Android XML解析学习——创建XML .

小鱼儿 2023-10-10 11:09 45阅读 0赞

一．基础知识

在前面的学习过程中，我们基本上比较全面的学习了Android平台上读取XML文档的方法，介绍了使用Java SAX、Android SAX、DOM和Pull等各种方式来读取XML文档内容。

目前为止，我们一直专注于解析已有的XML文档，实际上我们也是需要读XML的情形比较多。但是我们可能也有写XML的需要，应用程序可能需要将 XML 发送到远程服务器，或者需要以XML的形式保存数据等。因此在这部分内容中我们就来学习下Android平台上创建XML的方法。

Android系统中和创建XML相关的包为org.xmlpull.v1，在这个包中不仅提供了用来解析XML的Pull方式解析器XmlPullParser，还提供了一个用于创建XML的XmlSerializer。XmlSerializer没有像XmlPullParser那样提取XML事件，而是把它们推出到数据流OutputStream或Writer中。XmlSerializer提供了很直观的API，即使用startDocument开始文档，endDocument结束文档，startTag开始元素，endTag结束元素，text添加文本等。

下面我们就用上面介绍的创建XML方式来实现把解析出来的USGS地震数据重新保存为一个更简单的XML文件的Demo例子。

二．实例开发

我们要完成的效果图如下图1所示：

![0_12887906387tdB.gif][]

图1 创建XML

首先解析USGS的地震数据并以ListView的方式显示，然后点击最上方的“Create XML”按钮就会重新把解析获得的地震数据重新创建为一个XML文件。

新建一个Android工程AndroidXMLDemoSerialize。

添加进之前Demo工程AndroidXMLDemoSaxII中的EarthquakeEntry.java和AndroidSaxEarthquakeHandler.java文件。如果需要从本地读取xml数据的话，同时在assets文件夹下添加保存为xml格式了的USGS地震数据USGS\_Earthquake\_1M2\_5.xml，如果需要联网读取的话，在manifest.xml文件中添加权限：

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1.  <uses-permission android:name="android.permission.INTERNET" />

<uses-permission android:name="android.permission.INTERNET" />

并修改res/layout下的main.xml为：

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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.  >
7.  <Button
8.  android:id="@+id/serializeBtn"
9.  android:layout\_width="fill\_parent"
10. android:layout\_height="wrap\_content"
11. >
12. </Button>
13. <ListView
14. android:id="@+id/list"
15. android:layout\_width="fill\_parent"
16. android:layout\_height="fill\_parent"
17. />
18. </LinearLayout>

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout\_width="fill\_parent" android:layout\_height="fill\_parent" > <Button android:id="@+id/serializeBtn" android:layout\_width="fill\_parent" android:layout\_height="wrap\_content" > </Button> <ListView android:id="@+id/list" android:layout\_width="fill\_parent" android:layout\_height="fill\_parent" /></LinearLayout>

接下来就来新建添加一个类SerializeEarthquakeHandler，用来创建XML，内容如下：

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1.  public class SerializeEarthquakeHandler \{
2.  //写Xml数据
3.  public String writeXml(ArrayList<EarthquakeEntry> earthquakeEntryList)
4.  \{
5.  StringWriter xmlWriter = new StringWriter();
6.  try \{
7.  //创建XmlSerializer,有两种方式
8.  XmlPullParserFactory pullFactory;
9.  //方式一:使用工厂类XmlPullParserFactory的方式
10. pullFactory = XmlPullParserFactory.newInstance();
11. XmlSerializer xmlSerializer = pullFactory.newSerializer();
12. //方式二:使用Android提供的实用工具类android.util.Xml
13. // XmlSerializer xmlSerializer = Xml.newSerializer();
14. xmlSerializer.setOutput(xmlWriter);
15. //开始具体的写xml
16. //<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
17. xmlSerializer.startDocument("UTF-8", true);
18. //<feed number="25">
19. xmlSerializer.startTag("", "feed");
20. xmlSerializer.attribute("", "number", String.valueOf(earthquakeEntryList.size()));
21. for(EarthquakeEntry earthquakeEntry : earthquakeEntryList)
22. \{
23. //<entry>
24. xmlSerializer.startTag("", "entry");
25. //<title>Vanuatu</title>
26. xmlSerializer.startTag("", "title");
27. xmlSerializer.text(earthquakeEntry.getPlace());
28. xmlSerializer.endTag("", "title");
29. //<magnitude>5.3</magnitude>
30. xmlSerializer.startTag("", "magnitude");
31. xmlSerializer.text(String.valueOf(earthquakeEntry.getMagnitude()));
32. xmlSerializer.endTag("", "magnitude");
33. //<updated>2010-09-26 06:44:37</updated>
34. xmlSerializer.startTag("", "updated");
35. SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
36. String dateString = sdf.format(earthquakeEntry.getDate());
37. xmlSerializer.text(dateString);
38. xmlSerializer.endTag("", "updated");
39. //<link>http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us2010brar.php</link>
40. xmlSerializer.startTag("", "link");
41. xmlSerializer.text(earthquakeEntry.getLink());
42. xmlSerializer.endTag("", "link");
43. //<latitude>-14.3009</latitude>
44. xmlSerializer.startTag("", "latitude");
45. xmlSerializer.text(String.valueOf(earthquakeEntry.getLocation().getLatitude()));
46. xmlSerializer.endTag("", "latitude");
47. //<longitude>167.9491</longitude>
48. xmlSerializer.startTag("", "longitude");
49. xmlSerializer.text(String.valueOf(earthquakeEntry.getLocation().getLongitude()));
50. xmlSerializer.endTag("", "longitude");
51. //<elev>-80100.0</elev>
52. xmlSerializer.startTag("", "elev");
53. xmlSerializer.text(String.valueOf(earthquakeEntry.getElev()));
54. xmlSerializer.endTag("", "elev");
55. //</entry>
56. xmlSerializer.endTag("", "entry");
57. \}
58. //</feed>
59. xmlSerializer.endTag("", "feed");
60. xmlSerializer.endDocument();
61. \} catch (Exception e) \{
62. // TODO Auto-generated catch block
63. e.printStackTrace();
64. \}
65. return xmlWriter.toString();
66. \}
67. \}

public class SerializeEarthquakeHandler \{ //写Xml数据 public String writeXml(ArrayList<EarthquakeEntry> earthquakeEntryList) \{ StringWriter xmlWriter = new StringWriter(); try \{ //创建XmlSerializer,有两种方式 XmlPullParserFactory pullFactory; //方式一:使用工厂类XmlPullParserFactory的方式 pullFactory = XmlPullParserFactory.newInstance(); XmlSerializer xmlSerializer = pullFactory.newSerializer(); //方式二:使用Android提供的实用工具类android.util.Xml// XmlSerializer xmlSerializer = Xml.newSerializer(); xmlSerializer.setOutput(xmlWriter); //开始具体的写xml //<?xml version='1.0' encoding='UTF-8' standalone='yes' ?> xmlSerializer.startDocument("UTF-8", true); //<feed number="25"> xmlSerializer.startTag("", "feed"); xmlSerializer.attribute("", "number", String.valueOf(earthquakeEntryList.size())); for(EarthquakeEntry earthquakeEntry : earthquakeEntryList) \{ //<entry> xmlSerializer.startTag("", "entry"); //<title>Vanuatu</title> xmlSerializer.startTag("", "title"); xmlSerializer.text(earthquakeEntry.getPlace()); xmlSerializer.endTag("", "title"); //<magnitude>5.3</magnitude> xmlSerializer.startTag("", "magnitude"); xmlSerializer.text(String.valueOf(earthquakeEntry.getMagnitude())); xmlSerializer.endTag("", "magnitude"); //<updated>2010-09-26 06:44:37</updated> xmlSerializer.startTag("", "updated"); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String dateString = sdf.format(earthquakeEntry.getDate()); xmlSerializer.text(dateString); xmlSerializer.endTag("", "updated"); //<link>http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us2010brar.php</link> xmlSerializer.startTag("", "link"); xmlSerializer.text(earthquakeEntry.getLink()); xmlSerializer.endTag("", "link"); //<latitude>-14.3009</latitude> xmlSerializer.startTag("", "latitude"); xmlSerializer.text(String.valueOf(earthquakeEntry.getLocation().getLatitude())); xmlSerializer.endTag("", "latitude"); //<longitude>167.9491</longitude> xmlSerializer.startTag("", "longitude"); xmlSerializer.text(String.valueOf(earthquakeEntry.getLocation().getLongitude())); xmlSerializer.endTag("", "longitude"); //<elev>-80100.0</elev> xmlSerializer.startTag("", "elev"); xmlSerializer.text(String.valueOf(earthquakeEntry.getElev())); xmlSerializer.endTag("", "elev"); //</entry> xmlSerializer.endTag("", "entry"); \} //</feed> xmlSerializer.endTag("", "feed"); xmlSerializer.endDocument(); \} catch (Exception e) \{ // TODO Auto-generated catch block e.printStackTrace(); \} return xmlWriter.toString(); \}\}

在创建XML的方法中

//写Xml数据

**public** String writeXml(ArrayList<EarthquakeEntry> earthquakeEntryList)

首先创建XmlSerializer，

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1.  //创建XmlSerializer,有两种方式
2.  XmlPullParserFactory pullFactory;
3.  //方式一:使用工厂类XmlPullParserFactory的方式
4.  pullFactory = XmlPullParserFactory.newInstance();
5.  XmlSerializer xmlSerializer = pullFactory.newSerializer();
6.  //方式二:使用Android提供的实用工具类android.util.Xml
7.  // XmlSerializer xmlSerializer = Xml.newSerializer();

//创建XmlSerializer,有两种方式 XmlPullParserFactory pullFactory; //方式一:使用工厂类XmlPullParserFactory的方式 pullFactory = XmlPullParserFactory.newInstance(); XmlSerializer xmlSerializer = pullFactory.newSerializer(); //方式二:使用Android提供的实用工具类android.util.Xml// XmlSerializer xmlSerializer = Xml.newSerializer();

创建XmlSerializer有两种方式，一种是使用我们介绍的org.xmlpull.v1包中的工厂类XmlPullParserFactory。除了这种方式外，还可以使用Android SDK提供的实用工具包android.util中的类Xml的newSerializer()方法直接创建。

接着为XmlSerializer设置一个输出的Writer，

xmlSerializer.setOutput(xmlWriter);

这里将事件推送到了一个 java.io.StringWriter 实例中。

然后就可以使用具体的startDocument开始文档，endDocument结束文档，startTag开始元素，endTag结束元素，text添加文本等方法来创建具体的XML文档内容，具体方法参考上面的代码部分。从代码中我们可以看到，使用XmlSerializer创建XML还是相当直观和方便的。

最后添加AndroidXMLDemoSerialize.java文件中的内容为：

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1.  public class AndroidXMLDemoSerialize extends Activity \{
2.  /\*\* Called when the activity is first created. \*/
3.  //定义显示的List相关变量
4.  ListView list;
5.  Button serializeBtn;
6.  ArrayAdapter<EarthquakeEntry> adapter;
7.  ArrayList<EarthquakeEntry> earthquakeEntryList;
8.  @Override
9.  public void onCreate(Bundle savedInstanceState) \{
10. super.onCreate(savedInstanceState);
11. setContentView(R.layout.main);
12. //用于创建XML的按钮
13. serializeBtn = (Button)findViewById(R.id.serializeBtn);
14. serializeBtn.setEnabled(false);
15. //获取地震数据流
16. InputStream earthquakeStream = readEarthquakeDataFromFile();
17. //Android Sax方式进行解析
18. AndroidSaxEarthquakeHandler androidSaxHandler = new AndroidSaxEarthquakeHandler();
19. earthquakeEntryList = androidSaxHandler.parse(earthquakeStream);
20. //用ListView进行显示
21. list = (ListView)this.findViewById(R.id.list);
22. adapter = new ArrayAdapter<EarthquakeEntry>(this, android.R.layout.simple\_list\_item\_1, earthquakeEntryList);
23. list.setAdapter(adapter);
24. serializeBtn.setEnabled(true);
25. //点击按钮开始创建XML
26. serializeBtn.setOnClickListener(new OnClickListener() \{
27. @Override
28. public void onClick(View v) \{
29. // TODO Auto-generated method stub
30. //构造xml
31. SerializeEarthquakeHandler serializeHandler = new SerializeEarthquakeHandler();
32. String earthquakeXml = serializeHandler.writeXml(earthquakeEntryList);
33. //Log打印写成的xml数据
34. Log.v("XmlSerialize", earthquakeXml);
35. //把写成的xml数据输出到文件
36. OutputStream outStream;
37. try \{
38. outStream = openFileOutput("earthquake.xml", MODE\_PRIVATE);
39. OutputStreamWriter outStreamWriter = new OutputStreamWriter(outStream);
40. outStreamWriter.write(earthquakeXml);
41. outStreamWriter.close();
42. outStream.close();
43. \} catch (Exception e) \{
44. // TODO Auto-generated catch block
45. e.printStackTrace();
46. \}
47. \}
48. \});
49. \}
50. 
51. private InputStream readEarthquakeDataFromFile()
52. \{
53. //从本地获取地震数据
54. InputStream inStream = null;
55. try \{
56. inStream = this.getAssets().open("USGS\_Earthquake\_1M2\_5.xml");
57. \} catch (IOException e) \{
58. // TODO Auto-generated catch block
59. e.printStackTrace();
60. \}
61. return inStream;
62. \}
63. private InputStream readEarthquakeDataFromInternet()
64. \{
65. //从网络上获取实时地震数据
66. URL infoUrl = null;
67. InputStream inStream = null;
68. try \{
69. infoUrl = new URL("http://earthquake.usgs.gov/earthquakes/catalogs/1day-M2.5.xml");
70. URLConnection connection = infoUrl.openConnection();
71. HttpURLConnection httpConnection = (HttpURLConnection)connection;
72. int responseCode = httpConnection.getResponseCode();
73. if(responseCode == HttpURLConnection.HTTP\_OK)
74. \{
75. inStream = httpConnection.getInputStream();
76. \}
77. \} catch (MalformedURLException e) \{
78. // TODO Auto-generated catch block
79. e.printStackTrace();
80. \} catch (IOException e) \{
81. // TODO Auto-generated catch block
82. e.printStackTrace();
83. \}
84. return inStream;
85. \}
86. \}

public class AndroidXMLDemoSerialize extends Activity \{ /\*\* Called when the activity is first created. \*/ //定义显示的List相关变量 ListView list; Button serializeBtn; ArrayAdapter<EarthquakeEntry> adapter; ArrayList<EarthquakeEntry> earthquakeEntryList; @Override public void onCreate(Bundle savedInstanceState) \{ super.onCreate(savedInstanceState); setContentView(R.layout.main); //用于创建XML的按钮 serializeBtn = (Button)findViewById(R.id.serializeBtn); serializeBtn.setEnabled(false); //获取地震数据流 InputStream earthquakeStream = readEarthquakeDataFromFile(); //Android Sax方式进行解析 AndroidSaxEarthquakeHandler androidSaxHandler = new AndroidSaxEarthquakeHandler(); earthquakeEntryList = androidSaxHandler.parse(earthquakeStream); //用ListView进行显示 list = (ListView)this.findViewById(R.id.list); adapter = new ArrayAdapter<EarthquakeEntry>(this, android.R.layout.simple\_list\_item\_1, earthquakeEntryList); list.setAdapter(adapter); serializeBtn.setEnabled(true); //点击按钮开始创建XML serializeBtn.setOnClickListener(new OnClickListener() \{ @Override public void onClick(View v) \{ // TODO Auto-generated method stub //构造xml SerializeEarthquakeHandler serializeHandler = new SerializeEarthquakeHandler(); String earthquakeXml = serializeHandler.writeXml(earthquakeEntryList); //Log打印写成的xml数据 Log.v("XmlSerialize", earthquakeXml); //把写成的xml数据输出到文件 OutputStream outStream; try \{ outStream = openFileOutput("earthquake.xml", MODE\_PRIVATE); OutputStreamWriter outStreamWriter = new OutputStreamWriter(outStream); outStreamWriter.write(earthquakeXml); outStreamWriter.close(); outStream.close(); \} catch (Exception e) \{ // TODO Auto-generated catch block e.printStackTrace(); \} \} \}); \} private InputStream readEarthquakeDataFromFile() \{ //从本地获取地震数据 InputStream inStream = null; try \{ inStream = this.getAssets().open("USGS\_Earthquake\_1M2\_5.xml"); \} catch (IOException e) \{ // TODO Auto-generated catch block e.printStackTrace(); \} return inStream; \} private InputStream readEarthquakeDataFromInternet() \{ //从网络上获取实时地震数据 URL infoUrl = null; InputStream inStream = null; try \{ infoUrl = new URL("http://earthquake.usgs.gov/earthquakes/catalogs/1day-M2.5.xml"); URLConnection connection = infoUrl.openConnection(); HttpURLConnection httpConnection = (HttpURLConnection)connection; int responseCode = httpConnection.getResponseCode(); if(responseCode == HttpURLConnection.HTTP\_OK) \{ inStream = httpConnection.getInputStream(); \} \} catch (MalformedURLException e) \{ // TODO Auto-generated catch block e.printStackTrace(); \} catch (IOException e) \{ // TODO Auto-generated catch block e.printStackTrace(); \} return inStream; \}\}

程序前部分是使用Android SAX的方式解析XML文档，然后在按钮的点击回调函数中把解析获得的地震数据重新创建为XML文档的形式，并分别用Log打印和保存为文件。

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1.  //点击按钮开始创建XML
2.  serializeBtn.setOnClickListener(new OnClickListener() \{
3.  @Override
4.  public void onClick(View v) \{
5.  // TODO Auto-generated method stub
6.  //构造xml
7.  SerializeEarthquakeHandler serializeHandler = new SerializeEarthquakeHandler();
8.  String earthquakeXml = serializeHandler.writeXml(earthquakeEntryList);
9.  //Log打印写成的xml数据
10. Log.v("XmlSerialize", earthquakeXml);
11. //把写成的xml数据输出到文件
12. OutputStream outStream;
13. try \{
14. outStream = openFileOutput("earthquake.xml", MODE\_PRIVATE);
15. OutputStreamWriter outStreamWriter = new OutputStreamWriter(outStream);
16. outStreamWriter.write(earthquakeXml);
17. outStreamWriter.close();
18. outStream.close();
19. \} catch (Exception e) \{
20. // TODO Auto-generated catch block
21. e.printStackTrace();
22. \}
23. \}
24. \});

//点击按钮开始创建XML serializeBtn.setOnClickListener(new OnClickListener() \{ @Override public void onClick(View v) \{ // TODO Auto-generated method stub //构造xml SerializeEarthquakeHandler serializeHandler = new SerializeEarthquakeHandler(); String earthquakeXml = serializeHandler.writeXml(earthquakeEntryList); //Log打印写成的xml数据 Log.v("XmlSerialize", earthquakeXml); //把写成的xml数据输出到文件 OutputStream outStream; try \{ outStream = openFileOutput("earthquake.xml", MODE\_PRIVATE); OutputStreamWriter outStreamWriter = new OutputStreamWriter(outStream); outStreamWriter.write(earthquakeXml); outStreamWriter.close(); outStream.close(); \} catch (Exception e) \{ // TODO Auto-generated catch block e.printStackTrace(); \} \} \});

完成了，可以保存运行看下效果。

当点击屏幕上方的“Create XML”按钮时，程序就会创建一个形式更加简单的XML文档，同时在DDMS的LogCat里打印出创建的XML文档内容，如下图2所示：

![0_1288794003XpVW.gif][]

图2 Log打印出的创建的XML文档内容

同时还会把创建的XML以文件的形式保存在系统中，我们可以在DDMS的File Explorer的data/data/com.ichliebephone.xml.serialize/files文件夹下看到，如下图3所示：

![0_1288794011rwbI.gif][]

图3 保存着的创建出来的XML文件

并且我们可以把这个文件导出到电脑上，可以看到里面的内容为：

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1.  <?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
2.  <feed number="25">
3.  <entry>
4.  <title>Vanuatu</title>
5.  <magnitude>5.3</magnitude>
6.  <updated>2010-09-26 06:44:37</updated>
7.  <link>http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us2010brar.php</link>
8.  <latitude>-14.3009</latitude>
9.  <longitude>167.9491</longitude>
10. <elev>-80100.0</elev>
11. </entry>
12. <entry>
13. 
14. </entry>
15. </feed>

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?><feed number="25"> <entry> <title>Vanuatu</title> <magnitude>5.3</magnitude> <updated>2010-09-26 06:44:37</updated> <link>http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us2010brar.php</link> <latitude>-14.3009</latitude> <longitude>167.9491</longitude> <elev>-80100.0</elev> </entry> <entry>  </entry></feed>

就是我们解析获得的所有地震条目，并且其中的各个元素及其内容、属性等按我们在SerializeEarthquakeHandler中指定的组织方式保存。

三．总结

在这块内容中我们学习了Android平台上创建XML的方法，从以上的Demo例子中我们可以发现Android上不仅解析XML方式多，并且方便，而且创建XML也是很方便直观，好理解和实现的。

到这块为止，我们就学习完了Android平台上和XML相关的内容，包括解析和创建XML等和XML相关的读与写两个方面，有了这些基础，我想处理Android上的XML文档等基本可以轻松应付了，希望以上的学习内容对你也有所帮助，感谢你一直的关注！

注：

参考资料：[http://www.ibm.com/developerworks/cn/xml/x-android/][http_www.ibm.com_developerworks_cn_xml_x-android]

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