异常现象
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection, message from server: "Too many connections" at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:526) at com.mysql.jdbc.Util.handleNewInstance(Util.java:404) at com.mysql.jdbc.Util.getInstance(Util.java:387) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:917) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:896) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:885) at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1042) at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253) at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2284) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2083) at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806) at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47) at sun.reflect.GeneratedConstructorAccessor47.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:526) at com.mysql.jdbc.Util.handleNewInstance(Util.java:404) at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:410) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:328) at java.sql.DriverManager.getConnection(DriverManager.java:571) at java.sql.DriverManager.getConnection(DriverManager.java:215) at com.yuanhe.leasing.util.DBUtil.getConn(DBUtil.java:37) at com.yuanhe.leasing.service.StatusListService.showManage(StatusListService.java:221) at com.yuanhe.leasing.servlet.ListStatusServlet.doPost(ListStatusServlet.java:56) at javax.servlet.http.HttpServlet.service(HttpServlet.java:650) at javax.servlet.http.HttpServlet.service(HttpServlet.java:731) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:218) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:442) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1082) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:623) at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2517) at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2506) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)
原因分析:
1,未使用连接池,每次创建链接且没有关闭
解决方法:
关闭连接,且依次关闭数据库连接顺序关闭!(RS,PS,CONN),确保异常时也要关闭。
finally{ try { DBUtil.close(ps, conn, rs); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } }
原因2:连接数设置的太少
1.Mysql数据库的默认连接数是100。 2.默认值100对于一般的程序都不是很够用,如果只是在自己的电脑上调试程序,有可能发现不了这个问题,因为调试程序时会经常重起Tomcat。 3.如果使用Hibernate框架来进行数据库操作,这个问题尤其明显。 4.解决方法:加大Mysql连接数。在Mysql安装文件中,找到my.ini文件,在里面找到 max_connections=100,将这个100变大一点,直接来个1000