看看String类的构造方法

String
public String(byte[] bytes,
              String enc)
       throws UnsupportedEncodingException
Construct a new String by converting the specified array of bytes using the specified character encoding. The length of the new String is a function of the encoding, and hence may not be equal to the length of the byte array.
Parameters:
bytes - The bytes to be converted into characters
enc - The name of a supported character encoding
Throws:
UnsupportedEncodingException - If the named encoding is not supported
Since:
JDK1.1