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// 要放入临时文件的文件夹路径
String tempStr = AllTest.class.getResource("/").getPath() + "temp";

// 使用uuid，不覆盖
File tempFile;
try {
    tempFile = File.createTempFile(tempStr + UUID.randomUUID(), ".txt");
} catch (IOException e) {
    log.error("创建临时文件失败", e);
    throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "创建临时文件失败", e);
}

// 会覆盖
File tempFile;
try {
    tempFile = File.createTempFile(tempStr + "demo", ".txt");
} catch (IOException e) {
    log.error("创建临时文件失败", e);
    throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "创建临时文件失败", e);
}

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String urlStr = 类名.class.getResource("/").getPath() + "easyExcel" + File.separator + "demo.xlsx";
File file = new File(urlStr);

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String urlStr = 类名.class.getClassLoader().getResource("").getPath() + "easyExcel" + File.separator + "demo.xlsx";
File file = new File(urlStr);

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ResourceLoader resourceLoader = new DefaultResourceLoader();
Resource resource = resourceLoader.getResource("classpath:" + File.separator + "easyExcel" + File.separator + "demo.txt");
try {
    File file = resource.getFile();
} catch (IOException e) {
    log.error("读取文件失败", e);
    throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "读取文件失败", e);
}

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String folderStr = AllTest.class.getResource("/").getPath() + "folder";
File folder = new File(folderStr);
boolean mkdir = folder.mkdir();
log.info("创建文件夹: {}", mkdir);

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File file = new File(urlStr);

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Files.copy(file1, file2);
FileCopyUtils.copy(file1, file2);

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// 源文件
String sourceUrlStr = AllTest.class.getResource("/").getPath() + "easyExcel" + File.separator + "extra.xlsx";
File sourceFile = new File(sourceUrlStr);
// 目标文件（必须不存在，如果存在则报错，也就是说不可覆盖）
String targetUrlStr = AllTest.class.getResource("/").getPath() + "easyExcel" + File.separator;
File targetFile = new File(targetUrlStr + "demoNew2.txt");
// 移动文件
try {
    Files.move(sourceFile.toPath(), targetFile.toPath());
} catch (IOException e) {
    log.error("文件移动失败", e);
    throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "文件移动失败", e);
}

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FileSystemUtils.copyRecursively(file1, file2);

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FileSystemUtils.deleteRecursively(directoryFile);

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byte[] byteArray;
try {
    byteArray = FileUtils.readFileToByteArray(file);
} catch (IOException e) {
    log.error("文件转字节数组异常", e);
    throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "文件转字节数组异常", e);
}

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byte[] bytes = FileCopyUtils.copyToByteArray(inputStream);

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String string = FileCopyUtils.copyToString(reader);

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List<String> list;
try {
    list = Files.readLines(file, StandardCharsets.UTF_8);
} catch (IOException e) {
    log.error("文件读取异常", e);
    throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "文件读取异常", e);
}

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FileCopyUtils.copy(bytes, file);

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FileCopyUtils.copy(bytes, new FileOutputStream(file));

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FileCopyUtils.copy(new FileInputStream(file1), new FileOutputStream(file));

FileCopyUtils.copy(new FileReader(file1), new FileWriter(file));

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FileCopyUtils.copy(string, new FileWriter(file));

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try (InputStream inputStream = new FileInputStream(file)) {
    // 在这里处理输入流
} catch (IOException e) {
    log.error("文件转InputStream失败", e);
    throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "文件转InputStream失败", e);
}

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String urlStr = AllTest.class.getResource("/").getPath() + "easyExcel" + File.separator + "demo.xlsx";
File file = new File(urlStr);

// MultipartFile 转 File
try (InputStream inputStream = multipartFile.getInputStream();
     FileOutputStream outputStream = new FileOutputStream(file)) {
    byte[] buffer = new byte[4096];
    int bytesRead;
    while ((bytesRead = inputStream.read(buffer)) != -1) {
        outputStream.write(buffer, 0, bytesRead);
    }
} catch (IOException e) {
    log.error("文件写入失败", e);
    throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "文件写入失败", e);
}