Java JDBC連接被拒絕

Question

我知道其他人已經發布了關於這個，但他們似乎都沒有回答我的問題。每當我的一臺服務器啓動時，它必須連接到數據庫，並且我每天都在4-10臺服務器之間運行，其中一些服務器每隔一段時間就會啓動/關閉。只有有時mysql會拒絕localhost連接。

連接MySQL代碼：

Class.forName("com.mysql.jdbc.Driver"); 
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/DATABASE?connectTimeout=15000", "USERNAME", "PASSWORD"); 

凡說DATABASE，USERNAME &密碼，那些只是隱藏MySQL的用戶信息。

連接時，我得到這個錯誤只是偶爾：

[15:52:13] [Craft Scheduler Thread - 2/WARN]: com.mysql.jdbc.exceptions.jdbc4.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. 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.lang.reflect.Constructor.newInstance(Constructor.java:423) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.Util.handleNewInstance(Util.java:407) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:343) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2334) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2371) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2163) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.lang.reflect.Constructor.newInstance(Constructor.java:423) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.Util.handleNewInstance(Util.java:407) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:378) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.sql.DriverManager.getConnection(DriverManager.java:664) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.sql.DriverManager.getConnection(DriverManager.java:247) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at me.Swedz.core.MySQL.createPool(MySQL.java:17) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at me.Swedz.lobby.Lobby$1.run(Lobby.java:73) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftTask.run(CraftTask.java:71) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.lang.Thread.run(Thread.java:745) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: Caused by: java.net.ConnectException: Connection refused 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.net.PlainSocketImpl.socketConnect(Native Method) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.net.Socket.connect(Socket.java:589) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at java.lang.reflect.Method.invoke(Method.java:498) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:327) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:292) 
[15:52:13] [Craft Scheduler Thread - 2/WARN]: ... 21 more 

線17 me.Swedz.core.MySQL.createPool是其中連接被初始化（在MySQL連接第二行代碼之前提供這個錯誤）。

我的綁定地址當前= 127.0.0.1，這對我來說最合適。因爲當它設置爲0.0.0.0或localhost時，此錯誤更頻繁地發生。

隨着時間的推移，這種情況越來越頻繁。這真的讓人感到沮喪，幾乎不可能在我的服務器上解決這個問題。

編輯：我相信我設法解決了我自己的問題。我已將連接代碼更改爲稍有不同。而且它似乎完全沒有錯誤！我的新的MySQL連接代碼：

MysqlDataSource ds = new MysqlDataSource(); 
ds.setDatabaseName("DATABASE"); 
ds.setUser("USERNAME"); 
ds.setPassword("USER PASSWORD"); 
ds.setServerName("localhost"); 
ds.setPort(3306); 
connection = ds.getConnection(); 

Answer 1

我設法解決了我自己的問題。我已將連接代碼更改爲稍有不同。而且它似乎完全沒有錯誤！我的新的MySQL連接代碼：

MysqlDataSource ds = new MysqlDataSource(); 
ds.setDatabaseName("DATABASE"); 
ds.setUser("USERNAME"); 
ds.setPassword("USER PASSWORD"); 
ds.setServerName("localhost"); 
ds.setPort(3306); 
connection = ds.getConnection(); 

Answer 2

從下面的代碼，

connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/DATABASE?connectTimeout=15000", "USERNAME", "PASSWORD");<br/> 

刪除connectionTimeout=15000，失去它的連接每隔15第二個可能是。