Java以二进制方式读写文件

参考:https://www.codejava.net/java-se/file-io/how-to-read-and-write-binary-files-in-java

this is a very important image for all .

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1. Reading and Writing Binary Files Using FileInputStream and FileOutputStream

public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		String inputFile="C:\\Users\\Administrator\\Desktop\\test.pcm";
		String outputFile="C:\\Users\\Administrator\\Desktop\\test_result.pcm";
		
		InputStream inputStream=new FileInputStream(inputFile);
		OutputStream outputStream=new FileOutputStream(outputFile);
		
		int byteRead;
		while((byteRead=inputStream.read()) != -1){
			outputStream.write(byteRead);
		}
		inputStream.close();
		outputStream.close();
		
		return;
		
	}

And the following program runs much faster by copying a chunk of bytes at a time (exactly 4096 bytes at a time):

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		String inputFile="C:\\Users\\Administrator\\Desktop\\test.pcm";
		String outputFile="C:\\Users\\Administrator\\Desktop\\test_result.pcm";
		
		InputStream inputStream=new FileInputStream(inputFile);
		OutputStream outputStream=new FileOutputStream(outputFile);
		
		long fileSize=new File(inputFile).length();
		System.out.println(fileSize);
		byte[] allBytes = new byte[(int) fileSize]; //存疑。
		inputStream.read(allBytes);
		outputStream.write(allBytes);
		
		inputStream.close();
		outputStream.close();
		
		return;
		
	}

2. Reading and Writing Binary Files Using BufferedInputStream and BufferedOutputStream

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		String inputFile="C:\\Users\\Administrator\\Desktop\\test.pcm";
		String outputFile="C:\\Users\\Administrator\\Desktop\\test_result.pcm";
		
//		also.
//		int bufferSize = 16384; // 16KB buffer size
//		InputStream inputStream
//		    = new BufferedInputStream(new FileInputStream(inputFile), bufferSize);
//		 
//		OutputStream outputStream
//		    = new BufferedOutputStream(new FileOutputStream(outputFile), bufferSize);
		
		InputStream inputStream=new BufferedInputStream(new FileInputStream(inputFile));
		OutputStream outputStream=new BufferedOutputStream(new FileOutputStream(outputFile));
		
		int BUFFER_SIZE = 16384;
		byte[] buffer=new byte[BUFFER_SIZE];
		while (inputStream.read(buffer) != -1){
			outputStream.write(buffer);
		}
		inputStream.close();
		outputStream.close();
		
		return;
		
	}

3.Reading and Writing Binary Files Using New File I/O API (NIO)

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		String inputFile="C:\\Users\\Administrator\\Desktop\\test.pcm";
		String outputFile="C:\\Users\\Administrator\\Desktop\\test_result.pcm";
		
		byte[] allBytes=Files.readAllBytes(Paths.get(inputFile));
		Files.write(Paths.get(outputFile), allBytes);
		
		return;
		
	}