Android 創建與解析XML（三）—— Sax方式

1. Sax概述

SAX是一種佔用內存少且解析速度快的解析器，它採用的是事件啓動，不需要解析完整個文檔，而是按照內容順序看文檔某個部分是否符合xml語法，如果符合就觸發相應的事件，所謂的事件就是些回調方法（callback），這些方法 定義在ContentHandler中，下面是其主要方法：
startDocument（）：當遇到文檔的時候就觸發這個事件 調用這個方法 可以在其中做些預處理工作，如：申請對象資源

endDocument（）：當結束文檔的時候就觸發這個事件 調用這個方法 可以在其中做些善後工作，如：釋放申請的對象資源
startElement（String namespaceURI, String localName, String qName, Attributes atts）：當遇開始標籤的時候就會觸發這個方法。
endElement（String uri, String localName, String name）：當遇到結束標籤時觸發這個事件，調用此法可以做些善後工作。
charachers（char [] ch, int start, int length）：當遇到xml內容時觸發這個方法，用new String(ch,start,length)可以接受內容。 

Sax方式創建XML，應用了標準xml構造器 javax.xml.transform.sax.TransformerHandler 事件來創建 XML 文檔，需要導入以下內容

javax.xml.transform

javax.xml.transform.sax.SAXTransformerFactory;

javax.xml.transform.sax.TransformerHandler;

javax.xml.transform.Transformer;

javax.xml.transform.TransformerConfigurationException;

javax.xml.transform.TransformerFactoryConfigurationError;

javax.xml.transform.OutputKeys;
javax.xml.transform.stream.StreamResult;

javax.xml.transform.sax.SAXTransformerFactory;

javax.xml.parsers

javax.xml.parsers.SAXParser;

javax.xml.parsers.SAXParserFactory;

javax.xml.parsers.FactoryConfigurationError;

javax.xml.parsers.ParserConfigurationException;

org.xml.sax

org.xml.sax.Attributes;

org.xml.sax.SAXException;
org.xml.sax.helpers.AttributesImpl;

org.xml.sax.helpers.DefaultHandler;

sdk源碼查看路徑（google code）

Sax 創建和解析 XML 的效果圖：

2、Sax 創建 XML

首先，SAXTransformerFactory.newInstance() 創建一個工廠實例 factory

接着，factory.newTransformerHandler() 獲取 TransformerHandler 的 handler 對象

然後，通過 handler 事件創建handler.getTransformer()、 handler.setResult(result)，以及 startDocument()、startElement、characters、endElement、endDocument()等

Code

/** Sax方式，創建 XML  */
public String saxCreateXML(){
    StringWriter xmlWriter = new StringWriter();

    Person []persons = new Person[3];       // 創建節點Person對象
    persons[0] = new Person(1, "sunboy_2050", "http://blog.csdn.net/sunboy_2050");
    persons[1] = new Person(2, "baidu", "http://www.baidu.com");
    persons[2] = new Person(3, "google", "http://www.google.com");

    try {
        SAXTransformerFactory factory = (SAXTransformerFactory)SAXTransformerFactory.newInstance();
        TransformerHandler handler = factory.newTransformerHandler();

        Transformer transformer = handler.getTransformer();     // 設置xml屬性
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
        transformer.setOutputProperty(OutputKeys.ENCODING, "utf-8");
        transformer.setOutputProperty(OutputKeys.VERSION, "1.0");

        StreamResult result = new StreamResult(xmlWriter);      // 保存創建的xml
        handler.setResult(result);

        handler.startDocument();
        AttributesImpl attr = new AttributesImpl();

        attr.clear();
        attr.addAttribute("", "", "author", "", "homer");
        attr.addAttribute("", "", "date", "", "2012-04-27");
        handler.startElement("", "", "root", attr);

        int personsLen = persons.length;
        for(int i=0; i<personsLen; i++){
            attr.clear();
            handler.startElement("", "", "person", attr);

            attr.clear();
            handler.startElement("", "", "id", attr);
            String id = persons[i].getId() + "";
            handler.characters(id.toCharArray(), 0, id.length());
            handler.endElement("", "", "id");

            attr.clear();
            handler.startElement("", "", "name", attr);
            String name = persons[i].getName();
            handler.characters(name.toCharArray(), 0, name.length());
            handler.endElement("", "", "name");

            attr.clear();
            handler.startElement("", "", "blog", attr);
            String blog = persons[i].getBlog();
            handler.characters(blog.toCharArray(), 0, blog.length());
            handler.endElement("", "", "blog");

            handler.endElement("", "", "person");
        }

        handler.endElement("", "", "root");
        handler.endDocument();

    } catch (TransformerFactoryConfigurationError e) {      // SAXTransformerFactory.newInstance
        e.printStackTrace();
    } catch (TransformerConfigurationException e) {         // factory.newTransformerHandler
        e.printStackTrace();
    } catch (IllegalArgumentException e) {      // transformer.setOutputProperty
        e.printStackTrace();
    } catch (SAXException e) {      // handler.startDocument
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }

    savedXML(fileName, xmlWriter.toString());
    return xmlWriter.toString();
}

	/** Sax方式，創建 XML  */
	public String saxCreateXML(){
		StringWriter xmlWriter = new StringWriter();

		Person []persons = new Person[3];		// 創建節點Person對象
		persons[0] = new Person(1, "sunboy_2050", "http://blog.csdn.net/sunboy_2050");
		persons[1] = new Person(2, "baidu", "http://www.baidu.com");
		persons[2] = new Person(3, "google", "http://www.google.com");
		
		try {
			SAXTransformerFactory factory = (SAXTransformerFactory)SAXTransformerFactory.newInstance();
			TransformerHandler handler = factory.newTransformerHandler();
			
			Transformer transformer = handler.getTransformer();		// 設置xml屬性
			transformer.setOutputProperty(OutputKeys.INDENT, "yes");
			transformer.setOutputProperty(OutputKeys.ENCODING, "utf-8");
			transformer.setOutputProperty(OutputKeys.VERSION, "1.0");
			
			StreamResult result = new StreamResult(xmlWriter);		// 保存創建的xml
			handler.setResult(result);
			
			handler.startDocument();
			AttributesImpl attr = new AttributesImpl();
			
			attr.clear();
			attr.addAttribute("", "", "author", "", "homer");
			attr.addAttribute("", "", "date", "", "2012-04-27");
			handler.startElement("", "", "root", attr);
			
			int personsLen = persons.length;
			for(int i=0; i<personsLen; i++){
				attr.clear();
				handler.startElement("", "", "person", attr);
				
				attr.clear();
				handler.startElement("", "", "id", attr);
				String id = persons[i].getId() + "";
				handler.characters(id.toCharArray(), 0, id.length());
				handler.endElement("", "", "id");

				attr.clear();
				handler.startElement("", "", "name", attr);
				String name = persons[i].getName();
				handler.characters(name.toCharArray(), 0, name.length());
				handler.endElement("", "", "name");

				attr.clear();
				handler.startElement("", "", "blog", attr);
				String blog = persons[i].getBlog();
				handler.characters(blog.toCharArray(), 0, blog.length());
				handler.endElement("", "", "blog");
				
				handler.endElement("", "", "person");
			}
			
			handler.endElement("", "", "root");
			handler.endDocument();
			
		} catch (TransformerFactoryConfigurationError e) {		// SAXTransformerFactory.newInstance
			e.printStackTrace();
		} catch (TransformerConfigurationException e) {			// factory.newTransformerHandler
			e.printStackTrace();
		} catch (IllegalArgumentException e) {		// transformer.setOutputProperty
			e.printStackTrace();
		} catch (SAXException e) {		// handler.startDocument
			e.printStackTrace();
		} catch (Exception e) {
			e.printStackTrace();
		}
		
		savedXML(fileName, xmlWriter.toString());
		return xmlWriter.toString();
	}

運行結果：

3、Sax解析XML

Code

    /** Sax方式，解析 XML  */
    public String saxResolveXML(){
        StringWriter xmlWriter = new StringWriter();

        InputStream is = readXML(fileName);
        try {
            SAXParserFactory factory = SAXParserFactory.newInstance();
            SAXParser saxParser = factory.newSAXParser();

            PersonHandler handler = new PersonHandler();    // person處理Handler
            saxParser.parse(is, handler);                   // handler解析xml

            // 獲取解析的xml
            String xmlHeader = handler.getXMLHeader();
            xmlWriter.append(xmlHeader);

            List<Person> personsList = handler.getPersons();
            int personsLen = personsList.size();
            for(int i=0; i<personsLen; i++){
                xmlWriter.append(personsList.get(i).toString()).append("\n");
            }

        } catch (FactoryConfigurationError e) {         // SAXParserFactory.newInstance
            e.printStackTrace();
        } catch (ParserConfigurationException e) {      // factory.newSAXParser
            e.printStackTrace();
        } catch (SAXException e) {          // factory.newSAXParser
            e.printStackTrace();
        } catch (IllegalArgumentException e) {      // saxParser.parse
            e.printStackTrace();
        } catch (IOException e) {           // saxParser.parse
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return xmlWriter.toString();
    }

    /** Handler處理類 */
    private final class PersonHandler extends DefaultHandler{
        private List<Person> personsList = null;  // 保存person
        private Person person = null;
        private StringBuffer xmlHeader;             // 保存xml頭部信息
        private String tag = null;          // xml Element

        /** 返回解析的xml頭部信息 */
        public String getXMLHeader(){
            return xmlHeader.toString();
        }

        /** 返回解析的Person實例數組 */
        public List<Person> getPersons(){
            return personsList;
        }

        @Override
        public void startDocument() throws SAXException{
            super.startDocument();
            personsList = new ArrayList<Person>();
            xmlHeader = new StringBuffer();
        }

        @Override
        public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException{
            super.startElement(uri, localName, qName, attributes);
            if("root".equals(localName)) {
                String attrAuthor = attributes.getValue(0);
                String attrDate = attributes.getValue(1);
                xmlHeader.append("root").append("\t\t");
                xmlHeader.append(attrAuthor).append("\t");
                xmlHeader.append(attrDate).append("\n");
            } else if("person".equals(localName)) {
                person = new Person();
            }
            tag = localName;
        }

        @Override
        public void characters(char[] ch, int start, int length) throws SAXException {
            super.characters(ch, start, length);
            if (null != tag) {
                String value = new String(ch, start, length);
                System.out.println("value = " + value);
                if ("id".equals(tag)) {
                    person.setId(new Integer(value));
                } else if ("name".equals(tag)) {
                    person.setName(value);
                } else if ("blog".equals(tag)) {
                    person.setBlog(value);
                }
            }
        }

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

        @Override
        public void endDocument() throws SAXException{
//          personsList = null;
            super.endDocument();
        }
    }

	/** Sax方式，解析 XML  */
	public String saxResolveXML(){
		StringWriter xmlWriter = new StringWriter();

		InputStream is = readXML(fileName);
		try {
			SAXParserFactory factory = SAXParserFactory.newInstance();
			SAXParser saxParser = factory.newSAXParser();
			
			PersonHandler handler = new PersonHandler();	// person處理Handler
			saxParser.parse(is, handler);					// handler解析xml
			
			// 獲取解析的xml
			String xmlHeader = handler.getXMLHeader();
			xmlWriter.append(xmlHeader);
			
			List<Person> personsList = handler.getPersons();
			int personsLen = personsList.size();
			for(int i=0; i<personsLen; i++){
				xmlWriter.append(personsList.get(i).toString()).append("\n");
			}
			
		} catch (FactoryConfigurationError e) {			// SAXParserFactory.newInstance
			e.printStackTrace();
		} catch (ParserConfigurationException e) {		// factory.newSAXParser
			e.printStackTrace();
		} catch (SAXException e) {			// factory.newSAXParser
			e.printStackTrace();
		} catch (IllegalArgumentException e) {		// saxParser.parse
			e.printStackTrace();
		} catch (IOException e) {			// saxParser.parse
			e.printStackTrace();
		} catch (Exception e) {
			e.printStackTrace();
		}
		
		return xmlWriter.toString();
	}
	
	/** Handler處理類 */
	private final class PersonHandler extends DefaultHandler{
		private List<Person> personsList = null;	// 保存person
		private Person person = null;
		private StringBuffer xmlHeader;				// 保存xml頭部信息
		private String tag = null;			// xml Element
		
		/** 返回解析的xml頭部信息 */
		public String getXMLHeader(){
			return xmlHeader.toString();
		}
		
		/** 返回解析的Person實例數組 */
		public List<Person> getPersons(){
			return personsList;
		}
		
		@Override
		public void startDocument() throws SAXException{
			super.startDocument();
			personsList = new ArrayList<Person>();
			xmlHeader = new StringBuffer();
		}
		
		@Override
		public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException{
			super.startElement(uri, localName, qName, attributes);
			if("root".equals(localName)) {
				String attrAuthor = attributes.getValue(0);
				String attrDate = attributes.getValue(1);
				xmlHeader.append("root").append("\t\t");
				xmlHeader.append(attrAuthor).append("\t");
				xmlHeader.append(attrDate).append("\n");
			} else if("person".equals(localName)) {
				person = new Person();
			} 
			tag = localName;
		}
		
		@Override
		public void characters(char[] ch, int start, int length) throws SAXException {
			super.characters(ch, start, length);
			if (null != tag) {
				String value = new String(ch, start, length);
				System.out.println("value = " + value);
				if ("id".equals(tag)) {
					person.setId(new Integer(value));
				} else if ("name".equals(tag)) {
					person.setName(value);
				} else if ("blog".equals(tag)) {
					person.setBlog(value);
				}
			}
		}
		
		@Override
		public void endElement(String uri, String localName, String qName) throws SAXException {
			if("person".equals(qName)) {
				personsList.add(person);
				person = null;
			}
			tag = null;
			super.endElement(uri, localName, qName);
		}
		
		@Override
		public void endDocument() throws SAXException{
//			personsList = null;
			super.endDocument();
		}
	}

運行結果：

4、Person類

請參見前面博客 Android 創建與解析XML（二）—— Dom方式 【4、Person類】

代碼下載

參考推薦：

javax.xml.transform.sax

javax.xml.parsers

org.xml.sax

TransformerHandler

sax創建xml

Android 解析XML 之SAX