连接后仍在使用java数据库。关闭（）

Question

当我连接到一个数据库（其位置由JFileChooser提供）时，我会检查该数据库是否过时，如有必要，尝试删除并替换它。 我得到的错误如下：

java.io.IOException: Unable to delete file: C:\Users\User\Documents\POS-Data\Tables\seg0\cd1.dat
at org.apache.commons.io.FileUtils.forceDelete(FileUtils.java:2279)
at org.apache.commons.io.FileUtils.cleanDirectory(FileUtils.java:1653)
at org.apache.commons.io.FileUtils.deleteDirectory(FileUtils.java:1535)
at org.apache.commons.io.FileUtils.forceDelete(FileUtils.java:2270)
at org.apache.commons.io.FileUtils.cleanDirectory(FileUtils.java:1653)
at org.apache.commons.io.FileUtils.deleteDirectory(FileUtils.java:1535)
at Admin.SendReceiveData.SendData(SendReceiveData.java:226)
at Admin.SendReceiveData.SendAllBActionPerformed(SendReceiveData.java:183)
at Admin.SendReceiveData.access$100(SendReceiveData.java:13)
at Admin.SendReceiveData$3.actionPerformed(SendReceiveData.java:151)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6525)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3322)
at java.awt.Component.processEvent(Component.java:6290)
at java.awt.Container.processEvent(Container.java:2234)
at java.awt.Component.dispatchEventImpl(Component.java:4881)
at java.awt.Container.dispatchEventImpl(Container.java:2292)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
at java.awt.Container.dispatchEventImpl(Container.java:2278)
at java.awt.Window.dispatchEventImpl(Window.java:2739)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:751)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:702)
at java.awt.EventQueue$3.run(EventQueue.java:696)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:724)
at java.awt.EventQueue$4.run(EventQueue.java:722)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:721)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

我使用以下URL：

String URL = "jdbc:derby:" + DestinationFile.getAbsolutePath() + "\\Tables;create=true;user=root;password=root";

注意，我总是使用连接。close（），但在我关闭程序之前，数据库似乎是打开的。这阻止了我更新数据库，关于如何完全释放数据库资源有什么建议吗

（System.gc不起作用）

Answer 1

我找到了解决问题的方法：

DriverManager.getConnection(URL+";shutdown=true");

将关闭数据库

Answer 2

关闭与数据库的连接并不意味着datatbe将关闭并释放其类似于资源的文件句柄。您需要先关闭数据库

此外，如果您正在运行嵌入到应用程序中的Derby，这意味着数据库与应用程序运行在同一个JVM中。在那种情况下，这可能会对你有所帮助