utf8 unicode java_Java实现的utf8，gbk，unicode编码相互转换的代码

以下是 Java 实现的 utf8，gbk，unicode 编码相互转换的代码：

import java.io.UnsupportedEncodingException;

public class EncodingUtil {
  
  public static String utf8ToUnicode(String str) {
    try {
      byte[] bytes = str.getBytes("UTF-8");
      StringBuilder builder = new StringBuilder();
      for (int i = 0; i < bytes.length; i += 2) {
        builder.append("\\u");
        String hexStr = Integer.toHexString(bytes[i + 1] & 0xff | (bytes[i] & 0xff) << 8);
        if (hexStr.length() == 2) {
          builder.append("00");
        }
        builder.append(hexStr);
      }
      return builder.toString();
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
      return null;
    }
  }
  
  public static String unicodeToUtf8(String str) {
    StringBuilder builder = new StringBuilder();
    int i = 0;
    while (i < str.length()) {
      if (str.charAt(i) == '\\' && str.charAt(i + 1) == 'u') {
        String hexStr = str.substring(i + 2, i + 6);
        int codePoint = Integer.parseInt(hexStr, 16);
        builder.append((char) codePoint);
        i += 6;
      } else {
        builder.append(str.charAt(i));
        i++;
      }
    }
    try {
      return new String(builder.toString().getBytes("UTF-8"), "UTF-8");
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
      return null;
    }
  }
  
  public static String gbkToUtf8(String str) {
    try {
      return new String(str.getBytes("GBK"), "UTF-8");
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
      return null;
    }
  }
  
  public static String utf8ToGbk(String str) {
    try {
      return new String(str.getBytes("UTF-8"), "GBK");
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
      return null;
    }
  }
  
  public static String unicodeToGbk(String str) {
    return utf8ToGbk(unicodeToUtf8(str));
  }
  
  public static String gbkToUnicode(String str) {
    return utf8ToUnicode(gbkToUtf8(str));
  }

}

其中，`utf8ToUnicode` 方法将 utf8 编码的字符串转换为 unicode 编码的字符串，`unicodeToUtf8` 方法将 unicode 编码的字符串转换为 utf8 编码的字符串，`gbkToUtf8` 方法将 gbk 编码的字符串转换为 utf8 编码的字符串，`utf8ToGbk` 方法将 utf8 编码的字符串转换为 gbk 编码的字符串，`unicodeToGbk` 方法将 unicode 编码的字符串转换为 gbk 编码的字符串，`gbkToUnicode` 方法将 gbk 编码的字符串转换为 unicode 编码的字符串。