利用sax解析器解析xml文件

在android中有三种解析xml文件的方式，一种是dom解析xml，一种是sax解析xml，第三种是pull解析xml文件,第一种方式要将整个文件以树的方式读入内存，由于移动设备的内存有限，效率不高，所以很少使用，主要用到的是后两种，这篇文章主要是sax解析xml文件的详解。

我们先看项目代码：

1、先给出要解析的xml文件jindegege.xml

<?xml version="1.0" encoding="UTF-8"?>
<persons>
<person id="02">
<name>jindegege</name>
<age>28</age>
</person>
<person id="10">
<name>liubiyu</name>
<age>27</age>
</person>
</persons>

2、给出业务类SAXPersonService.java

import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import cn.itcast.domain.Person;
/**
 * 采用SAX解析XML内容
 */
public class SAXPersonService {
	
	public List<Person> getPersons(InputStream inStream)throws Exception{
		SAXParserFactory factory = SAXParserFactory.newInstance();
		SAXParser parser = factory.newSAXParser();
		PersonParser personParser =new PersonParser();
		parser.parse(inStream, personParser);
		return personParser.getPersons();
	}
	private final class PersonParser extends DefaultHandler{
		private List<Person> persons = null;
		private String tag =null;
		private Person person = null;
		 
		public List<Person> getPersons(){
			return persons;
		}

		


		@Override
		public void startDocument() throws SAXException {
			persons=new ArrayList<Person>();
		}

		@Override
		public void startElement(String uri, String localName, String qName,
				Attributes attributes) throws SAXException {
			if("person".equals(localName)){
				person=new Person();
				person.setId(new Integer(attributes.getValue(0)));
			}
			tag=localName;
		}
		@Override
		public void characters(char[] ch, int start, int length)
				throws SAXException {
			if(tag!=null){
				String data = new String(ch,start,length);
				if("name".equals(tag)){
					person.setName(data);
				}else if("age".equals(tag)){
					person.setAge(new Short(data));
				}
			}
		}


		@Override
		public void endElement(String uri, String localName, String qName)
				throws SAXException {
			if("person".equals(localName)){
				persons.add(person);
				person=null;
				}
			tag=null;
		}
		
	}

}

3、给出单元测试类

PersonServiceTest

必须继承AndroidTestCase类

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;

import cn.itcast.domain.Person;
import cn.itcast.service.DOMPersonService;
import cn.itcast.service.PULLPersonService;
import cn.itcast.service.SAXPersonService;
import android.content.Context;
import android.test.AndroidTestCase;
import android.util.Log;

public class PersonServiceTest extends AndroidTestCase {
	private static final String TAG = "PersonServiceTest";

	public void testSAXGetPersons() throws Throwable{
		SAXPersonService service = new SAXPersonService();
		InputStream inStream = getClass().getClassLoader().getResourceAsStream("jindegege.xml");
		List<Person> persons = service.getPersons(inStream);
		for(Person person : persons){
			Log.i(TAG, person.toString());    
		}
	
	}
        public void testSave() throws Throwable{
		List<Person> persons = new ArrayList<Person>();
		persons.add(new Person(51, "liudehua", (short)12));
		persons.add(new Person(58, "成龙", (short)32));
		StringWriter writer = new StringWriter();
		PULLPersonService.save(persons, writer);
		Log.i(TAG, writer.toString());
	}
     }

4、这里因为我们建立了单元测试类，所以需要在android manifest文件中添加 

<instrumentation android:name="android.test.InstrumentationTestRunner"
  android:targetPackage="com.cn" android:label="Tests for My App" />

给出代码：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.cn"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
         <uses-library android:name="android.test.runner" />
        <activity android:name=".MainActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>


    </application>
    <uses-sdk android:minSdkVersion="8" />
<instrumentation android:name="android.test.InstrumentationTestRunner"
  android:targetPackage="com.cn" android:label="Tests for My App" />
</manifest> 

5、运行单元测试方法testSAXGetPersons()

并设置好过滤器，在logcat上的结果如下：