java - 如何删除致命异常 : AsyncTask in android

Question

10-23 00:41:00.705: E/AndroidRuntime(3622): FATAL EXCEPTION: AsyncTask #1
10-23 00:41:00.705: E/AndroidRuntime(3622): java.lang.RuntimeException: An error occured while executing doInBackground()
10-23 00:41:00.705: E/AndroidRuntime(3622):     at android.os.AsyncTask$3.done(AsyncTask.java:299)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at java.util.concurrent.FutureTask.run(FutureTask.java:239)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at java.lang.Thread.run(Thread.java:856)
10-23 00:41:00.705: E/AndroidRuntime(3622): Caused by: java.lang.IllegalStateException: Content has been consumed
10-23 00:41:00.705: E/AndroidRuntime(3622):     at org.apache.http.entity.BasicHttpEntity.getContent(BasicHttpEntity.java:84)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at org.apache.http.entity.BasicHttpEntity.writeTo(BasicHttpEntity.java:126)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at org.apache.http.entity.HttpEntityWrapper.writeTo(HttpEntityWrapper.java:101)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at org.apache.http.conn.BasicManagedEntity.writeTo(BasicManagedEntity.java:126)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at com.firstgroup.webservice.RequestTask.doInBackground(RequestTask.java:51)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at com.firstgroup.webservice.RequestTask.doInBackground(RequestTask.java:1)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at android.os.AsyncTask$2.call(AsyncTask.java:287)
10-23 00:41:00.705: E/AndroidRuntime(3622):     at java.util.concurrent.FutureTask.run(FutureTask.java:234)
10-23 00:41:00.705: E/AndroidRuntime(3622):     ... 4 more

你好

我正在使用 gson 库调用我的 Web 服务，但出现异常。我不知道为什么会发生这种情况。能否请您告诉我如何删除此错误我会给你我所做的步骤..1 )主要 Activity

public class Appliacationload extends Activity implements WebserviceCallBack{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.appliacationload);

        /*WebserviceMethod callDepartudeDashboard=new WebserviceMethod();
        callDepartudeDashboard.setObserver(this);
        callDepartudeDashboard.getwebService(ConstantVariable.dashboardWebServiceURL+"a/"+"arrival"+"?crsCode=hnh");*/
        RequestTask callWebService=new RequestTask();
        callWebService.setObserver(this);
         callWebService.execute(ConstantVariable.dashboardWebServiceURL+"a/"+"arrival"+"?crsCode=vic");



    }

    @Override
    public void getWebserviceResponse(String response) {
        // TODO Auto-generated method stub
        Log.d("response", response);



    }

}

我有一个 holder 和 RequestTask 类来调用网络服务并返回回调。

public class RequestTask extends AsyncTask<String, String, String>{
    private  WebserviceCallBack callBack;
    private ProgressDialog progressDialog;
    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        progressDialog= new ProgressDialog((Context) callBack);
        super.onPreExecute();
        progressDialog.setTitle("Please Wait...");
        progressDialog.setMessage("Webservice Call...");
        progressDialog.setCancelable(true);
        progressDialog.show();
    }

    @Override
    protected String doInBackground(String... uri) {
        HttpClient httpclient = new DefaultHttpClient();
        HttpResponse response;
        String responseString = null;
        try {
            response = httpclient.execute(new HttpGet(uri[0]));
            StatusLine statusLine = response.getStatusLine();
            if(statusLine.getStatusCode() == HttpStatus.SC_OK){
                Reader reader = new InputStreamReader(response.getEntity().getContent());
                Gson gson = new Gson();
                Holder response1 = gson.fromJson(reader, Holder.class);
                ByteArrayOutputStream out = new ByteArrayOutputStream();
                response.getEntity().writeTo(out);
                out.close();
                responseString = out.toString();
            } else{
                //Closes the connection.
                response.getEntity().getContent().close();
                throw new IOException(statusLine.getReasonPhrase());
            }
        } catch (ClientProtocolException e) {
            //TODO Handle problems..\
            progressDialog.hide();
        } catch (IOException e) {
            //TODO Handle problems..
            progressDialog.hide();
        }
        return responseString;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        //Do anything with response..
        if(callBack!=null){
            callBack.getWebserviceResponse(result);
        }
        progressDialog.hide();
    }
    public void setObserver(WebserviceCallBack callback){
        callBack=callback;
    }


}

持有人类；

public class Holder {
    List<deparaturedaseboarddto> data;
}

New Update 当我像那样更改我的请求任务时..

public class RequestTask extends AsyncTask<String, String, InputStream>{
    private  WebserviceCallBack callBack;
    private ProgressDialog progressDialog;
    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        progressDialog= new ProgressDialog((Context) callBack);
        super.onPreExecute();
        progressDialog.setTitle("Please Wait...");
        progressDialog.setMessage("Webservice Call...");
        progressDialog.setCancelable(true);
        progressDialog.show();
    }

    @Override
    protected InputStream doInBackground(String... uri) {
        HttpClient httpclient = new DefaultHttpClient();
        HttpResponse response;
        String responseString = null;
        try {
            response = httpclient.execute(new HttpGet(uri[0]));
            StatusLine statusLine = response.getStatusLine();
            if(statusLine.getStatusCode() == HttpStatus.SC_OK){
                /*Reader reader = new InputStreamReader(response.getEntity().getContent());
                Gson gson = new Gson();
                Holder response1 = gson.fromJson(reader, Holder.class);
                ByteArrayOutputStream out = new ByteArrayOutputStream();
                response.getEntity().writeTo(out);
                out.close();
                responseString = out.toString();*/
                return response.getEntity().getContent();
            } else{
                //Closes the connection.
                response.getEntity().getContent().close();
                throw new IOException(statusLine.getReasonPhrase());
            }
        } catch (ClientProtocolException e) {
            //TODO Handle problems..\
            progressDialog.hide();
        } catch (IOException e) {
            //TODO Handle problems..
            progressDialog.hide();
        }
        return null;
    }

    @Override
    protected void onPostExecute(InputStream result) {
        super.onPostExecute(result);
        //Do anything with response..

        if(callBack!=null){
            callBack.getWebserviceResponse(result);
        }
        progressDialog.dismiss();
        progressDialog=null;

    }
    public void setObserver(WebserviceCallBack callback){
        callBack=callback;
    }


}

然后像那样回电话

public interface WebserviceCallBack {
    public void getWebserviceResponse(InputStream result);

}

和主要 Activity 那样

public class Appliacationload extends Activity implements WebserviceCallBack{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.appliacationload);

        /*WebserviceMethod callDepartudeDashboard=new WebserviceMethod();
        callDepartudeDashboard.setObserver(this);
        callDepartudeDashboard.getwebService(ConstantVariable.dashboardWebServiceURL+"a/"+"arrival"+"?crsCode=hnh");*/
        RequestTask callWebService=new RequestTask();
          callWebService.setObserver(this);
         callWebService.execute(ConstantVariable.dashboardWebServiceURL+"a/"+"arrival"+"?crsCode=vic");



    }

    @Override
    public void getWebserviceResponse(InputStream result) {
        // TODO Auto-generated method stub
        Reader reader = new InputStreamReader(result);
      Gson gson = new Gson();
    Holder response1 = gson.fromJson(reader, Holder.class);
    Log.d("-----", "naveen");
    }

我得到了这个异常，为什么..？我在回调时发送输入流并在主要 Activity 中进行..

异常(exception):

10-23 03:07:33.956: E/AndroidRuntime(22412): FATAL EXCEPTION: main
10-23 03:07:33.956: E/AndroidRuntime(22412): android.os.NetworkOnMainThreadException
10-23 03:07:33.956: E/AndroidRuntime(22412):    at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at libcore.io.BlockGuardOs.recvfrom(BlockGuardOs.java:163)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at libcore.io.IoBridge.recvfrom(IoBridge.java:513)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at java.net.PlainSocketImpl.read(PlainSocketImpl.java:488)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at java.net.PlainSocketImpl.access$000(PlainSocketImpl.java:46)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at java.net.PlainSocketImpl$PlainSocketInputStream.read(PlainSocketImpl.java:240)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at org.apache.http.impl.io.AbstractSessionInputBuffer.fillBuffer(AbstractSessionInputBuffer.java:103)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at org.apache.http.impl.io.AbstractSessionInputBuffer.read(AbstractSessionInputBuffer.java:134)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at org.apache.http.impl.io.ChunkedInputStream.read(ChunkedInputStream.java:161)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at org.apache.http.conn.EofSensorInputStream.read(EofSensorInputStream.java:159)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at java.io.InputStreamReader.read(InputStreamReader.java:244)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.google.gson.stream.JsonReader.fillBuffer(JsonReader.java:1298)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.google.gson.stream.JsonReader.nextQuotedValue(JsonReader.java:1028)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.google.gson.stream.JsonReader.nextName(JsonReader.java:796)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:178)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:81)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:95)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:183)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.google.gson.Gson.fromJson(Gson.java:805)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.google.gson.Gson.fromJson(Gson.java:743)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.firstgroup.applicationload.Appliacationload.getWebserviceResponse(Appliacationload.java:48)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.firstgroup.webservice.RequestTask.onPostExecute(RequestTask.java:77)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.firstgroup.webservice.RequestTask.onPostExecute(RequestTask.java:1)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at android.os.AsyncTask.finish(AsyncTask.java:631)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at android.os.AsyncTask.access$600(AsyncTask.java:177)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at android.os.Handler.dispatchMessage(Handler.java:99)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at android.os.Looper.loop(Looper.java:137)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at android.app.ActivityThread.main(ActivityThread.java:5041)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at java.lang.reflect.Method.invokeNative(Native Method)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at java.lang.reflect.Method.invoke(Method.java:511)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
10-23 03:07:33.956: E/AndroidRuntime(22412):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

原因是您只能从 Entity 消费一次 Content。

你在这里做了两次(也许你不知道)

Reader reader = new InputStreamReader(response.getEntity().getContent());

这里

response.getEntity().writeTo(out);

我知道这听起来有点奇怪，但实际上 writeTo() 函数将从实体获取内容以写入 OutputStream。您可以在文档中看到它 here

您可以使用的另一种解决方法是将其转换为字符串并让 GSON 处理它

@Override
protected String doInBackground(String... uri) {
    HttpClient httpclient = new DefaultHttpClient();
    HttpResponse response;
    String responseString = null;
    try {
        response = httpclient.execute(new HttpGet(uri[0]));
        StatusLine statusLine = response.getStatusLine();
        if(statusLine.getStatusCode() == HttpStatus.SC_OK){
            responseString = EntityUtils.toString(response.getEntity()); // content will be consume only once
            Gson gson = new Gson();
            Holder response1 = gson.fromJson(responseString, Holder.class);
        } else{
            //Closes the connection.
            response.getEntity().getContent().close();
            throw new IOException(statusLine.getReasonPhrase());
        }
    } catch (ClientProtocolException e) {
        //TODO Handle problems..\
        progressDialog.hide();
    } catch (IOException e) {
        //TODO Handle problems..
        progressDialog.hide();
    }
    return responseString;
}

希望我的回答能帮到你!