Java-Dateioperationen und Leistungsoptimierung: Bringen Sie Ihr Programm zum Fliegen

// 使用File类的createNewFile方法创建文件
File file = new File("test.txt");
file.createNewFile();

// 使用FileOutputStream类的FileOutpuStream(String fileName)构造方法创建文件
FileOutputStream fos = new FileOutputStream("test.txt");
fos.close();

// 使用File类的readFile方法读取文件
File file = new File("test.txt");
String content = new String(Files.readAllBytes(file.toPath()));

// 使用FileInputStream类的FileInpuStream(String fileName)构造方法读取文件
FileInputStream fis = new FileInputStream("test.txt");
byte[] bytes = new byte[1024];
int length = 0;
while ((length = fis.read(bytes)) != -1) {
//TODO: 对读取到的字节数组进行处理
}
fis.close();

// 使用File类的write方法写入文件
File file = new File("test.txt");
String content = "Hello World!";
Files.write(file.toPath(), content.getBytes());

// 使用FileOutputStream类的write(byte[] bytes)方法写入文件
FileOutputStream fos = new FileOutputStream("test.txt");
String content = "Hello World!";
fos.write(content.getBytes());
fos.close();

// 使用缓冲区读取文件
FileInputStream fis = new FileInputStream("test.txt");
BufferedInputStream bis = new BufferedInputStream(fis);
byte[] bytes = new byte[1024];
int length = 0;
while ((length = bis.read(bytes)) != -1) {
//TODO: 对读取到的字节数组进行处理
}
bis.close();

// 使用内存映射文件读取文件
File file = new File("test.txt");
RandoMaccessFile raf = new RandomAccessFile(file, "rw");
MappedByteBuffer mbb = raf.getChannel().map(FileChannel.MapMode.READ_WRITE, 0, file.length());
//TODO: 对内存映射文件进行处理
raf.close();

// 使用多线程并行处理文件操作
List<String> lines = Files.readAllLines(Paths.get("test.txt"));
ExecutorService executorService = Executors.newFixedThreadPool(10);
List<Future<String>> futures = new ArrayList<>();
for (String line : lines) {
Future<String> future = executorService.submit(() -> {
//TODO: 对文件行进行处理
return line;
});
futures.add(future);
}
executorService.shutdown();
while (!executorService.isTerminated()) {
//TODO: 等待所有线程执行完毕
}