java char and UTF
java中的char 占两个字节，默认使用UNICODE？转换成文件保存时，根据字符范围写入到文件中。0开使的字符为asc码的128个字符，用1byte保存；x<=0X7F
110开始的字符用2byte保存；0X7F<x<0X8F
111开始的字符用3byte保存。x>0X8F
不多说，上一段hsqldb里的代码。
public static int stringToUTFBytes(String str, HsqlByteArrayOutputStream out) { int strlen = str.length(); int c, count= 0; if (out.count + strlen + 8 > out.buffer.length) { out.ensureRoom(strlen + 8); } char[] arr = str.toCharArray(); for (int i = 0; i < strlen; i++) { c = arr; if (c >= 0x0001 && c <= 0x007F) { out.buffer = (byte) c; count++; } else if (c > 0x07FF) { out.buffer = (byte) (0xE0 | ((c >> 12) & 0x0F)); out.buffer = (byte) (0x80 | ((c >> 6) & 0x3F)); out.buffer = (byte) (0x80 | ((c >> 0) & 0x3F)); count += 3; } else { out.buffer = (byte) (0xC0 | ((c >> 6) & 0x1F)); out.buffer = (byte) (0x80 | ((c >> 0) & 0x3F)); count += 2; } if (out.count + 8 > out.buffer.length) { out.ensureRoom(strlen - i + 8); } } return count; }
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