1. 文本文件的读取

文本的读取,返回值是一个list, 如果需要返回一整个string 在while循环中使用StringBuilder.append 即可

<code>/**

* 逐行读取文本

*

* @param filePath 文件路径

* @return List<String>

*/

public static List<String> readTxtFile1(String filePath) throws IOException {

Path path = Paths.get(filePath);

//判断文件是否存在

if (!Files.exists(path)) {

log.error("file is not exist");

return null;

}

List<String> txtList = new ArrayList<>();

try (InputStreamReader read = new InputStreamReader(Files.newInputStream(path), StandardCharsets.UTF_8);

BufferedReader bufferedReader = new BufferedReader(read)) {

String lineTxt;

while (null != (lineTxt = bufferedReader.readLine())) {

if (StringUtils.isNotEmpty(lineTxt)) {

txtList.add(lineTxt);

}

}

}

return txtList;

}

2.文本文件的写入

/**

* 以指定的编码 写入数据

*/

private static void outputStreamWriter(String filePath, List<String> content, Charset charset, boolean append) throws IOException {

try (OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream(filePath, append), charset);

BufferedWriter bufferedWriter = new BufferedWriter(writer)) {

for (String item : content) {

bufferedWriter.write(item);

bufferedWriter.newLine();

}

}

}

3.文件的拷贝

/**

* 简单的文件拷贝,不使用缓冲区,适用于小文件

*

* @param sourceFile 源文件

* @param targetFile 目标文件

*/

public static void copyFile(String sourceFile, String targetFile) throws IOException {

try (FileInputStream fileInputStream = new FileInputStream(sourceFile);

FileOutputStream fileOutputStream = new FileOutputStream(targetFile)) {

byte[] b = new byte[1024];

int length;

while ((length = fileInputStream.read(b)) != -1) {

fileOutputStream.write(b, 0, length);

// 不能用 fileOutputStream.write(b) 因为最后有可能读不够而出错

}

}

}

4.大文件的拷贝

/**

* 进行文件的拷贝-高效

* 使用字节处理流 字节缓冲输入流和字节缓冲输出流

*

* @param source 源

* @param target 复制到

* @return boolean 结果

*/

public static boolean BufferedStreamFileCopy(String source, String target) {

if (StringUtils.isEmpty(source) || StringUtils.isEmpty(target)) {

log.error("文件路径不存在! path:{}", source);

return false;

}

if (source.equals(target)) {

log.error("复制的源文件和目标文件不能是同一个文件! path:{}", source);

return false;

}

Path path = Paths.get(source);

boolean exists = Files.exists(path);

if (!exists) {

log.error("文件不存在! path:{}", source);

return false;

}

long currentTimeMillis = System.currentTimeMillis();

try (BufferedInputStream bufferedInputStream = new BufferedInputStream(Files.newInputStream(path));

BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(Files.newOutputStream(Paths.get(target)))) {

byte[] bytes = new byte[1024];

int length;

while ((length = bufferedInputStream.read(bytes)) != -1) {

bufferedOutputStream.write(bytes, 0, length);

}

log.info("copy file success, time:{} ms", System.currentTimeMillis() - currentTimeMillis);

return true;

} catch (IOException e) {

log.error("BufferedStreamFileCopy 拷贝文件异常", e);

return false;

}

}

5.文本文件编码转换

/**

* 编码转换- 如一个文件的编码是 gb2312 转为 utf-8

* 请注意,请用文件本身的正确的编码尝试读取,否则会乱码

*

* @param filePath 原始文件

* @param oldCharset 原始字符编码

* @param newFilePath 新文件

* @param newCharset 新字符编码

* @throws IOException io异常

*/

private static void conversionCharset(String filePath, String oldCharset, String newFilePath, String newCharset) throws IOException {

try (InputStreamReader reader = new InputStreamReader(Files.newInputStream(Paths.get(filePath)), oldCharset);

BufferedReader bufferedReader = new BufferedReader(reader);

OutputStreamWriter outputStreamWriter = new OutputStreamWriter(Files.newOutputStream(Paths.get(newFilePath)), newCharset);

BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter)) {

String line;

while (null != (line = bufferedReader.readLine())) {

bufferedWriter.write(line);

bufferedWriter.newLine();

}

}

}