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  1. import java.io.ByteArrayOutputStream;
  2. import java.nio.ByteBuffer;
  3. import java.nio.charset.Charset;
  4. import java.util.Scanner;
  5.  
  6. /*
  7. プログラミングのお題スレ Part12 
  8. ttps://mevius.5ch.net/test/read.cgi/tech/1538096947/576
  9.  
  10. 576 名前：デフォルトの名無しさん[sage] 投稿日：2018/11/18(日) 22:42:22.16 ID:qz83zcM7
  11. お題
  12. UTF-8のバイト列が与えられるので、Unicodeのコードポイントを求めよ
  13.  
  14. 6F 64 61 69
  15. => U+006F U+0064 U+0061 U+0069
  16.  
  17. E3 81 8A E9 A1 8C
  18. => U+304A U+984C
  19.  
  20. C2 A9 F0 9F 8D 94 E9 A6 99 41
  21. => U+00A9 U+1F354 U+9999 U+0041
  22. */
  23. class Ideone
  24. {
  25.     static final int REPLACEMENT_CHARACTER = 0xFFFD;
  26.     public static void main(String[] args)
  27.     {
  28.         System.out.println("言語任せ");
  29.         printUnicodeCodePoint(toByteArray("6F 64 61 69"));
  30.         printUnicodeCodePoint(toByteArray("E3 81 8A E9 A1 8C"));
  31.         printUnicodeCodePoint(toByteArray("C2 A9 F0 9F 8D 94 E9 A6 99 41"));
  32.  
  33.         System.out.println("自力デコード");
  34.         printUnicodeCodePoint2(toByteArray("6F 64 61 69"));
  35.         printUnicodeCodePoint2(toByteArray("E3 81 8A E9 A1 8C"));
  36.         printUnicodeCodePoint2(toByteArray("C2 A9 F0 9F 8D 94 E9 A6 99 41"));
  37.     }
  38.  
  39.     static byte[] toByteArray(String s)
  40.     {
  41.         Scanner in = new Scanner(s);
  42.         ByteArrayOutputStream baos = new ByteArrayOutputStream();
  43.         while (in.hasNextInt(16))
  44.         {
  45.             baos.write(in.nextInt(16));
  46.         }
  47.         in.close();
  48.         return baos.toByteArray();
  49.     }
  50.  
  51.     // 言語任せ
  52.     static void printUnicodeCodePoint(byte[] bs)
  53.     {
  54.         for (byte b : bs)
  55.         {
  56.             System.out.printf("%02X ", b & 0xFF);
  57.         }
  58.         System.out.println();
  59.  
  60.         System.out.print("=> ");
  61.         String str = new String(bs, Charset.forName("UTF-8"));
  62.         str.codePoints().forEach(i -> System.out.printf("U+%04X ", i));
  63.  
  64.         System.out.println();
  65.         System.out.println();
  66.     }
  67.  
  68.     // 自力
  69.     static void printUnicodeCodePoint2(byte[] bs)
  70.     {
  71.         for (byte b : bs)
  72.         {
  73.             System.out.printf("%02X ", b & 0xFF);
  74.         }
  75.         System.out.println();
  76.  
  77.         System.out.print("=> ");
  78.  
  79.         ByteBuffer buf = ByteBuffer.wrap(bs);
  80.         while (buf.hasRemaining())
  81.         {
  82.             System.out.printf("U+%04X ", utf8decode(buf));
  83.         }
  84.  
  85.         System.out.println();
  86.         System.out.println();
  87.     }
  88.  
  89.     // ByteBufferから1文字デコードする
  90.     static int utf8decode(ByteBuffer buf)
  91.     {
  92.         byte b1 = buf.get();
  93.         if (b1 >= 0) return b1 & 0b01111111;
  94.         if (b1 <= -65) return REPLACEMENT_CHARACTER;
  95.  
  96.         byte b2 = buf.get();
  97.         if (!test(b2))
  98.         {
  99.             buf.position(buf.position() - 1);
  100.             return REPLACEMENT_CHARACTER;
  101.         }
  102.  
  103.         if (b1 <= -33) return (b1 & 0b00011111) << 6 | (b2 & 0b00111111);
  104.  
  105.         byte b3 = buf.get();
  106.         if (!test(b3))
  107.         {
  108.             buf.position(buf.position() - 1);
  109.             return REPLACEMENT_CHARACTER;
  110.         }
  111.  
  112.         if (b1 <= -17) return (b1 & 0b00001111) << 12 | (b2 & 0b00111111) << 6 | (b3 & 0b00111111);
  113.  
  114.         byte b4 = buf.get();
  115.         if (!test(b4))
  116.         {
  117.             buf.position(buf.position() - 1);
  118.             return REPLACEMENT_CHARACTER;
  119.         }
  120.  
  121.         if (b1 <= -9) return (b1 & 0b00000111) << 18 | (b2 & 0b00111111) << 12 | (b3 & 0b00111111) << 6 | (b4 & 0b00111111);
  122.  
  123.         byte b5 = buf.get();
  124.         if (!test(b5))
  125.         {
  126.             buf.position(buf.position() - 1);
  127.             return REPLACEMENT_CHARACTER;
  128.         }
  129.         if (b1 <= -5) return REPLACEMENT_CHARACTER;
  130.  
  131.         byte b6 = buf.get();
  132.         if (!test(b6))
  133.         {
  134.             buf.position(buf.position() - 1);
  135.             return REPLACEMENT_CHARACTER;
  136.         }
  137.  
  138.         return REPLACEMENT_CHARACTER;
  139.     }
  140.  
  141.     static boolean test(byte b)
  142.     {
  143.         return (b & 0b11000000) == 0b10000000;
  144.     }
  145. }
  146.  
Success #stdin #stdout 0.18s 2184192KB
comments (?)
stdin 
Standard input is empty
stdout 
言語任せ
6F 64 61 69 
=> U+006F U+0064 U+0061 U+0069 

E3 81 8A E9 A1 8C 
=> U+304A U+984C 

C2 A9 F0 9F 8D 94 E9 A6 99 41 
=> U+00A9 U+1F354 U+9999 U+0041 

自力デコード
6F 64 61 69 
=> U+006F U+0064 U+0061 U+0069 

E3 81 8A E9 A1 8C 
=> U+304A U+984C 

C2 A9 F0 9F 8D 94 E9 A6 99 41 
=> U+00A9 U+1F354 U+9999 U+0041
https://ideone.com/uuHw3q
お題12の576
language:
Java (HotSpot 12)
created:
5 years ago
visibility:
secret

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