DOM 解析 XML

DOM(Document Object Model)是一種用於解析XML文檔的對象模型，可直接訪問XML文檔的各部分。
【優點】易於理解，不涉及回調和複雜的狀態管理
【缺點】將XML節點保存在內存中，效率較爲低下
--------------------詳細見《android4.0網絡編程詳解》87頁
使用步驟：
①：針對從XML中獲取到的信息，需對其建立一個對象（例：Person）,存放相關信息
②：創建DocumentBuilderFactory，由該對象可創建DocumentBuilder
③：解析文件獲得包含XML信息的Document對象
④：測試需要，建立一個person.xml文件，內容如下：
<?xml version="1.0" encoding="UTF-8" ?>
<persons>
<person id="23">
<name>Test</name>
<age>21</age>
</person>
</persons> 
⑤：在應用中通過
InputStream is = MainActivity.class.getClassLoader().getResourceAsStream("person.xml");
加載需要解析的文件


【附】：android應用單元測試方法
①：在AndroidManifest.xml中添加節點
<uses-library android:name="android.test.runner" />
<instrumentation android:name="android.test.InstrumentationTestRunner"
        android:targetPackage="cn.gzu.xmlparsertest" />
②：建立測試類繼承AndroidTestCase


【源代碼如下：】
*/
/****************************************【源碼】START**************************************************/

//1.Person.java

public class Person {
	private Integer id;
	private String name;
	private short age;
	
	public Person() {
		super();
	}
	public Person(String name, short age) {
		super();
		this.name = name;
		this.age = age;
	}
	public Person(Integer id, String name, short age) {
		super();
		this.id = id;
		this.name = name;
		this.age = age;
	}
	// getter and setter ...
}


//2.DomParserService.java
public class DomParserService {
	/** DOM 解析Xml文檔 */
	public static List<Person> getPersons(InputStream is) throws Exception{
		List<Person> persons = new ArrayList<Person>();
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		DocumentBuilder builder = factory.newDocumentBuilder();
		Document document = builder.parse(is);
		
		Element root = document.getDocumentElement();
		
		NodeList personsNodes = root.getElementsByTagName("person");
		
		for(int i=0;i<personsNodes.getLength();i++){
			Element personElement = (Element) personsNodes.item(i);
			int id = Integer.valueOf(personElement.getAttribute("id"));
			Person person = new Person();
			
			person.setId(id);
			NodeList childNodes = personElement.getChildNodes();
			for(int j=0;j<childNodes.getLength();j++){
				if(childNodes.item(j).getNodeType() == Node.ELEMENT_NODE){
					if("name".equals(childNodes.item(j).getNodeName())){
						person.setName(childNodes.item(j).getFirstChild().getNodeValue());
					}else if("age".equals(childNodes.item(j).getNodeName())){
						person.setAge(new Short(childNodes.item(j).getFirstChild().getNodeValue()));
					}
				}
			}
			persons.add(person);
		}
		is.close();
		return persons;
	}
}



//3.單元測試類 SAXParserTest.java
public class SAXParserTest extends AndroidTestCase {
	private static final String TAG = "SAXParserTest";
	
	public void testDOMGetPerson() throws Throwable{
		InputStream is = this.getClass().getClassLoader().getResourceAsStream("person.xml");
		List<Person> persons = DomParserService.getPersons(is);
		String text = "";
		for(Person p:persons){
			text = text + "ID: "+p.getId()+" Name: "+p.getName()+" Age: "+p.getAge()+"\n";
		}
		Log.i(TAG, text);
	}
}




//4.MainActivity.java
public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		TextView main = (TextView) findViewById(R.id.main_content);
		
		InputStream is = MainActivity.class.getClassLoader().getResourceAsStream("person.xml");
		try {
			List<Person> persons = testDOM(is);
			String text = "";
			for(Person p:persons){
				text = text + "ID: "+p.getId()+" Name: "+p.getName()+" Age: "+p.getAge()+"\n";
			}
			main.setText(text);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	private List<Person> testDOM(InputStream is) throws Exception{
		return DomParserService.getPersons(is);
	}
	
}

//6.AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="cn.gzu.xmlparsertest"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <uses-library android:name="android.test.runner" />
        
        <activity
            android:name="cn.gzu.xmlparsertest.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>
    
    <instrumentation android:name="android.test.InstrumentationTestRunner"
        android:targetPackage="cn.gzu.xmlparsertest" />

</manifest>

/****************************************【源碼】END**************************************************/