mysql workbench連線問題、MySQL 共用、Mysql 連不上在PTT/mobile01評價與討論，在ptt社群跟網路上大家這樣說

開發環境作業系統: win8.1

開發環境: Netbeans 8.0.2 + jdk1.8.0_171

MySQL版本: 8.0.1

connector/J 版本: 8.0.11

小弟新手(還請各位前輩鞭小力點)

最近在學習MySQL連JDBC

但網路上的資源都是第五版的connector/J

一開始用的是JDBC v8.0.11而jdk是1.7.0_80

後來有更新jdk到1.8.0_171

也有更換driver為:"com.mysql.cj.jdbc.Driver"

系統有成功載入driver但始終連不上伺服器

google以後發現8.0版以後getConnection的url不太一樣(但怎麼試還是無法QQ)

我的account: root 密碼:souseasou3 table名稱: customertable

因此url為: "jdbc:mysql://locolhost:3306/customertable"

也有照這個篇去增加權限:https://goo.gl/PYGNL2

方法為:

mysql> CREATE USER 'root'@'%' IDENTIFIED BY 'root';
mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' WITH GRANT OPTION;

但始終連接不上QQ

以下是錯誤訊息:

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link
failure

The last packet sent successfully to the server was 0 milliseconds ago. The
driver has not received any packets from the server.
at
com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:172)
at
com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:862)
at com.mysql.cj.jdbc.ConnectionImpl.(ConnectionImpl.java:444)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:230)
at
com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:226)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:270)
at crawler_to_db.Crawler_to_db.main(Crawler_to_db.java:32)
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications
link failure

The last packet sent successfully to the server was 0 milliseconds ago. The
driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at
com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:59)
at
com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:103)
at
com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:149)
at
com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:165)
at
com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:92)
at com.mysql.cj.NativeSession.connect(NativeSession.java:152)
at
com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:982)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:852)
... 6 more
Caused by: java.net.UnknownHostException: localtest
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928)
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323)
at java.net.InetAddress.getAllByName0(InetAddress.java:1276)
at java.net.InetAddress.getAllByName(InetAddress.java:1192)
at java.net.InetAddress.getAllByName(InetAddress.java:1126)
at
com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:150)
at
com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:66)
... 9 more

google後各種url都試過(如:https://goo.gl/HHFMD5這篇的解法，或是

改成:conn = DriverManager.getConnection("jdbc:mysql://localhost/mysql?"
+ "user=root&password=onelife");)

還是出現一樣的問題

還請各位高手指點，謝謝!

以下是我的code:

package crawler_to_db;

import java.sql.*;
/**
*
* @author Angelo
*/
public class Crawler_to_db {

/**
* @param args the command line arguments
*/
static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://locolhost:3306/customertable";

static final String usr = "root"; //username of db
static final String pss = "souseasou3"; //password of db

public static void main(String[] args) {
// TODO code application logic here
Connection conn = null;
Statement stmt = null;
try{
Class.forName(JDBC_DRIVER);
System.out.println("Loading driver successfully!.");
conn = DriverManager.getConnection(DB_URL,usr,pss);
System.out.println("Connecting successfully.");

}catch(SQLException se){
se.printStackTrace();
}catch(Exception e) { //Handling for Class.forName()
e.printStackTrace();
}
}

}

--

→ asd56799001: 我會先找一個mysql客戶端軟體來連連看 07/02 03:45
→ asd56799001: 如果客戶端軟體可以連 表示程式有問題 07/02 03:46
→ asd56799001: 如果客戶端軟體也不能練 表示mysql可能沒設置好 07/02 03:47
→ Souseasou3: MySQL Workbench 8.0CE 算嗎? 我用這個可以連喔 07/02 10:26
→ Souseasou3: 用cmd連也可以 07/02 10:26
→ sqrt998001: localhost？ 07/02 10:33
→ sqrt998001: 為啥你的範例都是locolhost 07/02 10:34
→ Souseasou3: 不是用local host嗎? 07/02 11:21
→ sqrt998001: 但你的code都打locolhost 07/02 12:09
→ Souseasou3: 所以要用什麼? 不是localhost的話 07/02 12:36
→ Souseasou3: https://goo.gl/HHFMD5我看這篇也是localhost 07/02 12:37
推 asd56799001: 要不要試試把locolhost改成本地IP 07/02 14:54
→ Souseasou3: 試過了 還是無法QQ 07/02 15:30
→ Souseasou3: 我是用筆電 在不同地方上網會有不同ip 07/02 15:30
→ asd56799001: mysql和java程式是在同一台電腦上嗎 07/02 15:31
→ Souseasou3: 對! 07/02 18:59
→ sqrt998001: 我的意思是你可能拼錯字了 07/02 19:11
→ Souseasou3: 真的欸!低級錯誤 07/02 19:43
→ Souseasou3: 但我改了變成以下錯誤 07/02 19:44
→ Souseasou3: https://imgur.com/a/u9EVZEL 07/02 19:45
→ Souseasou3: Stackoverflow了一下 似乎連成了 07/02 19:51
→ Souseasou3: https://imgur.com/VsJr6X1 正確url 07/02 19:52
→ Souseasou3: 感謝幫我發現低級錯誤的大大>< 07/02 19:52
→ asd56799001: 恭喜 連我複製你的都沒發現 07/02 20:03
→ Souseasou3: 低級錯誤 (攤) 07/02 20:08
→ adrianshum: 其實有留心看stack trace 的話，最原始的cause 就是 07/04 22:34
→ adrianshum: 說unknown host. 07/04 22:34