我在android中编写XML解析器的应用程序但是当我下载代码并运行它时，它运行得很好， 但我写了相同的代码，但没有工作，为什么这样？
有什么先决条件吗？请帮帮我这个
我在XMLParser.java
package com.xmlparser;
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));
}
}
我的日志猫
11-22 15:35:53.675: E/AndroidRuntime(19208): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.xmlparser/com.xmlparser.Xparser}: android.os.NetworkOnMainThreadException
11-22 15:35:53.675: E/AndroidRuntime(19208): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100)
11-22 15:35:53.675: E/AndroidRuntime(19208): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125)
11-22 15:35:53.675: E/AndroidRuntime(19208): at android.app.ActivityThread.access$600(ActivityThread.java:140)
11-22 15:35:53.675: E/AndroidRuntime(19208): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227)
11-22 15:35:53.675: E/AndroidRuntime(19208): at android.os.Handler.dispatchMessage(Handler.java:99)
11-22 15:35:53.675: E/AndroidRuntime(19208): at android.os.Looper.loop(Looper.java:137)
11-22 15:35:53.675: E/AndroidRuntime(19208): at android.app.ActivityThread.main(ActivityThread.java:4898)
11-22 15:35:53.675: E/AndroidRuntime(19208): at java.lang.reflect.Method.invokeNative(Native Method)
11-22 15:35:53.675: E/AndroidRuntime(19208): at java.lang.reflect.Method.invoke(Method.java:511)
11-22 15:35:53.675: E/AndroidRuntime(19208): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1008)
11-22 15:35:53.675: E/AndroidRuntime(19208): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:775)
11-22 15:35:53.675: E/AndroidRuntime(19208): at dalvik.system.NativeStart.main(Native Method)
11-22 15:35:53.675: E/AndroidRuntime(19208): Caused by: android.os.NetworkOnMainThreadException
11-22 15:35:53.675: E/AndroidRuntime(19208): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1118)
11-22 15:19:21.500: E/AndroidRuntime(16631): at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
11-22 15:19:21.500: E/AndroidRuntime(16631): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
11-22 15:19:21.500: E/AndroidRuntime(16631): at java.net.InetAddress.getAllByName(InetAddress.java:214)
11-22 15:19:21.500: E/AndroidRuntime(16631): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
11-22 15:19:21.500: E/AndroidRuntime(16631): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
11-22 15:19:21.500: E/AndroidRuntime(16631): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
11-22 15:19:21.500: E/AndroidRuntime(16631): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
11-22 15:19:21.500: E/AndroidRuntime(16631): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:670)
11-22 15:19:21.500: E/AndroidRuntime(16631): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:509)
11-22 15:19:21.500: E/AndroidRuntime(16631): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
11-22 15:19:21.500: E/AndroidRuntime(16631): at com.xmlparser.XMLParser.getXmlFromUrl(XMLParser.java:45)
11-22 15:19:21.500: E/AndroidRuntime(16631): at com.xmlparser.Xparser.onCreate(Xparser.java:37)
11-22 15:19:21.500: E/AndroidRuntime(16631): at android.app.Activity.performCreate(Activity.java:5206)
11-22 15:19:21.500: E/AndroidRuntime(16631): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
11-22 15:19:21.500: E/AndroidRuntime(16631): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2064)
这是我的Xparser.java
package com.xmlparser;
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.Menu;
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 Xparser extends ListActivity {
static final String URL = "http://api.androidhive.info/pizza/?format=xml";
// XML key nodes
static final String KEY_ITEM = "item";
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
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_xmlparser);
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 n1 = doc.getElementsByTagName(KEY_ITEM);
// looping through all item nodes <item>
for(int i=0 ; i < n1.getLength(); i++){
HashMap<String,String> map = new HashMap<String,String>();
Element e = (Element) n1.item(i);
//adding each child to Hashmap node key
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_select_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) {
// TODO Auto-generated method stub
String name = ((TextView) view.findViewById(R.id.name)).getText().toString();
String cost = ((TextView) view.findViewById(R.id.cost)).getText().toString();
String desc = ((TextView) view.findViewById(R.id.desciption)).getText().toString();
Intent in = new Intent();
in.putExtra(KEY_NAME, name);
in.putExtra(KEY_DESC, desc);
in.putExtra(KEY_COST, cost);
startActivity(in);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.xmlparser, menu);
return true;
}
}
答案 0 :(得分：4)
您需要了解的例外tells you everything。您正在尝试在主线程上提交数据。在单独的线程中进行网络操作。
There's a link in the docs that explains it和this might help you to move on。