将一个文件由gbk 转成 utf-8

	public void transform(String fileName) {
		try {
			String line_separator = System.getProperty("line.separator");
			FileInputStream fis;
			fis = new FileInputStream(fileName);
			StringBuffer content = new StringBuffer();
			DataInputStream in = new DataInputStream(fis);
			BufferedReader d = new BufferedReader(new InputStreamReader(in,
					"GBK"));// , "UTF-8"
			String line = null;
			while ((line = d.readLine()) != null)
				content.append(line + line_separator);
			d.close();
			in.close();
			fis.close();

			Writer ow = new OutputStreamWriter(new FileOutputStream(fileName),
					"utf-8");
			ow.write(content.toString());
			ow.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

//或 
//IOUtils来自org.apache.commons.io.IOUtils

	public String handle(String gbkString) {
		try {
			return IOUtils.toString(IOUtils.toInputStream(gbkString, "UTF-8"));
		} catch (IOException e) {
			e.printStackTrace();
		}
		return null;
	}