为验证偶数个字符在UTF8<->GBK互转时也会出现乱码 https://github.com/program-in-chinese/overview/issues/26#issuecomment-336012338

UTF8_GBK.java

import java.io.UnsupportedEncodingException;

public class UTF8_GBK {

  public static void main(String[] args) throws UnsupportedEncodingException {
    String 初始字符串 = "开始";

    byte[] 字节 = 初始字符串.getBytes("utf-8");
    System.out.println("转码前:" + encodeHex(字节));
    String 转编码后 = new String(字节, "GBK");
    byte[] 转码字节 = 转编码后.getBytes("GBK");
    System.out.println("转码后:" + encodeHex(转码字节));
    String 二转编码后 = new String(转码字节, "utf-8");
    System.out.println(二转编码后);
  }

  public static final String encodeHex(byte[] bytes) {
    StringBuffer buff = new StringBuffer(bytes.length * 2);
    String b;
    for (int i = 0; i < bytes.length; i++) {
      b = Integer.toHexString(bytes[i]);
      // byte是两个字节的,而上面的Integer.toHexString会把字节扩展为4个字节
      buff.append(b.length() > 2 ? b.substring(6, 8) : b);
      buff.append(" ");
    }
    return buff.toString();
  }
}