0

我有以下代码：

public String test(){
        URL url = null;
        try {
            url = new URL("http://api.heroesofnewerth.com/player_statistics/ranked/nickname/Hieratic/?token=0CZGH8ZI7UR8J2GN");
        } catch (MalformedURLException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        BufferedReader reader = null;
        String x = "";
        try {
            reader = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"));
            for (String line; (line = reader.readLine()) != null;) {
                System.out.println(line);
                x = line;
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally{
            if (reader !=null) try{reader.close();} catch (IOException ignore) {
            }{}
        }
        JsonElement root = new JsonParser().parse(x);
        return x;
    }
}

现在我想将文本插入到下面的 textView 中。

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_create_competetion);

    TextView tv = (TextView) findViewById(R.id.competetion_text);
    JsonCollector jc = new JsonCollector();

    tv.setText(jc.test());

但是，当我尝试运行它时。我收到以下错误：

FATAL EXCEPTION: main
 E/AndroidRuntime(1800): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.konkurrencesigner/com.example.konkurrencesigner.CreateCompetetion}: android.os.NetworkOnMainThreadException
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
 E/AndroidRuntime(1800):    at android.app.ActivityThread.access$600(ActivityThread.java:141)
 E/AndroidRuntime(1800):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
 E/AndroidRuntime(1800):    at android.os.Handler.dispatchMessage(Handler.java:99)
  E/AndroidRuntime(1800):   at android.os.Looper.loop(Looper.java:137)
    E/AndroidRuntime(1800):     at android.app.ActivityThread.main(ActivityThread.java:5039)
    E/AndroidRuntime(1800):     at java.lang.reflect.Method.invokeNative(Native Method)
    E/AndroidRuntime(1800):     at java.lang.reflect.Method.invoke(Method.java:511)
    E/AndroidRuntime(1800):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
    E/AndroidRuntime(1800):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
    E/AndroidRuntime(1800):     at dalvik.system.NativeStart.main(Native Method)
    E/AndroidRuntime(1800): Caused by: android.os.NetworkOnMainThreadException
    E/AndroidRuntime(1800):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)
    E/AndroidRuntime(1800):     at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
     E/AndroidRuntime(1800):    at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
 E/AndroidRuntime(1800):    at java.net.InetAddress.getAllByName(InetAddress.java:214)
 E/AndroidRuntime(1800):    at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
 E/AndroidRuntime(1800):    at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
 E/AndroidRuntime(1800):    at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
E/AndroidRuntime(1800):     at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
 E/AndroidRuntime(1800):    at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
 E/AndroidRuntime(1800):    at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:316)
    E/AndroidRuntime(1800):     at libcore.net.http.HttpEngine.connect(HttpEngine.java:311)
 E/AndroidRuntime(1800):    at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:290)
 E/AndroidRuntime(1800):    at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:240)
 E/AndroidRuntime(1800):    at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:282)

谁能告诉我为什么会这样？

请注意，我已经在我的 android 清单中添加了以下行：

    <uses-permission android:name="android.permission.INTERNET" />
4

2 回答 2

4

您正在主线程上进行 HTTP 通信，这就是您获得NetworkOnMainThreadException. 在单独的线程中执行此操作，使用 anAsyncTask将是一个理想的解决方案，这是一个如何实现它的示例：

private TextView tv;

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_create_competetion);

    tv = (TextView) findViewById(R.id.competetion_text);
    JsonCollector jc = new JsonCollector();

    // Create and execute a new AsyncTask, the TextView will
    // be updated asynchronously when the task has finished.
    updateTextView();
}

private void updateTextView() {
    new AsyncTask<Void, Void, String>() {

        @Override
        /* Runs on a separate thread */
        protected String doInBackground(Void... params) {
            String result = null;
            BufferedReader reader = null;
            try {
                URL url = new URL("http://api.heroesofnewerth.com/player_statistics/ranked/nickname/Hieratic/?token=0CZGH8ZI7UR8J2GN");
                reader = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"));
                for (String line; (line = reader.readLine()) != null;) {
                    System.out.println(line);
                    result = line;
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (reader != null) {
                    try {
                        reader.close();
                    } catch (IOException e) {
                        // Ignore
                    }
                }
            }

            return result;  
        }

        @Override
        /* Runs on the UI/Main thread when doInBackground()
         * has finished */
        protected void onPostExecute(String result) {
            if(result != null) {
                // Update the TextView only if we got a result
                // from the HTTP request
                tv.setText(result);
            }
        }

    }.execute();
}
于 2013-05-15T18:21:18.817 回答
1

如果您需要在主线程中联网，请在 onCreate() 方法中添加这些代码行

StrictMode.ThreadPolicy policy = 
        new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
于 2013-05-15T20:56:13.993 回答