ByteBuffer和String的互相转换

import java.nio.ByteBuffer;  
import java.nio.CharBuffer;  
import java.nio.charset.Charset;  
import java.nio.charset.CharsetDecoder;  
  
public class TopNTool  
{  
    /** 
     * String 转换 ByteBuffer 
     * @param str 
     * @return 
     */  
    public static ByteBuffer getByteBuffer(String str)  
    {  
        return ByteBuffer.wrap(str.getBytes());  
    }  
  
    /** 
     * ByteBuffer 转换 String 
     * @param buffer 
     * @return 
     */  
    public static String getString(ByteBuffer buffer)  
    {  
        Charset charset = null;  
        CharsetDecoder decoder = null;  
        CharBuffer charBuffer = null;  
        try  
        {  
            charset = Charset.forName("UTF-8");  
            decoder = charset.newDecoder();  
            // charBuffer = decoder.decode(buffer);//用这个的话，只能输出来一次结果，第二次显示为空  
            charBuffer = decoder.decode(buffer.asReadOnlyBuffer());  
            return charBuffer.toString();  
        }  
        catch (Exception ex)  
        {  
            ex.printStackTrace();  
            return "";  
        }  
    }  
}