java - 使用 PrintWriter 将 ASCII 代码写入文件

Question

我想知道当我PrintWriter用于写入文件时。它将用文件或二进制格式的ASCII码写入？谢谢。

Answer 1

AWriter写入字符，因此最终在文件中的二进制数据取决于编码。

例如，如果您使用 UTF-16 等 16 位编码，那么每个 ASCII 字节都会有一个额外的零字节：

public class TestWriter
{
    public static void main(String[] args)
    throws UnsupportedEncodingException
    {
        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
        final OutputStreamWriter out = new OutputStreamWriter(baos, "UTF-16");
        final PrintWriter writer = new PrintWriter(out);

        writer.printf("abc");
        writer.close();

        for (final byte b : baos.toByteArray())
        {
            System.out.printf("0x%02x ", b);
        }
        System.out.printf("\n");
    }
}

打印0xfe 0xff 0x00 0x61 0x00 0x62 0x00 0x63。

Answer 2

You can write most ASCII letters as text or binary and you will get the same outcome with most characters encodings. Two of the ASCII characters have a special meaning in text files, are newline \n and carriage return \r. This means that if you have text file and you want to write a String which contains these characters it can be hard or impossible for the reader to distinguish between end-of-line in the text file e.g. println() and end-of-line you put in a String e.g. print("1\n2\n3\n")

Answer 3

它将输出字符数据。但这可能超出了 ASCII 集，它只包含 128 个字符，其中前 32 个是特殊控制字符。