Node.js和jdbc：TypeError：无法读取未定义的属性'url'

Question

我是nodejs和JavaScript的新手。我正在尝试一个将MySQL连接到nodejs的非常基本的示例。我为此使用了一个npm jdbc包。下面是我用于连接和获取异常下面的代码片段。 你能帮我解决这个问题吗？

代码：

var express = require('express'); 
var app = express(); 
var server = require('http').Server(app); 
var https =require('http'); 
var io = require('socket.io')(server); 
var kafka = require('kafka-node'); 
var cassandra = require('cassandra-driver'); 
var jdbc = new (require('jdbc')); 
var jinst = require('jdbc/lib/jinst'); 
var Pool = require('jdbc/lib/pool'); 
var _ = require('underscore'); 
// var cors = require("cors"); 
app.use(express.static(__dirname + '/view')); 

server.listen(3000); 
app.use('/bower_components', express.static(__dirname + '/bower_components')); 
app.get('/', function (req, res, next) { res.sendFile(__dirname + '/index.html');}); 

if (!jinst.isJvmCreated()) { 
    jinst.addOption("-Xrs"); 
    jinst.setupClasspath(['../mysql-connector-java-5.1.39-bin.jar']); 
} 

var config = { 
    url: 'jdbc:mysql://localhost:3306/DB', 
    user : 'root', 
    password: 'root', 
    minpoolsize: 2, 
    maxpoolsize: 3, 
    drivername: 'com.mysql.jdbc.Driver' 
}; 


//Initialize jdbc object 
jdbc.initialize(config, function(err, res){ if (err){ console.log(err); } }); 

jdbc.open(function(err, conn) { 
    if (conn) { 
    //Run first query 
    jdbc.executeQuery('show databases', function(err, results){ 
     if (err){ console.log(err); } 
     else if (results) { console.log(results); } 
    }); 
    }else{ 
    console.log('Connection object:' + conn); 
    console.log(err); 
    } 
}); 

jdbc.close(function(err){ 
    if(err) { console.log(err); } 
    else { console.log('Connection closed successfully!');} 
}); 

例外：

Field_Test\node_modules\jdbc\lib\pool.js:64 
    this._url = config.url; 
        ^

TypeError: Cannot read property 'url' of undefined 
    at JDBC.Pool (<Dir>\node_modules\jdbc\lib\pool.js:64:21) 
    at new JDBC (<Dir>\node_modules\jdbc\lib\jdbc.js:6:8) 
    at Object.<anonymous> (Web\app.js:10:12) 
    at Module._compile (module.js:570:32) 
    at Object.Module._extensions..js (module.js:579:10) 
    at Module.load (module.js:487:32) 
    at tryModuleLoad (module.js:446:12) 
    at Function.Module._load (module.js:438:3) 
    at Module.runMain (module.js:604:10) 
    at run (bootstrap_node.js:394:7) 

Answer 1

您的问题与需要在顶部，按照该文档https://www.npmjs.com/package/jdbc，当你创建一个新的实例，你需要通过配置参数你可以做到两种方式

var config = {url: 'jdbc:mysql://localhost:3306/DB'} 
var jdbc = new (require('jdbc'))(config); 

或者你可以做到在线代码

var Jdbc = require('jdbc'); 
... 
var config = {url: 'jdbc:mysql://localhost:3306/DB'} 
var jdbc = new Jdbc(config) 

在你的代码

var express = require('express'); 
var app = express(); 
var server = require('http').Server(app); 
var https =require('http'); 
var io = require('socket.io')(server); 
var kafka = require('kafka-node'); 
var cassandra = require('cassandra-driver'); 
var Jdbc = require('jdbc'); 
var jinst = require('jdbc/lib/jinst'); 
var Pool = require('jdbc/lib/pool'); 
var _ = require('underscore'); 
// var cors = require("cors"); 
app.use(express.static(__dirname + '/view')); 

server.listen(3000); 
app.use('/bower_components', express.static(__dirname + '/bower_components')); 
app.get('/', function (req, res, next) { res.sendFile(__dirname + '/index.html');}); 

if (!jinst.isJvmCreated()) { 
    jinst.addOption("-Xrs"); 
    jinst.setupClasspath(['../mysql-connector-java-5.1.39-bin.jar']); 
} 

var config = { 
    url: 'jdbc:mysql://localhost:3306/DB', 
    user : 'root', 
    password: 'root', 
    minpoolsize: 2, 
    maxpoolsize: 3, 
    drivername: 'com.mysql.jdbc.Driver' 
}; 

var jdbc = new JDBC(config); 


//Initialize jdbc object 
jdbc.initialize(config, function(err, res){ if (err){ console.log(err); } }); 

jdbc.open(function(err, conn) { 
    if (conn) { 
    //Run first query 
    jdbc.executeQuery('show databases', function(err, results){ 
     if (err){ console.log(err); } 
     else if (results) { console.log(results); } 
    }); 
    }else{ 
    console.log('Connection object:' + conn); 
    console.log(err); 
    } 
}); 

jdbc.close(function(err){ 
    if(err) { console.log(err); } 
    else { console.log('Connection closed successfully!');} 
});