new FileOutputStream() tomcat提示 likely to create a memory leak

Question

我在一个线程中创建Excel文件使用
OutputStream stream = new FileOutputStream(path+fileName);
结果创建完对象后Tomcat发出警告

六月 11, 2018 3:22:33 下午 org.apache.catalina.loader.WebappClassLoaderBase clearReferencesJdbc
警告: The web application [ACI] registered the JDBC driver [oracle.jdbc.driver.OracleDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
六月 11, 2018 3:22:33 下午 org.apache.catalina.loader.WebappClassLoaderBase clearReferencesThreads
警告: The web application [ACI] appears to have started a thread named [startAutoChargeBackEmailJob_Worker-0] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
org.apache.commons.logging.LogFactory.getContextClassLoaderInternal(LogFactory.java:859)
org.apache.commons.logging.LogFactory.getFactory(LogFactory.java:423)
org.apache.commons.logging.LogFactory.getLog(LogFactory.java:685)
org.quartz.simpl.SimpleThreadPool.getLog(SimpleThreadPool.java:126)
org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:547)

这是什么原因导致的呢 有没有人遇到相同情况

Answer 1

基本上，你可以忽略这个警告，和你的FileOutputStream没关系，是因为JDBC驱动没有unregister，但这仅发生在tomcat关闭的时候，所以可以忽略。 如果你一定要解决，这样做：

在web.xml里注册一个listener：

<web-app version="2.5"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <listener>
      <listener-class>
          example.ServletContextExample
      </listener-class>
  </listener>
</web-app>

然后在这个listener实现里，把jdbc驱动unregister：

Enumeration<Driver> drivers = DriverManager.getDrivers();
while (drivers.hasMoreElements()) {
    Driver driver = drivers.nextElement();
    try {
        DriverManager.deregisterDriver(driver);
    } catch (SQLException e) {
    }
}