Web应用程序[]注册了JDBC驱动程序[com.mysql.jdbc.Driver],但在Web应用程序停止时无法注销它

Question

我在stackoverflow上看到了类似的问题,但我无法弄清楚如何解决我的问题.将Spring Security添加到我的Spring MVC项目后,我遇到以下异常:

Jul 20, 2014 3:18:04 PM org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
SEVERE: The web application [] registered the JDBC driver [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.

这是我在pom.xml中的 mysql-connecter

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.31</version>
    </dependency>

这是我添加的课程:

@Component
@Transactional
public class UserDetailsServiceImpl implements UserDetailsService{

@Autowired
private UserDAO userDAO;

@Autowired
private UserAssembler userAssembler;

private static final Logger logger = LoggerFactory.getLogger(UserDetailsServiceImpl.class);

@Transactional(readOnly = true)
public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException, DataAccessException {
    User user = userDAO.findByEmail(username);

    if(null == user) throw new UsernameNotFoundException("User not found");

    return userAssembler.buildUserFromUser(user);
}
}

和汇编程序

 @Service("assembler")

public class UserAssembler {

@Autowired
private UserDAO userDAO;

@Transactional(readOnly = true)
public User buildUserFromUser(net.viralpatel.contact.model.User user) {
    String role = "ROLE_USER";//userEntityDAO.getRoleFromUserEntity(userEntity);

    Collection<GrantedAuthority> authorities = new ArrayList<GrantedAuthority>();
    authorities.add(new GrantedAuthorityImpl(role));

    return new User(user.getLogin(), user.getPassword(), true, true, true, true,  authorities);
}
}

这是我的spring-security.xml

<beans:bean id="webexpressionHandler" class="org.springframework.security.web.access.expression.DefaultWebSecurityExpressionHandler" />

<http auto-config="true">
    <intercept-url pattern="/account/*" access="ROLE_ADMIN" />
    <form-login login-page="/login" default-target-url="/account/overview" authentication-failure-url="/login?error=true"/>
    <remember-me/>
</http>

<beans:bean id="myUserDetailsService" class="net.viralpatel.contact.service.UserDetailsServiceImpl" />


<authentication-manager alias="authenticationManager">
    <authentication-provider user-service-ref="myUserDetailsService" />
</authentication-manager>

编辑:

INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: /opt/idea-IU-135.909/bin::/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
Jul 20, 2014 3:58:36 PM org.apache.catalina.core.JreMemoryLeakPreventionListener lifecycleEvent
SEVERE: Failed to load class com.mysql.jdbc.NonRegisteringDriver during Tomcat start to prevent possible memory leaks.
java.lang.ClassNotFoundException: com.mysql.jdbc.NonRegisteringDriver

Answer 1

您的申请没有缺陷.它是JDBC的设计.第一次创建数据库连接时,webapp会加载并注册JDBC驱动程序.

这意味着驱动程序加载了Web应用程序类加载器.在取消部署时,驱动程序不会被取消注册,这反过来会阻止您的Web应用程序类.这有效地造成了内存泄漏.

为防止此特定内存泄漏,您应编辑tomcat/conf/server.xml并更改

<Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />

至

<Listener 
className="org.apache.catalina.core.JreMemoryLeakPreventionListener"
classesToInitialize="com.mysql.jdbc.NonRegisteringDriver" />

从webapp工件中排除JDBC驱动程序并将其放入tomcat/lib目录中.现在,JDBC驱动程序在启动时由Tomcat加载,并且未链接到任何webapps类加载器.

我为什么要修改server.xml？

由于MySQL的"被遗弃的连接清理线程",另一个内存泄漏显现.该线程从第一个请求开始,并保存对webapp的类加载器的引用.随着classesToInitialize您可以防止这种内存泄漏了.

Answer 2

我所做的只是mysql-connector-java-5.1.31-bin.jar将$CATALINA_HOME/lib. 没有对server.xml.