XPath获取XML指定节点属性值的两种方法
前面有文章介绍了通过XPath解析xml报文的方法，今天工作中遇到了需要解析指定节点属性值的问题，现在总结一下，下面提供两种方法去获取属性值。
首先是xml结构：
1.
2.
3.
4.
Everyday Italian 5.
Giada De Laurentiis 6.
2005 7.
30.00 8.
9.
10.
Harry Potter 11.
J K. Rowling 12.
2005 13.
29.99 14.
15.
16.
Learning XML 17.
Erik T. Ray 18.
2003 19.
39.95 20.
21.
解析代码：
1.import org.w3c.dom.Document;
2.import org.w3c.dom.Node;
3.import org.w3c.dom.NodeList;
4.import org.xml.sax.SAXException;
5.
6.import javax.xml.parsers.DocumentBuilderFactory;
7.import javax.xml.parsers.ParserConfigurationException;
8.import javax.xml.transform.Transformer;
9.import javax.xml.transform.TransformerException;
10.import javax.xml.transform.TransformerFactory;
11.import javax.xml.transform.dom.DOMSource;
12.import javax.xml.transform.stream.StreamResult;
13.import javax.xml.xpath.XPath;
14import javax.xml.xpath.XPathConstants;
15.import javax.xml.xpath.XPathFactory;
16.import java.io.*;
17.
18./**
19.* Created by hasee on 2017/2/14.
20. * liqinghe
21. * 获取xml指定节点属性值
22. */
23.public class PropertyValueTest {
24.
25. public static void main(String[] args) throws Exception {
26. //XML文档路径
27. String xmlUrl = "D:\\FTP\\测试XML\\book.xml";
28. //需要获取的节点属性值位置
29. String propertyUrl = "bookstore/book/title";
30. String propertyName = "lang";
31. Document document = getXmlDocument(xmlUrl);
32. //获取该位置的节点集合
33. NodeList nodeList = nodeList(propertyUrl, document);
34.
35. //第一种方法 node直接获取
36. for (int i = 0; i < nodeList.getLength(); i++) {
37. Node node = nodeList.item(i);
38. Node attr = node.getAttributes().getNamedItem(propertyName);
39. String propertyValue = attr.getNodeValue(); //属性值
40. System.out.println(propertyValue);
41. }
42.
43. //第二种方法 用xpath获取
44. for (int i = 0; i < nodeList.getLength(); i++) {
45. Node node = nodeList.item(i);
46. //将node对象转成string字符串
47. String nodeString = NodetoString(node);
48. Document document1 =stringDoc(nodeString);
49. //注意需要用到@符号
50. String path = "title"+"/@"+propertyName;
51. String propertyValue = propertyValue(path,document1); //属性值
52. System.out.println(propertyValue);
53. }
54. }
55.
56. /**
57. * 根据xml文档路径生成Document对象
58. *
59. * @param xmlFilePath XML文档路径
60. * @return Document
61. */
62. public static Document getXmlDocument(String xmlFilePath) {
63. Document doc = null;
64. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
65. dbf.setNamespaceAware(true);
66. try {
67. doc = dbf.newDocumentBuilder().parse(new FileInputStream(xmlFilePath));
68. } catch (ParserConfigurationException ex) {
69. ex.printStackTrace();
70. } catch (FileNotFoundException ex) {
71. ex.printStackTrace();
72. } catch (SAXException ex) {
73. ex.printStackTrace();
74. } catch (IOException ex) {
75. ex.printStackTrace();
76. }
77. return doc;
78. }
79.
80. /**
81. * 获取节点集合
82. *
83. * @param path 节点位置 head/MessageID
84. * @param document
85. * @return
86. */
87. public static NodeList nodeList(String path, Node document) {
88. NodeList nodeList = null;
89. try {
90. // 生成XPath对象
91. XPath xpath = XPathFactory.newInstance().newXPath();
92. // 获取节点值
93. nodeList = (NodeList) xpath.evaluate(
94. path, document,
95. XPathConstants.NODESET);
96. } catch (Exception e) {
97. }
98. return nodeList;
99. }
100.
101.
102. /**
103. * string 转换成 doc
104. * @param docStr
105 * @return
106. * @throws Exception
107. */
108. public static Document stringDoc(String docStr) throws Exception {
109. InputStream is = new ByteArrayInputStream(docStr.getBytes());
110. Document doc = null;
111. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
112. dbf.setNamespaceAware(true);
113. try {
114. doc = dbf.newDocumentBuilder().parse(is);
115. } catch (ParserConfigurationException ex) {
116. ex.printStackTrace();
117. } catch (FileNotFoundException ex) {
118. ex.printStackTrace();
119. } catch (SAXException ex) {
120. ex.printStackTrace();
121. } catch (IOException ex) {
122. ex.printStackTrace();
123. }
124. return doc;
125. }
126.
127. /**
128. * 获取节点属性值
129. * @param path 节点属性值位置 head/@propertyName
130. * @param node xml对象
131. * @return
132. */
133. public static String propertyValue(String path, Node node) {
134. String nodeValue = "";
135. try {
136. // 生成XPath对象
137. XPath xpath = XPathFactory.newInstance().newXPath();
138. // 获取节点值
139. nodeValue = (String) xpath.evaluate(
140. path, node,
141. XPathConstants.STRING);
142. } catch (Exception e) {
143. }
145. return nodeValue;
146. }
147.
148. /**
149. * 将传入的一个DOM Node对象输出成字符串。如果失败则返回一个空字符串""。
150. *
151. * @param node DOM Node 对象。
152. * @return a XML String from node
153. */
154. public static String NodetoString(Node node) {
155. Transformer transformer = null;
156. String result = null;
157. if (node == null) {
158. throw new IllegalArgumentException();
159. }
160. try {
161. transformer = TransformerFactory.newInstance().newTransformer();
162. } catch (Exception e) {
163. throw new RuntimeException(e.getMessage());
164. }
165. if (transformer != null) {
166. try {
167. StringWriter sw = new StringWriter();
168. transformer.transform(new DOMSource(node), new StreamResult(sw));
169. return sw.toString();
170. } catch (TransformerException te) {
171. throw new RuntimeException(te.getMessage());
172. }
173. }
174. return result;
175. }
176.}
代码注释写得很清楚了，注意所用的Document是 w3c下面的。
运行结果：
1.en1
2.en2
3.en3
4.en1
5.0en2
6.en3