Java字符集

通常而言,把明文的字符序列转换成计算机能理解的二进制序列称为编码,把二进制序列转换成普通人能看懂的明文字符串称为解码。

JDK1.4提供了Charset来处理字节序列和字符序列之间的转换关系,该类包含了用于创建解码器和编码器的方法,还提供了Charset所支持的字符集的方法,Charset类是不可变的。

Charset类提供了一个availableCharset()的静态方法来获取当前JDK所支持的所有字符集,下面小试牛刀

import java.nio.charset.Charset;
import java.util.SortedMap;
public class Test {
	public static void main(String[] args) throws Exception
	{
		SortedMap<String,Charset> sm= Charset.availableCharsets();
		for(String str:sm.keySet())
		{
			System.out.println(sm.get(str));
		}
	}
}
结果如下

Big5
Big5-HKSCS
EUC-JP
EUC-KR
GB18030
GB2312
GBK
IBM-Thai
IBM00858
IBM01140
IBM01141
IBM01142
IBM01143
IBM01144
IBM01145
IBM01146
IBM01147
IBM01148
IBM01149
IBM037
IBM1026
IBM1047
IBM273
IBM277
IBM278
IBM280
IBM284
IBM285
IBM297
IBM420
IBM424
IBM437
IBM500
IBM775
IBM850
IBM852
IBM855
IBM857
IBM860
IBM861
IBM862
IBM863
IBM864
IBM865
IBM866
IBM868
IBM869
IBM870
IBM871
IBM918
ISO-2022-CN
ISO-2022-JP
ISO-2022-JP-2
ISO-2022-KR
ISO-8859-1
ISO-8859-13
ISO-8859-15
ISO-8859-2
ISO-8859-3
ISO-8859-4
ISO-8859-5
ISO-8859-6
ISO-8859-7
ISO-8859-8
ISO-8859-9
JIS_X0201
JIS_X0212-1990
KOI8-R
KOI8-U
Shift_JIS
TIS-620
US-ASCII
UTF-16
UTF-16BE
UTF-16LE
UTF-32
UTF-32BE
UTF-32LE
UTF-8
windows-1250
windows-1251
windows-1252
windows-1253
windows-1254
windows-1255
windows-1256
windows-1257
windows-1258
windows-31j
x-Big5-HKSCS-2001
x-Big5-Solaris
x-euc-jp-linux
x-EUC-TW
x-eucJP-Open
x-IBM1006
x-IBM1025
x-IBM1046
x-IBM1097
x-IBM1098
x-IBM1112
x-IBM1122
x-IBM1123
x-IBM1124
x-IBM1364
x-IBM1381
x-IBM1383
x-IBM33722
x-IBM737
x-IBM833
x-IBM834
x-IBM856
x-IBM874
x-IBM875
x-IBM921
x-IBM922
x-IBM930
x-IBM933
x-IBM935
x-IBM937
x-IBM939
x-IBM942
x-IBM942C
x-IBM943
x-IBM943C
x-IBM948
x-IBM949
x-IBM949C
x-IBM950
x-IBM964
x-IBM970
x-ISCII91
x-ISO-2022-CN-CNS
x-ISO-2022-CN-GB
x-iso-8859-11
x-JIS0208
x-JISAutoDetect
x-Johab
x-MacArabic
x-MacCentralEurope
x-MacCroatian
x-MacCyrillic
x-MacDingbat
x-MacGreek
x-MacHebrew
x-MacIceland
x-MacRoman
x-MacRomania
x-MacSymbol
x-MacThai
x-MacTurkish
x-MacUkraine
x-MS932_0213
x-MS950-HKSCS
x-MS950-HKSCS-XP
x-mswin-936
x-PCK
x-SJIS_0213
x-UTF-16LE-BOM
X-UTF-32BE-BOM
X-UTF-32LE-BOM
x-windows-50220
x-windows-50221
x-windows-874
x-windows-949
x-windows-950
x-windows-iso2022jp
一旦知道了字符集的别名之后,程序就可以调用Charset的forName()来创建对应的Charset对象,forName()方法的参数就是相应字符集的别名

Charset cs=Charset.forName("ISO-8859-1");

Charset cs=Charset.forName("GBK");

获得了Charset对象的之后,就可已通过该对象的newDecode()和newEncode()这两个方法分别返回CharsetDecode和CharsetEncode对象,代表该Charset的解码器和编码器,调用CharsetDecode的decode()方法就可以将ByteBuffer转换成CharBuffer,调用CharsetEncode就可以将CharBuffer或String转换成ByteBuffer。

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
public class Test {
	public static void main(String[] args) throws Exception
	{
		Charset cs=Charset.forName("GBK");
		CharsetDecoder cd=cs.newDecoder();
		CharsetEncoder ce=cs.newEncoder();
		CharBuffer cb=CharBuffer.allocate(6);
		cb.put("张");
		cb.put("译");
		cb.put("成");
		cb.flip();
		ByteBuffer bb=ce.encode(cb);
		for(int i=0;i<bb.capacity();i++)
		{
			System.out.println(bb.get(i));
		}
		System.out.println(cd.decode(bb));
	}
}

Charset还提供了一下方法处理编码问题

CharBuffer decode(ByteBuffer bb)

ByteBuffer encode(CharBuffer cb)

ByteBuffer encode(String str)

我就不解释这三个方法了,估计都能估计出来

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