Question

首先，我将用文字简要描述过程/问题。之后，我将附上所有代码。

我在调试模式下启动android应用程序。
调用主要活动。
通过＆＃34;意图＆＃34;。
然后（在onCreate中）我启动Async活动以从Web服务器获取信息。我用这个命令＆＃34;新的Kontakt（info1，info2，信息）.execute（）;＆＃34;
我在＆＃34; Kontakt＆＃34;中的onPostExecute方法中设置了一个断点。看看会发生什么。但！！它并没有止步于此。所以我想，＆＃34; okey，doInBackground方法由于某种原因没有被调用＆＃34;
当我继续运行代码时，出乎意料的是，onPostExecute被调用（在onClick结束时的某个地方）并在断点处停止，就像我想要的那样，但是为时已晚，因为我希望输出已经在onCreate方法中，我调用了＃34; new Kontakt（info1，info2，information）.execute（）;＆＃34;。
那么为什么它太晚调用onPostExecute以及我该怎样做才能使进程在onCreate中已经正确地调用它＆＃34; new Kontakt（info1，info2，information）.execute（）; ＆＃34;在Activity2？

代码在

MainActivity.java

    package com.example.myapplication;

    import android.content.Context;
    import android.content.Intent;
    import android.content.SharedPreferences;
    import android.graphics.Color;
    import android.graphics.PorterDuff;
    import android.graphics.drawable.Drawable;
    import android.preference.PreferenceManager;
    import android.support.v7.app.ActionBarActivity;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.Menu;
    import android.view.MenuItem;
    import android.view.View;
    import android.widget.Button;
    import android.widget.TextView;


    public class MainActivity extends ActionBarActivity implements View.OnClickListener {
        Button button1;

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

            button1 = (Button) findViewById(R.id.button1);
            button1.setOnClickListener(this);
        }


        @Override
        public void onClick(View view) {
            switch (view.getId()) {
                case R.id.button1:
                    Intent intent = new Intent(this, Activity2.class);
                    startActivity(intent);
                    break;
            }
        }
    }

Activity2.java

        package com.example.myapplication;

        import android.app.AlertDialog;
        import android.content.Context;
        import android.content.DialogInterface;
        import android.content.SharedPreferences;
        import android.net.ConnectivityManager;
        import android.net.NetworkInfo;
        import android.preference.PreferenceManager;
        import android.support.v7.app.ActionBarActivity;
        import android.os.Bundle;
        import android.text.InputType;
        import android.text.TextUtils;
        import android.util.Log;
        import android.view.Menu;
        import android.view.MenuItem;
        import android.view.View;
        import android.view.WindowManager;
        import android.view.inputmethod.InputMethodManager;
        import android.widget.Button;
        import android.widget.EditText;

        import org.apache.http.NameValuePair;
        import org.apache.http.client.HttpClient;
        import org.apache.http.client.entity.UrlEncodedFormEntity;
        import org.apache.http.client.methods.HttpPost;
        import org.apache.http.impl.client.DefaultHttpClient;
        import org.apache.http.message.BasicNameValuePair;
        import org.apache.http.params.BasicHttpParams;
        import org.apache.http.params.HttpConnectionParams;
        import org.apache.http.params.HttpParams;

        import java.io.IOException;
        import java.net.MalformedURLException;
        import java.util.ArrayList;


public class Activty2 extends ActionBarActivity implements View.OnClickListener {

    Button button;
    Context information;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity2);
        information=this;
        String info1="Yeah";
        String info2="Yeah";
        new Kontakt(info1, info2, information).execute();

        button = (Button) findViewById(R.id.button);
        button.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        if (view.getId() == R.id.button) {
        }
    }

Kontakt.java

package com.example.myapplication;

import android.content.Context;
import android.content.DialogInterface;
import android.content.SharedPreferences;
import android.os.AsyncTask;
import android.util.Log;



import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.json.JSONObject;

import java.util.ArrayList;

public class Kontakt extends AsyncTask<Void, Void, Integer> {

    public static final int CONNECTION_TIMEOUT = 1000 * 15;
    public static final String SERVER_ADDRESS = "http://test.site.net/";

    String info1;
    String info2;
    private final Context information;

public Kontakt(String info1, String info2, Context context) {
this.info1=info1;
this.Info2=info2;
    this.information=context;
}


        @Override
        protected Integer doInBackground(Void... params) {


            ArrayList<NameValuePair> dataToSend = new ArrayList<>();
            dataToSend.add(new BasicNameValuePair("user", info1));
            dataToSend.add(new BasicNameValuePair("password", info2));

            HttpParams httpRequestParams = getHttpRequestParams();

            HttpClient client = new DefaultHttpClient(httpRequestParams);
            HttpPost post = new HttpPost(SERVER_ADDRESS
                    + "Register.php");

            try {
                post.setEntity(new UrlEncodedFormEntity(dataToSend));
                client.execute(post);
                int result=1;
                return result;

            } catch (Exception e) {
                e.printStackTrace();
                int result=0;
                return result;
            }
//return null;

        }

    private HttpParams getHttpRequestParams() {
        HttpParams httpRequestParams = new BasicHttpParams();
        HttpConnectionParams.setConnectionTimeout(httpRequestParams,
                CONNECTION_TIMEOUT);
        HttpConnectionParams.setSoTimeout(httpRequestParams,
                CONNECTION_TIMEOUT);
        return httpRequestParams;
    }

    @Override
    protected void onPostExecute(Integer result)
    {
        super.onPostExecute(result);
        SharedPreferences.Editor editor = information.getSharedPreferences("INTERNET_KOLL", Context.MODE_PRIVATE).edit();
        editor.putString("internet_status", String.valueOf(result));
        editor.commit();
    }

}

Answer 1

在Activity2，当onCreate()拨打new Kontakt(info1, info2, information).execute();时：

异步任务（Kontakt）在后台启动
执行onCreate()继续

所以你没有立即得到回应是正常的。

onPostExecute调用得太晚

1 个答案: