ANDROID – 从localhost读取文件(ERROR)

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文件中添加了权限internet.

   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

解决方法:

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,从而导致应用无法响应.

你应该做这样的事情(未经测试)
try块应该是：

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,并在onPostExecute方法中更新UI,这样您就不需要乱用线程了.基本上AsyncTask做我上面描述的.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.