我也不准备花时间测试了,重新安装felixge/node-mysql的包。
重新安装node-mysql
~ D:\workspace\javascript\nodejs-node-mysql>rm -rf node_modules~ D:\workspace\javascript\nodejs-node-mysql>npm install mysql@2.0.0-alpha9npm http GET https://registry.npmjs.org/mysql/2.0.0-alpha9npm http 200 https://registry.npmjs.org/mysql/2.0.0-alpha9npm http GET https://registry.npmjs.org/mysql/-/mysql-2.0.0-alpha9.tgznpm http 200 https://registry.npmjs.org/mysql/-/mysql-2.0.0-alpha9.tgznpm http GET https://registry.npmjs.org/require-all/0.0.3npm http GET https://registry.npmjs.org/bignumber.js/1.0.1npm http 304 https://registry.npmjs.org/require-all/0.0.3npm http 304 https://registry.npmjs.org/bignumber.js/1.0.1mysql@2.0.0-alpha9 node_modules\mysql├── require-all@0.0.3└── bignumber.js@1.0.1
这回就对了,继续下面的开发!
创建node程序启动文件:app.js
第一个测试
~ vi app.jsvar mysql = require('mysql');var conn = mysql.createConnection({ host: 'localhost', user: 'nodejs', password: 'nodejs', database:'nodejs', port: 3306});conn.connect();conn.query('SELECT 1 + 1 AS solution', function(err, rows, fields) { if (err) throw err; console.log('The solution is: ', rows[0].solution);});conn.end();
运行node
~ D:\workspace\javascript\nodejs-node-mysql>node app.jsThe solution is: 2
这样我们就让Nodejs连接上了MySQL。
4. node-mysql使用
下面我们要对node-mysql的API进行常用的测试。
- 表新删改查
- 连接池配置
- MySQL断线重连
- 连接池超时测试
1). 表新删改查
修改app.js~ vi app.jsvar mysql = require('mysql');var conn = mysql.createConnection({ host: 'localhost', user: 'nodejs', password: 'nodejs', database: 'nodejs', port: 3306});conn.connect();var insertSQL = 'insert into t_user(name) values("conan"),("fens.me")';var selectSQL = 'select * from t_user limit 10';var deleteSQL = 'delete from t_user';var updateSQL = 'update t_user set name="conan update" where name="conan"';//deleteconn.query(deleteSQL, function (err0, res0) { if (err0) console.log(err0); console.log("DELETE Return ==> "); console.log(res0); //insert conn.query(insertSQL, function (err1, res1) { if (err1) console.log(err1); console.log("INSERT Return ==> "); console.log(res1); //query conn.query(selectSQL, function (err2, rows) { if (err2) console.log(err2); console.log("SELECT ==> "); for (var i in rows) { console.log(rows[i]); } //update conn.query(updateSQL, function (err3, res3) { if (err3) console.log(err3); console.log("UPDATE Return ==> "); console.log(res3); //query conn.query(selectSQL, function (err4, rows2) { if (err4) console.log(err4); console.log("SELECT ==> "); for (var i in rows2) { console.log(rows2[i]); } }); }); }); });});//conn.end();
控制台输出:
D:\workspace\javascript\nodejs-node-mysql>node app.jsDELETE Return ==>{ fieldCount: 0, affectedRows: 2, insertId: 0, serverStatus: 34, warningCount: 0, message: '', protocol41: true, changedRows: 0 }INSERT Return ==>{ fieldCount: 0, affectedRows: 2, insertId: 33, serverStatus: 2, warningCount: 0, message: '&Records: 2 Duplicates: 0 Warnings: 0', protocol41: true, changedRows: 0 }SELECT ==>{ id: 33, name: 'conan', create_date: Wed Sep 11 2013 12:09:15 GMT+0800 (中国标准时间) }{ id: 34, name: 'fens.me', create_date: Wed Sep 11 2013 12:09:15 GMT+0800 (中国标准时间) }UPDATE Return ==>{ fieldCount: 0, affectedRows: 1, insertId: 0, serverStatus: 2, warningCount: 0, message: '(Rows matched: 1 Changed: 1 Warnings: 0', protocol41: true, changedRows: 1 }SELECT ==>{ id: 33, name: 'conan update', create_date: Wed Sep 11 2013 12:09:15 GMT+0800 (中国标准时间) }{ id: 34, name: 'fens.me', create_date: Wed Sep 11 2013 12:09:15 GMT+0800 (中国标准时间) }
由于node的异步的,上面是一个连续的操作,代码会被写的支离破碎。我们可以通过async库对上面代码进行封装,请参考文章:
2). 连接池配置
增加文件:app-pooling.js
~ vi app-pooling.jsvar mysql = require('mysql');var pool = mysql.createPool({ host: 'localhost', user: 'nodejs', password: 'nodejs', database: 'nodejs', port: 3306});var selectSQL = 'select * from t_user limit 10';pool.getConnection(function (err, conn) { if (err) console.log("POOL ==> " + err); conn.query(selectSQL,function(err,rows){ if (err) console.log(err); console.log("SELECT ==> "); for (var i in rows) { console.log(rows[i]); } conn.release(); });});
控制台输出:
D:\workspace\javascript\nodejs-node-mysql>node app-pooling.jsSELECT ==>{ id: 39, name: 'conan update', create_date: Wed Sep 11 2013 13:41:18 GMT+0800 (中国标准时间) }{ id: 40, name: 'fens.me', create_date: Wed Sep 11 2013 13:41:18 GMT+0800 (中国标准时间) }
3). MySQL断线重连
分别模拟3种错误
- 登陆密码错误
- 数据库宕机
- 数据库连接超时
新增文件:app-reconnect.js
~ vi app-reconnect.jsvar mysql = require('mysql');var conn;function handleError () { conn = mysql.createConnection({ host: 'localhost', user: 'nodejs', password: 'nodejs', database: 'nodejs', port: 3306 }); //连接错误,2秒重试 conn.connect(function (err) { if (err) { console.log('error when connecting to db:', err); setTimeout(handleError , 2000); } }); conn.on('error', function (err) { console.log('db error', err); // 如果是连接断开,自动重新连接 if (err.code === 'PROTOCOL_CONNECTION_LOST') { handleError(); } else { throw err; } });}handleError();
a. 模拟密码错误
修改password: ‘nodejs11’
控制台输出。
D:\workspace\javascript\nodejs-node-mysql>node app-reconnect.jserror when connecting to db: { [Error: ER_ACCESS_DENIED_ERROR: Access denied for user 'nodejs'@'localhost' (using passrd: YES)] code: 'ER_ACCESS_DENIED_ERROR', errno: 1045, sqlState: '28000', fatal: true }error when connecting to db: { [Error: ER_ACCESS_DENIED_ERROR: Access denied for user 'nodejs'@'localhost' (using passrd: YES)] code: 'ER_ACCESS_DENIED_ERROR', errno: 1045, sqlState: '28000', fatal: true }
b. 模拟数据库宕机
正常启动node,然后杀掉mysqld的进程。控制台输出。
D:\workspace\javascript\nodejs-node-mysql>node app-reconnect.jsdb error { [Error: read ECONNRESET] code: 'ECONNRESET', errno: 'ECONNRESET', syscall: 'read', fatal: true }Error: read ECONNRESET at errnoException (net.js:884:11) at TCP.onread (net.js:539:19)
这个异常,直接导致node程序被杀死!
c. 模拟连接超时,PROTOCOL_CONNECTION_LOST
切换到root账户, 修改MySQL的wait_timeout参数,设置为10毫秒超时。~ mysql -uroot -pmysql> show variables like 'wait_timeout';+---------------+-------+| Variable_name | Value |+---------------+-------+| wait_timeout | 28800 |+---------------+-------+1 row in set (0.00 sec)mysql> set global wait_timeout=10;Query OK, 0 rows affected (0.00 sec)mysql> show variables like 'wait_timeout';+---------------+-------+| Variable_name | Value |+---------------+-------+| wait_timeout | 10 |+---------------+-------+1 row in set (0.00 sec)
修改文件:app-reconnection.js,在最后增加代码
~ vi app-reconnection.jsfunction query(){ console.log(new Date()); var sql = "show variables like 'wait_timeout'"; conn.query(sql, function (err, res) { console.log(res); });}query();setInterval(query, 15*1000);
程序会每融15秒,做一次查询。
控制台输出
D:\workspace\javascript\nodejs-node-mysql>node app-reconnect.jsWed Sep 11 2013 15:21:14 GMT+0800 (中国标准时间)[ { Variable_name: 'wait_timeout', Value: '10' } ]db error { [Error: Connection lost: The server closed the connection.] fatal: true, code: 'PROTOCOL_CONNECTION_LOST' }Wed Sep 11 2013 15:21:28 GMT+0800 (中国标准时间)[ { Variable_name: 'wait_timeout', Value: '10' } ]db error { [Error: Connection lost: The server closed the connection.] fatal: true, code: 'PROTOCOL_CONNECTION_LOST' }Wed Sep 11 2013 15:21:43 GMT+0800 (中国标准时间)[ { Variable_name: 'wait_timeout', Value: '10' } ]
我们自己的程序捕获了“PROTOCOL_CONNECTION_LOST”异常,并自动的实现了数据库重连。
4). MySQL连接池的超时测试
针对wait_timeout问题,我们再对连接做一下测试。
修改app-pooling.js文件
var mysql = require('mysql');var pool = mysql.createPool({ host: 'localhost', user: 'nodejs', password: 'nodejs', database: 'nodejs', port: 3306});var selectSQL ="show variables like 'wait_timeout'";pool.getConnection(function (err, conn) { if (err) console.log("POOL ==> " + err); function query(){ conn.query(selectSQL, function (err, res) { console.log(new Date()); console.log(res); conn.release(); }); } query(); setInterval(query, 5000);});
控制台输出:
D:\workspace\javascript\nodejs-node-mysql>node app-pooling.jsWed Sep 11 2013 15:32:25 GMT+0800 (中国标准时间)[ { Variable_name: 'wait_timeout', Value: '10' } ]Wed Sep 11 2013 15:32:30 GMT+0800 (中国标准时间)[ { Variable_name: 'wait_timeout', Value: '10' } ]Wed Sep 11 2013 15:32:35 GMT+0800 (中国标准时间)[ { Variable_name: 'wait_timeout', Value: '10' } ]
连接池,已经解决了自动重连的问题了,后面我们的开发,可以尽量使用pooling的方式。
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