Question

我有一个代码从我的localhost加载文本文件，我使用xampp，我把我的文件放在htdocs下的xampp文件夹中。这是我的代码：

public class MainActivity extends Activity {

TextView httpStuff;


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    httpStuff = (TextView)findViewById(R.id.tvHttp);        
    try {
        URL url = new URL("http://10.0.2.2/name.txt");
        BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));           
        String str = in.readLine();
        in.close();
        httpStuff.setText(str);
        } catch (MalformedURLException e) {  
        e.printStackTrace();
    }catch (IOException e) {
        // TODO: handle exception
    }

}}

我收到了这个错误。我不知道出了什么问题。我还在androidmanifest.xml文件中添加了internet权限。

   10-24 17:17:45.024: E/AndroidRuntime(7544): FATAL EXCEPTION: main
10-24 17:17:45.024: E/AndroidRuntime(7544): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.name.in.a.textfile/com.example.name.in.a.textfile.MainActivity}: android.os.NetworkOnMainThreadException
10-24 17:17:45.024: E/AndroidRuntime(7544):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at android.app.ActivityThread.access$600(ActivityThread.java:130)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at android.os.Handler.dispatchMessage(Handler.java:99)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at android.os.Looper.loop(Looper.java:137)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at android.app.ActivityThread.main(ActivityThread.java:4745)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at java.lang.reflect.Method.invokeNative(Native Method)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at java.lang.reflect.Method.invoke(Method.java:511)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at dalvik.system.NativeStart.main(Native Method)
10-24 17:17:45.024: E/AndroidRuntime(7544): Caused by: android.os.NetworkOnMainThreadException
10-24 17:17:45.024: E/AndroidRuntime(7544):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.io.IoBridge.connect(IoBridge.java:112)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at java.net.Socket.connect(Socket.java:842)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:76)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:341)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:315)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.net.http.HttpEngine.connect(HttpEngine.java:310)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:289)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:239)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at java.net.URL.openStream(URL.java:462)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at com.example.name.in.a.textfile.MainActivity.onCreate(MainActivity.java:27)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at android.app.Activity.performCreate(Activity.java:5008)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
10-24 17:17:45.024: E/AndroidRuntime(7544):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
10-24 17:17:45.024: E/AndroidRuntime(7544):     ... 11 more

Answer 1

您的问题显示在此行中 android.os.NetworkOnMainThreadException 10-24 17:07:44.745: E/AndroidRuntime(7143)

在android中，您无法在主线程中执行网络操作，因为它可能会阻止UI更新超过5秒，导致应用无响应。

你应该这样做（未经测试） try块应为：

Thread t = new Thread(new Runnable() {
    @Override
    public void run() {
        URL url = new URL("http://10.0.2.2/name.txt");
        BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));           
        String str = in.readLine();
        in.close();
        runOnUIThread(new Runnable() {
           @Override
           public void run() { 
               httpStuff.setText(str);
           }
        });

    });
t.start();

这样您就可以在不同的线程上执行网络连接，但由于您需要在网络完成后更新UI，因此您需要使用runOnUIThread，因为在UI上线程可以更新UI组件。

另一个可能更好的选择是AsyncTask 您将网络任务放在其doInBackground方法中，并使用onPostExecute方法更新UI，这样您就不需要乱用线程了。基本上AsyncTask做了我上面所描述的。你应该研究一下，因为所有的网络应该在不同于UI的线程中完成，AsyncTask是一个很好的选择。

Answer 2

7点以后，这里的答案有了改善，因为我也遇到了这个问题

private class myStreamReader extends AsyncTask<String, Void, String> {
    String str = "";
    @Override
    protected String doInBackground(String... params) {
        try {
            URL url = new URL(""http://10.0.2.2/name.txt"");
            BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
            str = in.readLine();
            in.close();
        } catch (MalformedURLException e) {
        } catch (IOException e) {
        }

        return "Executed";
    }

    @Override
    protected void onPostExecute(String result) {
        //do something here
         httpStuff.setText(str);
    }

    @Override
    protected void onPreExecute() {}

    @Override
    protected void onProgressUpdate(Void... values) {}
}

在使用时只需调用

new.myStreamReader().execute();

ANDROID - 从localhost读取文件（ERROR）

2 个答案: