斯卡拉http请求中的Android应用程序

Question

我正在尝试使用Scala制作Android应用程序。它应该发出GET请求。我看到一些实现这种功能的Java代码，但这对我没有多大帮助。那么，有人可以解释我该怎么做，或者给出一个代码示例吗？ 现在我有：

protected override def onCreate(savedInstanceState: Bundle) { 
    super.onCreate(savedInstanceState) 

    val intent: Intent = getIntent() 
    val massage: String = makeJson(intent.getExtras()) 
    val url:String = """http://something.I.dont.want.to.show?info=""" + URLEncoder.encode(massage, "utf-8") 
    val req = new MyAsyncTask() 
    req.execute(url) 
    val data:JSONArray = req.get() 

    // Create the text view 
    val textView:TextView = new TextView(this) 
    textView.setTextSize(40) 
    textView.setText(data.toString()) 

    // Set the text view as the activity layout 
    setContentView(textView) 
} 

而且MyNewTask类：

class MyAsyncTask extends AsyncTask[String, Void, JSONArray] { 


override protected def doInBackground(arg0: String*): JSONArray = { 
    val httpclient: HttpClient = new DefaultHttpClient() 
    try { 
     val response: HttpResponse = httpclient.execute(new HttpGet(arg0(0))) 
     val statusLine: StatusLine = response.getStatusLine() 
     if(statusLine.getStatusCode() == HttpStatus.SC_OK){ 
      val out:ByteArrayOutputStream = new ByteArrayOutputStream() 
      response.getEntity().writeTo(out) 
      out.close() 
      val responseString = out.toString() 
      new JSONArray(responseString) 
      } 
     else{ 
       //Closes the connection. 
       response.getEntity().getContent().close() 
       throw new IOException(statusLine.getReasonPhrase()) 
       null 
      } 
     } 
    catch { 
     case e: ClientProtocolException => {new JSONArray()} 
     case ioe: IOException => {new JSONArray()} 
    } 
} 

}

登录：

03-30 20:25:34.105: D/dalvikvm(30197): --- called into dvmAbstractMethodStub 
03-30 20:25:34.105: D/AndroidRuntime(30197): Shutting down VM 
03-30 20:25:34.105: W/dalvikvm(30197): threadid=1: thread exiting with uncaught exception (group=0x419d6930) 
03-30 20:25:34.110: E/AndroidRuntime(30197): FATAL EXCEPTION: main 
03-30 20:25:34.110: E/AndroidRuntime(30197): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myscalaandroidapp2/com.example.myscalaandroidapp2.DisplayMassageActivity}: java.util.concurrent.ExecutionException: java.lang.AbstractMethodError: abstract method not implemented 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2249) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2299) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.app.ActivityThread.access$700(ActivityThread.java:154) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1284) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.os.Handler.dispatchMessage(Handler.java:99) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.os.Looper.loop(Looper.java:137) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.app.ActivityThread.main(ActivityThread.java:5306) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at java.lang.reflect.Method.invokeNative(Native Method) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at java.lang.reflect.Method.invoke(Method.java:511) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at dalvik.system.NativeStart.main(Native Method) 
03-30 20:25:34.110: E/AndroidRuntime(30197): Caused by: java.util.concurrent.ExecutionException: java.lang.AbstractMethodError: abstract method not implemented 
03-30 20:25:34.110: E/AndroidRuntime(30197): at java.util.concurrent.FutureTask.report(FutureTask.java:94) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at java.util.concurrent.FutureTask.get(FutureTask.java:160) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.os.AsyncTask.get(AsyncTask.java:482) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at com.example.myscalaandroidapp2.DisplayMassageActivity.onCreate(DisplayMassageActivity.scala:60) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.app.Activity.performCreate(Activity.java:5255) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2213) 
03-30 20:25:34.110: E/AndroidRuntime(30197): ... 11 more 
03-30 20:25:34.110: E/AndroidRuntime(30197): Caused by: java.lang.AbstractMethodError: abstract method not implemented 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.os.AsyncTask.doInBackground(AsyncTask.java) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.os.AsyncTask$2.call(AsyncTask.java:287) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at java.util.concurrent.FutureTask.run(FutureTask.java:234) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) 
03-30 20:25:34.110: E/AndroidRuntime(30197): at java.lang.Thread.run(Thread.java:856) 
03-30 20:25:34.115: W/dalvikvm(30197): threadid=11: thread exiting with uncaught exception (group=0x419d6930) 
03-30 20:25:34.115: I/Process(30197): Sending signal. PID: 30197 SIG: 9 

如果我理解正确的失败与开始的AsyncTask什么像那样。代码很可能是非常蹩脚的。正因为如此，我并没有要求如何解决这个问题，而是要求如何从一开始就做到这一点。但是，如果你看到错误的位置，我很乐意听到它。

Answer 1

我的第一个打赌是，因为上面的代码没有直接引用MyAsyncTask的doInBackground方法，Progruard删除它。

尽量addign以下到您的ProGuard配置文件：

-keep class * extends android.os.AsyncTask { 
    *; 
} 

编辑：

我真的认为，如果你已经使用Scala的为Android使用期货。另外，如果你在Scala中执行大部分代码，我也可以推荐Scaloid library。