XML現在已經成為一種通用的數據交換格式,它的平臺無關性,語言無關性,系統無關性,給數據集成與交互帶來了極大的方便。對于XML本身的語法知識與技術細節,需要閱讀相關的技術文獻,這里面包括的內容有DOM(Document Object Model),DTD(Document Type Definition),SAX(Simple API for XML),XSD(Xml Schema Definition),XSLT(Extensible Stylesheet Language Transformations),具體可參閱w3c官方網站文檔http://www.w3.org獲取更多信息。
XML在不同的語言里解析方式都是一樣的,只不過實現的語法不同而已。基本的解析方式有兩種,一種叫SAX,另一種叫DOM。SAX是基于事件流的解析,DOM是基于XML文檔樹結構的解析。假設我們XML的內容和結構如下:
1
2
3
4
5
6
7
8
|
<? xml version = "1.0" encoding = "UTF-8" ?> < employees > < employee > < name >ddviplinux</ name > < sex >m</ sex > < age >30</ age > </ employee > </ employees > |
本文使用Java語言來實現DOM與SAX的XML文檔生成與解析。
首先定義一個操作XML文檔的接口XmlDocument 它定義了XML文檔的建立與解析的接口。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
|
/** * * @author hongliang.dinghl * 定義XML文檔建立與解析的接口 */ public interface XmlDocument { /** * 建立XML文檔 * @param fileName 文件全路徑名稱 */ public void createXml(String fileName); /** * 解析XML文檔 * @param fileName 文件全路徑名稱 */ public void parserXml(String fileName); } |
1.DOM生成和解析XML文檔
為 XML 文檔的已解析版本定義了一組接口。解析器讀入整個文檔,然后構建一個駐留內存的樹結構,然后代碼就可以使用 DOM 接口來操作這個樹結構。優點:整個文檔樹在內存中,便于操作;支持刪除、修改、重新排列等多種功能;缺點:將整個文檔調入內存(包括無用的節點),浪費時間和空間;使用場合:一旦解析了文檔還需多次訪問這些數據;硬件資源充足(內存、CPU)。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
|
import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.transform.OutputKeys; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerConfigurationException; import javax.xml.transform.TransformerException; import javax.xml.transform.TransformerFactory; import javax.xml.transform.dom.DOMSource; import javax.xml.transform.stream.StreamResult; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; /** * * @author hongliang.dinghl * DOM生成與解析XML文檔 */ public class DomDemo implements XmlDocument { private Document document; private String fileName; public void init() { try { DocumentBuilderFactory factory = DocumentBuilderFactory .newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); this .document = builder.newDocument(); } catch (ParserConfigurationException e) { System.out.println(e.getMessage()); } } public void createXml(String fileName) { Element root = this .document.createElement( "employees" ); this .document.appendChild(root); Element employee = this .document.createElement( "employee" ); Element name = this .document.createElement( "name" ); name.appendChild( this .document.createTextNode( "丁宏亮" )); employee.appendChild(name); Element sex = this .document.createElement( "sex" ); sex.appendChild( this .document.createTextNode( "m" )); employee.appendChild(sex); Element age = this .document.createElement( "age" ); age.appendChild( this .document.createTextNode( "30" )); employee.appendChild(age); root.appendChild(employee); TransformerFactory tf = TransformerFactory.newInstance(); try { Transformer transformer = tf.newTransformer(); DOMSource source = new DOMSource(document); transformer.setOutputProperty(OutputKeys.ENCODING, "gb2312" ); transformer.setOutputProperty(OutputKeys.INDENT, "yes" ); PrintWriter pw = new PrintWriter( new FileOutputStream(fileName)); StreamResult result = new StreamResult(pw); transformer.transform(source, result); System.out.println( "生成XML文件成功!" ); } catch (TransformerConfigurationException e) { System.out.println(e.getMessage()); } catch (IllegalArgumentException e) { System.out.println(e.getMessage()); } catch (FileNotFoundException e) { System.out.println(e.getMessage()); } catch (TransformerException e) { System.out.println(e.getMessage()); } } public void parserXml(String fileName) { try { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); Document document = db.parse(fileName); NodeList employees = document.getChildNodes(); for ( int i = 0 ; i < employees.getLength(); i++) { Node employee = employees.item(i); NodeList employeeInfo = employee.getChildNodes(); for ( int j = 0 ; j < employeeInfo.getLength(); j++) { Node node = employeeInfo.item(j); NodeList employeeMeta = node.getChildNodes(); for ( int k = 0 ; k < employeeMeta.getLength(); k++) { System.out.println(employeeMeta.item(k).getNodeName() + ":" + employeeMeta.item(k).getTextContent()); } } } System.out.println( "解析完畢" ); } catch (FileNotFoundException e) { System.out.println(e.getMessage()); } catch (ParserConfigurationException e) { System.out.println(e.getMessage()); } catch (SAXException e) { System.out.println(e.getMessage()); } catch (IOException e) { System.out.println(e.getMessage()); } } } |
2.SAX生成和解析XML文檔
為解決DOM的問題,出現了SAX。SAX ,事件驅動。當解析器發現元素開始、元素結束、文本、文檔的開始或結束等時,發送事件,程序員編寫響應這些事件的代碼,保存數據。優點:不用事先調入整個文檔,占用資源少;SAX解析器代碼比DOM解析器代碼小,適于Applet,下載。缺點:不是持久的;事件過后,若沒保存數據,那么數據就丟了;無狀態性;從事件中只能得到文本,但不知該文本屬于哪個元素;使用場合:Applet;只需XML文檔的少量內容,很少回頭訪問;機器內存少;
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import javax.xml.parsers.ParserConfigurationException; import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; /** * * @author hongliang.dinghl * SAX文檔解析 */ public class SaxDemo implements XmlDocument { public void createXml(String fileName) { System.out.println( "<<" +filename+ ">>" ); } public void parserXml(String fileName) { SAXParserFactory saxfac = SAXParserFactory.newInstance(); try { SAXParser saxparser = saxfac.newSAXParser(); InputStream is = new FileInputStream(fileName); saxparser.parse(is, new MySAXHandler()); } catch (ParserConfigurationException e) { e.printStackTrace(); } catch (SAXException e) { e.printStackTrace(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } } class MySAXHandler extends DefaultHandler { boolean hasAttribute = false ; Attributes attributes = null ; public void startDocument() throws SAXException { System.out.println( "文檔開始打印了" ); } public void endDocument() throws SAXException { System.out.println( "文檔打印結束了" ); } public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { if (qName.equals( "employees" )) { return ; } if (qName.equals( "employee" )) { System.out.println(qName); } if (attributes.getLength() > 0 ) { this .attributes = attributes; this .hasAttribute = true ; } } public void endElement(String uri, String localName, String qName) throws SAXException { if (hasAttribute && (attributes != null )) { for ( int i = 0 ; i < attributes.getLength(); i++) { System.out.println(attributes.getQName( 0 ) + attributes.getValue( 0 )); } } } public void characters( char [] ch, int start, int length) throws SAXException { System.out.println( new String(ch, start, length)); } } package com.alisoft.facepay.framework.bean; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import javax.xml.parsers.ParserConfigurationException; import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; /** * * @author hongliang.dinghl * SAX文檔解析 */ public class SaxDemo implements XmlDocument { public void createXml(String fileName) { System.out.println( "<<" +filename+ ">>" ); } public void parserXml(String fileName) { SAXParserFactory saxfac = SAXParserFactory.newInstance(); try { SAXParser saxparser = saxfac.newSAXParser(); InputStream is = new FileInputStream(fileName); saxparser.parse(is, new MySAXHandler()); } catch (ParserConfigurationException e) { e.printStackTrace(); } catch (SAXException e) { e.printStackTrace(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } } class MySAXHandler extends DefaultHandler { boolean hasAttribute = false ; Attributes attributes = null ; public void startDocument() throws SAXException { System.out.println( "文檔開始打印了" ); } public void endDocument() throws SAXException { System.out.println( "文檔打印結束了" ); } public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { if (qName.equals( "employees" )) { return ; } if (qName.equals( "employee" )) { System.out.println(qName); } if (attributes.getLength() > 0 ) { this .attributes = attributes; this .hasAttribute = true ; } } public void endElement(String uri, String localName, String qName) throws SAXException { if (hasAttribute && (attributes != null )) { for ( int i = 0 ; i < attributes.getLength(); i++) { System.out.println(attributes.getQName( 0 ) + attributes.getValue( 0 )); } } } public void characters( char [] ch, int start, int length) throws SAXException { System.out.println( new String(ch, start, length)); } } |
3.DOM4J生成和解析XML文檔
DOM4J 是一個非常非常優秀的Java XML API,具有性能優異、功能強大和極端易用使用的特點,同時它也是一個開放源代碼的軟件。如今你可以看到越來越多的 Java 軟件都在使用 DOM4J 來讀寫 XML,特別值得一提的是連 Sun 的 JAXM 也在用 DOM4J。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
|
import java.io.File; import java.io.FileWriter; import java.io.IOException; import java.io.Writer; import java.util.Iterator; import org.dom4j.Document; import org.dom4j.DocumentException; import org.dom4j.DocumentHelper; import org.dom4j.Element; import org.dom4j.io.SAXReader; import org.dom4j.io.XMLWriter; /** * * @author hongliang.dinghl * Dom4j 生成XML文檔與解析XML文檔 */ public class Dom4jDemo implements XmlDocument { public void createXml(String fileName) { Document document = DocumentHelper.createDocument(); Element employees=document.addElement( "employees" ); Element employee=employees.addElement( "employee" ); Element name= employee.addElement( "name" ); name.setText( "ddvip" ); Element sex=employee.addElement( "sex" ); sex.setText( "m" ); Element age=employee.addElement( "age" ); age.setText( "29" ); try { Writer fileWriter= new FileWriter(fileName); XMLWriter xmlWriter= new XMLWriter(fileWriter); xmlWriter.write(document); xmlWriter.close(); } catch (IOException e) { System.out.println(e.getMessage()); } } public void parserXml(String fileName) { File inputXml= new File(fileName); SAXReader saxReader = new SAXReader(); try { Document document = saxReader.read(inputXml); Element employees=document.getRootElement(); for (Iterator i = employees.elementIterator(); i.hasNext();){ Element employee = (Element) i.next(); for (Iterator j = employee.elementIterator(); j.hasNext();){ Element node=(Element) j.next(); System.out.println(node.getName()+ ":" +node.getText()); } } } catch (DocumentException e) { System.out.println(e.getMessage()); } System.out.println( "dom4j parserXml" ); } } |
4.JDOM生成和解析XML
為減少DOM、SAX的編碼量,出現了JDOM;優點:20-80原則,極大減少了代碼量。使用場合:要實現的功能簡單,如解析、創建等,但在底層,JDOM還是使用SAX(最常用)、DOM、Xanan文檔。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
|
import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.util.List; import org.jdom.Document; import org.jdom.Element; import org.jdom.JDOMException; import org.jdom.input.SAXBuilder; import org.jdom.output.XMLOutputter; /** * * @author hongliang.dinghl * JDOM 生成與解析XML文檔 * */ public class JDomDemo implements XmlDocument { public void createXml(String fileName) { Document document; Element root; root= new Element( "employees" ); document= new Document(root); Element employee= new Element( "employee" ); root.addContent(employee); Element name= new Element( "name" ); name.setText( "ddvip" ); employee.addContent(name); Element sex= new Element( "sex" ); sex.setText( "m" ); employee.addContent(sex); Element age= new Element( "age" ); age.setText( "23" ); employee.addContent(age); XMLOutputter XMLOut = new XMLOutputter(); try { XMLOut.output(document, new FileOutputStream(fileName)); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } public void parserXml(String fileName) { SAXBuilder builder= new SAXBuilder( false ); try { Document document=builder.build(fileName); Element employees=document.getRootElement(); List employeeList=employees.getChildren( "employee" ); for ( int i= 0 ;iElement employee=(Element)employeeList.get(i); List employeeInfo=employee.getChildren(); for ( int j= 0 ;jSystem.out.println(((Element)employeeInfo.get(j)).getName()+ ":" +((Element)employeeInfo.get(j)).getValue()); } } } catch (JDOMException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } } |
以上就是本文的全部內容,希望對大家的學習有所幫助,也希望大家多多支持服務器之家。