/** * MD5编码 * @param origin 原始字符串 * @return 经过MD5加密之后的结果 */ public static String MD5Encode(String origin) { String resultString = null; try { resultString = origin; MessageDigest md = MessageDigest.getInstance("MD5"); // resultString = byteArrayToHexString(md.digest(resultString.getBytes()));//原文件内容，可能原因是：win2003时系统缺省编码为GBK，win7为utf-8 resultString = byteArrayToHexString(md.digest(resultString.getBytes("utf-8")));//正确的写法 } catch (Exception e) { e.printStackTrace(); } return resultString; } private static String byteArrayToHexString(byte[] digest) {

StringBuffer hexValue = new StringBuffer();	for (int i = 0; i < digest.length; i++) {		int val = ((int) digest[i]) & 0xff;		if (val < 16)			hexValue.append("0");		hexValue.append(Integer.toHexString(val));	}	return hexValue.toString();}	String sign = MD5Encode(parbuffer.toString());	data.setSign(sign);	HttpRequest httpRequest = HttpRequest.post("https://api.mch.weixin.qq.com/pay/unifiedorder");	String x = xstream.toXML(data);	httpRequest.body( StringUtil.convertCharset(x, "UTF-8", "ISO-8859-1"));	HttpResponse response = httpRequest.send();	String body = response.body();	body = StringUtil.convertCharset(body, "ISO-8859-1", "UTF-8");

这样就把问题解决了 注意一下：给微信提交数据的时候需要是ISO-8859-1编码

httpRequest.body( StringUtil.convertCharset(x, "UTF-8", "ISO-8859-1"));