Cannot create PoolableConnectionFactory (Communications link failure)Connection refused: connect

今天在做web项目的时候碰到了这样的一个异常：

Caused by: java.lang.RuntimeException: org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (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 edu.gzucm.yjsglxt.base.util.TimeSetUtils.getTimeSets(TimeSetUtils.java:52)
	at edu.gzucm.yjsglxt.base.util.TimeSetUtils.<clinit>(TimeSetUtils.java:22)
	... 3 more
Caused by: org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (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 org.apache.tomcat.dbcp.dbcp.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:1549)
	at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1388)
	at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
	at edu.gzucm.yjsglxt.base.util.TimeSetUtils.getTimeSets(TimeSetUtils.java:32)
	... 4 more
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(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:407)
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
	at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:346)
	at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2334)
	at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2371)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2163)
	at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794)
	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:407)
	at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:378)
	at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
	at org.apache.tomcat.dbcp.dbcp.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:38)
	at org.apache.tomcat.dbcp.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:582)
	at org.apache.tomcat.dbcp.dbcp.BasicDataSource.validateConnectionFactory(BasicDataSource.java:1556)
	at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:1545)
	... 7 more
Caused by: java.net.ConnectException: Connection refused: connect
	at java.net.PlainSocketImpl.socketConnect(Native Method)
	at java.net.PlainSocketImpl.doConnect(Unknown Source)
	at java.net.PlainSocketImpl.connectToAddress(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:254)
	at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:295)
	... 23 more
2012-2-19 15:35:27 edu.gzucm.yjsglxt.base.util.InitInfoUtil <clinit>
严重: null
org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (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 org.apache.tomcat.dbcp.dbcp.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:1549)
	at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1388)
	at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
	at edu.gzucm.yjsglxt.base.util.DataSourceUtil.getConnection(DataSourceUtil.java:67)
	at edu.gzucm.yjsglxt.base.util.InitInfoUtil.<clinit>(InitInfoUtil.java:265)
	at edu.gzucm.yjsglxt.base.filter.PrepareFilter.init(PrepareFilter.java:116)
	at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:273)
	at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:254)
	at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:372)
	at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:98)
	at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4584)
	at org.apache.catalina.core.StandardContext$2.call(StandardContext.java:5262)
	at org.apache.catalina.core.StandardContext$2.call(StandardContext.java:5257)
	at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
	at java.util.concurrent.FutureTask.run(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
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(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:407)
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
	at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:346)
	at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2334)
	at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2371)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2163)
	at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794)
	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:407)
	at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:378)
	at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
	at org.apache.tomcat.dbcp.dbcp.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:38)
	at org.apache.tomcat.dbcp.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:582)
	at org.apache.tomcat.dbcp.dbcp.BasicDataSource.validateConnectionFactory(BasicDataSource.java:1556)
	at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:1545)
	... 17 more
Caused by: java.net.ConnectException: Connection refused: connect
	at java.net.PlainSocketImpl.socketConnect(Native Method)
	at java.net.PlainSocketImpl.doConnect(Unknown Source)
	at java.net.PlainSocketImpl.connectToAddress(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:254)
	at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:295)
	... 33 more
2012-2-19 15:35:27 org.apache.coyote.AbstractProtocol start
信息: Starting ProtocolHandler ["http-bio-8080"]
2012-2-19 15:35:27 org.apache.coyote.AbstractProtocol start
信息: Starting ProtocolHandler ["ajp-bio-8009"]
2012-2-19 15:35:27 org.apache.catalina.startup.Catalina start
信息: Server startup in 2983 ms

 我知道是连接数据库的时候出现了错误，我检查了我的tomcat的配置文件context.xml文件

配置如下：

<?xml version="1.0" encoding="UTF-8"?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with
  the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
--><!-- The contents of this file will be loaded for each web application --><Context>

    <!-- Default set of monitored resources -->
    <WatchedResource>WEB-INF/web.xml</WatchedResource>

    <!-- Uncomment this to disable session persistence across Tomcat restarts -->
    <!--
    <Manager pathname="" />
-->

    <!-- Uncomment this to enable Comet connection tacking (provides events
         on session expiration as well as webapp lifecycle) -->
    <!--
    <Valve className="org.apache.catalina.valves.CometConnectionManagerValve" />
-->
     <Resource auth="Container" 
     driverClassName="com.mysql.jdbc.Driver" 
     maxActive="100" 
     maxIdle="30" 
     maxWait="10000" 
     name="jdbc/mysql" 
     password="root" 
     type="javax.sql.DataSource" 
     url="jdbc:mysql:///yjsglxt?characterEncoding=UTF-8" 
     username="root"/>
</Context>

查了一下，才发现原来是url这里有问题：

url="jdbc:mysql:///yjsglxt?characterEncoding=UTF-8" 

应该改成：

url="jdbc:mysql://localhost:3306/yjsglxt?characterEncoding=UTF-8" 

这样做了以后，再次运行一下项目，嘿嘿，可以了……………………