NoRouteToHostException：No route to host

    使用proxool数据库连接池，平常都好好的，今天出现这个异常：

2014-03-19 14:41:05 [ERROR] [org.logicalcobwebs.proxool.Prototyper-sweep] Prototype

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.

        at sun.reflect.GeneratedConstructorAccessor51.newInstance(Unknown Source)

        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:406)

        at com.mysql.jdbc.Util.getInstance(Util.java:381)

        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:984)

        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)

        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)

        at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2359)

        at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:776)

        at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)

        at sun.reflect.GeneratedConstructorAccessor29.newInstance(Unknown Source)

        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:406)

        at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:352)

        at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:284)

        at java.sql.DriverManager.getConnection(DriverManager.java:582)

        at java.sql.DriverManager.getConnection(DriverManager.java:154)

        at org.logicalcobwebs.proxool.DefaultConnectionBuilder.buildConnection(DefaultConnectionBuilder.java:39)

        at org.logicalcobwebs.proxool.Prototyper.buildConnection(Prototyper.java:159)

        at org.logicalcobwebs.proxool.Prototyper.sweep(Prototyper.java:102)

        at org.logicalcobwebs.proxool.PrototyperThread.run(PrototyperThread.java:44)

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.GeneratedConstructorAccessor28.newInstance(Unknown Source)

        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:406)

        at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)

        at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:343)

        at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2283)

        … 14 more

Caused by: java.net.NoRouteToHostException: No route to host

        at java.net.PlainSocketImpl.socketConnect(Native Method)

        at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351)

        at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213)

        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200)

        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)

        at java.net.Socket.connect(Socket.java:529)

        at java.net.Socket.connect(Socket.java:478)

        at java.net.Socket.<init>(Socket.java:375)

        at java.net.Socket.<init>(Socket.java:218)

        at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:253)

        at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:292)

        … 15 more

提示无法创建数据库连接，解决方案：

1，ping一下数据库的ip，看看是不是还通着，是不是写错了（针对使用内网ip的,看看内网ip是不是还通着，否则就是内网网线断了）

2，看看mysql服务器的防火墙是不是开着

3，看看端口3306是不是被占用了

4，看看用户名和密码是不是写错了

5，重启mysql试一试吧

6，继续google吧 ，找到方案了回个贴吧，哈哈，谢谢