Parsing XML using Dom4j

dom4j It's a Java Of XML API, Be similar to jdom, For reading and writing XML Of documents .dom4j It's a very, very good Java XML API, Excellent performance 、 Powerful and extremely easy to use features , It is also an open source Software , Can be in SourceForge Find it on the .

To the mainstream Java XML API Performance in progress 、 Function and usability evaluation ,dom4j It's excellent in that respect . Now you can see more and more Java Software All in use dom4j Read and write XML, for example Hibernate, Include sun The company's own JAXM Also used. Dom4j.

Use Dom4j Development , Need to download dom4j Corresponding jar file

1. Download from the official website : http://www.dom4j.org/dom4j-1.6.1/

2.dom4j yes sourceforge.net An open source project on , So you can http://sourceforge.net/projects/dom4j Download its latest version .

For downloaded zip The effect of decompressing the file is as follows :

open dom4j-1.6.1 The unzip file of

You can see here that there are docs Folder for help , There is also a need to use dom4j analysis xml Of documents dom4j-1.6.1.jar file . We just have to take dom4j-1.6.1.jar The file can be used when it is built into the project we develop dom4j Developed .

Now I will Myeclipse establish Java Take the construction method of the project as an example .

First create a demo project , stay demo Create a lib file , hold dom4j-1.6.1.jar File copy to lib in , And then right-click dom4j-1.6.1jar file

Click on Add to Build Path It can be built into the project .

remarks ： If we're going to web Project development , We just need to copy it to web-inf/lib Just go to the middle , Will be automatically built to web In the project .

In the process of project development, you can refer to docs The folder （ Help document ）, find index.html open , Click on Quick start You can learn through help documents dom4j Conduct xml Parsing .

Now I think api The important methods of translation are described as follows ：

One 、DOM4j in , get Document There are three ways to object ：

1. 1. Read XML file , get document object
2. SAXReader reader = new SAXReader();
3. Document document = reader.read(new File(“csdn.xml”));
4. 2. analysis XML Formal text , obtain document object .
5. String text = “<csdn></csdn>”;
6. Document document = DocumentHelper.parseText(text);
7. 3. Active creation document object .
8. Document document = DocumentHelper.createDocument(); // Create a root node
9. Element root = document.addElement(“csdn”);

Two 、 How to operate node objects

1. 1. Get the root node of the document .
2. Element root = document.getRootElement();
3. 2. Get the children of a node .
4. Element element=node.element(“ Four masterpieces ”);
5. 3. Get the text of the node
6. String text=node.getText();
7. 4. Get all the names under a node “csdn” Child nodes of , And traverse .
8. List nodes = rootElm.elements(“csdn”);
9. for (Iterator it = nodes.iterator(); it.hasNext();) {
10. Element elm = (Element) it.next();
11. // do something
12. }
13. 5. Traverse all the child nodes under a certain node .
14. for(Iterator it=root.elementIterator();it.hasNext();){
15. Element element = (Element) it.next();
16. // do something
17. }
18. 6. Add children under a node
19. Element elm = newElm.addElement(“ Dynasty ”);
20. 7. Set node text . elm.setText(“ The Ming dynasty ”);
21. 8. Delete a node .//childElement Is the node to be deleted ,parentElement It's the parent node parentElement.remove(childElment);
22. 9. Add one CDATA node .Element contentElm = infoElm.addElement(“content”);contentElm.addCDATA(“cdata Area ”);

3、 ... and 、 Operation of attribute method of node object

1. 1. Get an attribute under a node Element root=document.getRootElement(); // Property name name
2. Attribute attribute=root.attribute(“id”);
3. 2. Get attribute text
4. String text=attribute.getText();
5. 3. Delete a property Attribute attribute=root.attribute(“size”); root.remove(attribute);
6. 4. Traverse all properties of a node
7. Element root=document.getRootElement();
8. for(Iterator it=root.attributeIterator();it.hasNext();){
9. Attribute attribute = (Attribute) it.next();
10. String text=attribute.getText();
11. System.out.println(text);
12. }
13. 5. Set the attributes and text of a node . newMemberElm.addAttribute(“name”, “sitinspring”);
14. 6. Set attribute text Attribute attribute=root.attribute(“name”); attribute.setText(“csdn”);

Four 、 Write the document to XML file

1. 1. All the documents are in English , No coding , The form of direct writing .
2. XMLWriter writer = new XMLWriter(new FileWriter(“ot.xml”));
3. writer.write(document);
4. writer.close();
5. 2. The document contains Chinese , Set the encoding format to write to .
6. OutputFormat format = OutputFormat.createPrettyPrint();// When creating a file output , Auto indent format
7. format.setEncoding(“UTF-8”);// Set encoding
8. XMLWriter writer = new XMLWriter(newFileWriter(“output.xml”),format);
9. writer.write(document);
10. writer.close();

5、 ... and 、 String and XML Transformation

1. 1. Converts a string to XML
2. String text = “<csdn> <java>Java class </java></csdn>”;
3. Document document = DocumentHelper.parseText(text);
4. 2. Of a document or node XML Convert to string .
5. SAXReader reader = new SAXReader();
6. Document document = reader.read(new File(“csdn.xml”));
7. Element root=document.getRootElement();
8. String docXmlText=document.asXML();
9. String rootXmlText=root.asXML();
10. Element memberElm=root.element(“csdn”);
11. String memberXmlText=memberElm.asXML();

6、 ... and 、 Case study ( analysis sida.xml Document and carry out curd The operation of )

1.sida.xml Describe the operation of the four masterpieces , The contents of the document are as follows

1. <?xml version=“1.0” encoding=“UTF-8”?>
2. < Four masterpieces >
3. < Journey to the west id=“x001”>
4. < author > Wu chengen 1</ author >
5. < author > Wu chengen 2</ author >
6. < Dynasty > The Ming dynasty </ Dynasty >
7. </ Journey to the west >
8. < A dream of red mansions id=“x002”>
9. < author > Cao xueqin </ author >
10. </ A dream of red mansions >
11. </ Four masterpieces >

2. Parse class test operation

1. package dom4j;
3. import java.io.File;
4. import java.io.FileOutputStream;
5. import java.io.FileWriter;
6. import java.io.OutputStreamWriter;
7. import java.nio.charset.Charset;
8. import java.nio.charset.CharsetEncoder;
9. import java.util.Iterator;
10. import java.util.List;
12. import org.dom4j.Attribute;
13. import org.dom4j.Document;
14. import org.dom4j.Element;
15. import org.dom4j.io.OutputFormat;
16. import org.dom4j.io.SAXReader;
17. import org.dom4j.io.XMLWriter;
18. import org.junit.Test;
20. public class Demo01 {
22. @Test
23. public void test() throws Exception {
25. // establish saxReader object
26. SAXReader reader = new SAXReader();
27. // adopt read Method to read a file convert to Document object
28. Document document = reader.read(new File(“src/dom4j/sida.xml”));
29. // Get the root node element object
30. Element node = document.getRootElement();
31. // Traverse all element nodes
32. listNodes(node);
34. // Get the four famous elements in the node , The name of the child node is the element node of the dream of Red Mansions .
35. Element element = node.element(“ A dream of red mansions ”);
36. // obtain element Of id Attribute node object
37. Attribute attr = element.attribute(“id”);
38. // Delete attribute
39. element.remove(attr);
40. // Add new properties
41. element.addAttribute(“name”, “ author ”);
42. // Add the node of dynasty element to the element node of dream of Red Mansions
43. Element newElement = element.addElement(“ Dynasty ”);
44. newElement.setText(“ Qing Dynasty ”);
45. // obtain element Author element node object in
46. Element author = element.element(“ author ”);
47. // Delete element nodes
48. boolean flag = element.remove(author);
49. // return true Code deletion succeeded , Otherwise failure
50. System.out.println(flag);
51. // add to CDATA Area
52. element.addCDATA(“ A dream of red mansions , It's a love story .”);
53. // Write to a new file
54. writer(document);
56. }
58. /**
59. * hold document Object to write to a new file
60. *
61. * @param document
62. * @throws Exception
63. */
64. public void writer(Document document) throws Exception {
65. // Compact format
66. // OutputFormat format = OutputFormat.createCompactFormat();
67. // The format of typesetting indentation
68. OutputFormat format = OutputFormat.createPrettyPrint();
69. // Set encoding
70. format.setEncoding(“UTF-8”);
71. // establish XMLWriter object , Specify write file and encoding format
72. // XMLWriter writer = new XMLWriter(new FileWriter(new
73. // File(“src//a.xml”)),format);
74. XMLWriter writer = new XMLWriter(new OutputStreamWriter(
75. new FileOutputStream(new File(“src//a.xml”)), “UTF-8”), format);
76. // write in
77. writer.write(document);
78. // Write now
79. writer.flush();
80. // Close operation
81. writer.close();
82. }
84. /**
85. * Traverse all of the following under the current node element ( Elemental ) Child node
86. *
87. * @param node
88. */
89. public void listNodes(Element node) {
90. System.out.println(“ The name of the current node ：：” + node.getName());
91. // Get all the attribute nodes of the current node
92. List<Attribute> list = node.attributes();
93. // Traverse attribute nodes
94. for (Attribute attr : list) {
95. System.out.println(attr.getText() + “—–” + attr.getName()
96. + “—” + attr.getValue());
97. }
99. if (!(node.getTextTrim().equals(“”))) {
100. System.out.println(“ Text content ：：：：” + node.getText());
101. }
103. // Current node face child node iterator
104. Iterator<Element> it = node.elementIterator();
105. // Traverse
106. while (it.hasNext()) {
107. // Get a child node object
108. Element e = it.next();
109. // Traverse the child nodes
110. listNodes(e);
111. }
112. }
114. /**
115. * Introduce Element Medium element Methods and elements Use of methods
116. *
117. * @param node
118. */
119. public void elementMethod(Element node) {
120. // obtain node In nodes , The element name of the child node is the element node of journey to the West .
121. Element e = node.element(“ Journey to the west ”);
122. // Get element node of journey to the West , The child node is the author's element node ( You can see that you can only get the first author element node )
123. Element author = e.element(“ author ”);
125. System.out.println(e.getName() + “—-” + author.getText());
127. // Get the element node of journey to the West in , All child nodes are named author element nodes .
129. List<Element> authors = e.elements(“ author ”);
130. for (Element aut : authors) {
131. System.out.println(aut.getText());
132. }
134. // Get the element node of journey to the West Children of all elements .
135. List<Element> elements = e.elements();
137. for (Element el : elements) {
138. System.out.println(el.getText());
139. }
141. }
143. }

Comment part of the code appropriately and observe the running effect , Practice over and over again , I hope you are right dom4j Have a further understanding of .

7、 ... and 、 String and XML Mutual conversion cases

1. package dom4j;
3. import java.io.File;
4. import java.io.FileOutputStream;
5. import java.io.OutputStreamWriter;
7. import org.dom4j.Document;
8. import org.dom4j.DocumentHelper;
9. import org.dom4j.Element;
10. import org.dom4j.io.OutputFormat;
11. import org.dom4j.io.SAXReader;
12. import org.dom4j.io.XMLWriter;
13. import org.junit.Test;
15. public class Demo02 {
17. @Test
18. public void test() throws Exception {
20. // establish saxreader object
21. SAXReader reader = new SAXReader();
22. // Read a file , Convert this file into Document object
23. Document document = reader.read(new File(“src//c.xml”));
24. // Get the root element
25. Element root = document.getRootElement();
26. // Convert the document into a string
27. String docXmlText = document.asXML();
28. System.out.println(docXmlText);
29. System.out.println(“—————————“);
30. // csdn Content of element tag root transformation
31. String rootXmlText = root.asXML();
32. System.out.println(rootXmlText);
33. System.out.println(“—————————“);
34. // obtain java The element tag Internal content
35. Element e = root.element(“java”);
36. System.out.println(e.asXML());
38. }
40. /**
41. * Create a document object Go to document Add node elements to the object Transfer to xml file
42. *
43. * @throws Exception
44. */
45. public void test2() throws Exception {
47. Document document = DocumentHelper.createDocument();// Create a root node
48. Element root = document.addElement(“csdn”);
49. Element java = root.addElement(“java”);
50. java.setText(“java class ”);
51. Element ios = root.addElement(“ios”);
52. ios.setText(“ios class ”);
54. writer(document);
55. }
57. /**
58. * Convert a text string Document object
59. *
60. * @throws Exception
61. */
62. public void test1() throws Exception {
63. String text = “<csdn><java>Java class </java><net>Net class </net></csdn>”;
64. Document document = DocumentHelper.parseText(text);
65. Element e = document.getRootElement();
66. System.out.println(e.getName());
67. writer(document);
68. }
70. /**
71. * hold document Object to write to a new file
72. *
73. * @param document
74. * @throws Exception
75. */
76. public void writer(Document document) throws Exception {
77. // Compact format
78. // OutputFormat format = OutputFormat.createCompactFormat();
79. // The format of typesetting indentation
80. OutputFormat format = OutputFormat.createPrettyPrint();
81. // Set encoding
82. format.setEncoding(“UTF-8”);
83. // establish XMLWriter object , Specify write file and encoding format
84. // XMLWriter writer = new XMLWriter(new FileWriter(new
85. // File(“src//a.xml”)),format);
86. XMLWriter writer = new XMLWriter(new OutputStreamWriter(
87. new FileOutputStream(new File(“src//c.xml”)), “UTF-8”), format);
88. // write in
89. writer.write(document);
90. // Write now
91. writer.flush();
92. // Close operation
93. writer.close();
94. }
95. }

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