java IO异常:流已关闭
这是我目前拥有的代码:java IO异常:流已关闭,java,ioexception,Java,Ioexception,这是我目前拥有的代码: public class FileStatus extends Status{ FileWriter writer; public FileStatus(){ try { writer = new FileWriter("status.txt",true); } catch (IOException e) { e.printStackTrace(); } } public void writeToFile(){
public class FileStatus extends Status{
FileWriter writer;
public FileStatus(){
try {
writer = new FileWriter("status.txt",true);
} catch (IOException e) {
e.printStackTrace();
}
}
public void writeToFile(){
String file_text= pedStatusText + " " + gatesStatus + " " + DrawBridgeStatusText;
try {
writer.write(file_text);
writer.flush();
writer.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
一切都按预期工作(调用writeToFile方法时会写入文件)。但是,当第二次调用writeToFile方法时,出现以下错误:
java.io.IOException: Stream closed
at sun.nio.cs.StreamEncoder.ensureOpen(StreamEncoder.java:45)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:118)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:135)
at java.io.OutputStreamWriter.write(OutputStreamWriter.java:220)
at java.io.Writer.write(Writer.java:157)
at FileStatus.writeToFile(FileStatus.java:19)
at MenuBar$9.actionPerformed(MenuBar.java:115)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:703)
at java.awt.EventQueue.access$000(EventQueue.java:102)
at java.awt.EventQueue$3.run(EventQueue.java:662)
at java.awt.EventQueue$3.run(EventQueue.java:660)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:676)
at java.awt.EventQueue$4.run(EventQueue.java:674)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:673)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)
java.io.IOException: Stream closed
at sun.nio.cs.StreamEncoder.ensureOpen(StreamEncoder.java:45)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:118)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:135)
at java.io.OutputStreamWriter.write(OutputStreamWriter.java:220)
at java.io.Writer.write(Writer.java:157)
at FileStatus.writeToFile(FileStatus.java:19)
at MenuBar$9.actionPerformed(MenuBar.java:115)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:703)
at java.awt.EventQueue.access$000(EventQueue.java:102)
at java.awt.EventQueue$3.run(EventQueue.java:662)
at java.awt.EventQueue$3.run(EventQueue.java:660)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:676)
at java.awt.EventQueue$4.run(EventQueue.java:674)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:673)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)
java.io.IOException: Stream closed
at sun.nio.cs.StreamEncoder.ensureOpen(StreamEncoder.java:45)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:118)
at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:135)
at java.io.OutputStreamWriter.write(OutputStreamWriter.java:220)
at java.io.Writer.write(Writer.java:157)
at FileStatus.writeToFile(FileStatus.java:19)
at MenuBar$9.actionPerformed(MenuBar.java:115)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
文件仍按预期第二次写入,但在第二次和以后调用writeToFile()时会抛出此错误。我想知道是什么导致了这个错误的发生 不要在
writeToFile()
中调用write.close()
您正在调用的writer.close()代码>完成写入后。流一旦关闭,就不能再次写入。通常,我实现这一点的方法是将write-to方法的结尾移出
public void writeToFile(){
String file_text= pedStatusText + " " + gatesStatus + " " + DrawBridgeStatusText;
try {
writer.write(file_text);
writer.flush();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
并添加一个方法cleanUp
来关闭流
public void cleanUp() {
writer.close();
}
这意味着您有责任确保在完成对文件的写入时调用cleanUp
。否则将导致内存泄漏和资源锁定
EDIT:每次要写入文件时,您都可以通过将writer
移动到writeToFile()
方法中来创建新流
public void writeToFile() {
FileWriter writer = new FileWriter("status.txt", true);
// ... Write to the file.
writer.close();
}
调用writer.close()
在writeToFile
中,因此在您第二次调用writeToFile
时,写入程序已关闭
为什么不将FileStatus
合并到writeToFile
?堆栈跟踪的第一行说明了一切:java.io.IOException:Stream closed
。您不能先关闭它,然后再写入。调用write.close()
的目的是什么?因为我希望可以多次写入文件,但如果无法预测文件需要写入多少次,我看不出您如何知道何时调用write.close()
write.close()
释放系统上的资源。你应该尽快这样做。您可以选择的一个方法是,每次编写时只需打开一个新流,然后每次关闭它。。检查我的编辑。