面试必备：Android笔试总结-技术开发专区

面试必备：Android笔试总结

作者：潘玉武编辑：胡铭娅 2011-06-09 17:51 来源：潘玉武博客

　　(2)DOM解析XML文件时，会将XML文件的所有内容读取到内存中，然后允许您使用DOM API遍历XML树、检索所需的数据。

　　DOMPerson.java

import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import com.sinber.domain.Person;
public class DOMPerson {
public static List<Person> getPerson() throws Exception{
List<Person> pers = new ArrayList<Person>();
InputStream inStream = SAXPersonService.class.getClassLoader().getResourceAsStream("person.xml");
DocumentBuilderFactory factory =DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document dom = builder.parse(inStream);
Element root = dom.getDocumentElement();
NodeList persons = root.getElementsByTagName("person");
for(int i=0;i<persons.getLength();i++){ Element personNode =(Element)persons.item(i);
Person person = new Person();
person.setId(new Integer(personNode.getAttribute("id")));
NodeList childNodes = personNode.getChildNodes();
for(int j=0;j<childNodes.getLength();
j++;
{
Node childNode = childNodes.item(j);
if(childNode.getNodeType()==Node.ELEMENT_NODE){
Element element = (Element)childNode;
if("name".equals(childNode.getNodeName())){ person.setName(new String(element.getFirstChild().getNodeValue()));
}else if("age".equals(childNode.getNodeName())){
person.setAge(new Short(element.getFirstChild().getNodeValue()));
}
}
}
pers.add(person);
}
inStream.close();
return pers;
}
}

　　(3)使用Pull解析器读取XML文件

　　PullPerson.java

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlSerializer;
import android.os.Environment;
import android.util.Xml;
import com.sinber.domain.Person;
public class PullPerson {
public static void save(List<Person> persons) throws Exception{
XmlSerializer serializer = Xml.newSerializer();
File file = new File(Environment.getExternalStorageDirectory(),"person.xml");
FileOutputStream outStream = new FileOutputStream(file);
serializer.setOutput(outStream,"UTF-8");
serializer.startDocument("UTF-8", true);
serializer.startTag("", "persons");
for(Person person:persons){
serializer.startTag("", "person"); //person serializer.attribute("", "id", ""+person.getId());
serializer.startTag("", "name"); //name
serializer.text(person.getName());
serializer.endTag("", "name"); //name serializer.startTag("", "age"); //age
serializer.text(person.getAge().toString());
serializer.endTag("", "age");//age serializer.endTag("", "person"); //person
}
serializer.endTag("", "persons");
serializer.endDocument();
outStream.close();
}
public static List<Person> getPersons() throws Exception{
List<Person> persons = null;
Person person = null;
XmlPullParser parser= Xml.newPullParser();
InputStream inStream = PullPersonService.class.getClassLoader().getResourceAsStream("person.xml");
parser.setInput(inStream, "UTF-8");
int eventType = parser.getEventType();
//触发第一个事件
while(eventType!=XmlPullParser.END_DOCUMENT){
switch(eventType){
case XmlPullParser.START_DOCUMENT: persons = new ArrayList<Person>();
break;
case XmlPullParser.START_TAG: //开始元素事件
if("person".equals(parser.getName())){
person = new Person();
person.setId(new Integer(parser.getAttributeValue(0)));
}
else if(person!=null){
if("name".equals(parser.getName())){
person.setName(parser.nextText());
}else if("age".equals(parser.getName())){
person.setAge(new Short(parser.nextText()));
}
} break;
case
XmlPullParser.END_TAG: //结束元素事件
if("person".equals(parser.getName())){
persons.add(person);
person = null;
} break; default: break;
}
eventType = parser.next();
}
return persons;
}

}

　　以上三种方式任选其一即可。

第1页：Android常见的基础问题第2页：解析XML文档问题第3页：SAX读取XML文件问题第4页：使用DOM和Pull解析问题第5页：单链表的逆序问题

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