Question

我正在编写一个小应用程序，它应该从npm json-server获取数据。它引发了一个例外。我确实使用AsyncTask扩展了连接类，并在＆＃34; doInBackground＆＃34;中执行了代码。但它仍然会引发异常。请帮助我。

以下是代码：

import android.os.AsyncTask;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class Network extends AsyncTask <String, Void, String> {
    public String urlString = ("http://localhost:3000");

    @Override
    protected String doInBackground(String... params) {
        StringBuffer chaine = new StringBuffer("");
        try {
            URL url = new URL(urlString);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestProperty("User-Agnet", "");
            connection.setRequestMethod("POST");
            connection.setDoInput(true);
            connection.connect();

            InputStream inputStream = connection.getInputStream();

            BufferedReader rd = new BufferedReader(new InputStreamReader(inputStream));
            String line = "";
            while ((line = rd.readLine()) != null) {
                chaine.append(line);
            }

        } catch (IOException e) {
            e.printStackTrace();
        } catch (UnsupportedOperationException e) {
            e.printStackTrace();

        }
        return chaine.toString();
    }
}

logcat告诉：

android.os.NetworkOnMainThreadException 在android.os.StrictMode $ AndroidBlockGuardPolicy.onNetwork（StrictMode.java:1147） at java.net.InetAddress.lookupHostByName（InetAddress.java:418） at java.net.InetAddress.getAllByNameImpl（InetAddress.java:252）在java.net.InetAddress.getAllByName（InetAddress.java:215）在com.android.okhttp.HostResolver $ 1.getAllByName（HostResolver.java:29）在com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress（RouteSelector.java:232）在com.android.okhttp.internal.http.RouteSelector.next（RouteSelector.java:124）在com.android.okhttp.internal.http.HttpEngine.connect（HttpEngine.java:361）在com.android.okhttp.internal.http.HttpEngine.sendRequest（HttpEngine.java:289）在com.android.okhttp.internal.http.HttpURLConnectionImpl.execute（HttpURLConnectionImpl.java:373）在com.android.okhttp.internal.http.HttpURLConnectionImpl.connect（HttpURLConnectionImpl.java:106）在smoca.ch.kreagen.Network.doInBackground（Network.java:25）在smoca.ch.kreagen.BackendMockup.getData（BackendMockup.java:11）在smoca.ch.kreagen.FillRealm.initRealm（FillRealm.java:43）在smoca.ch.kreagen.Fragments.HomeFragment.onCreateView（HomeFragment.java:42）在android.support.v4.app.Fragment.performCreateView（Fragment.java:1789）在android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:955）在android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:1138）在android.support.v4.app.BackStackRecord.run（BackStackRecord.java:740）在android.support.v4.app.FragmentManagerImpl.execPendingActions（FragmentManager.java:1501）在android.support.v4.app.FragmentManagerImpl $ 1.run（FragmentManager.java:458）在android.os.Handler.handleCallback（Handler.java:739）在android.os.Handler.dispatchMessage（Handler.java:95）在android.os.Looper.loop（Looper.java:145）在android.app.ActivityThread.main（ActivityThread.java:5832） at java.lang.reflect.Method.invoke（Native Method）在java.lang.reflect.Method.invoke（Method.java:372）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1399）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1194）

我知道问题出在＆＃34; connection.connect（）;＆＃34;被调用因为它应该在主线程中。但不应该。正确？

问候约翰

Answer 1

    public class Network extends AsyncTask <String, Void, String> {
    public String urlString = ("http://localhost:3000");
    HttpURLConnection connection;
    URL url;
    StringBuffer chaine;

    @Override
    protected String doInBackground(String... params) {

    Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                chaine = new StringBuffer("");
        try {
            url = new URL(urlString);
            connection = (HttpURLConnection) url.openConnection();
            connection.setRequestProperty("User-Agnet", "");
            connection.setRequestMethod("POST");
            connection.setDoInput(true);
            connection.connect();

            InputStream inputStream = connection.getInputStream();

            BufferedReader rd = new BufferedReader(new       InputStreamReader(inputStream));
            String line = "";
            while ((line = rd.readLine()) != null) {
                chaine.append(line);
            }

        } catch (IOException e) {
            e.printStackTrace();
        } catch (UnsupportedOperationException e) {
            e.printStackTrace();

        }
            }
        });
        thread.start();

        return chaine.toString();
    }
}

来自NPM json-server的GET数据抛出NetworkOnMainThreadException

1 个答案: