Be careful with the XmlPullParser. netText () method

Using XmlPullParser on Android is an efficient and easy-to-maintain method for parsing XML. Android has two implementation classes in history: using XmlPullParser on Android is an efficient and easy-to-maintain method for parsing XML. Android has two implementation classes in history:

• KXmlParser, via XmlPullParserFactory. newPullParser ().

• ExpatPullParser, via Xml. newPullParser ().

An error occurred when calling nextText () to implement Xml. newPullParser (). nextText () does not always give priority to END_TAG execution.

Therefore, some applications may encounter bugs when calling next () or nextTag ();

throws XmlPullParserException, IOException {      XmlPullParser parser = Xml.newPullParser();      parser.setInput(reader);        parser.nextTag();      parser.require(XmlPullParser.START_TAG, null, "menu");      while (parser.nextTag() == XmlPullParser.START_TAG) {          parser.require(XmlPullParser.START_TAG, null, "item");          String itemText = parser.nextText();          parser.nextTag(); // this call shouldn’t be necessary!          parser.require(XmlPullParser.END_TAG, null, "item");          System.out.println("menu option: " + itemText);      }      parser.require(XmlPullParser.END_TAG, null, "menu");  }    public static void main(String[] args) throws Exception {      new Menu().parseXml(new StringReader("
 "              + "
 
  "              + "  
  
   Waffles
  "              + "  
  
   Coffee
  "              + "
 "));  }

In android4.0, the Xml. newPullParser () returned KxmlParser class is changed and the ExpatPullParser class is deleted. This fixes the nextTag () bug.

Unfortunately, the applications that may crash at present are all earlier than android4.0, and the following is an error message.

org.xmlpull.v1.XmlPullParserException: expected: END_TAG {null}item (position:START_TAG 
 
  @1:37 in java.io.StringReader@40442fa8)        at org.kxml2.io.KXmlParser.require(KXmlParser.java:2046)       at com.publicobject.waffles.Menu.parseXml(Menu.java:25)   at com.publicobject.waffles.Menu.main(Menu.java:32)
 

The solution is to use nextTag () only after nextText () is called. only when the current position is not END_TAG.

while (parser.nextTag() == XmlPullParser.START_TAG) {       parser.require(XmlPullParser.START_TAG, null, "item");       String itemText = parser.nextText();       if (parser.getEventType() != XmlPullParser.END_TAG) {           parser.nextTag();       }       parser.require(XmlPullParser.END_TAG, null, "item");       System.out.println("menu option: " + itemText);   }

The above code can correctly parse all xml versions. if the application uses nextText (), use the following auxiliary method in the nextText () field.

private String safeNextText(XmlPullParser parser)           throws XmlPullParserException, IOException {       String result = parser.nextText();       if (parser.getEventType() != XmlPullParser.END_TAG) {           parser.nextTag();       }       return result;   }

Using a single XmlPullParse simplifies our maintenance and allows us to spend more time tuning system performance.

The above is the content of the XmlPullParser. netText () method. For more information, see The PHP Chinese website (www.php1.cn )!