如何在文件被编辑后覆盖（保存）该文件？

huangapple
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英文:

How to overwrite (save) a file when it has been edited?

问题

我正在开发一个小型数据管理应用程序，希望除了现有的“另存为 -> XML / CSV”菜单项之外，还能有另一个“保存”项。

此项应在不再打开对话框的情况下，覆盖上次加载的文件并保存更改后的数据（类似于 MS Excel 或 Word 中的操作）。

当然，我已经进行了一些研究，但没有找到合适的解决方案，或者可能搜索错了。

我已经拥有并且正在使用的这些条目和功能：

  1. MenuItem saveXML = new MenuItem("另存为 XML");
  2. saveXML.setOnAction((e) -> {
  3. // 将文件保存为 XML
  4. });
  6. MenuItem saveCSV = new MenuItem("另存为 CSV");
  7. saveCSV.setOnAction((e) -> {
  8. // 将文件保存为 CSV
  9. });

我想创建这个条目：

  1. MenuItem save = new MenuItem("保存");
  2. save.setOnAction((e) -> {
  3. // 以相同格式（XML 或 CSV）保存上次打开的文档，无需任何对话框
  4. });

这是我的应用程序

英文:

I am currently developing a small data management application and would like to have another "Save" entry besides the existing "Save as -> XML / CSV" menu items.

This entry should overwrite the last loaded file with the changed data without opening a dialog again (like in MS Excel or Word).

Of course I have already done some research, but didn't find anything suitable or searched for the wrong one.

These entries and functions I already have and they work:

  1. MenuItem saveXML = new MenuItem("Save as XML");
  2. saveXML.setOnAction((e) -> {
  3. // save file as XML
  4. });
  6. MenuItem saveCSV = new MenuItem("Save as CSV");
  7. saveCSV.setOnAction((e) -> {
  8. // save file as CSV
  9. });

I would like to create this entry:

  1. MenuItem save = new MenuItem("Save");
  2. saveCSV.setOnAction((e) -> {
  3. // Save the last opened document in the same format (XML or CSV) without any dialog
  4. });

This is my application

答案1

得分: 0

根据Abra的建议，您必须通过将其存储在私有字段中来记住最近加载文件的位置：

  1. private File currentFile;

然后在加载文件时进行设置：

  1. MenuItem load = new MenuItem("Load");
  2. load.setOnAction(e -> {
  3.     FileChooser chooser = new FileChooser();
  4.     // （在此设置FileChooser的标题和过滤器）
  5.     File file = chooser.showOpenDialog(stage);
  6.     if (file != null) {
  7.         // （将文件加载到应用程序中）
  8.         this.currentFile = file;
  9.     }
  10. });

现在，您可以使用currentFile的值进行保存：

  1. MenuItem save = new MenuItem("Save");
  2. save.setOnAction(e -> {
  3.     if (currentFile != null) {
  4.         // （写入currentFile）
  5.     } else {
  6.         // 新文件；询问用户保存位置。
  8.         FileChooser chooser = new FileChooser();
  9.         // （在此设置FileChooser的标题和过滤器）
  10.         File file = chooser.showSaveDialog(stage);
  11.         if (file != null) {
  12.             // （根据选择的过滤器将文件保存为CSV或XML）
  13.             this.currentFile = file;
  14.         }
  15.     }
  16. });

如果尚未完成，您可能希望将保存逻辑移到私有方法中。

英文:

As Abra suggested, you must remember the location of the most recently loaded file by storing it in a private field:

  1. private File currentFile;

Then you set it whenever you load a file:

  1. MenuItem load = new MenuItem("Load");
  2. load.setOnAction(e -> {
  3.     FileChooser chooser = new FileChooser();
  4.     // (set FileChooser's title and filters here)
  5.     File file = chooser.showOpenDialog(stage);
  6.     if (file != null) {
  7.         // (load file into application)
  8.         this.currentFile = file;
  9.     }
  10. });

Now, you can use that currentFile value to save:

  1. MenuItem save = new MenuItem("Save");
  2. save.setOnAction(e -> {
  3.     if (currentFile != null) {
  4.         // (write to currentFile)
  5.     } else {
  6.         // New file;  ask user for save location.
  8.         FileChooser chooser = new FileChooser();
  9.         // (set FileChooser's title and filters here)
  10.         File file = chooser.showSaveDialog(stage);
  11.         if (file != null) {
  12.             // (save file as CSV or XML depending on chosen filter)
  13.             this.currentFile = file;
  14.         }
  15.     }
  16. });

You may want to move your save logic into private methods, if you haven’t already.

答案2

得分: 0

我有一个对我有效的解决方案。这可能不是最优解，但仍然可能有用。

我将一个包含文件路径的属性传递给我的menuItem，例如 .put("FILE_LOCATION",..)，然后在保存事件中使用这个属性来选择最后一个路径。

由于我还想自动保存为CSV或XML文件，我会从包含另一个路径的变量中删除该路径，如果存在的话。例如 .remove("FILE_LOCATION")

  1. loadCSV.setOnAction(e -> {
  2. 		...
  3. 		File f = fileChooser.showOpenDialog(null);
  4. 		loadCSV.getProperties().put("FILE_LOCATION", f.getAbsolutePath());
  5. 		loadXML.getProperties().remove("FILE_LOCATION");
  6. });

然后我检查哪个变量已填充，然后运行相应的方法。

  1. save.setOnAction(e -> {
  2. 		try {
  3. 			if (loadCSV.getProperties().isEmpty() == false) {
  4. 				File saveCSV = new File(loadCSV.getProperties().get("FILE_LOCATION").toString());
  5. 				if (saveCSV != null) {
  6. 					CSV.writeCSV(saveCSV, DataHandler.INSTANCE.foodlist());
  7. 				}
  8. 			} else if (loadXML.getProperties().isEmpty() == false) {
  9. 				File saveXML = new File(loadXML.getProperties().get("FILE_LOCATION").toString());
  10. 				if (saveXML != null) {
  11. 					XML.writeXMLList(saveXML, DataHandler.INSTANCE.foodlist());
  12. 				}
  13. 			}
  14. 	});
英文:

I have a solution that works for me. It may not be the optimal solution, but it could still be useful.

I pass a property to my menuItem that contains the path of my file .put("FILE_LOCATION",..) and use this property in the save-event to select the last path.

Since I also want to save automatically as either CSV or XML file, I delete the path from the variable that contains the other one, if it exists. .remove("FILE_LOCATION")

  1. loadCSV.setOnAction(e -> {
  2. 		...
  3. 		File f = fileChooser.showOpenDialog(null);
  4. 		loadCSV.getProperties().put("FILE_LOCATION", f.getAbsolutePath());
  5. 		loadXML.getProperties().remove("FILE_LOCATION");
  6. });

Then I check which variable is filled and then run the respective method.

  1. save.setOnAction(e -> {
  2. 		try {
  3. 			if (loadCSV.getProperties().isEmpty() == false) {
  4. 				File saveCSV = new File(loadCSV.getProperties().get("FILE_LOCATION").toString());
  5. 				if (saveCSV != null) {
  6. 					CSV.writeCSV(saveCSV, DataHandler.INSTANCE.foodlist());
  7. 				}
  8. 			} else if (loadXML.getProperties().isEmpty() == false) {
  9. 				File saveXML = new File(loadXML.getProperties().get("FILE_LOCATION").toString());
  10. 				if (saveXML != null) {
  11. 					XML.writeXMLList(saveXML, DataHandler.INSTANCE.foodlist());
  12. 				}
  13. 			}
  14. 	});

huangapple
  • 本文由 发表于 2020年7月25日 16:51:44
  • 转载请务必保留本文链接：https://go.coder-hub.com/63086335.html
  • file
  • java
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