IDEA中的SQLNestedException异常 |
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IDEA中的SQLNestedException异常
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IDEA中的SQLNestedException异常
最近在B站上学习颜群老师的Java Web课程,今天在学习dbcp连接池时.掉进了异常世界,苦战2小时,回到原来的轨迹. SQLNestedException异常如下: Connected to the target VM, address: '127.0.0.1:1732', transport: 'socket' Exception in thread "main" org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Communications link failure Last packet sent to the server was 0 ms ago.) at org.apache.commons.dbcp.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:1549) at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1388) at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044) at com.gr2.dbcp.TestDBCP.main(TestDBCP.java:36) Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure Last packet sent to the server was 0 ms ago. at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:408) at com.mysql.jdbc.Util.handleNewInstance(Util.java:353) at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074) at com.mysql.jdbc.Connection.createNewIO(Connection.java:2001) at com.mysql.jdbc.Connection.(Connection.java:716) at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:46) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:408) at com.mysql.jdbc.Util.handleNewInstance(Util.java:353) at com.mysql.jdbc.Connection.getInstance(Connection.java:295) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:266) at org.apache.commons.dbcp.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:38) at org.apache.commons.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:582) at org.apache.commons.dbcp.BasicDataSource.validateConnectionFactory(BasicDataSource.java:1556) at org.apache.commons.dbcp.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:1545) ... 3 more Caused by: java.net.ConnectException: Connection refused: connect at java.net.DualStackPlainSocketImpl.connect0(Native Method) at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79) at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345) at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) at java.net.Socket.connect(Socket.java:589) at java.net.Socket.connect(Socket.java:538) at java.net.Socket.(Socket.java:434) at java.net.Socket.(Socket.java:244) at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:168) at com.mysql.jdbc.MysqlIO.(MysqlIO.java:262) at com.mysql.jdbc.Connection.createNewIO(Connection.java:1926) ... 16 more学习是自己的事,不得强迫,也不得欺骗自己. 咳咳~ 一不小心又想扯道理(明明还是个比白纸还白的小白,哈哈哈) 还好及时发现,我们切回正题 : 首先, 排查关键信息是否错误 :我在学习dbcp,配置信息如👇 dbcp.setDriverClassName("com.mysql.jdbc.Driver" ); dbcp.setUrl("jdbc:mysql://localhost:3306/myschool"); dbcp.setUsername("root"); dbcp.setPassword(null); dbcp.setInitialSize(20); dbcp.setMaxActive(10); dbcp.setMinIdle(5);却认信息无误,小纠结来袭. 此刻惶恐3秒钟(重复一下: 俺还是小白) 复制问题问度娘,没错度娘就是依靠,给咱力量,和前行的方向.我解决的流程是:看看大家有没有遇见同样的问题,或者类似的,然后去找问题的根源,前面确定代码无误,然后检查Jar文件是否缺失,或者引用错误. 检查过后没有错误,就打开了服务检查,原来问题就出现在这里,MySQL的服务处于关闭状态接下来,启动服务,在次运行项目.问题正解!!!
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今天的错误呢,唉~羞愧 (>_【本文地址】