Java 即使在实现AsyncTask之后，NetworkOnMainThreadException也会发生异常

我不确定这里到底发生了什么，但我已经实现了AsyncTask，我仍然得到一个NetworkOnMainThreadException，我不知道为什么

错误发生在第（116）行：

我觉得很奇怪，因为它在

doInBackground

中

有什么建议吗

资料来源： 日志：

---

您没有像应该的那样使用asynctask。调用AsyncTask.execute（），它将为您调用

doInBackground

。事实上，它会为您调用空存根。您应该移动代码。

您没有像应该的那样使用asynctask。调用AsyncTask.execute（），它将为您调用

doInBackground

。事实上，它会为您调用空存根。您应该移动代码。

您有两个

doInBackground（）

方法，一个是对

AsyncTask

方法的重写，其中您只返回

null

，另一个是参数不匹配的自定义实现

---

网络操作应该在重写的方法

doInBackground（）

中完成，如果在您自己的自定义方法中完成，您将得到该异常。

您有两个

doInBackground（）

方法，一个是对

AsyncTask

方法的重写，您只需返回

null

，另一个是自定义实现，因为参数不匹配

---

网络操作应在重写方法

doInBackground（）

中完成，如果您使用自己的自定义方法进行操作，您将得到该异常。

您已经做了两次备份，但缺少AsyncTask使用文档中的此示例创建asynk任务我尝试了进行建议的更改-结果是：您做了两次备份，但缺少AsyncTask使用文档中的此示例创建asynk任务我尝试了进行建议的更改更改-我以以下内容结束：我尝试了建议的更改-我以以下内容结束：

类型XMLParser必须实现继承的抽象方法AsyncTask.doInBackground（类型…）XMLParser.java/AndroidXMLParsing/src/com/androidhive/xmlparsing line 27 java问题

您删除了必须实现的方法，重写

AsyncTask

的

doInBackground（）

方法。我尝试进行建议的更改，结果是：

类型XMLParser必须实现继承的抽象方法AsyncTask。doInBackground（类型…）XMLParser.java/AndroidXMLParsing/src/com/androidhive/xmlparsing第27行java问题

您已经删除了必须实现的方法，覆盖了

AsyncTask

的

doInBackground（）。
HttpResponse httpResponse = httpClient.execute(httpPost);

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.os.AsyncTask;
import android.util.Log;

public class XMLParser extends AsyncTask {

    // constructor
    public XMLParser() {

    }

    /**
     * Getting XML from URL making HTTP request
     * 
     * @param url
     *            string
     * */

    /**
     * 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));
    }

    protected Object doInBackground(String url) {
        // TODO Auto-generated method stub

        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;
    }

    @Override
    protected Object doInBackground(Object... params) {
        // TODO Auto-generated method stub
        return null;
    }
}

01-20 10:47:14.396: E/AndroidRuntime(1629): FATAL EXCEPTION: main
01-20 10:47:14.396: E/AndroidRuntime(1629): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.androidhive.xmlparsing/com.androidhive.xmlparsing.AndroidXMLParsingActivity}: android.os.NetworkOnMainThreadException
01-20 10:47:14.396: E/AndroidRuntime(1629):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at android.app.ActivityThread.access$700(ActivityThread.java:140)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at android.os.Looper.loop(Looper.java:137)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at android.app.ActivityThread.main(ActivityThread.java:4921)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at java.lang.reflect.Method.invokeNative(Native Method)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at java.lang.reflect.Method.invoke(Method.java:511)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at dalvik.system.NativeStart.main(Native Method)
01-20 10:47:14.396: E/AndroidRuntime(1629): Caused by: android.os.NetworkOnMainThreadException
01-20 10:47:14.396: E/AndroidRuntime(1629):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1118)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at java.net.InetAddress.getAllByName(InetAddress.java:214)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:670)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:509)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at com.androidhive.xmlparsing.XMLParser.doInBackground(XMLParser.java:116)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at com.androidhive.xmlparsing.AndroidXMLParsingActivity.onCreate(AndroidXMLParsingActivity.java:46)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at android.app.Activity.performCreate(Activity.java:5206)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
01-20 10:47:14.396: E/AndroidRuntime(1629):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074)
01-20 10:47:14.396: E/AndroidRuntime(1629):     ... 11 more
01-20 10:47:14.406: I/Process(1629): Sending signal. PID: 1629 SIG: 9
01-20 10:48:04.316: D/AbsListView(2017): Get MotionRecognitionManager
01-20 10:48:04.331: D/AndroidRuntime(2017): Shutting down VM
01-20 10:48:04.331: W/dalvikvm(2017): threadid=1: thread exiting with uncaught exception (group=0x40ff42a0)
01-20 10:48:04.331: E/AndroidRuntime(2017): FATAL EXCEPTION: main
01-20 10:48:04.331: E/AndroidRuntime(2017): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.androidhive.xmlparsing/com.androidhive.xmlparsing.AndroidXMLParsingActivity}: android.os.NetworkOnMainThreadException
01-20 10:48:04.331: E/AndroidRuntime(2017):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at android.app.ActivityThread.access$700(ActivityThread.java:140)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at android.os.Looper.loop(Looper.java:137)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at android.app.ActivityThread.main(ActivityThread.java:4921)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at java.lang.reflect.Method.invokeNative(Native Method)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at java.lang.reflect.Method.invoke(Method.java:511)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at dalvik.system.NativeStart.main(Native Method)
01-20 10:48:04.331: E/AndroidRuntime(2017): Caused by: android.os.NetworkOnMainThreadException
01-20 10:48:04.331: E/AndroidRuntime(2017):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1118)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at java.net.InetAddress.getAllByName(InetAddress.java:214)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:670)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:509)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at com.androidhive.xmlparsing.XMLParser.doInBackground(XMLParser.java:116)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at com.androidhive.xmlparsing.AndroidXMLParsingActivity.onCreate(AndroidXMLParsingActivity.java:46)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at android.app.Activity.performCreate(Activity.java:5206)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
01-20 10:48:04.331: E/AndroidRuntime(2017):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074)
01-20 10:48:04.331: E/AndroidRuntime(2017):     ... 11 more