Java P tomcat_can_network_connect_db 1“是的，通过上述步骤问题已经解决。 $ uname -a Linux bogon 3.10.0-957.el7.x86_64 #1 SMP Thu Nov 8 23:39:32 UTC 20

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P tomcat_can_network_connect_db 1“是的，通过上述步骤问题已经解决。

$ uname -a
Linux bogon 3.10.0-957.el7.x86_64 #1 SMP Thu Nov 8 23:39:32 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
$ mysql --version
mysql  Ver 15.1 Distrib 5.5.60-MariaDB, for Linux (x86_64) using readline 5.1
$ tomcat version
Server version: Apache Tomcat/7.0.76
Server built:   Mar 12 2019 10:11:36 UTC
Server number:  7.0.76.0
OS Name:        Linux
OS Version:     3.10.0-957.el7.x86_64
Architecture:   amd64
JVM Version:    1.8.0_212-b04
JVM Vendor:     Oracle Corporation

$ systemctl status tomcat
● tomcat.service - Apache Tomcat Web Application Container
   Loaded: loaded (/usr/lib/systemd/system/tomcat.service; disabled; vendor preset: disabled)
   Active: active (running) since 二 2019-09-03 09:25:46 CST; 6s ago
 Main PID: 31464 (java)
    Tasks: 46
   CGroup: /system.slice/tomcat.service
           └─31464 /usr/lib/jvm/jre/bin/java -classpath /usr/share/tomcat/bin...

# systemctl status mariadb
● mariadb.service - MariaDB database server
   Loaded: loaded (/usr/lib/systemd/system/mariadb.service; disabled; vendor preset: disabled)
   Active: active (running) since 二 2019-09-03 07:15:24 CST; 2h 28min ago
  Process: 17937 ExecStartPost=/usr/libexec/mariadb-wait-ready $MAINPID (code=exited, status=0/SUCCESS)
  Process: 17905 ExecStartPre=/usr/libexec/mariadb-prepare-db-dir %n (code=exited, status=0/SUCCESS)
 Main PID: 17936 (mysqld_safe)
    Tasks: 20
   CGroup: /system.slice/mariadb.service
           ├─17936 /bin/sh /usr/bin/mysqld_safe --basedir=/usr
           └─18112 /usr/libexec/mysqld --basedir=/usr --datadir=/var/lib/mysq...

9月 03 07:15:20 bogon systemd[1]: Starting MariaDB database server...
9月 03 07:15:20 bogon mariadb-prepare-db-dir[17905]: Database MariaDB is pro...
9月 03 07:15:20 bogon mariadb-prepare-db-dir[17905]: If this is not the case...
9月 03 07:15:20 bogon mysqld_safe[17936]: 190903 07:15:20 mysqld_safe unkno...'
9月 03 07:15:20 bogon mysqld_safe[17936]: 190903 07:15:20 mysqld_safe Loggi....
9月 03 07:15:21 bogon mysqld_safe[17936]: 190903 07:15:21 mysqld_safe Start...l
9月 03 07:15:24 bogon systemd[1]: Started MariaDB database server.
Hint: Some lines were ellipsized, use -l to show in full.

# cd /usr/share/tomcat/webapps/
# ll
总用量 19880
drwxr-xr-x. 4 tomcat tomcat     4096 9月   3 07:35 online
-rw-r--r--. 1 root   root   20350442 9月   3 07:34 online.war

# cat localhost.2019-09-03.log
九月 03, 2019 7:17:51 上午 org.apache.catalina.core.ApplicationContext log
信息: No Spring WebApplicationInitializer types detected on classpath
九月 03, 2019 7:17:52 上午 org.apache.catalina.core.ApplicationContext log
信息: Initializing Spring FrameworkServlet 'spring'
九月 03, 2019 7:18:06 上午 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet [spring] in context with path [/online] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException
    at bright.spring.dao.LoginDao.login(LoginDao.java:20)
    at bright.spring.controller.LoginController.login(LoginController.java:25)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:114)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    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:110)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:506)
    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:962)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1087)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2549)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2538)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:748)

Class.forName("org.mariadb.jdbc.Driver")

Connection connection = DriverManager.getConnection("jdbc:mariadb://127.0.0.1:3306/onlineexp?useUnicode=true&characterEncoding=utf-8", "root", "ch96");