我们的微信支付，使用的是第三方的支付，某银行的微信支持渠道。所有的接口请求、应答都是xml格式报文，这样就需要用到xml格式报文的拼装和解析，这儿简单讲一下。

拼接xml格式报文。

从页面表单提交和配置文件中读取出参数，或用实体类接收的页面传来的参数。建立map对象，用put()方法把参数添加进去。然后遍历map，将map转换成xml。

  StringBuffer soapResultData = new StringBuffer();





		//xml声明





		soapResultData.append("<?xml version=\"1.0\" encoding=\"GBK\"?><ROOT><MSG_HEAD>");





		//请求头





		soapResultData.append(requesttoxml(msgHead));





		soapResultData.append("</MSG_HEAD><MSG_BODY>");





		//请求体





		soapResultData.append(requesttoxml(resmap));





		soapResultData.append("</MSG_BODY></ROOT>");

  /**





	 * 将map转化为XML格式的字符串





	 * @param resmap





	 * @return





	 */





	public static String requesttoxml(Map<String, String> resmap){





		StringBuffer soapResultData = new StringBuffer();





		for(String key : resmap.keySet()){





			soapResultData.append("<");





			soapResultData.append(key);





			soapResultData.append(">");





			soapResultData.append(resmap.get(key));





			soapResultData.append("</");





			soapResultData.append(key);





			soapResultData.append(">");





		}





		return soapResultData.toString();





	}

将接收到的xml格式报文，转换成实体类。

package com.ustcsoft.business.model;





 





import java.io.Serializable;





 





import org.apache.commons.digester3.annotations.rules.BeanPropertySetter;





import org.apache.commons.digester3.annotations.rules.ObjectCreate;





 





@ObjectCreate(pattern = "ROOT/MSG_HEAD")





public class ResponseMsgHead implements Serializable {





	/**





	 * 





	 */





	private static final long serialVersionUID = -2793215313546940251L;





	@BeanPropertySetter(pattern = "ROOT/MSG_HEAD/TRAN_CODE")





	private String TRAN_CODE;





	@BeanPropertySetter(pattern = "ROOT/MSG_HEAD/PARTNER_CODE")





	private String PARTNER_CODE;





	@BeanPropertySetter(pattern = "ROOT/MSG_HEAD/REQUEST_SERIAL")





	private String REQUEST_SERIAL;





	@BeanPropertySetter(pattern = "ROOT/MSG_HEAD/RESPONSE_DATE")





	private String RESPONSE_DATE;





	@BeanPropertySetter(pattern = "ROOT/MSG_HEAD/RESPONSE_TIMESTAMP")





	private String RESPONSE_TIMESTAMP;





	@BeanPropertySetter(pattern = "ROOT/MSG_HEAD/RESULT_CODE")





	private String RESULT_CODE;





	@BeanPropertySetter(pattern = "ROOT/MSG_HEAD/RESULT_MESSAGE")





	private String RESULT_MESSAGE;





	//get set 省略，不贴在这儿，自己使用时别忘了生成个set和get方法





}

import static org.apache.commons.digester3.binder.DigesterLoader.newLoader;





 





import java.io.StringReader;





import java.text.SimpleDateFormat;





import java.util.HashMap;





import java.util.Map;





import java.util.TreeMap;





 





import org.apache.commons.digester3.Digester;





import org.apache.commons.digester3.annotations.FromAnnotationsRuleModule;





import org.apache.log4j.Logger;





 





import com.ustcsoft.business.model.CreditPayResponseBody;;





import com.ustcsoft.business.model.ResponseMsgHead;





import com.ustcsoft.framework.util.HTTPUtil;





import com.ustcsoft.framework.util.XMlUtil;





 





public class PayService {





	private final Map<Class<?>, FromAnnotationsRuleModule> xmlAnnotationModule = new HashMap<Class<?>, FromAnnotationsRuleModule>();





	private static final Logger logger=Logger.getLogger(PayService.class);





	





	public PayService() {





		xmlAnnotationModule.put(ResponseMsgHead.class,





				new FromAnnotationsRuleModule() {





					@Override





					protected void configureRules() {





						bindRulesFrom(ResponseMsgHead.class);





					}





				});





		xmlAnnotationModule.put(CreditPayResponseBody.class,





				new FromAnnotationsRuleModule() {





					@Override





					protected void configureRules() {





						bindRulesFrom(CreditPayResponseBody.class);





					}





				});





	}





	





	//中间业务代码省略……





			





	public <T> T parseXml(String xml, Class<T> clazz) throws Exception {





		StringReader sr = null;





		try {





			Digester digester = newLoader(xmlAnnotationModule.get(clazz)).newDigester();





			sr = new StringReader(xml);





			T pi = digester.parse(sr);





			digester.clear();





			return pi;





		} finally {





			if (sr != null) {





				sr.close();





			}





		}





	}





}

    logger.info("统一下单接口请求报文："+requestxml);





			String resultxml = HTTPUtil.postByHttps(url, requestxml,"GBK");





			logger.info("统一下单接口返回报文："+resultxml);





			if(resultxml != null){





				resultxml = XMlUtil.xmltoUpperCase(resultxml);//将XML报文中的标签，全部转化为大写





				ResponseMsgHead head = parseXml(resultxml, ResponseMsgHead.class);





				CreditPayResponseBody body = parseXml(resultxml, CreditPayResponseBody.class);





				if (null != head) {





					if(head.getRESULT_CODE().equals("000000")){





						logger.info("下单成功");





						logger.info("返回参数：sub_mch_id="+body.getSUB_MCH_ID()+"，total_fee="+body.getTOTAL_FEE()+"，out_trade_no="+body.getOUT_TRADE_NO());





						return body;





					}else{





						logger.info("下单失败，错误码："+head.getRESULT_CODE()+"，错误信息："+head.getRESULT_MESSAGE());





					}





				}





			}

  /**





	 * 将XML报文中的标签，全部转化为大写





	 * @param xmlMessage





	 * @return





	 */





	public static String xmltoUpperCase(String xmlMessage) {





        Pattern pattern = Pattern.compile("<.+?>");





        String xml = xmlMessage.split(">")[0];





        String xml0 = xmlMessage.substring(0, xml.length()+1);





        String xml1 = xmlMessage.substring(xml.length()+1);





        StringBuilder res = new StringBuilder();





        int lastIdx = 0;





        Matcher matchr = pattern.matcher(xml1);





        while (matchr.find()) {





            String str = matchr.group();





            res.append(xml1.substring(lastIdx, matchr.start()));





            res.append(str.toUpperCase());





            lastIdx = matchr.end();





        }





        res.append(xml1.substring(lastIdx));





        String result = xml0 + res.toString();





		return result;





    }

以上就是拼接xml格式报文和解析xml格式报文。需要注意的是，在解析xml格式报文时，由于对方返回的报文的标签有小写的，结果解析出错，所以在里面做了个处理，将标签全部转化为大写。