Getting started with Android: parsing XML with pull

Document directory

• Application: Create the person. xml file mentioned above to/data/package/files.

I. Introduction to pull parser

Pull Parsing is similar to sax \ Dom and is used to parse XML;

Ii. Use the pull parser to read XML data

The template code is as follows:

Xmlpullparser parser = xml. newpullparser (); // create a pull parser. setinput (in, "UTF-8"); // The read encoding is UTF-8int event = parser. geteventtype (); // call while (event! = Xmlpullparser. end_document) {// parser. getname (); // obtain the name of the tag to which the current tag is directed. // parser. getattributevalue (0); // obtain the 1st attribute values of the current tag. // parser. nexttext (); // obtain the tag value of the current tag switch (event) {Case xmlpullparser. start_document: // if it points to start_document // process break; Case xmlpullparser. start_tag: // if it is directed to start_tag // process break; Case xmlpullparser. end_tag: // if it points to end_tag // process break;} event = parser. next (); // point to the next tag}

Application: Read the person. xml file in the/data/package/files/directory.

The XML file is as follows:

<?xml version="1.0" encoding="UTF-8"?><persons>    <person id="1">        <name>xiazdong-1</name>        <age>20</age>    </person>    <person id="2">        <name>xiazdong-2</name>        <age>30</age>    </person></persons>

As shown above, <person> </person> can be considered as a JavaBean, while <persons> </persons> forms a person queue;

Therefore, we create a person JavaBean:

package org.xiazdong.vo;public class Person {private int id;private String name;private int age;public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public Person(int id, String name, int age) {this.id = id;this.name = name;this.age = age;}public Person() {}@Overridepublic String toString() {return "Person [id=" + id + ", name=" + name + ", age=" + age + "]";}}

Next, we will write the following readxml method to convert the data in the XML file into a person queue;

Public class xmlservice {public list <person> readxml (inputstream in) throws exception {xmlpullparser parser = xml. newpullparser (); parser. setinput (in, "UTF-8"); List <person> List = NULL; person = NULL; int event = parser. geteventtype (); // start parsing and obtain the event/** optional events include: * (1) start_document * (2) end_document * (3) start_tag * (4) end_tag **/while (event! = Xmlpullparser. end_document) {Switch (event) {Case xmlpullparser. start_document: List = new arraylist <person> (); break; Case xmlpullparser. start_tag: If ("person ". equals (parser. getname () {person = new person (); int id = integer. parseint (parser. getattributevalue (0); person. setid (ID);} If ("name ". equals (parser. getname () {person. setname (parser. nexttext ();} If ("age ". equals (parser. getname () {person. setage (integer. parseint (parser. nexttext ();} break; Case xmlpullparser. end_tag: If ("person ". equals (parser. getname () list. add (person); break;} event = parser. next (); // read the next} return list ;}}

After writing this method, we can test this method:

public class XmlTest extends AndroidTestCase{private static final String TAG = "XmlTest";public void testRead() throws Exception{XmlService service = new XmlService();List<Person> list = service.readXml(this.getContext().openFileInput("person.xml"));Log.i(TAG, String.valueOf(list.size()));for(Person p:list){Log.i(TAG, p.toString());}}}

The running effect is as follows:

3. Use the serializer parser to write XML files

The core code is as follows:

Xmlserializer serializer = xml. newserializer (); // create a serializer parser serializer. setoutput (Out, "UTF-8"); // set the encoding of the output stream and output to UTF-8serializer.startDocument ("UTF-8", true); // output start document <? XML version = "1.0" encoding = "UTF-8" standalone = "true"?> Serializer. starttag (null, "tagname"); // output <tagname> serializer. attribute (null, "name", "value"); // output <tagname = "value"> serializer. text ("value"); // output <tagname> </tagname> serializer. endtag (null, "tagname"); // end label serializer. enddocument (); // end document

Application: Create the person. xml file mentioned above to/data/package/files. The following code is used to write the person queue to the output stream file (this is the file output stream)

public class XmlService {public void writeXml(List<Person> list,OutputStream out)throws Exception{XmlSerializer serializer = Xml.newSerializer();serializer.setOutput(out, "UTF-8");serializer.startDocument("UTF-8", true);serializer.startTag(null, "persons");for(Person p:list){serializer.startTag(null,"person");serializer.attribute(null, "id", String.valueOf(p.getId()));serializer.startTag(null, "name");serializer.text(p.getName());serializer.endTag(null, "name");serializer.startTag(null, "age");serializer.text(p.getAge()+"");serializer.endTag(null, "age");serializer.endTag(null, "person");}serializer.endTag(null, "persons");serializer.endDocument();out.flush();out.close();}}

The test code is as follows:

public class XmlTest extends AndroidTestCase{public void testWrite()throws Exception{XmlService service = new XmlService();List<Person> list = new ArrayList<Person>();for(int i=0;i<3;i++){Person p = new Person();p.setId(i);p.setName("xiazdong-"+i);p.setAge(20+i);list.add(p);}OutputStream out = this.getContext().openFileOutput("person.xml", Context.MODE_PRIVATE);service.writeXml(list, out);}}

Conclusion: Use the pull parser to read data and use serializer to write data;