将UTF-8文件转换为ISO-8859-1

Question

新问题：

资源：

C:\\temp\\test.csv
"Русслэнд";"Ελλάς";"Réunion"

预期结果：

C:\\temp\\test.properties
"\u0420\u0443\u0441\u0441\u043b\u044d\u043d\u0434";"\u0395\u03bb\u03bb\u03ac\u03c2";"R\u00e9unio"

当前结果：

C:\\temp\\test.properties
"????????", "?????","R궮ion"

码：

try {

            File file = new File("C:\\temp\\test.csv");

            FileInputStream is = new FileInputStream(file);

            InputStreamReader r = new InputStreamReader(is, Charset.forName("UTF-8"));

            FileOutputStream os = new FileOutputStream("C:\\temp\\test.properties");

            OutputStreamWriter ow = new OutputStreamWriter(os, "ISO-8859-1");

            char[] buffer = new char[1024];

            int x;
            while ((x = r.read(buffer)) == buffer.length) {
                ow.write(buffer);
            }

            ow.write(buffer, 0, x);
            ow.flush();

            ow.close();
            r.close();

        } catch (IOException e) {
            e.printStackTrace();
        }

**

旧问题：

**

如何在Java 1.6中将大UTF-8 .csv文件转换为ISO-8859-1？ 我想读取一个给定的文件，进行转换并保存。

private byte[] convertToISO(File file, Charset enc) {
    // enc = Charset.forName("UTF-8");
    try {

        FileInputStream is = new FileInputStream(file);
        InputStreamReader r = new InputStreamReader(is, enc);

        char[] buffer = new char[1024];
        StringWriter w = new StringWriter();

        int x = 0;
        while ((x = r.read(buffer)) == buffer.length) {
            w.write(buffer);
        }

        w.write(buffer, 0, x);
        w.flush();

        String res = w.toString();

        r.close();
        return res.getBytes("ISO-8859-1");

    } catch (IOException e) {
        System.err.println("Failed to read file: " + file.getPath());
        e.printStackTrace();

        return null;
    }
}

Answer 1

我假设您正在尝试将结果打印到控制台中。 默认情况下，任何jdk / JRE在控制台中打印任何内容时都将使用UTF-8。

要使用ISO-8859-1字符集，您可以在JVM参数中使用-Dfile.encoding=ISO-8859-1 。

或者，您可以如下所示配置IDE

Answer 2

您并不是要从UTF-8转换为ISO-8859-1，而是要将Unicode字符转义为ASCII流。 这不同于仅重新编码。

这是一个执行此功能的函数，它在写入输出流时会快速转义unicode字符：

public class OutputEscapingStreamWriter extends OutputStreamWriter {

    public OutputEscapingStreamWriter(OutputStream out, Charset cs) {
        super(out, cs);
    }

    public OutputEscapingStreamWriter(OutputStream out) {
        super(out);
    }

    public OutputEscapingStreamWriter(OutputStream out, String cs) throws UnsupportedEncodingException {
        super(out, cs);
    }

    public OutputEscapingStreamWriter(OutputStream out, CharsetEncoder cs) {
        super(out, cs);
    }

    private static String HEX_DIGITS = "0123456789abcdef";

    @Override
    public void write(int c) throws IOException {
        if (c < 128) {
            super.write(c);
        }
        else {
            super.write(toHexString(c));
        }
    }

    @Override
    public void write(String str, int off, int len) throws IOException {
        for (int i = off; i < (off + len); i++) {
            write(str.charAt(i));
        }
    }

    @Override
    public void write(char cbuf[], int off, int len) throws IOException {
        for (int i = off; i < (off + len); i++) {
            write(cbuf[i]);
        }
    }

    private String toHexString(int c) {
        StringBuilder sb = new StringBuilder("\\u");
        sb.append(HEX_DIGITS.charAt((c & 0xF000) >> 12));
        sb.append(HEX_DIGITS.charAt((c & 0x0F00) >> 8));
        sb.append(HEX_DIGITS.charAt((c & 0x00F0) >> 4));
        sb.append(HEX_DIGITS.charAt((c & 0x000F) ));
        return sb.toString();
    }
}

要在文件上使用它，只需打开FileOutputStream并用OutputEscapingStreamWriter包裹起来，如下所示：

OutputEscapingStreamWriter out = new OutputEscapingStreamWriter(new FileOutputStream("file.txt"));

一个快速而肮脏的单元测试，证明它产生了您期望的输出：

@Test
public void testConversion() throws Exception {
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    OutputEscapingStreamWriter wrapper = new OutputEscapingStreamWriter(output);
    wrapper.write("\"Русслэнд\";\"Ελλάς\";\"Réunion\"");
    wrapper.flush();
    wrapper.close();
    String result = output.toString();

    assertEquals("\"\\u0420\\u0443\\u0441\\u0441\\u043b\\u044d\\u043d\\u0434\";\"\\u0395\\u03bb\\u03bb\\u03ac\\u03c2\";\"R\\u00e9union\"", 
            result);
}