XML解析详解

SAX是一种占用内存少且解析速度快的解析器，它采用的是事件启动，它不需要解析完整个文档，而是按照内容顺序 看文档某个部分是否符合xml语法，如果符合就触发相应的事件，所谓的事件就是些回调方法（callback）,这些方法 定义在ContentHandler中，下面是其主要方法：

startDocument:当遇到文档的时候就触发这个事件 调用这个方法 可以在其中做些预处理工作

startElement: (String namespaceURI,String localName,String qName,Attributes atts)当遇开始标签的时候就会触发这个方法。

endElement（String uri,String localName,String name）：当遇到结束标签时触发这个事件，调用此法可以做些善后工作。

charachers(char [] ch,int start,int length):当遇到xml内容时触发这个方法，用new String(ch,start,length)可以接受内容。 

首先在 res目录下新建一个raw文件夹，然后再里面么新建一个student.xml

代码片段(5)

[代码] student.xml

01 <?xml version="1.0" encoding="utf-8"?>
02 <stundets>
03   <student id="2009081315">
04     <name>饶伟</name>
05     <speciality>计算机科学与技术</speciality>
06     <qq>812200157</qq>
07   </student>
08
09     <student id="2009081316">
10     <name>小伟</name>
11     <speciality>网络工程</speciality>
12     <qq>812200156</qq>
13   </student>
14     <student id="2009081318">
15     <name>伟哥</name>
16     <speciality>软件工程</speciality>
17     <qq>812200158</qq>
18   </student>
19
20 </stundets>

[代码] Student.java

01 public class Student {
02
03 long Id;
04 String Name;
05 String Speciality;
06 long QQ;
07
08 public Student(long id, String name, String speciality, long qQ) {
09     super();
10     Id = id;
11     Name = name;
12     Speciality = speciality;
13     QQ = qQ;
14 }
15
16 public Student() {
17     super();
18 }
19
20
21 public long getId() {
22     return Id;
23 }
24
25 public String getName() {
26     return Name;
27 }
28
29 public long getQQ() {
30     return QQ;
31 }
32
33 public String getSpeciality() {
34     return Speciality;
35 }
36
37 public void setId(long id) {
38     Id = id;
39 }
40
41 public void setName(String name) {
42     Name = name;
43 }
44
45 public void setQQ(long qQ) {
46     QQ = qQ;
47 }
48
49 public void setSpeciality(String speciality) {
50     Speciality = speciality;
51 }
52
53 }

[代码] StudentHandler.java

01 package rw.Xml_SAX;
02
03 import java.util.List;
04
05 import org.xml.sax.Attributes;
06 import org.xml.sax.SAXException;
07 import org.xml.sax.helpers.DefaultHandler;
08
09 import Android.util.Log;
10
11 public class StudentHandler extends DefaultHandler {
12
13
14     private String preTAG;
15     private List<Student> ListStudent;
16     private Student stu;
17
18     public StudentHandler() {
19         super();
20     }
21
22     public StudentHandler(List<Student> listStudent) {
23         super();
24         ListStudent = listStudent;
25     }
26
27
28     public void startDocument() throws SAXException {
29         // TODO Auto-generated method stub
30     Log.i("------>", "文档开始");
31         super.startDocument();
32     }
33
34     public void startElement(String uri, String localName, String qName,
35             Attributes attributes) throws SAXException {
36
37
38         Log.i("localName-------->", localName);
39         preTAG=localName;
40         if ("student".equals(localName)) {
41             stu=new Student();
42             stu.setId(Long.parseLong(attributes.getValue(0)));
43
44         for (int i = 0; i < attributes.getLength(); i++) {
45             //Log.i("attributes-------->", attributes.getValue(i));
46             Log.i("attributes-------->",String.valueOf(stu.getId()));
47         }
48     }
49         super.startElement(uri, localName, qName, attributes);
50     }
51
52     public void endDocument() throws SAXException {
53
54         Log.i("------>", "文档结束");
55         super.endDocument();
56     }
57
58     public void endElement(String uri, String localName, String qName)
59             throws SAXException {
60         preTAG="";
61         if ("student".equals(localName)) {
62         ListStudent.add(stu);
63         Log.i("-------->", "一个元素解析完成");
64         }
65         super.endElement(uri, localName, qName);
66     }
67
68
69 public void characters(char[] ch, int start, int length)
70         throws SAXException {
71
72         String dateString;
73        if ("name".equals(preTAG)) {
74             dateString=new String(ch,start,length);
75             stu.setName(dateString);
76             Log.i("name=", stu.getName());
77         }else if ("speciality".equals(preTAG)) {
78             dateString=new String(ch,start,length);
79             stu.setSpeciality(dateString);
80             Log.i("speciality=", stu.getSpeciality());
81         }else if ("qq".equals(preTAG)) {
82             dateString=new String(ch,start,length);
83             stu.setQQ(Long.parseLong((dateString)));
84             Log.i("QQ=", String.valueOf(stu.getQQ()));
85         }
86
87         super.characters(ch, start, length);
88 }
89
90
91 public List<Student> getListStudent() {
92     return ListStudent;
93 }
94
95 public void setListStudent(List<Student> listStudent) {
96     ListStudent = listStudent;
97 }
98
99 }

[代码] XMl_Sax1Activity.java

01 import java.util.ArrayList;
02 import java.util.Iterator;
03 import java.util.List;
04
05 import javax.xml.parsers.SAXParserFactory;
06
07 import org.xml.sax.InputSource;
08 import org.xml.sax.XMLReader;
09
10
11 import Android.app.Activity;
12 import Android.os.Bundle;
13 import Android.util.Log;
14 import Android.view.View;
15 import Android.view.View.OnClickListener;
16 import Android.widget.Adapter;
17 import Android.widget.ArrayAdapter;
18 import Android.widget.Button;
19 import Android.widget.ListView;
20 import Android.widget.TextView;
21
22 public class XMl_Sax1Activity extends Activity {
23   private Button button;
24   private TextView textView;
25   private ListView listView;
26   private List<String> list=new ArrayList<String>();
27 public void onCreate(Bundle savedInstanceState) {
28     super.onCreate(savedInstanceState);
29     setContentView(R.layout.main);
30     button=(Button)findViewById(R.id.button1);
31     textView=(TextView)findViewById(R.id.textView1);
32     listView=(ListView) findViewById(R.id.listView1);
33     //InputSource xMLResourceString=new InputSource(XMl_Sax1Activity.this.getResources().openRawResource(R.raw.student));
34     button.setOnClickListener(new ButtonListener());
35 }
36
37 class ButtonListener implements OnClickListener{
38
39     @Override
40     public void onClick(View v) {
41
42        List<Student> students=parserXMl();
43        for (Iterator iterator = students.iterator(); iterator.hasNext();) {
44        Student student = (Student) iterator.next();
45         list.add(String.valueOf(student.getId())+" "+student.getName()+" "+student.getSpeciality()+" "+String.valueOf((student.getQQ())));
46     }
47
48        ArrayAdapter<String> adapter=new ArrayAdapter<String>(getApplicationContext(), Android.R.layout.simple_list_item_1, list);
49        listView.setAdapter(adapter);
50     }
51
52 }
53
54 private List<Student> parserXMl()
55 {
56     SAXParserFactory factory=SAXParserFactory.newInstance();
57     List<Student>students=null;
58     Student student=null;
59     try {
60     XMLReader reader=factory.newSAXParser().getXMLReader();
61     students=new ArrayList<Student>();
62     reader.setContentHandler(new StudentHandler(students));
63     reader.parse(new InputSource(XMl_Sax1Activity.this.getResources().openRawResource(R.raw.student)));
64     for (Iterator iterator = students.iterator(); iterator.hasNext();) {
65          student = (Student) students.iterator();
66     }
67     students.add(student);
68     } catch (Exception e) {
69     // TODO: handle exception
70     }
71     return students;
72 }
73 }

[代码] 布局文件main.xml

01	<?xml version="1.0" encoding="utf-8"?>

02	<LinearLayout xmlns:Android="http://schemas.android.com/apk/res/android"

03	Android:orientation="vertical"

04	Android:layout_width="fill_parent"

05	Android:layout_height="fill_parent"

06

>

07

08	<Button Android:text="SAX解析" android:id="@+id/button1" android:layout_height="wrap_content" android:layout_width="match_parent"></Button>

09	<TextView Android:text="" android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content"></TextView>

10	<ListView Android:layout_height="wrap_content" android:id="@+id/listView1" android:layout_width="match_parent"></ListView>

11	</LinearLayout>