使用 SAXparser 获取多个元素的信息 (Android)

Question

我是 Android 新手（也是 Java 新手），但现在我开始使用 Web 服务。

为了更好地理解如何解析 XML，我开始尝试这个教程：

http://www.anddev.org/novice-tutorials-f8/parsing-xml-from-the-net-using-the-saxparser-t353.html

使用本示例中使用的 XML：

<outertag>
<innertag sampleattribute="innertagAttribute">
<mytag>anddev.org rulez =)</mytag>
<tagwithnumber thenumber="1337"/>
</innertag>
</outertag>

我了解它是如何工作的（我猜），但是如果 XML 是这样的：

<outertag>
<innertag sampleattribute="innertagAttribute">
<mytag>anddev.org rulez =)</mytag>
<tagwithnumber thenumber="1337"/>
</innertag>
<innertag sampleattribute="innertagAttribute2">
<mytag>something</mytag>
<tagwithnumber thenumber="14214"/>
</innertag>
</outertag>

应用程序的类需要改变什么来获取各个元素的数据？

我很感激任何建议...

完整源代码：

• ParseXML.java

  包org.anddev.android.parsingxml；

  导入 java.net.URL;

  导入 javax.xml.parsers.SAXParser; 导入 javax.xml.parsers.SAXParserFactory;

  导入 org.xml.sax.InputSource; 导入 org.xml.sax.XMLReader;

  导入android.app.Activity； 导入android.os.Bundle； 导入android.util.Log； 导入android.widget.TextView；

  公共类 ParsingXML 扩展 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. */
          URL url = new URL("http://www.anddev.org/images/tut/basic/parsingxml/example.xml");
  
          /* 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. */
          xr.parse(new InputSource(url.openStream()));
          /* 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(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);
  }
  

  }

• 示例处理程序

  包org.anddev.android.parsingxml；

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

  公共类 ExampleHandler 扩展 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 namespaceURI, String localName,
          String qName, Attributes atts) throws SAXException {
      if (localName.equals("outertag")) {
          this.in_outertag = true;
      }else if (localName.equals("innertag")) {
          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, start, length));
      }
  }
  

  }

• ParsedExampleDataSet

  包org.anddev.android.parsingxml；

  公共类 ParsedExampleDataSet { 私有字符串提取字符串 = null; private int extractInt = 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 "ExtractedString = " + this.extractedString
              + "nExtractedInt = " + this.extractedInt;
  }
  

  }

Answer 1

问题解决了！

以下是提供有用信息的网站：

• https://stackoverflow.com/a/4828765
• https://stackoverflow.com/a/5709544
• http://as400samplecode.blogspot.com/2011/11/android-parse-xml-file-example-using.html
• http://www.anddev.org/novice-tutorials-f8/parsing-xml-from-the-net-using-the-saxparser-t353.html

我最初的问题是如何为要从 XML 中提取的数据定义类。在我弄清楚我应该怎么做之后（回顾 JAVA 编程的基本概念），我将 ExampleHandler 返回的数据类型更改为 ArrayList。

下面我举个例子：

• 您要解析的 XML 示例：

  <outertag>
  <cartag type="Audi">
      <itemtag name="model">A4</itemtag>
      <itemtag name="color">Black</itemtag>
      <itemtag name="year">2005</itemtag>
  </cartag>
  <cartag type="Honda">
      <itemtag name="model">Civic</itemtag>
      <itemtag name="color">Red</itemtag>
      <itemtag name="year">2001</itemtag>
   </cartag>
   <cartag type="Seat">
      <itemtag name="model">Leon</itemtag>
      <itemtag name="color">White</itemtag>
      <itemtag name="year">2009</itemtag>
   </cartag>
   </outertag>
  

所以在这里你应该定义一个具有适当属性（字符串类型、型号、颜色、年份；）、setter 和 getter 的类“car”...

• 我对这个 XML 的 ExampleHandler 的建议是：

公共类 ExampleHandler 扩展 DefaultHandler{

// ===========================================================
// Fields
// ===========================================================

private int numberOfItems=3;    
private boolean in_outertag = false;
private boolean in_cartag = false;
private boolean[] in_itemtag = new boolean[numberOfItems];

Car newCar = new Car(); 

private ArrayList<Car> list = new ArrayList<Car>(); 

// ===========================================================
// Getter & Setter
// ===========================================================

public ArrayList<Car> getParsedData() {
    return this.list;
}

// ===========================================================
// Methods
// ===========================================================
@Override
public void startDocument() throws SAXException {
    this.list = new ArrayList<Car>();
}

@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 namespaceURI, String localName,
        String qName, Attributes atts) throws SAXException {
    if (localName.equals("outertag")) {
        this.in_outertag = true;
    }else if (localName.equals("cartag")) {
        this.in_cartag = true;
        newCar.setType(atts.getValue("type"));  //setType(...) is the setter defined in car class
    }else if (localName.equals("itemtag")) {
        if((atts.getValue("name")).equals("model")){
            this.in_itemtag[0] = true;
        }else if((atts.getValue("name")).equals("color")){
            this.in_itemtag[1] = true;
        }else if((atts.getValue("name")).equals("year")){
            this.in_itemtag[2] = true;
        }
    }
}

/** 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("cartag")) {
        this.in_cartag = false;
        Car carTemp = new Car();
        carTemp.copy(newCar, carTemp);  //this method is defined on car class, and is used to copy the
                                        //properties of the car to another Object car to be added to the list
        list.add(carTemp);
    }else if (localName.equals("itemtag")){
        if(in_itemtag[0]){
            this.in_itemtag[0] = false;
        }else if(in_itemtag[1]){
            this.in_itemtag[1] = false;
        }else if(in_itemtag[2]){
            this.in_itemtag[2] = false;
        }
    }
}

/** Gets be called on the following structure: 
 * <tag>characters</tag> */
@Override
public void characters(char ch[], int start, int length) {

    if(in_itemtag[0]){
        newCar.setModel(new String(ch, start, length));
    }else if(in_itemtag[1]){
        newCar.setColor(new String(ch, start, length));
    }else if(in_itemtag[2]){
        newCar.setYear(new String(ch, start, length));
    }
}

}

在此之后，您可以使用以下方式在Activity中获取解析后的数据：

...
ArrayList<Car> ParsedData = myExampleHandler.getParsedData();
...

我希望这对某人有所帮助。

注意：我没有完全这样测试过，但与我的解决方案几乎相同，所以它应该可以工作......

对不起，我的英语不好......