WxPayData.java

package me.ixfan.wechatkit.wxpay;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.TreeMap;
import java.util.stream.Collectors;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

/**
 * <p>微信支付参数</p>
 * @author	Fan Weijun
 */
public class WxPayData {
	
	private final TreeMap<String, Object> params = new TreeMap<>();
	
	public WxPayData() {}
	
	/**
	 * <p>从 XML 构建 WxPayData 对象实例。</p>
	 * @return
	 */
	public static WxPayData fromXml(String xml) {
		Document document = null;
		try {
			DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
			dbFactory.setIgnoringElementContentWhitespace(true);
			dbFactory.setIgnoringComments(true);
			DocumentBuilder docBuilder = dbFactory.newDocumentBuilder();
			document = docBuilder.parse(new ByteArrayInputStream(xml.getBytes()));
		} catch (ParserConfigurationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SAXException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		WxPayData wxpayData = new WxPayData();
		
		Node xmlNode = document.getFirstChild();
		NodeList paramNodes = xmlNode.getChildNodes();
		int paramsCount = paramNodes.getLength();
		for (int i = 0; i < paramsCount; ++i) {
			Node item = paramNodes.item(i);
			if (item.getNodeType() == Node.ELEMENT_NODE) {
				item.getFirstChild();
				wxpayData.setValue(item.getNodeName(), item.getFirstChild().getNodeValue());
			}
		}

		return wxpayData;
	}
	
	/**
	 * <p>设置某个参数的值。</p>
	 * @param key 参数名，需区分大小写。
	 * @param value 参数值，只接受 {@link Integer} 和 {@link String} 类型。
	 */
	public void setValue(String key, Object value) {
		params.put(key, value);
	}
	
	/**
	 * <p>获取某个参数的值。</p>
	 * @param key 参数名，需区分大小写。
	 * @return 若参数没设值则返回 null。
	 */
	public Object getValue(String key) {
		return params.get(key);
	}
	
	/**
	 * <p>将支付参数转换成 XML。</p>
	 * @return
	 */
	public String toXml() {
		final StringBuilder xml = new StringBuilder();
		xml.append("<xml>");
		
		this.params.forEach((key,value) -> {
			if (null == value || key.equals("sign")) {
				return;
			}
			if (value instanceof Integer) {
				xml.append(String.format("<%s>%d</%s>", key, value, key));
			} else if (value instanceof String) {
				xml.append(String.format("<%s><![CDATA[%s]]</%s>", key, value, key));
			}
		});
		xml.append(String.format("<sign>![CDATA[%s]]</sign>", sign("192006250b4c09247ec02edce69f6a2d")));
		
		xml.append("</xml>");
		return xml.toString();
	}
	
	public String toUrl() {
		return this.params.entrySet()
				.stream()
				.map((entry) -> {
					if (entry.getKey().equals("sign") || null == entry.getValue()) {
						return "";
					}
					return String.format("%s=%s", entry.getKey(),entry.getValue().toString());
				})
				.filter(s -> !s.equals(""))
				.collect(Collectors.joining("&"));
	}
	
	/**
	 * <p>生成签名。API密钥(key)不参与签名。</p>
	 * @return
	 */
	public String sign() {
		return StringUtil.encodeMD5(toUrl()).toUpperCase();
	}
	
	/**
	 * <p>生成签名。API密钥(key)参与签名。</p>
	 * @param key
	 * @return
	 */
	public String sign(String key) {
		String paramUrl = toUrl();
		paramUrl += String.format("&key=%s", key);
		return StringUtil.encodeMD5(paramUrl).toUpperCase();
	}
	
	/**
	 * <p>验证签名是否正确。</p>
	 * @return 
	 */
	public boolean checkSign() {
		if (null == this.params.get("sign")) { 
			return false;
		}
		String wxSign = (String) this.params.get("sign");
		String mySign = sign("192006250b4c09247ec02edce69f6a2d");
		
		return wxSign.equals(mySign);
	}

}