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 "";
        }
    }
}