【发布时间】：2013-05-13 16:55:41
【问题描述】：
与 Linux 相比，我很难理解 Windows 如何处理文件。我正在尝试删除我用作“数据库”的文件中的条目（它只是一个常规文件）。不幸的是，Java 没有提供这样做的方法，所以我必须将除我要删除的条目之外的所有条目复制到临时文件中，删除旧数据库，创建一个新的空数据库文件，将临时文件的内容复制到新的数据库文件，然后删除临时文件。
这是我的函数的代码：
private void removeSelectedItem(String entryToRemove) {
//original database file
File database = new File("catalog");
//all entries except selected will be written here first
File temp = new File("temp");
boolean endOfFileFlag = false;
String line = "";
try {
//used for reading original database file
BufferedReader databaseReader =
new BufferedReader(new FileReader(database));
//used for writing to newly-created temp file
BufferedWriter tempWriter =
new BufferedWriter(new FileWriter(temp, true));
/*
* Read original database line by line and test to see if the line
* has the course prefix and id. If it does, it won't be written to
* the temp file.
*/
while (endOfFileFlag == false) {
line = databaseReader.readLine();
/*
* This code is ugly. If possible, this check needs to be
* made in the conditions of the while loop.
*/
if (line == null) {
endOfFileFlag = true;
break;
}
//tests to see if the line is to be removed
if ( !line.contains(entryToRemove))
tempWriter.write(line + "\r\n");
}
endOfFileFlag = false; //reset this for the next loop
databaseReader.close(); //database will be deleted
tempWriter.close(); //temp file is written
database.delete(); //delete this to create a new updated one below
database.createNewFile();
//writes to the new database
BufferedWriter databaseWriter =
new BufferedWriter(new FileWriter(database, true));
//reads from the temp file
BufferedReader tempReader =
new BufferedReader(new FileReader(temp));
//read temp line by line and add each line to a new catalog file
while (endOfFileFlag == false) {
line = tempReader.readLine();
/*
* This code is ugly. If possible, this check needs to be made
* in the conditions of the while loop. Attempts thus far have
*/
if(line == null){
endOfFileFlag = true;
break;
}
databaseWriter.write(line + "\r\n");
}
tempReader.close(); //temp will be deleted
databaseWriter.close(); //new database has been written
temp.delete(); //temp file no longer needed
setUpInfo(); //update the lists with the new catalog info
}catch(IOException e){
System.out.println("removeSelectedItem()");
e.printStackTrace();
}
}
这段代码（“\r\n”除外，在 Linux 中只有“\n”）在 Linux 下完美执行，但在 Windows 中，我发现当我激活事件处理程序以删除条目时，程序只会添加额外的条目。调试后我发现对database.delete() 的调用实际上并没有删除数据库文件，而对temp.delete() 的调用正在删除临时文件（就像它应该删除的那样）。我发现这很奇怪，所以我检查了文件的权限并将它们设置为“读/写”。我尝试了在互联网上找到的以下修复：
endOfFileFlag = false; //reset this for the next loop
databaseReader.close(); //database will be deleted
tempWriter.close(); //temp file is written
database.delete(); //delete this to create a new updated one below
//new code
database = null;
System.gc();
但它没有用。我想不出还有什么可能发生的事情。
【问题讨论】：
标签： java delete-file platform-specific