java 获取本地文件乱码问题

乱码原因一般是读取格式与文件的文本格式不一致

判断文件的格式工具类

public class CharsetUtil {

    /**
     * 如果文件是utf8编码返回true,反之false
     * @param file
     * @return
     */
    public static Boolean isUtf8(File file) {
        boolean isUtf8 = true;
        byte[] buffer = readByteArrayData(file);
        int end = buffer.length;
        for (int i = 0; i < end; i++) {
            byte temp = buffer[i];
            if ((temp & 0x80) == 0) {// 0xxxxxxx
                continue;
            } else if ((temp & 0xC0) == 0xC0 && (temp & 0x20) == 0) {// 110xxxxx 10xxxxxx
                if (i + 1 < end && (buffer[i + 1] & 0x80) == 0x80 && (buffer[i + 1] & 0x40) == 0) {
                    i = i + 1;
                    continue;
                }
            } else if ((temp & 0xE0) == 0xE0 && (temp & 0x10) == 0) {// 1110xxxx 10xxxxxx 10xxxxxx
                if (i + 2 < end && (buffer[i + 1] & 0x80) == 0x80 && (buffer[i + 1] & 0x40) == 0
                        && (buffer[i + 2] & 0x80) == 0x80 && (buffer[i + 2] & 0x40) == 0) {
                    i = i + 2;
                    continue;
                }
            } else if ((temp & 0xF0) == 0xF0 && (temp & 0x08) == 0) {// 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
                if (i + 3 < end && (buffer[i + 1] & 0x80) == 0x80 && (buffer[i + 1] & 0x40) == 0
                        && (buffer[i + 2] & 0x80) == 0x80 && (buffer[i + 2] & 0x40) == 0
                        && (buffer[i + 3] & 0x80) == 0x80 && (buffer[i + 3] & 0x40) == 0) {
                    i = i + 3;
                    continue;
                }
            }
            isUtf8 = false;
            break;
        }
        return isUtf8;
    }

    /**
     * 如果文件是gbk编码或者gb2312返回true,反之false
     * @param file
     * @return
     */
    public static Boolean isGbk(File file) {
        boolean isGbk = true;
        byte[] buffer = readByteArrayData(file);
        int end = buffer.length;
        for (int i = 0; i < end; i++) {
            byte temp = buffer[i];
            if ((temp & 0x80) == 0) {
                continue;// B0A1-F7FE//A1A1-A9FE
            } else if ((Byte.toUnsignedInt(temp) < 0xAA && Byte.toUnsignedInt(temp) > 0xA0)
                    || (Byte.toUnsignedInt(temp) < 0xF8 && Byte.toUnsignedInt(temp) > 0xAF)) {
                if (i + 1 < end) {
                    if (Byte.toUnsignedInt(buffer[i + 1]) < 0xFF && Byte.toUnsignedInt(buffer[i + 1]) > 0xA0
                            && Byte.toUnsignedInt(buffer[i + 1]) != 0x7F) {
                        i = i + 1;
                        continue;
                    }
                } // 8140-A0FE
            } else if (Byte.toUnsignedInt(temp) < 0xA1 && Byte.toUnsignedInt(temp) > 0x80) {
                if (i + 1 < end) {
                    if (Byte.toUnsignedInt(buffer[i + 1]) < 0xFF && Byte.toUnsignedInt(buffer[i + 1]) > 0x3F
                            && Byte.toUnsignedInt(buffer[i + 1]) != 0x7F) {
                        i = i + 1;
                        continue;
                    }
                } // AA40-FEA0//A840-A9A0
            } else if ((Byte.toUnsignedInt(temp) < 0xFF && Byte.toUnsignedInt(temp) > 0xA9)
                    || (Byte.toUnsignedInt(temp) < 0xAA && Byte.toUnsignedInt(temp) > 0xA7)) {
                if (i + 1 < end) {
                    if (Byte.toUnsignedInt(buffer[i + 1]) < 0xA1 && Byte.toUnsignedInt(buffer[i + 1]) > 0x3F
                            && Byte.toUnsignedInt(buffer[i + 1]) != 0x7F) {
                        i = i + 1;
                        continue;
                    }
                }
            }
            isGbk = false;
            break;
        }
        return isGbk;
    }

    /**
     * 从文件中直接读取字节
     * @param file
     * @return
     */
    public static byte[] readByteArrayData(File file) {
        byte[] rebyte = null;
        BufferedInputStream bis;
        ByteArrayOutputStream output;
        try {
            bis = new BufferedInputStream(new FileInputStream(file));
            output = new ByteArrayOutputStream();
            byte[] byt = new byte[1024 * 4];
            int len;
            try {
                while ((len = bis.read(byt)) != -1) {
                    if (len < 1024 * 4) {
                        output.write(byt, 0, len);
                    } else
                        output.write(byt);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            rebyte = output.toByteArray();
            if (bis != null) {
                bis.close();
            }
            if (output != null) {
                output.close();
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return rebyte;
    }

}

java读取文件

      File file = new File("D://1.txt");          
      String charsetName="GBK";
      if (CharsetUtil.isUtf8(file)){
          charsetName="UTF-8";
      }
      // 读取文件内容到Stream流中，按行读取
List list =Files.readAllLines(Paths.get("D://1.txt"),Charset.forName(charsetName));