1. Unicode编码
Unicode编码是一种涵盖了世界上所有语言、标点等字符的编码方式，简单一点说，就是一种通用的世界码；其编码范围：U 0000 .. U 10FFFF。按Unicode硬编码的区间进行划分，Unicode编码被分成若干个block ( Unicode block)；每一个Unicode编码专属于唯一的Unicode block，Unicode block之间互不重叠。从码字的本身的属性出发，Unicode编码被分成了若干script ( Unicode script)；比如，与中文相关的字符、标点的scriptHan包括block如下：
- CJK Radicals Supplement
- Kangxi Radicals
- CJK Symbols and Punctuation中的15个字符
- CJK Unified Ideographs Extension A
- CJK Unified Ideographs
- CJK Compatibility Ideographs
- CJK Unified Ideographs Extension B
- CJK Unified Ideographs Extension C
- CJK Unified Ideographs Extension D
- CJK Unified Ideographs Extension E
- CJK Compatibility Ideographs Supplement
其中，常见的中文字符在CJK Unified Ideographs block；此外，考虑繁体字及不常见字等，CJK还有A、B、C、D、E五个extension。Basic Latin block完整地包含了ASCII码的控制字符、标点字符与英文字母字符。
2. Java的字符编码
JDK完整实现Unicode的block与script：
代码语言：javascript复制Char c = '☎'
Character.UnicodeBlock ub = Character.UnicodeBlock.of(c)
Character.UnicodeScript uc = Character.UnicodeScript.of(c);</pre>
Java中的字符char内置的编码方式是UTF-16，当char强转成int类型时，其返回值是unicode编码值，只有当getbyte时才返回的是utf-8编码的byte：
<pre>String s = "u00a0";
String.format("\ux", (int) s.charAt(0)) // --> u00a0
import org.apache.commons.codec.binary.Hex;
Hex.encodeHex(s.getBytes()) // --> c2a0
UTF-8是Unicode字符的变长前缀编码的一种实现，二者之间的对应关系在这里.现在我们回到开篇过滤中文乱码的问题，有一个基本解决思路：
UTF-8是Unicode字符的变长前缀编码的一种实现，二者之间的对应关系在这里.现在我们回到开篇过滤中文乱码的问题，有一个基本解决思路：
去掉各种标点字符、控制字符，
计算剩下字符中非中文字符所占的比例，如果超过阈值，则认为该字符串为乱码串
完整代码如下：
代码语言：javascript复制public class ChineseUtill {
private static boolean isChinese(char c) {
Character.UnicodeScript sc = Character.UnicodeScript.of(c);
if (sc == Character.UnicodeScript.HAN) {
return true;
}
return false;
}
public static boolean isPunctuation(char c) {
Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);
if ( // punctuation, spacing, and formatting characters
ub == Character.UnicodeBlock.GENERAL_PUNCTUATION
// symbols and punctuation in the unified Chinese, Japanese and Korean script
|| ub == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION
// fullwidth character or a halfwidth character
|| ub == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS
// vertical glyph variants for east Asian compatibility
|| ub == Character.UnicodeBlock.CJK_COMPATIBILITY_FORMS
// vertical punctuation for compatibility characters with the Chinese Standard GB 18030
|| ub == Character.UnicodeBlock.VERTICAL_FORMS
// ascii
|| ub == Character.UnicodeBlock.BASIC_LATIN
) {
return true;
} else {
return false;
}
}
private static Boolean isUserDefined(char c) {
Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);
if (ub == Character.UnicodeBlock.NUMBER_FORMS
|| ub == Character.UnicodeBlock.ENCLOSED_ALPHANUMERICS
|| ub == Character.UnicodeBlock.LETTERLIKE_SYMBOLS
|| c == 'ufeff'
|| c == 'u00a0'
)
return true;
return false;
}
public static Boolean isMessy(String str) {
float chlength = 0;
float count = 0;
for(int i = 0; i < str.length(); i ) {
char c = str.charAt(i);
if(isPunctuation(c) || isUserDefined(c))
continue;
else {
if(!isChinese(c)) {
count = count 1;
}
chlength ;
}
}
float result = count / chlength;
if(result > 0.3)
return true;
return false;
}
}
为了得到更为完整的可接受的字符表，定义isUserDefined方法（具体字符表与日志中的字符有关系）；加上了Number Forms、Enclosed Alphanumerics、Letterlike Symbols这三个block，以及u00a0（Non-breaking space）字符与ufeff（ZERO WIDTH NO-BREAK SPACE）字符。
