Question

我正在关注Google tutorial中提供的示例，为我的Android应用创建Google App Engine后端。在本教程中，MainActivity如下：

import java.io.IOException;
import java.util.Date;

import android.os.AsyncTask;
import android.content.Context;
import com.cloudnotes.noteendpoint.Noteendpoint;
import com.cloudnotes.noteendpoint.model.Note;
import com.google.api.client.extensions.android.http.AndroidHttp;
import com.google.api.client.http.HttpRequest;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.json.jackson.JacksonFactory;


import android.os.Bundle;
import android.app.Activity;

import android.view.Menu;

public class MainActivity extends Activity {

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

  new EndpointsTask().execute(getApplicationContext());
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

public class EndpointsTask extends AsyncTask<Context, Integer, Long> {
    protected Long doInBackground(Context... contexts) {

      Noteendpoint.Builder endpointBuilder = new Noteendpoint.Builder(
          AndroidHttp.newCompatibleTransport(),
          new JacksonFactory(),
          new HttpRequestInitializer() {
          public void initialize(HttpRequest httpRequest) { }
          });
  Noteendpoint endpoint = CloudEndpointUtils.updateBuilder(
  endpointBuilder).build();
  try {
      Note note = new Note().setDescription("Note Description");
      String noteID = new Date().toString();
      note.setId(noteID);

      note.setEmailAddress("E-Mail Address");      
      Note result = endpoint.insertNote(note).execute();
   } catch (IOException e) {
    e.printStackTrace();
   }
       return (long) 0;
    }
   }
   }

这种情况很糟糕，每次运行应用程序时都会创建实体。所以我通过添加textfields来修改它，以便从用户那里获取description和email的值并得到此信息作为新的MainActivity

public class MainActivity extends Activity implements View.OnClickListener{

EditText descriptionTF;
EditText emailTF;
Button submitBtn;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    submitBtn  = (Button) findViewById(R.id.submitButton);
    descriptionTF = (EditText) findViewById(R.id.descriptionTextField);
    emailTF = (EditText) findViewById(R.id.emailTextField);
}

public class EndpointsTask extends AsyncTask<Context, Integer, Long> {
    protected Long doInBackground(Context... contexts) {

      Noteendpoint.Builder endpointBuilder = new Noteendpoint.Builder(
          AndroidHttp.newCompatibleTransport(),
          new JacksonFactory(),
          new HttpRequestInitializer() {
          public void initialize(HttpRequest httpRequest) { }
          });
  Noteendpoint endpoint = CloudEndpointUtils.updateBuilder(
  endpointBuilder).build();

      String descrptn = descriptionTF.getText().toString();
      String email = emailTF.getText().toString();
      String noteID = new Date().toString();
  try {
      Note note = new Note();


      note.setDescription(descrptn);

      note.setId(noteID);

      note.setEmailAddress(email);      
      Note result = endpoint.insertNote(note).execute();
  } catch (IOException e) {
    e.printStackTrace();
  }
      return (long) 0;
    }
}

@Override
public void onClick(View v) {
    if (v.getId()== R.id.submitButton) {
     new EndpointsTask().execute(getApplicationContext());
    }
}
 }

当我点击submit按钮时，没有任何反应。我猜测问题来自于我从new EndpointsTask().execute(getApplicationContext());方法调用onClick()而不是像教程中所做的那样onCreate()方法。有人知道解决这个问题吗？

Answer 1

最后通过将onClick()方法移动到onCreate()方法解决了这个问题：

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

    submitBtn  = (Button) findViewById(R.id.submitButton);
    descriptionTF = (EditText) findViewById(R.id.descriptionTextField);
    emailTF = (EditText) findViewById(R.id.emailTextField);

    submitBtn.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            if (v.getId()== R.id.submitButton) {
         new EndpointsTask().execute(getApplicationContext());
        }
        }
    });
}

无法将实体从Android应用程序保存到Google App Engine后端

1 个答案: