我正在使用java.nio.file包，并尝试使用以下代码创建文件。
private static void printReport(String filename, String str)throws Exception{
ErrorCheck ec = new ErrorCheck();
String fileName = "/var/Emails_log/"+filename;
Path filePath = Paths.get(fileName);
File file = new File(fileName);
final BufferedWriter out = Files.newBufferedWriter(filePath, StandardCharsets.UTF_8, StandardOpenOption.APPEND);
try{
final Path tmp = filePath.getParent();
if (tmp != null){ // null will be returned if the path has no parent
Files.createDirectories(tmp);
} else {
out.write(str);
out.write('\n');
}
} catch(Exception e) {
ec.errorMsg("ERROR: GSW.SendEmail.Exception =>",e);
} finally {
if (out != null) {
out.flush();
out.close();
}
}
}
这将引发以下异常：
java.nio.file.NoSuchFileException: /var/Emails_log/GSWvalidSentAddresses.txt
at sun.nio.fs.UnixException.translateToIOException(UnixException.java:86)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)
at sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:214)
at java.nio.file.spi.FileSystemProvider.newOutputStream(FileSystemProvider.java:430)
at java.nio.file.Files.newOutputStream(Files.java:170)
at java.nio.file.Files.newBufferedWriter(Files.java:2720)
at SendEmail.printReport(SendEmail.java:114) SendEmail.send(SendEmail.java:87)
我的问题是为什么不创建文件？
请告知
感谢您的期待
更新后的答案：
现在您已经显示了完整的代码，有两个主要问题：
您正在尝试打开文件，然后确保导致该文件的目录存在，以及
您正在使用StandardOpenOption.APPEND，但不会创建文件；它将附加到existing文件。
...以及围绕最佳实践的大量问题，与实际代码的行数有关。
查看评论：
private static void printReport(String filename, String str) throws Exception /* No, it doesn't. The only calls you had outside your catch-all `try` don't throw exceptions. */ {
ErrorCheck ec = new ErrorCheck(); // Recommend not creating this until/unless you need it
String fileName = "/var/Emails_log/"+filename; // VERY poor practice having two locals that only differ by the capitalization of one character in the middle (`filename` and `fileName`)
Path filePath = Paths.get(fileName);
// File file = new File(fileName); <== Removed, since you never use it for anything
try {
// Make sure the directories exist
Files.createDirectories(filePath.getParent()); // No need for your null check, so I removed it; based on `fileName`, it will always have a parent
// Open the file, creating it if it doesn't exist
try (
final BufferedWriter out = Files.newBufferedWriter(
filePath,
StandardCharsets.UTF_8,
StandardOpenOption.CREATE,
StandardOpenOption.APPEND)
) {
// Write to out here
}
} catch (Exception e) {
// Log-and-continue isn't generally best practice; and if you're going to do it
ec.errorMsg("ERROR: GSW.SendEmail.Exception =>",e); // <== Um...send mail failed? This isn't sending mail, it's putting something in a file.
}
// Using the try-with-resources, we don't have to worry about the flush and close calls
}
但是这是我建议您写的方式：
private static void printReport(String filename, String str) throws IOException {
Path filePath = Paths.get("/var/Emails_log/" + filename);
// Make sure the directories exist
Files.createDirectories(filePath.getParent());
// Open the file, creating it if it doesn't exist
try (
final BufferedWriter out = Files.newBufferedWriter(
filePath,
StandardCharsets.UTF_8,
StandardOpenOption.CREATE,
StandardOpenOption.APPEND)
) {
// Write to out here, perhaps outputting `str`?
}
}
...并在调用层处理异常。再次注意，因为我们使用的是try-with-resources，所以close是自动的（有异常时和无异常时）。
或者，如果您确实要执行日志记录并继续：
：private static void printReport(String filename, String str) { try { Path filePath = Paths.get("/var/Emails_log/" + filename); // Make sure the directories exist Files.createDirectories(filePath.getParent()); // Open the file, creating it if it doesn't exist try ( final BufferedWriter out = Files.newBufferedWriter( filePath, StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.APPEND) ) { // Write to out here, perhaps outputting `str`? } } catch (Exception e) { new ErrorCheck().errorMsg("ERROR: GSW.SendEmail.Exception =>", e); // <== But surely this message is suspect? I don't see anything sending email here. } }原始答案
您尚未显示实际失败的代码，这是对newBufferedWriter（this 1或this 1）的调用。 newBufferedWriter占用OpenOption，可从StandardOpenOption获得其标准集。确保您指定了StandardOpenOption或StandardOpenOption.CREATE，
如果您使用这些标志之一，而您的问题中的代码是[StandardOpenOption.CREATE调用之前[[之前
StandardOpenOption.CREATE_NEW