Java Nio 简明教程
Java NIO - CharSet
在 Java 中，每个字符都都有一个由 JVM 内部处理的明确定义的 unicode 代码单元。因此，Java NIO 包定义了一个名为 Charset 的抽象类，该类主要用于编码和解码字符集和 unicode。
In Java for every character there is a well defined unicode code units which is internally handled by JVM.So Java NIO package defines an abstract class named as Charset which is mainly used for encoding and decoding of charset and UNICODE.
Standard charsets
下面给出了 Java 中支持的 Charset。
The supported Charset in java are given below.
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US-ASCII − Seven bit ASCII characters.
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ISO-8859-1 − ISO Latin alphabet.
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UTF-8 − This is 8 bit UCS transformation format.
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UTF-16BE − This is 16 bit UCS transformation format with big endian byte order.
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UTF-16LE − This is 16 bit UCS transformation with little endian byte order.
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UTF-16 − 16 bit UCS transformation format.
Important methods of Charset class
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forName() − This method creates a charset object for the given charset name.The name can be canonical or an alias.
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displayName() − This method returns the canonical name of given charset.
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canEncode() − This method checks whether the given charset supports encoding or not.
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decode() − This method decodes the string of a given charset into charbuffer of Unicode charset.
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encode() − This method encodes charbuffer of unicode charset into the byte buffer of given charset.
Example
以下示例说明了 Charset 类的重要方法。
Following example illustrate important methods of Charset class.
package com.java.nio;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
public class CharsetExample {
public static void main(String[] args) {
Charset charset = Charset.forName("US-ASCII");
System.out.println(charset.displayName());
System.out.println(charset.canEncode());
String str= "Demo text for conversion.";
//convert byte buffer in given charset to char buffer in unicode
ByteBuffer byteBuffer = ByteBuffer.wrap(str.getBytes());
CharBuffer charBuffer = charset.decode(byteBuffer);
//convert char buffer in unicode to byte buffer in given charset
ByteBuffer newByteBuffer = charset.encode(charBuffer);
while(newbb.hasRemaining()){
char ch = (char) newByteBuffer.get();
System.out.print(ch);
}
newByteBuffer.clear();
}
}