我有一个自定义的 contentHandler（称为 XMLHandler），我通过 Google 和 StackOverflow 访问过很多网站，详细说明了如何设置它。
我不明白的是如何使用它。
Xml.parse(...,...) 什么也不返回，因为它是一个 void 方法。
如何访问已解析的 XML 数据？
我意识到这个问题可能是微不足道的，但我一直在寻找（字面意思）几个小时，但没有找到解决方案。
请帮忙。
String result = fetchData(doesntmatter);
Xml.parse(result, new XMLHandler());
【问题讨论】：
这是一个例子，希望对理解“SAXParser”有所帮助
package test.example;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
public class XMLParsingDemo extends Activity {
private final String MY_DEBUG_TAG = "WeatherForcaster";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
/* Create a new TextView to display the parsingresult later. */
TextView tv = new TextView(this);
try {
/* Create a URL we want to load some xml-data from. */
DefaultHttpClient hc = new DefaultHttpClient();
ResponseHandler <String> res = new BasicResponseHandler();
HttpPost postMethod = new HttpPost("http://www.anddev.org/images/tut/basic/parsingxml/example.xml");
String response=hc.execute(postMethod,res);
/* Get a SAXParser from the SAXPArserFactory. */
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
/* Get the XMLReader of the SAXParser we created. */
XMLReader xr = sp.getXMLReader();
/* Create a new ContentHandler and apply it to the XML-Reader*/
ExampleHandler myExampleHandler = new ExampleHandler();
xr.setContentHandler(myExampleHandler);
/* Parse the xml-data from our URL. */
InputSource inputSource = new InputSource();
inputSource.setEncoding("UTF-8");
inputSource.setCharacterStream(new StringReader(response));
/* Parse the xml-data from our URL. */
xr.parse(inputSource);
/* Parsing has finished. */
/* Our ExampleHandler now provides the parsed data to us. */
ParsedExampleDataSet parsedExampleDataSet = myExampleHandler.getParsedData();
/* Set the result to be displayed in our GUI. */
tv.setText(response + "\n\n\n***************************************" + parsedExampleDataSet.toString());
} catch (Exception e) {
/* Display any Error to the GUI. */
tv.setText("Error: " + e.getMessage());
Log.e(MY_DEBUG_TAG, "WeatherQueryError", e);
}
/* Display the TextView. */
this.setContentView(tv);
}
public class ExampleHandler extends DefaultHandler {
// ===========================================================
// Fields
// ===========================================================
private boolean in_outertag = false;
private boolean in_innertag = false;
private boolean in_mytag = false;
private ParsedExampleDataSet myParsedExampleDataSet = new ParsedExampleDataSet();
// ===========================================================
// Getter & Setter
// ===========================================================
public ParsedExampleDataSet getParsedData() {
return this.myParsedExampleDataSet;
}
// ===========================================================
// Methods
// ===========================================================
@Override
public void startDocument() throws SAXException {
this.myParsedExampleDataSet = new ParsedExampleDataSet();
}
@Override
public void endDocument() throws SAXException {
// Nothing to do
}
/** Gets be called on opening tags like:
* <tag>
* Can provide attribute(s), when xml was like:
* <tag attribute="attributeValue">*/
@Override
public void startElement(String uri, String localName, String qName, org.xml.sax.Attributes atts) throws SAXException {
super.startElement(uri, localName, qName, atts);
if (localName.equals("outertag")) {
this.in_outertag = true;
}
else if (localName.equals("innertag")) {
String attrValue = atts.getValue("sampleattribute");
myParsedExampleDataSet.setExtractedString(attrValue);
this.in_innertag = true;
}
else if (localName.equals("mytag")) {
this.in_mytag = true;
}
else if (localName.equals("tagwithnumber")) {
// Extract an Attribute
String attrValue = atts.getValue("thenumber");
int i = Integer.parseInt(attrValue);
myParsedExampleDataSet.setExtractedInt(i);
}
}
/** Gets be called on closing tags like:
* </tag> */
@Override
public void endElement(String namespaceURI, String localName, String qName)
throws SAXException {
if (localName.equals("outertag")) {
this.in_outertag = false;
}else if (localName.equals("innertag")) {
this.in_innertag = false;
}else if (localName.equals("mytag")) {
this.in_mytag = false;
}else if (localName.equals("tagwithnumber")) {
// Nothing to do here
}
}
/** Gets be called on the following structure:
* <tag>characters</tag> */
@Override
public void characters(char ch[], int start, int length) {
if(this.in_mytag){
myParsedExampleDataSet.setExtractedString(new String(ch));
}
}
}
public class ParsedExampleDataSet {
private String extractedString = null;
private int extractedInt = 0;
public String getExtractedString() {
return extractedString;
}
public void setExtractedString(String extractedString) {
this.extractedString = extractedString;
}
public int getExtractedInt() {
return extractedInt;
}
public void setExtractedInt(int extractedInt) {
this.extractedInt = extractedInt;
}
public String toString(){
return "\n\n\nExtractedString = " + this.extractedString
+ "\n\n\nExtractedInt = " + this.extractedInt;
}
}
}
【讨论】：
您必须将您的 XML 数据访问到您由 XMLHandler()
定义的处理程序中你必须重写
public void startElement(String uri, String localName, String qName, org.xml.sax.Attributes atts) throws SAXException {
}
@Override
public void endElement(String namespaceURI, String localName, String qName) {
}
和
@Override
public void characters(char ch[], int start, int length) {
}
【讨论】：