我已经在这个应用程序上工作了一段时间，但我即将完成此错误：
java.lang.RuntimeException：无法启动活动 ComponentInfo {org.marsfirst.mars_app / org.marsfirst.mars_app.TeamNews}： android.os.NetworkOnMainThreadException at android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2413） 在 android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2471） 在android.app.ActivityThread.access $ 900（ActivityThread.java:175）at android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1308） 在android.os.Handler.dispatchMessage（Handler.java:102）at android.os.Looper.loop（Looper.java:146）at android.app.ActivityThread.main（ActivityThread.java:5602）at java.lang.reflect.Method.invokeNative（Native Method）at java.lang.reflect.Method.invoke（Method.java:515）at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1283） 在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1099）at dalvik.system.NativeStart.main（Native方法）引起： android.os.NetworkOnMainThreadException at android.os.StrictMode $ AndroidBlockGuardPolicy.onNetwork（StrictMode.java:1166） 在 com.android.org.conscrypt.OpenSSLSocketImpl.close（OpenSSLSocketImpl.java:1009） 在 org.apache.http.impl.SocketHttpClientConnection.close（SocketHttpClientConnection.java:205） 在 org.apache.http.impl.conn.DefaultClientConnection.close（DefaultClientConnection.java:161） 在 org.apache.http.impl.conn.tsccm.AbstractConnPool.closeConnection（AbstractConnPool.java:320） 在 org.apache.http.impl.conn.tsccm.AbstractConnPool.shutdown（AbstractConnPool.java:296） 在 org.apache.http.impl.conn.tsccm.ConnPoolByRoute.shutdown（ConnPoolByRoute.java:670） 在 org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager.shutdown（ThreadSafeClientConnManager.java:256） 在com.parse.ParseRequest.initialize（ParseRequest.java:118）at com.parse.Parse.initialize（Parse.java:109）at org.marsfirst.mars_app.TeamNews.onCreate（TeamNews.java:41）at at android.app.Activity.performCreate（Activity.java:5451）at android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1093） 在 android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2377）
在对问题进行了大量研究后，我知道我需要在我的应用程序中添加以下代码：
AsyncTask<Void, Void, Void> task = new AsyncTask<Void, Void, Void>() {
@Override
protected Void doInBackground(Void... params) {
Parse.initialize(this, "Key",
"Key");;
}
};
但是我不确定在何处放置代码。
我的MainPage.Java：
package org.marsfirst.mars_app;
import android.app.Activity;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
public class MainPage extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.mainpage);
ImageView website = (ImageView) findViewById(R.id.imageButton6);
website.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
new CallWebpage().execute();
}
});
ImageView logo1 = (ImageView) findViewById(R.id.imageButton7);
logo1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
new CallEvent().execute();
}
});
ImageView contactpage = (ImageView) findViewById(R.id.imagebutton8);
contactpage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
new CallContact().execute();
}
});
ImageView teamNews = (ImageView) findViewById(R.id.imagebutton1);
teamNews.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
new CallTeamNews().execute();
}
});
ImageView mechPage = (ImageView) findViewById(R.id.imageButton2);
mechPage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
new CallMechPage().execute();
}
});
ImageView driveNews = (ImageView) findViewById(R.id.imagebutton3);
driveNews.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
new CallDriveNews().execute();
}
});
ImageView oprPage = (ImageView) findViewById(R.id.imagebutton4);
oprPage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
new CallOprPage().execute();
}
});
ImageView ProgramingPage = (ImageView) findViewById(R.id.imagebutton5);
ProgramingPage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
new CallProgramingPage().execute();
}
});
ImageView food = (ImageView) findViewById(R.id.imageButton9);
food.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
new CallFood().execute();
}
});
ImageView travel = (ImageView) findViewById(R.id.imagebutton10);
travel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
new CallTravel().execute();
}
});
}
public class CallWebpage extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... urls) {
Intent intent = new Intent(MainPage.this, Webpage.class);
MainPage.this.startActivity(intent);
return "";
}
}
public class CallTeamNews extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... urls) {
Intent intent = new Intent(MainPage.this, TeamNews.class);
MainPage.this.startActivity(intent);
return "";
}
}
public class CallOprPage extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... urls) {
Intent intent = new Intent(MainPage.this, OprPage.class);
MainPage.this.startActivity(intent);
return "";
}
}
public class CallDriveNews extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... urls) {
Intent intent = new Intent(MainPage.this, DriveNews.class);
MainPage.this.startActivity(intent);
return "";
}
}
public class CallMechPage extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... urls) {
Intent intent = new Intent(MainPage.this, MechPage.class);
MainPage.this.startActivity(intent);
return "";
}
}
public class CallProgramingPage extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... urls) {
Intent intent = new Intent(MainPage.this, ProgramingPage.class);
MainPage.this.startActivity(intent);
return "";
}
}
public class CallEvent extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... urls) {
Intent intent = new Intent(MainPage.this, Event.class);
MainPage.this.startActivity(intent);
return "";
}
}
public class CallContact extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... urls) {
Intent intent = new Intent(MainPage.this, Contact.class);
MainPage.this.startActivity(intent);
return "";
}
}
public class CallFood extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... urls) {
Intent intent = new Intent(MainPage.this, Food.class);
MainPage.this.startActivity(intent);
return "";
}
}
public class CallTravel extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... urls) {
Intent intent = new Intent(MainPage.this, Travel.class);
MainPage.this.startActivity(intent);
return "";
}
}
}
Would I place the the code in somewhere like this:
public class CallProgramingPage extends AsyncTask<Void, Void, String> {
protected String doInBackground(Void... urls) {
Intent intent = new Intent(MainPage.this, ProgramingPage.class);
MainPage.this.startActivity(intent);
return "";
}
}
and if so how because when I did I received many errors.
However would it be better to set up an Async Task in my actual activity that uses parse:
package org.marsfirst.mars_app;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.StreamCorruptedException;
import android.app.Activity;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
import com.parse.GetCallback;
import com.parse.Parse;
import com.parse.ParseException;
import com.parse.ParseObject;
import com.parse.ParseQuery;
public class TeamNews extends Activity {
private Context c;
private ParseProxyObject saved;
private TextView title, date, content;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Parse.initialize(this, "QmmXYAxVVSoT7MGlE3ZcAseCoLehfZko3BZJbo1P",
"SQHTLKcpNKDCLZWTgfOOFPEcmFYkdmWywKNProWG");
setContentView(R.layout.announcements);
c = getApplicationContext();
new CallUpdate(TeamNews.this).execute();
title = (TextView) findViewById(R.id.textView1);
date = (TextView) findViewById(R.id.textView2);
content = (TextView) findViewById(R.id.textView3);
saved = (ParseProxyObject) readObjectFromMemory("announce");
setTexts(saved);
if (title.getText().equals("Connect to internet and press refresh.")) {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
@Override
public void onResume() {
super.onResume();
c = getApplicationContext();
if (isNetworkAvailable())
(new CallUpdate(TeamNews.this)).execute();
title = (TextView) findViewById(R.id.textView1);
date = (TextView) findViewById(R.id.textView2);
content = (TextView) findViewById(R.id.textView3);
saved = (ParseProxyObject) readObjectFromMemory("announce");
setTexts(saved);
}
public void setTexts(ParseProxyObject saved) {
if (saved == null) {
emptyTexts();
title.setText("Connect to internet and press refresh.");
return;
}
String format = "\t";
title.setText(format + saved.getString("name"));
String format2 = "\t";
date.setText(format2 + saved.getString("date_updated"));
String format3 = "\t";
content.setText(format3 + saved.getString("content_1"));
}
public ParseProxyObject readObjectFromMemory(String filename) {
FileInputStream fis;
ParseProxyObject object = null;
try {
fis = openFileInput(filename);
ObjectInputStream is = new ObjectInputStream(fis);
object = (ParseProxyObject) is.readObject();
is.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (StreamCorruptedException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
return object;
}
public void emptyTexts() {
title.setText("");
date.setText("");
content.setText("");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu items for use in the action bar
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle presses on the action bar items
switch (item.getItemId()) {
case R.id.action_refresh_k:
(new CallUpdate(c)).execute();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
public class CallUpdate extends AsyncTask<Void, Void, String> {
private Context c;
public CallUpdate(Context newC) {
c = newC;
}
@Override
protected void onPreExecute() {
View v = findViewById(R.id.action_refresh_k);
if (v != null)
v.setVisibility(View.GONE);
}
protected String doInBackground(Void... urls) {
ParseQuery<ParseObject> query;
saved = (ParseProxyObject) readObjectFromMemory("announce");
query = ParseQuery.getQuery("Announcements");
query.getInBackground("1XLhLinldW", new GetCallback<ParseObject>() {
public void done(ParseObject object, ParseException e) {
if (e == null) {
if (object != null
&& (saved == null || !(object.getInt("version") == saved
.getInt("version")))) {
saved = new ParseProxyObject(object);
(new CallSave(c, saved, "announce")).execute();
}
} else {
// something went wrong
return;
}
}
});
return "";
}
protected void onPostExecute(String result) {
View v = findViewById(R.id.action_refresh_k);
if (v != null)
v.setVisibility(View.VISIBLE);
saved = (ParseProxyObject) readObjectFromMemory("announce");
setTexts(saved);
}
}
public void writeObjectToMemory(String filename, ParseProxyObject object) {
FileOutputStream fos;
try {
fos = c.openFileOutput(filename, Context.MODE_PRIVATE);
ObjectOutputStream os = new ObjectOutputStream(fos);
os.writeObject(object);
os.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
public void makeToast(String text) {
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(c, text, duration);
toast.show();
}
public class CallSave extends AsyncTask<Void, Void, String> {
Context c;
ParseProxyObject object;
String filename;
public CallSave(Context newC, ParseProxyObject newObject,
String newFileName) {
c = newC;
object = newObject;
filename = newFileName;
}
@Override
protected void onPreExecute() {
}
@Override
protected String doInBackground(Void... urls) {
FileOutputStream fos;
try {
fos = openFileOutput(filename, Context.MODE_PRIVATE);
ObjectOutputStream os = new ObjectOutputStream(fos);
os.writeObject(((ParseProxyObject) object));
os.flush();
os.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return "";
}
@Override
protected void onPostExecute(String result) {
}
}
private boolean isNetworkAvailable() {
ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetworkInfo = connectivityManager
.getActiveNetworkInfo();
return activeNetworkInfo != null && activeNetworkInfo.isConnected();
}
}
请帮助我，我完全迷失了，我不知道我能把它放在哪里，如果我的代码风格错误，请告诉我。我仍然在学习和自学，所以请用我的白痴。 谢谢。
答案 0 :(得分：0)
您需要将所有网络代码放在DoInBackground方法中。有四种方法可用于异步onPreExecute，它在UiThread上运行并在输入doInBackgound之前执行所需的所有更新。 doInBackground完成UI线程的所有工作，你不会在mainThread Exception上获得网络。和onPostExecute一旦doinbackground完成，就会调用它，你可以显示结果并更新UI，因为onPostExecute在UIThread上运行，还有一些其他可用的也像oncanceled等。
AsyncTask可以正确，轻松地使用UI线程。该类允许执行后台操作并在UI线程上发布结果，而无需操纵线程和/或处理程序。
AsyncTask旨在成为Thread和Handler的辅助类，并不构成通用的线程框架。理想情况下，AsyncTasks应该用于短操作（最多几秒钟。）如果需要保持线程长时间运行，强烈建议您使用java.util.concurrent pacakge提供的各种API，例如Executor，ThreadPoolExecutor和FutureTask。
异步任务由在后台线程上运行的计算定义，其结果在UI线程上发布。异步任务由3种泛型类型定义，称为Params，Progress和Result，以及4个步骤，称为onPreExecute，doInBackground，onProgressUpdate和onPostExecute。
你可以查看这些帖子他们是AsyncTasks的好例子你所有的困惑都可以解决:)
http://www.vogella.com/tutorials/AndroidBackgroundProcessing/article.html
http://android.programmerguru.com/android-asynctask-example/
了解更多信息。
http://developer.android.com/reference/android/os/AsyncTask.html