我正在运行 Ubuntu，并最终尝试使用 JDBC 将 Tomcat 连接到我的 MySQL 数据库。
它以前可以工作，但在重新启动后，实例现在无法连接。
- Tomcat 6 和 MySQL 5.0.75 都在同一台机器上
- 连接字符串：jdbc:mysql:///localhost:3306
mysql我可以使用以下命令在命令行上连接到 MySQL- my.cnf 文件非常标准（可根据要求提供）绑定地址：127.0.0.1
- 尽管 netstat 说 MySQL 正在侦听，但我无法 Telnet 到 MySQL 端口
- 我有一个 IpTables 规则来转发 80 -> 8080 并且我知道没有防火墙。
我对此很陌生，我不确定还有什么要测试的。我不知道我是否应该在 etc/interfaces 中寻找，以及我是否做了要寻找的东西。这很奇怪，因为它曾经可以工作，但重新启动后它就关闭了，所以我必须改变一些东西...... :)。
我意识到超时表明服务器没有响应，我认为这是因为请求实际上没有通过。我通过 apt-get 和 Tomcat 手动安装了 MySQL。
MySqld 进程
root@88:/var/log/mysql# ps -ef | grep mysqld
root 21753 1 0 May27 ? 00:00:00 /bin/sh /usr/bin/mysqld_safe
mysql 21792 21753 0 May27 ? 00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld/mysqld.pid --skip-external-locking --port=3306 --socket=/var/run/mysqld/mysqld.sock
root 21793 21753 0 May27 ? 00:00:00 logger -p daemon.err -t mysqld_safe -i -t mysqld
root 21888 13676 0 11:23 pts/1 00:00:00 grep mysqld
网络统计
root@88:/var/log/mysql# netstat -lnp | grep mysql
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN 21792/mysqld
unix 2 [ ACC ] STREAM LISTENING 1926205077 21792/mysqld /var/run/mysqld/mysqld.sock
玩具连接类
root@88:~# cat TestConnect/TestConnection.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class TestConnection {
public static void main(String args[]) throws Exception {
Connection con = null;
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
System.out.println("Got driver");
con = DriverManager.getConnection(
"jdbc:mysql:///localhost:3306",
"uname", "pass");
System.out.println("Got connection");
if(!con.isClosed())
System.out.println("Successfully connected to " +
"MySQL server using TCP/IP...");
} finally {
if(con != null)
con.close();
}
}
}
玩具连接类输出
注意：这与我从 Tomcat 得到的错误相同。
root@88:~/TestConnect# java -cp mysql-connector-java-5.1.12-bin.jar:. TestConnection
Got driver
Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 1 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:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1122)
at TestConnection.main(TestConnection.java:14)
Caused by: 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(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1122)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:344)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2181)
... 12 more
Caused by: java.net.ConnectException: Connection timed out
at java.net.PlainSocketImpl.socketConnect(Native Method)
... 13 more
远程登录输出
root@88:~/TestConnect# telnet localhost 3306
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection timed out