我一直在尝试在Android上使用SAX解析器来显示一些xml，这是查询数据库的结果。
我从数据库中得到了正确的答案，但是当我想解析xml并将内容转储到Text视图中时，ExampleHandler（ParsedExampleDataSet）返回一个空字符串的Object。我一直试图追踪问题所在，但它让我望而却步。
到目前为止，我知道数据在字符方法中正确解析，我设法将内容打印到日志文件，但我不能在那时返回字符串。
我相信更多经过实验的程序员可以很容易地解决这个问题：
我的xml文件很基本，<body> blablablah </body>。
以下是文件：
package com.ignacio.BilingualSTT;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import android.util.Log;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.ByteArrayBuffer;
import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
public class PostAndGet extends Activity {
private static String Utterance = null;
TextView Title;
TextView Content;
private static final String TAG = "TextToSpeechDemo";
String text;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.en_results);
Title = (TextView)findViewById(R.id.A1_title);
Content= (TextView) findViewById(R.id.A1_content);
text = "";
Bundle b = this.getIntent().getExtras();
if (b !=null){
Utterance = b.getString("query");
}
postData(Utterance);
}
/**
* Handle the action of the Back button
*/
public void sendback(View v)
{
Intent Sendback=new Intent(this, EnglishRecognizer.class);
startActivity(Sendback);
}
/**
* Start HTTP Post call
*/
public void postData(String Utterance){
// Create a new HttpClient and Post Header
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://hcc.cs.clemson.edu/~ignm/ignacio/Android_QueryResults.php");
try {
// Add data to the HTTP Request data has to be named query since the PHP page in the server is expecting that name to run the query on the DB
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("query", Utterance));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
// Execute HTTP Post Request and retrieve answer from PHP side.
HttpResponse response = httpclient.execute(httppost);
InputStream is = response.getEntity().getContent();
BufferedInputStream bis = new BufferedInputStream(is);
ByteArrayBuffer baf = new ByteArrayBuffer(20);
int current = 0;
while((current = bis.read()) != -1){
baf.append((byte)current);
}
// Convert the Bytes read to a String and display it in the Title Container
text = new String(baf.toByteArray());
Title.setText(text);
//Send Text to
parseXML (text);
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
Toast.makeText(this, "Error in the connection", Toast.LENGTH_SHORT).show();
} catch (IOException e) {
// TODO Auto-generated catch block
Toast.makeText(this,"IO Exception error", Toast.LENGTH_SHORT).show();
}
}
public void parseXML (String text){
String AnswerExt = text;
try {
/* Create a URL we want to load some xml-data from. */
URL url = new URL("http://hcc.cs.clemson.edu/~ignm/ignacio/"+AnswerExt.toString());
Log.i(TAG, url.toString());
/* 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. */
Content.setText(parsedExampleDataSet.getExtractedString());
} catch (Exception e) {
/* Display any Error to the GUI. */
Content.setText("Error: " + e.getMessage());
Log.e(TAG, "QueryError", e);
}
}
}
修改了示例Handler以适合我的xml的解析。
package com.ignacio.BilingualSTT;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
public class ExampleHandler extends DefaultHandler{
// ===========================================================
// Fields
// ===========================================================
private boolean bodytag = false;
private static final String TAG = "TextToSpeechDemo";
public ParsedExampleDataSet myParsedExampleDataSet = new ParsedExampleDataSet();
public String myReturnString = null;
// ===========================================================
// 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("body")) {
this.bodytag = true;
}
}
/** Gets be called on closing tags like:
* </tag> */
@Override
public void endElement(String namespaceURI, String localName, String qName)
throws SAXException {
if (localName.equals("body")) {
this.bodytag = false;
}
}
/** Gets be called on the following structure:
* <tag>characters</tag> */
@Override
public void characters(char ch[], int start, int length) {
if(this.bodytag){
myParsedExampleDataSet.setExtractedString(new String(ch, start, length));
//String Temp = myParsedExampleDataSet.getExtractedString();
//Log.i(TAG, Temp);
}
}
}
ParsedExampleDataSet：
package com.ignacio.BilingualSTT;
public class ParsedExampleDataSet {
private String extractedString = "No content yet";
public String getExtractedString() {
return extractedString;
}
public void setExtractedString(String extractedString) {
this.extractedString = extractedString;
}
public String toString(){
return this.extractedString;
}
}
非常感谢你！
答案 0 :(得分：0)
characters方法可以在标记内多次调用，尤其是在元素值包含空格的情况下。
您可能会在Logcat来电中看到这种情况发生了多行打印。
Parser将调用此方法来报告每个字符块 数据。 SAX解析器可以在单个中返回所有连续的字符数据 大块，或者他们可能将它分成几个块;但是，所有的 任何单个事件中的字符必须来自同一个外部实体 以便定位器提供有用的信息。
您应该附加到正在构建的字符串，而不是使用setExtractedString，可能使用StringBuilder。
查看已接受的答案here。