编码：字符串 -> 字节数组
解码：字节数组 -> 字符串

示例

查看Charset集合: 

Charset.availableCharsets().entrySet().forEach(entry -> {
    System.out.println(entry.getKey() + " = " + entry.getValue());
});
/*
    Big5 = Big5
    Big5-HKSCS = Big5-HKSCS
    CESU-8 = CESU-8
    EUC-JP = EUC-JP
    EUC-KR = EUC-KR
    ....
    x-windows-iso2022jp = x-windows-iso2022jp
 */

编码解码: 

Charset charset = Charset.forName("UTF-8");
CharBuffer source = CharBuffer.allocate(1024);
source.put("包子");

// 编码
source.flip();
ByteBuffer byteBuffer = charset.encode(source);

// 解码
byteBuffer.flip();
CharBuffer charBuffer = charset.decode(byteBuffer);