Android Sax方法讀取xml文件

SAX（Simple API for XML）提供了一種基於事件的處理思路，不需要裝載、遍歷整個XML文件，只要發現你所關心的標簽或數據，就可以隨時停止解析。

1. xml讀取代碼，繼承DefaultHandler（內含解析XML文檔中產生的各種類型的事件的空實現，只需重寫用到的事件即可）。
事件處理的順序：一般在 startDocument() 初始化工作，在 endDocument() 中收尾的處理工作；startElement() - characters() - endDocument() 是一個XML節點讀取的過程，startElement() 用來初始判斷，characters() 獲取節點的字符數據，endDocument() 將數據寫入數據結構。

1. package mytest.xml;
3. import org.xml.sax.Attributes;
4. import org.xml.sax.SAXException;
5. import org.xml.sax.helpers.DefaultHandler;
7. public class XmlHandler extends DefaultHandler {
9. private String _name = null, _address = null;
10. private int _id = 0, _age = 0, _flag = 0;
12. private String _str = "";
13. public String getString() {
14. return _str;
15. }
17. @Override
18. // 開始處理文檔時觸發
19. public void startDocument() throws SAXException {
20. super.startDocument();
21. }
23. @Override
24. // 開始處理元素時觸發
25. public void startElement(String uri, String localName, String name, Attributes attributes) throws SAXException {
26. if(localName.equalsIgnoreCase("Student"))
27. {
28. String tmp = attributes.getValue("id");
29. if(tmp != null) _id = Integer.parseInt(tmp);
30. }
31. else if(localName.equalsIgnoreCase("name"))
32. _flag = 1;
33. else if(localName.equalsIgnoreCase("age"))
34. _flag = 2;
35. else if(localName.equalsIgnoreCase("address"))
36. _flag = 3;
37. }
39. @Override
40. // 處理元素字符內容時觸發
41. public void characters(char[] ch, int start, int length) throws SAXException {
42. String tmp = new String(ch, start, length);
43. if(_flag == 1) _name = tmp;
44. else if(_flag == 2) _age = Integer.parseInt(tmp);
45. else if(_flag == 3) _address = tmp;
46. _flag = 0;
47. super.characters(ch, start, length);
48. }
50. @Override
51. // 元素處理結束時觸發
52. public void endElement(String uri, String localName, String name)
53. throws SAXException {
54. if(localName.equalsIgnoreCase("Student"))
55. {
56. this._str += this._name + "\n" + "Id: " + this._id + "\nAge: " + this._age +
57. "\nAddress: " + this._address + "\n\n";
58. }
59. super.endElement(uri, localName, name);
60. }
62. @Override
63. // 文檔處理結束時觸發
64. public void endDocument() throws SAXException {
65. super.endDocument();
66. }
67. }

2. 主activity

1. package mytest.xml;
3. import java.io.File;
4. import javax.xml.parsers.SAXParser;
5. import javax.xml.parsers.SAXParserFactory;
7. import Android.app.Activity;
8. import android.os.Bundle;
9. import android.view.View;
10. import android.view.View.OnClickListener;
11. import android.widget.Button;
12. import android.widget.TextView;
14. public class TestActivity extends Activity {
15. /** Called when the activity is first created. */
16. @Override
17. public void onCreate(Bundle savedInstanceState) {
18. super.onCreate(savedInstanceState);
19. setContentView(R.layout.main);
21. Button btn = (Button)this.findViewById(R.id.xmlReadBtn);
22. btn.setOnClickListener(new OnClickListener() {
23. @Override
24. public void onClick(View args0) {
25. TextView text = (TextView)findViewById(R.id.xmlPathEdit);
26. String str = readXml(text.getText().toString());
27. text = (TextView)findViewById(R.id.shownText);
28. if(str != null)
29. text.setText(str);
30. }
31. });
32. }
34. private String readXml(String filepath) {
35. String str = null;
36. File f = new File(filepath);
37. if(f.exists())
38. {
39. SAXParserFactory factory = SAXParserFactory.newInstance();
40. try {
41. SAXParser sp = factory.newSAXParser();
42. XmlHandler handler = new XmlHandler();
43. sp.parse(f, handler);
44. str = handler.getString();
45. } catch(Exception e) {
46. e.printStackTrace();
47. }
48. }
49. return str;
50. }
51. }

3. 頁面代碼

1. <?xml version="1.0" encoding="utf-8"?>
2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
3. android:orientation="vertical"
4. android:layout_width="fill_parent"
5. android:layout_height="fill_parent"
6. android:weightSum="1">
8. <TextView android:layout_width="wrap_content"
9. android:layout_height="wrap_content"
10. android:text="Path:"
11. android:textSize="8pt"
12. android:gravity="left" />
14. <LinearLayout android:layout_height="wrap_content"
15. android:orientation="horizontal" android:layout_width="fill_parent">
17. <EditText android:id="@+id/xmlPathEdit"
18. android:layout_width="278dp"
19. android:layout_height="wrap_content"/>
21. <Button android:layout_height="40dp"
22. android:text="OK"
23. android:layout_width="wrap_content"
24. android:id="@+id/xmlReadBtn" />
26. </LinearLayout>
28. <TextView android:layout_width="fill_parent"
29. android:layout_height="wrap_content"
30. android:id="@+id/shownText"
31. android:textSize="8pt"
32. android:gravity="left"
33. android:layout_weight="0.86"/>
35. </LinearLayout>

4. 讀取的xml文件結構

1. <?xml version="1.0" encoding="utf-8" standalone="yes"?>
2. <Students count="2">
3. <Student id="0">
4. <name>Bill</name>
5. <age>13</age>
6. <address>ABCDEFG</address>
7. </Student>
8. <Student id="1">
9. <name>Nancy</name>
10. <age>17</age>
11. <address>HIJKLMN</address>
12. </Student>
13. </Students>