com.microsoft.sqlserver.jdbc.SQLServerException: 到主机 的 TCP/IP 连接失败。 java.net.ConnectException: Conn

今天碰到一个奇怪的问题，开发的一个项目突然连接不上数据库了，之前好好的，捣鼓了好一会才弄明白怎么回事。

首先介绍一下，我用的是sqlserver 2005 数据库（本人连接的是本机服务器，所以可以随便修改，如果是公用服务器，就要小心喽），因为修改端口的问题不小心把TCP/IP协议关闭了，但是当时也没有注意，所以就出现了下面的情况了。登录开发的项目时报以下异常：

2014-01-14 09:15:26 无法创建连接池DefaultPool的下列URL的连接: jdbc:sqlserver://localhost:1433;DatabaseName=zhyz;SelectMethod=cursor for User= sa

com.microsoft.sqlserver.jdbc.SQLServerException: 到主机 的 TCP/IP 连接失败。 java.net.ConnectException: Connection refused: connect

at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(Unknown Source)

at com.microsoft.sqlserver.jdbc.SQLServerConnection.connectHelper(Unknown Source)

at com.microsoft.sqlserver.jdbc.SQLServerConnection.loginWithoutFailover(Unknown Source)

at com.microsoft.sqlserver.jdbc.SQLServerConnection.connect(Unknown Source)

at com.microsoft.sqlserver.jdbc.SQLServerDriver.connect(Unknown Source)

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

at java.sql.DriverManager.getConnection(DriverManager.java:185)

at com.db.ConnectionManager$ConnectionPool.newConnection(ConnectionManager.java:346)

at com.db.ConnectionManager$ConnectionPool.getConnection(ConnectionManager.java:378)

at com.db.ConnectionManager.getConnection(ConnectionManager.java:202)

at com.db.Database.ResultRow(Database.java:235)

at com.javabean.UserBean.login(UserBean.java:235)

at com.servlet.UserServlet.login(UserServlet.java:53)

at com.servlet.UserServlet.doPost(UserServlet.java:34)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at com.filter.LoginFilter.doFilter(LoginFilter.java:39)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at com.filter.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:87)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)

at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)

at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)

at java.lang.Thread.run(Thread.java:619)

2014-01-14 09:15:26 从连接池DefaultPool获取连接失败

2014-01-14 09:15:26 错误提示: null错误SQL：select * from tbuser where uloginname='admin'

java.lang.NullPointerException

at com.db.Database.ResultRow(Database.java:236)

at com.javabean.UserBean.login(UserBean.java:235)

at com.servlet.UserServlet.login(UserServlet.java:53)

at com.servlet.UserServlet.doPost(UserServlet.java:34)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at com.filter.LoginFilter.doFilter(LoginFilter.java:39)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at com.filter.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:87)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)

at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)

at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)

at java.lang.Thread.run(Thread.java:619)

这是报出来的异常，本人登录sqlserver 用户名 sa，密码 1001，这个保证是没有问题的，登录的数据库名为 zhyz，端口号为 1433，显然都没有问题。但是老是拒绝连接，用sqlserver连接工具可以登录连接，操作也都没有问题，可就是项目连接不上数据库，当时也是满肚子气，查了好多才找到原因，就是自己把 TCP/IP协议关了，打开就好了。

碰到这个异常解决的办法：

1. 确保连接的数据库的名称（如我的数据库名 zhyz），端口号，以及登录数据库的用户名，密码正确。

2. 检查TCP/IP协议是否打开（打开sqlserver 配置工具，找到 SQL SERVER Configuration Manager，点击打开，找到sqlserver 网络配置，启用TCP/IP协议）



3. 重启 sqlserver 服务 OK，问题解决。