Java – Create a File – Java – 创建一个文件

最后修改: 2014年 6月 28日

中文/混合/英文(键盘快捷键：t)

1. Overview

1.概述

In this quick tutorial, we’re going to learn how to create a new File in Java – first using the Files and Path classes from NIO, then the Java File and FileOutputStream classes, Google Guava, and finally the Apache Commons IO library.

在这个快速教程中，我们将学习如何在Java中创建一个新的文件–首先使用NIO的Files和Path类，然后是Java File和FileOutputStream类，Google Guava，最后是Apache Commons IO库。

This article is part of the “Java – Back to Basic” series here on Baeldung.

本文是Baeldung网站上“Java – Back to Basic “系列的一部分。

2. Setup

2.设置

In the examples, we’ll define a constant for the file name:

在例子中，我们将为文件名定义一个常量。

private final String FILE_NAME = "src/test/resources/fileToCreate.txt";

And we’ll also add a clean-up step to make sure that the file doesn’t already exist before each test, and to delete it after each test runs:

我们还将添加一个清理步骤，以确保在每次测试前文件不已经存在，并在每次测试运行后删除它。

@AfterEach
@BeforeEach
public void cleanUpFiles() {
    File targetFile = new File(FILE_NAME);
    targetFile.delete();
}

3. Using NIO Files.createFile()

3.使用NIO Files.createFile()

Let’s start by using the Files.createFile() method from the Java NIO package:

让我们从使用Java NIO包中的Files.createFile()方法开始。

@Test
public void givenUsingNio_whenCreatingFile_thenCorrect() throws IOException {
    Path newFilePath = Paths.get(FILE_NAME);
    Files.createFile(newFilePath);
}

As you can see the code is still very simple; we’re now using the new Path interface instead of the old File.

正如你所看到的，代码仍然非常简单；我们现在使用新的Path接口而不是旧的File。

One thing to note here is that the new API makes good use of exceptions. If the file already exists, we no longer have to check a return code. Instead, we’ll get a FileAlreadyExistsException:

这里需要注意的一点是，新的API很好地利用了异常情况。如果文件已经存在，我们不再需要检查一个返回代码。相反，我们会得到一个FileAlreadyExistsException。

java.nio.file.FileAlreadyExistsException: <code class="language-java">src/test/resources/fileToCreate.txt at sun.n.f.WindowsException.translateToIOException(WindowsException.java:81)

4. Using File.createNewFile()

4.使用File.createNewFile()

Let’s now look at how we can do the same using the java.io.File class:

现在让我们看看我们如何使用java.io.File类来做同样的事情：。

@Test
public void givenUsingFile_whenCreatingFile_thenCorrect() throws IOException {
    File newFile = new File(FILE_NAME);
    boolean success = newFile.createNewFile();
    assertTrue(success);
}

Note that the file must not exist for this operation to succeed. If the file does exist, then the createNewFile() operation will return false.

请注意，该文件必须不存在，该操作才能成功。如果文件确实存在，那么createNewFile()操作将返回false。

5. Using FileOutputStream

5.使用FileOutputStream

Another way to create a new file is to use the java.io.FileOutputStream:

另一种创建新文件的方法是使用java.io.FileOutputStream。

@Test
public void givenUsingFileOutputStream_whenCreatingFile_thenCorrect() throws IOException {
    try(FileOutputStream fileOutputStream = new FileOutputStream(FILE_NAME)){
    }
}

In this case, a new file is created when we instantiate the FileOutputStream object. If a file with a given name already exists, it will be overwritten. If, however, the existing file is a directory or a new file cannot be created for any reason, then we’ll get a FileNotFoundException.

在这种情况下，当我们实例化FileOutputStream对象时，会创建一个新文件。如果一个具有给定名称的文件已经存在，它将被覆盖。然而，如果现有的文件是一个目录，或者由于任何原因不能创建一个新的文件，那么我们将得到一个FileNotFoundException。

Additionally, note we used a try-with-resources statement – to be sure that a stream is properly closed.

此外，注意我们使用了一个try-with-resources语句–以确保一个流被正确关闭。

6. Using Guava

6.使用番石榴

The Guava solution for creating a new file is a quick one-liner as well:

Guava创建新文件的方案也是一个快速的单行程序。

@Test
public void givenUsingGuava_whenCreatingFile_thenCorrect() throws IOException {
    com.google.common.io.Files.touch(new File(FILE_NAME));
}

7. Using Apache Commons IO

7.使用Apache Commons IO

The Apache Commons library provides the FileUtils.touch() method which implements the same behavior as the “touch” utility in Linux.

Apache Commons库提供了FileUtils.touch()方法，实现了与Linux中”touch“工具相同的行为。

Therefore it creates a new empty file or even a file and the full path to it in a file system:

因此，它在文件系统中创建一个新的空文件，甚至是一个文件和它的完整路径。

@Test
public void givenUsingCommonsIo_whenCreatingFile_thenCorrect() throws IOException {
    FileUtils.touch(new File(FILE_NAME));
}

Note that this behaves slightly differently than the previous examples: if the file already exists, the operation doesn’t fail, it simply doesn’t do anything.

注意，这与前面的例子略有不同：如果文件已经存在，操作不会失败，只是不做任何事情。

And there we have it – 4 quick ways to create a new file in Java.

就这样，我们有了–在Java中创建新文件的4种快速方法。

8. Conclusion

8.结论

In this article, we looked at different solutions for creating a file in Java. We used classes that are part of the JDK and external libraries.

在这篇文章中，我们研究了在Java中创建文件的不同解决方案。我们使用了属于JDK的类和外部库。

The code for the examples is available over on GitHub.

例子的代码可在GitHub上找到。