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Я использую сервлет, чтобы попытаться подключиться к базе данных mysql на своем веб-сайте, но он всегда говорит, что он был отключен и что произошел сбой связи.JDBC SQL-сервер в сети не может подключиться
final String DB_URL = "jdbc:mysql://blah.org/blah_DbName";
conn = DriverManager.getConnection(DB_URL, USER, PASS);
Это то, что я использую для подключения, но оно не работает. Правильно ли создан мой url? Кроме того, я не знаю пароль root, поэтому я добавил пользователя в базу данных, и я использую имя пользователя и пароль для подключения, так что есть способ получить пароль root.
Кроме того, некоторые люди говорят, что номер порта требуется в URL-адресе, но где я могу найти номер порта? Мой хостинг-провайдер - хостмантис.
Трассировка стека
Feb 19, 2013 12:15:11 AM org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
SEVERE: The web application [/servlettest] registered the JDBC driver [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
Feb 19, 2013 12:15:11 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/servlettest] is still processing a request that has yet to finish. This is very likely to create a memory leak. You can control the time allowed for requests to finish by using the unloadDelay attribute of the standard Context implementation.
Feb 19, 2013 12:15:12 AM org.apache.catalina.core.StandardContext reload
INFO: Reloading Context with name [/servlettest] is completed
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.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:355)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2461)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2498)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2283)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:822)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:404)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:317)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at servlets.DatabaseAccess.doGet(DatabaseAccess.java:59)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:306)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:380)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:288)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.net.ConnectException: Connection timed out: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:259)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:305)
... 32 more
Всегда обеспечивают полную трассировку стека. –
Возможный дубликат http://stackoverflow.com/questions/2121829/mysql-jdbc-communications-link-failure –
Также см. ..http: //serverfault.com/questions/89955/unable-to-connect-to-mysql -through-jdbc-connector-through-tomcat-or-externally –