作者：blouc@qq.com
本文为作者原创，转载请注明出处：https://www.cnblogs.com/oucbl/p/5940556.html

今天学习SSM框架整合，完成Spring和mybatis这两大框架的整合做测试时候出来很多问题，主要来自于配置文件。

我这里重点说一下Mysql数据驱动配置。

配置pom.xml时候去网站 MySQL Connector/J 找到了最新版本，也是出于好奇就配置了...

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->

<dependency>

    <groupId>mysql</groupId>

    <artifactId>mysql-connector-java</artifactId>

    <version>6.0.4</version>

</dependency>

解决问题

原来新版的驱动配置有些变化：

1. url连接必须设置时区

### MySQL Connector/J 5.x   (旧版连接)

#jdbc.url=jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf8

### MySQL Connector/J 6.x   (新版连接)

jdbc.url=jdbc:mysql:///test?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=false

说明： 新版驱动url默认地址为127.0.0.1:3306，所以访问本机mysql数据库地址可以用 /// 表示。

2. 的驱动类位置有了变化（不影响使用，但会报警告）

### MySQL Connector/J 5.x   (旧版驱动)

#jdbc.driver_class=com.mysql.jdbc.Driver

### MySQL Connector/J 6.x   (新版驱动)

jdbc.driver_class=com.mysql.cj.jdbc.Driver

 异常查看

[INFO] Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> 1hgev419te1s9xe1nd08ye|1a79131, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> com.mysql.jdbc.Driver, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, forceSynchronousCheckins -> false, forceUseNamedDriverClass -> false, identityToken -> 1hgev419te1s9xe1nd08ye|1a79131, idleConnectionTestPeriod -> 0, initialPoolSize -> 3, jdbcUrl -> jdbc:mysql://localhost:3306/ssm?useSSL=false, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 15, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 3, numHelperThreads -> 3, preferredTestQuery -> null, privilegeSpawnedThreads -> false, properties -> {user=******, password=******}, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, userOverrides -> {}, usesTraditionalReflectiveProxies -> false ]
Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
[WARNING] com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@1eb28fe -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception:
java.sql.SQLException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:545)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:513)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:505)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:479)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:489)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:69)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:1606)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:633)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:347)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:219)
at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1138)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1125)
at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1870)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)
Caused by: com.mysql.cj.core.exceptions.InvalidConnectionAttributeException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
at sun.reflect.GeneratedConstructorAccessor28.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.cj.core.exceptions.ExceptionFactory.createException(ExceptionFactory.java:54)
at com.mysql.cj.core.exceptions.ExceptionFactory.createException(ExceptionFactory.java:73)
at com.mysql.cj.jdbc.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:118)
at com.mysql.cj.mysqla.MysqlaSession.configureTimezone(MysqlaSession.java:293)
at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:2399)
at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:1739)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:1596)
... 12 more
[WARNING] Having failed to acquire a resource, com.mchange.v2.resourcepool.BasicResourcePool@1e877aa is interrupting all Threads waiting on a resource to check out. Will try again in response to new client requests.
一月 26, 2018 9:23:48 下午 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet [springmvc] in context with path [/maven_ssm_01] threw exception [Request processing failed; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is java.sql.SQLException: Connections could not be acquired from the underlying database!] with root cause
com.mysql.cj.core.exceptions.InvalidConnectionAttributeException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
at sun.reflect.GeneratedConstructorAccessor28.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.cj.core.exceptions.ExceptionFactory.createException(ExceptionFactory.java:54)
at com.mysql.cj.core.exceptions.ExceptionFactory.createException(ExceptionFactory.java:73)
at com.mysql.cj.jdbc.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:118)
at com.mysql.cj.mysqla.MysqlaSession.configureTimezone(MysqlaSession.java:293)
at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:2399)
at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:1739)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:1596)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:633)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:347)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:219)
at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1138)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1125)
at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1870)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)

[WARNING] com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@1f869cf -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception:
java.sql.SQLException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:545)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:513)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:505)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:479)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:489)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:69)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:1606)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:633)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:347)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:219)
at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1138)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1125)
at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1870)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)
Caused by: com.mysql.cj.core.exceptions.InvalidConnectionAttributeException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
at sun.reflect.GeneratedConstructorAccessor28.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.cj.core.exceptions.ExceptionFactory.createException(ExceptionFactory.java:54)
at com.mysql.cj.core.exceptions.ExceptionFactory.createException(ExceptionFactory.java:73)
at com.mysql.cj.jdbc.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:118)
at com.mysql.cj.mysqla.MysqlaSession.configureTimezone(MysqlaSession.java:293)
at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:2399)
at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:1739)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:1596)
... 12 more
[WARNING] Having failed to acquire a resource, com.mchange.v2.resourcepool.BasicResourcePool@1e877aa is interrupting all Threads waiting on a resource to check out. Will try again in response to new client requests.
[WARNING] com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@1dd8d61 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception:
java.sql.SQLException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:545)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:513)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:505)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:479)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:489)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:69)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:1606)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:633)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:347)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:219)
at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1138)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1125)
at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1870)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)
Caused by: com.mysql.cj.core.exceptions.InvalidConnectionAttributeException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
at sun.reflect.GeneratedConstructorAccessor28.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.cj.core.exceptions.ExceptionFactory.createException(ExceptionFactory.java:54)
at com.mysql.cj.core.exceptions.ExceptionFactory.createException(ExceptionFactory.java:73)
at com.mysql.cj.jdbc.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:118)
at com.mysql.cj.mysqla.MysqlaSession.configureTimezone(MysqlaSession.java:293)
at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:2399)
at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:1739)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:1596)
... 12 more
[WARNING] Having failed to acquire a resource, com.mchange.v2.resourcepool.BasicResourcePool@1e877aa is interrupting all Threads waiting on a resource to check out. Will try again in response to new client requests.

maven搭建ssm框架是使用最新mysql 6.0jar遇到的问题的更多相关文章

  1. Eclipse中使用Maven搭建SSM框架

    Eclipse中不使用Maven搭建SSM框架:https://www.cnblogs.com/xuyiqing/p/9569459.html IDEA中使用Maven搭建SSM框架:https:// ...

  2. 使用maven搭建ssm框架的javaweb项目

    目前主流的javaweb项目,常会用到ssm(Spring+Spring MVC+Mybatis)框架来搭建项目的主体框架,本篇介绍搭建SSM框架的maven项目的实施流程.记之共享! 一.SSM框架 ...

  3. 使用maven搭建SSM框架

    使用maven搭建SSM框架,首先得准备好maven环境. 搭建maven环境 第一步:下载maven http://maven.apache.org/download.cgi 下载后解压就可以了. ...

  4. 使用Maven搭建SSM框架（Eclipse）

    今天学习一下使用Maven搭建SSM框架,以前都是用别人配置好的框架写代码,今天试试自己配置一下SSM框架. 这里我的参数是Windows7 64位,tomcat9,eclipse-jee-neon- ...

  5. 使用maven搭建ssm框架环境

    1.前言 因为经常换环境,在搭ssm框架的时候老是出错,所以记录一下最近搭建的环境,以供参考. 本文讲解如何使用maven搭建ssm框架,并能用于简单的登录注册. IDE:IDEA,JDK版本:1.8 ...

  6. Maven项目搭建（二）：Maven搭建SSM框架

    上一章给大家讲解了如何使用Maven搭建web项目. 这次给大家介绍一下怎么使用Maven搭建SSM框架项目. 首先我们来看一下pom.xml的属性介绍: project: pom的xml根元素. p ...

  7. 【原】无脑操作：eclipse + maven搭建SSM框架

    网上看到一些Spring + Spring MVC + MyBatis框架的搭建教程,不是很详细或是时间久远了,自己动手整一个简单无脑的! 0.系统环境 1)Windows 10 企业版 2)JDK ...

  8. Maven 搭建 SSM框架——Spring+SpringMVC+Mybatis的搭建教程

    一:概述 SSM框架在项目开发中经常使用到,相比于SSH框架,它在仅几年的开发中运用的更加广泛. Spring作为一个轻量级的框架,有很多的拓展功能,最主要的我们一般项目使用的就是IOC和AOP.Sp ...

  9. IDEA使用 maven 搭建 SSM 框架

    文章目录 pom 文件的编写 项目结构 SSM 配置文件的编写 web.xml 的配置 总结 公司有个小的内部使用的软件,让开发,自己选择使用 SSM :因为之前自己学过,本以为一切水到渠成,但是好久 ...

随机推荐

  1. SQL 循环 FOR 语句

    ) DECLARE My_Cursor CURSOR --定义游标 FOR (SELECT userid FROM User) --查出需要的集合放到游标中 OPEN My_Cursor; --打开游 ...

  2. has~和belongsTo的区别？

    在某一个class里面,class_name所对应的表为主表(父), 关系函数方法里面的第一个参数所对应的表为从属表(子), 即为与主表相关联的表. $has~ 1.外键保存在关联表中:  2.保存时 ...

  3. C# 人民币转成大写

    /// <summary> /// 转换人民币大小金额 /// </summary> /// <param name="num">金额</ ...

  4. [WCF安全1]使用basicHttpBinding构建UserName授权的WCF应用程序

    最近到了新公司,leader让我研究一下WCF的传输安全机制.以前也做过WCF的应用,但是很少涉及安全方面的东西.所以,花了三天的时间研究了一下如何在WCF的应用程序中配置安全.在这个系列文章中,我会 ...

  5. pathway一些网站

    1.BioCarta_Pathways https://cgap.nci.nih.gov/Pathways/BioCarta_Pathways

  6. 《用 Python 学微积分》笔记 2

    <用 Python 学微积分>原文见参考资料 1. 13.大 O 记法 比较两个函数时,我们会想知道,随着输入值 x 的增长或减小,两个函数的输出值增长或减小的速度究竟谁快谁慢.通过绘制函 ...

  7. Mercurial的使用心得

    本文发表地址:http://www.xiabingbao.com/mercurial/2015/01/22/mercurial-understanding/ 本人接触版本控制的历史 在很久很久以前,我 ...

  8. confluence+Mysql5.7 版本安装破解

    此篇稍微过下msyql 的处理方案:其他详细请参照上一篇文章地址:https://www.cnblogs.com/flyrock/p/9693327.html mysql 最新版本8.0 有点坑,co ...

  9. Jdev 本地RUN页面时候，将异常直接显示出来，而不是乱码

    本地运行页面时,经常会遇到以下错误 oracle.jbo.JboException: JBO-29000: JBO-29000: JBO-26028: ???? MemberAttributesDis ...

  10. 【转】linux 新建用户、用户组 以及为新用户分配权限

    Linux 系统是一个多用户多任务的分时操作系统,任何一个要使用系统资源的用户,都必须首先向系统管理员申请一个账号,然后以这个账号的身份进入系统.用户的账号一方面可以帮助系统管理员对使用系统的用户进行 ...