我已经编写了用于解析和显示 xml 文件中的数据的代码。但它不起作用。它在我的主要活动中显示错误。AndroidXMLParsingActivity：
package com.androidhive.xmlparsing;
import java.util.ArrayList;
import java.util.HashMap;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class AndroidXMLParsingActivity extends ListActivity {
// All static variables
static final String URL = "file:///sdcard/download.xml";
// XML node keys
static final String KEY_ITEM = "item"; // parent node
static final String KEY_ID = "id";
static final String KEY_NAME = "name";
static final String KEY_COST = "cost";
static final String KEY_DESC = "description";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ArrayList<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>();
XMLParser parser = new XMLParser();
String xml = parser.getXmlFromUrl(URL); // getting XML
Document doc = parser.getDomElement(xml); // getting DOM element
NodeList nl = doc.getElementsByTagName(KEY_ITEM);
// looping through all item nodes <item>
for (int i = 0; i < nl.getLength(); i++) {
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
Element e = (Element) nl.item(i);
// adding each child node to HashMap key => value
map.put(KEY_ID, parser.getValue(e, KEY_ID));
map.put(KEY_NAME, parser.getValue(e, KEY_NAME));
map.put(KEY_COST, "Rs." + parser.getValue(e, KEY_COST));
map.put(KEY_DESC, parser.getValue(e, KEY_DESC));
// adding HashList to ArrayList
menuItems.add(map);
}
// Adding menuItems to ListView
ListAdapter adapter = new SimpleAdapter(this, menuItems,
R.layout.list_item,
new String[] { KEY_NAME, KEY_DESC, KEY_COST }, new int[] {
R.id.name, R.id.desciption, R.id.cost });
setListAdapter(adapter);
// selecting single ListView item
ListView lv = getListView();
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String name = ((TextView) view.findViewById(R.id.name)).getText().toString();
String cost = ((TextView) view.findViewById(R.id.cost)).getText().toString();
String description = ((TextView) view.findViewById(R.id.desciption)).getText().toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(), SingleMenuItemActivity.class);
in.putExtra(KEY_NAME, name);
in.putExtra(KEY_COST, cost);
in.putExtra(KEY_DESC, description);
startActivity(in);
}
});
}
}
日志猫在这里：
10-06 19:06:34.849: W/dalvikvm(25780): threadid=1: thread exiting with uncaught exception (group=0x40d452a0)
10-06 19:06:34.849: E/AndroidRuntime(25780): FATAL EXCEPTION: main
10-06 19:06:34.849: E/AndroidRuntime(25780): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.androidhive.xmlparsing/com.androidhive.xmlparsing.AndroidXMLParsingActivity}: java.lang.IllegalArgumentException: Host name may not be null
10-06 19:06:34.849: E/AndroidRuntime(25780): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100)
10-06 19:06:34.849: E/AndroidRuntime(25780): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125)
10-06 19:06:34.849: E/AndroidRuntime(25780): at android.app.ActivityThread.access$600(ActivityThread.java:140)
10-06 19:06:34.849: E/AndroidRuntime(25780): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227)
10-06 19:06:34.849: E/AndroidRuntime(25780): at android.os.Handler.dispatchMessage(Handler.java:99)
10-06 19:06:34.849: E/AndroidRuntime(25780): at android.os.Looper.loop(Looper.java:137)
10-06 19:06:34.849: E/AndroidRuntime(25780): at android.app.ActivityThread.main(ActivityThread.java:4898)
10-06 19:06:34.849: E/AndroidRuntime(25780): at java.lang.reflect.Method.invokeNative(Native Method)
10-06 19:06:34.849: E/AndroidRuntime(25780): at java.lang.reflect.Method.invoke(Method.java:511)
10-06 19:06:34.849: E/AndroidRuntime(25780): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
10-06 19:06:34.849: E/AndroidRuntime(25780): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
10-06 19:06:34.849: E/AndroidRuntime(25780): at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:112)
10-06 19:06:34.849: E/AndroidRuntime(25780): at dalvik.system.NativeStart.main(Native Method)
10-06 19:06:34.849: E/AndroidRuntime(25780): Caused by: java.lang.IllegalArgumentException: Host name may not be null
10-06 19:06:34.849: E/AndroidRuntime(25780): at org.apache.http.HttpHost.<init>(HttpHost.java:83)
10-06 19:06:34.849: E/AndroidRuntime(25780): at org.apache.http.impl.client.AbstractHttpClient.determineTarget(AbstractHttpClient.java:519)
10-06 19:06:34.849: E/AndroidRuntime(25780): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:509)
10-06 19:06:34.849: E/AndroidRuntime(25780): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
10-06 19:06:34.849: E/AndroidRuntime(25780): at com.androidhive.xmlparsing.XMLParser.getXmlFromUrl(XMLParser.java:45)
10-06 19:06:34.849: E/AndroidRuntime(25780): at com.androidhive.xmlparsing.AndroidXMLParsingActivity.onCreate(AndroidXMLParsingActivity.java:40)
10-06 19:06:34.849: E/AndroidRuntime(25780): at android.app.Activity.performCreate(Activity.java:5206)
10-06 19:06:34.849: E/AndroidRuntime(25780): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1083)
10-06 19:06:34.849: E/AndroidRuntime(25780): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2064)
10-06 19:06:34.849: E/AndroidRuntime(25780): ... 12 more
10-06 19:06:34.854: D/WindowManager(2297): mInputFocus is not null.
10-06 19:06:34.904: E/android.os.Debug(2297): !@Dumpstate > dumpstate -k -t -z -d -o /data/log/dumpstate_app_error
我已将 download.xml 文件保存在我的 SD 卡中。我知道的位置没有问题。但查不出问题。请帮我解决这个问题。
这是 xmlParser 类：
package com.androidhive.xmlparsing;
import java.io.IOException;
import java.io.StringReader;
import java.io.UnsupportedEncodingException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import android.util.Log;
public class XMLParser {
// constructor
public XMLParser() {
}
/**
* Getting XML from URL making HTTP request
* @param url string
* */
public String getXmlFromUrl(String url) {
String xml = null;
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
xml = EntityUtils.toString(httpEntity);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
// return XML
return xml;
}
/**
* Getting XML DOM element
* @param XML string
* */
public Document getDomElement(String xml){
Document doc = null;
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder db = dbf.newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader(xml));
doc = db.parse(is);
} catch (ParserConfigurationException e) {
Log.e("Error: ", e.getMessage());
return null;
} catch (SAXException e) {
Log.e("Error: ", e.getMessage());
return null;
} catch (IOException e) {
Log.e("Error: ", e.getMessage());
return null;
}
return doc;
}
/** Getting node value
* @param elem element
*/
public final String getElementValue( Node elem ) {
Node child;
if( elem != null){
if (elem.hasChildNodes()){
for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){
if( child.getNodeType() == Node.TEXT_NODE ){
return child.getNodeValue();
}
}
}
}
return "";
}
/**
* Getting node value
* @param Element node
* @param key string
* */
public String getValue(Element item, String str) {
NodeList n = item.getElementsByTagName(str);
return this.getElementValue(n.item(0));
}
}