android連接到json/xml api

Question

我試圖與其他API進行通信以檢索JSON文檔，但是當我在Eclipse Android模擬器中運行應用程序時，應用程序一旦啓動就關閉（「不幸的是TestRest已經停止「）。由於對httpClient.execute方法的調用，它似乎關閉了。

爲主要活動的代碼如下：

public class TestRestActivity extends Activity { 
    /** Called when the activity is first created. */ 
    TextView info; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     info = (TextView) findViewById(R.id.debug); 

     String testUri = "http://www.entireweb.com/xmlquery?pz=MYAPIKEY&ip=IP&q=pizza&n=50&format=json"; 
     // print the uri to the screen - (not seen if rest of code runs) 
     info.setText(testUri); 

     HttpClient httpclient = new DefaultHttpClient(); 
     HttpContext localContext = new BasicHttpContext(); 
     HttpGet httpget = new HttpGet(testUri); 


     HttpResponse response = null; 
     try { 
      // TODO fails on this line 
      response = httpclient.execute(httpget, localContext); 

      HttpEntity entity = response.getEntity(); 
      if (entity != null) { 
       info.setText("got it"); 
      } 

     } catch (ClientProtocolException e) { 
      // Auto-generated catch block 
      e.printStackTrace(); 
     } catch (IOException e) { 
      // Auto-generated catch block 
      e.printStackTrace(); 
     } finally { 
     } 

    } 
} 

而且我已經包括在下面我的清單文件的Web權限：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="org.john.testRes" 
    android:versionCode="1" 
    android:versionName="1.0" > 
    <uses-permission android:name="android.permission.INTERNET" /> 

不太熟悉Android開發和真對於導致問題的原因一無所知。我使用的api很好，並從我的瀏覽器返回預期的json文檔。我使用的AVD可以在瀏覽器中連接到互聯網，我已經在幾種不同的AVD上嘗試過這款應用。

有什麼建議是造成這個問題的原因？謝謝。

編輯：添加錯誤

11-22 18:13:14.221: D/AndroidRuntime(556): Shutting down VM 
11-22 18:13:14.221: W/dalvikvm(556): threadid=1: thread exiting with uncaught exception (group=0x409951f8) 
11-22 18:13:14.251: E/AndroidRuntime(556): FATAL EXCEPTION: main 
11-22 18:13:14.251: E/AndroidRuntime(556): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.john.testRes/org.john.testRes.TestRestActivity}: android.os.NetworkOnMainThreadException 
11-22 18:13:14.251: E/AndroidRuntime(556): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955) 
11-22 18:13:14.251: E/AndroidRuntime(556): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980) 
11-22 18:13:14.251: E/AndroidRuntime(556): at android.app.ActivityThread.access$600(ActivityThread.java:122) 
11-22 18:13:14.251: E/AndroidRuntime(556): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146) 
11-22 18:13:14.251: E/AndroidRuntime(556): at android.os.Handler.dispatchMessage(Handler.java:99) 
11-22 18:13:14.251: E/AndroidRuntime(556): at android.os.Looper.loop(Looper.java:137) 
11-22 18:13:14.251: E/AndroidRuntime(556): at android.app.ActivityThread.main(ActivityThread.java:4340) 
11-22 18:13:14.251: E/AndroidRuntime(556): at java.lang.reflect.Method.invokeNative(Native Method) 
11-22 18:13:14.251: E/AndroidRuntime(556): at java.lang.reflect.Method.invoke(Method.java:511) 
11-22 18:13:14.251: E/AndroidRuntime(556): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
11-22 18:13:14.251: E/AndroidRuntime(556): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
11-22 18:13:14.251: E/AndroidRuntime(556): at dalvik.system.NativeStart.main(Native Method) 
11-22 18:13:14.251: E/AndroidRuntime(556): Caused by: android.os.NetworkOnMainThreadException 
11-22 18:13:14.251: E/AndroidRuntime(556): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1084) 
11-22 18:13:14.251: E/AndroidRuntime(556): at java.net.InetAddress.lookupHostByName(InetAddress.java:391) 
11-22 18:13:14.251: E/AndroidRuntime(556): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242) 
11-22 18:13:14.251: E/AndroidRuntime(556): at java.net.InetAddress.getAllByName(InetAddress.java:220) 
11-22 18:13:14.251: E/AndroidRuntime(556): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137) 
11-22 18:13:14.251: E/AndroidRuntime(556): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 
11-22 18:13:14.251: E/AndroidRuntime(556): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 
11-22 18:13:14.251: E/AndroidRuntime(556): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360) 
11-22 18:13:14.251: E/AndroidRuntime(556): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 
11-22 18:13:14.251: E/AndroidRuntime(556): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 
11-22 18:13:14.251: E/AndroidRuntime(556): at org.john.testRes.TestRestActivity.onCreate(TestRestActivity.java:41) 
11-22 18:13:14.251: E/AndroidRuntime(556): at android.app.Activity.performCreate(Activity.java:4465) 
11-22 18:13:14.251: E/AndroidRuntime(556): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 
11-22 18:13:14.251: E/AndroidRuntime(556): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919) 
11-22 18:13:14.251: E/AndroidRuntime(556): ... 11 more 
11-22 18:13:48.321: I/Process(556): Sending signal. PID: 556 SIG: 9 
11-22 18:14:01.552: D/AndroidRuntime(597): Shutting down VM 

Answer 1

的問題是，你正在試圖做的主UI線程上的網絡操作。您需要在單獨的線程上執行這些操作。您可以使用AsyncTask或僅使用標準Thread。

下面是一個簡單的例子：

final Handler handler = new Handler(); 
new Thread(new Runnable() { 

    @Override 
    public void run() { 
      // Do something long running 
      handler.post(new Runnable() { 

       @Override 
       public void run() { 
        // Do something on the UI Thread 
       } 
      }); 
    } 
}).start();