java - 使用 JFileChooser 写入文件

Question

我尝试在单击按钮时使用 JFileChooser 保存文件。因此，当我单击它时，窗口会按我的预期出现，然后我输入文件名并保存它。所有工作，我都按照我想要的方式在确切的位置和 .txt 中获取了我的文件，但是当我打开它时，什么也没有。我已经测试了写入和打印，但没有任何效果。所以我想知道我错在哪里以及我应该怎么做。

谢谢!

这是我的代码:

jbSave.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        JFileChooser fileChooser = new JFileChooser();
        if (fileChooser.showSaveDialog(null) == JFileChooser.APPROVE_OPTION) {
            File file = fileChooser.getSelectedFile();
            try {
                String path = file.getPath() + ".txt";
                file = new File(path);
                FileWriter filewriter = new FileWriter(file.getPath(), true);
                BufferedWriter buff = new BufferedWriter(filewriter);
                PrintWriter writer = new PrintWriter(buff);
                writer.write("start");                                      
            } catch (FileNotFoundException e2) {
                e2.printStackTrace();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
        }       
    }           
});

Answer 1

只是为了添加更多详细信息或替代方案 this answer ，您可以使用 try-with-resource block 并让 JVM 为您处理关闭(和刷新)编写器。

try(PrintWriter writer = ...))
{
    writer.write("start");
} 
catch (IOException e) 
{
    // Handle exception.
}

此外，您可以编写一个实用函数来创建 PrintWriter:

/**
 * Opens the file for writing, creating the file if it doesn't exist. Bytes will
 * be written to the end of the file rather than the beginning.
 *
 * The returned PrintWriter uses a BufferedWriter internally to write text to
 * the file in an efficient manner.
 *
 * @param path
 *            the path to the file
 * @param cs
 *            the charset to use for encoding
 * @return a new PrintWriter
 * @throws IOException
 *             if an I/O error occurs opening or creating the file
 * @throws SecurityException
 *             in the case of the default provider, and a security manager is
 *             installed, the checkWrite method is invoked to check write access
 *             to the file
 * @see Files#newBufferedWriter(Path, Charset, java.nio.file.OpenOption...)
 */
public static PrintWriter newAppendingPrintWriter(Path path, Charset cs) throws IOException
{
    return new PrintWriter(Files.newBufferedWriter(path, cs, CREATE, APPEND, WRITE));
}

另一种可能性是使用Files.write()如果所有数据都可以在一次操作中写入:

try 
{
    byte[] bytes = "start".getBytes(StandardCharsets.UTF_8);
    Files.write(file.toPath(), bytes)
} 
catch (IOException e) 
{
    // Handle exception.
}