字符串的截取处理

有时候需要处理xml格式的报文，修改其中的数据，可以用到以下 的方法：

/**
     * 生成head报文
     * 
     * @param headParams
     * @return String
     */
    protected String getGWHead(Context context, List<String> headParams)
            throws EMPException {
        StringBuffer result = new StringBuffer();
        result.append("<"+SEND_HEAD_ROOT_TAG_NAME+">");
        if (headParams != null) {
            for (int i = 0; i < headParams.size(); i++) {
                String param = (String) headParams.get(i);
                String[] paramArray = param.split(",");
                String field = paramArray[0];
                String value = paramArray[1];
                result.append("<").append(field).append(">").append(value).append("</").append(field).append(">");
            }
        }
        result.append("</"+SEND_HEAD_ROOT_TAG_NAME+">");
        return result.toString();
    }

/**
     * 添加标签List下内容
     * @param message 报文内容
     * @param tagName 标签名
     * @return
     */
    private String setTextListContent(String message, String tagName )
    {
        String tagBegin="<"+tagName+">";
         String tagEnd="</"+tagName+">";
         int tagBeginPos = message.indexOf( tagBegin );
         int tagEndPos = message.lastIndexOf(tagEnd) + tagEnd.length();
         if ( tagBeginPos >= 0 )
        {
            String text=message.substring(0, message.indexOf("<"+tagName+">"));//+("</"+tagName+">").length() 获取字符串前边内容 message.indexOf("<"+SEND_BODY_ROOT_TAG_NAME+">")
            StringBuffer pub=new StringBuffer();
            pub.append(text);
            //替换List的内容
            pub.append("<m>");
            String mid = message.substring(tagBeginPos, tagEndPos);
            pub.append(mid);
            pub.append("</m></response></"+SEND_BODY_ROOT_TAG_NAME+">");
            return pub.toString();
        }
        
         
//        int tagBeginPos = message.indexOf( tagBegin );
//        if ( tagBeginPos >= 0 )
//        {        
//                tagBeginPos=tagBeginPos+tagBegin.length();
//                int tagEndPos = message.lastIndexOf(tagEnd);
//                return message.substring(tagBeginPos, tagEndPos);
//        }
        return "";
    }