Question

我正在开发一个应用程序，当没有移动信号覆盖区域时，数据会保存到数据库中。当服务返回时，它将从数据库中获取所有数据并在服务器上上传。

现在我有两个问题。

当第一次数据插入数据库时，IntentService停止。（当网络服务恢复时，它也会在服务器上传数据，用于检查我使用计时器的网络连接。）我不想停止服务。
当我第二次启动服务时，它再次创建并提供Nullpointerexception。因为数据库中没有数据，所以它也提供了一些关于数据反转的其他错误。

我的代码有什么问题？我只是希望当用户启动服务时，它将一直运行到数据库中的最后一个数据，之后它将停止。我在intentservice中使用了线程，因为我的应用程序崩溃了。

LogCat错误

10-14 20:44:02.135: E/Service(10042): Service Created.. 
10-14 20:44:02.505: E/Service Started(10042): Successful
10-14 20:44:03.585: E/Service Network(10042): Network is offline
10-14 20:44:08.656: E/Service Network(10042): Network is offline
10-14 20:44:13.616: E/Service Network(10042): Network is offline
10-14 20:44:18.646: E/Service Network(10042): Network is offline
10-14 20:44:23.595: E/Service Network(10042): Network is offline
10-14 20:44:29.526: E/Service Network(10042): Network is online
10-14 20:44:31.256: E/Data Sent(10042): Response 200
10-14 20:44:33.599: E/Service Network(10042): Network is online
10-14 20:44:34.446: E/Data Sent(10042): Response 200
10-14 20:44:38.646: E/Service Network(10042): Network is online
10-14 20:44:40.616: E/Data Sent(10042): Response 200
10-14 20:44:43.625: E/Service Network(10042): Network is offline
10-14 20:44:48.595: E/Service Network(10042): Network is offline
10-14 20:44:53.586: E/Service Network(10042): Network is offline
10-14 20:45:20.486: E/Service(10042): Service Created.. 
10-14 20:45:20.587: E/Service Started(10042): Successful
10-14 20:45:20.627: E/Insertion(10042): java.lang.NullPointerException
10-14 20:45:21.666: E/Service Network(10042): Network is offline
10-14 20:45:23.616: E/Service Network(10042): Network is offline
10-14 20:45:36.645: E/Service Network(10042): Network is offline
10-14 20:45:38.585: E/Service Network(10042): Network is offline
10-14 20:45:41.786: E/Service Network(10042): Network is online
10-14 20:45:42.026: E/AndroidRuntime(10042): FATAL EXCEPTION: Timer-1
10-14 20:45:42.026: E/AndroidRuntime(10042): java.lang.NullPointerException
10-14 20:45:42.026: E/AndroidRuntime(10042):    at com.remote.synchronizer.haris.SQLiteAdapter.getAllContacts(SQLiteAdapter.java:93)
10-14 20:45:42.026: E/AndroidRuntime(10042):    at com.remote.synchronizer.haris.OfflineDataService$1$1.run(OfflineDataService.java:80)
10-14 20:45:42.026: E/AndroidRuntime(10042):    at java.util.Timer$TimerImpl.run(Timer.java:284)
10-14 20:45:43.646: E/Service Network(10042): Network is online
10-14 20:45:44.266: E/Data Sent(10042): Response 200

SQLiteAdapter.java

package com.remote.synchronizer.haris;

import java.util.ArrayList;
import java.util.List;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class SQLiteAdapter extends SQLiteOpenHelper {

    public static final String DATABASE_NAME = "Product";
    public static final String TABLE_NAME = "Orders";
    public static final int DATABASE_VERSION = 1;
    public static final String KEY_ID = " _id";  //
    public static final String KEY_NAME = "name";
    public static final String KEY_SHOP = "shop";
    private static final String KEY_CITY = "city";
    private static final String KEY_DATE = "datee";
    private static final String KEY_ORDER = "orderr";

    private SQLiteDatabase sqLiteDatabase;
    private SQLiteAdapter sqLiteHelper=this;

    private static final String CREATE_TABLE =
            "CREATE TABLE " + TABLE_NAME + " ("
                    + KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
                    + KEY_NAME + " VARCHAR,"
                    + KEY_SHOP + " VARCHAR," + KEY_CITY + " VARCHAR, " + KEY_DATE + " VARCHAR, " + KEY_ORDER + " VARCHAR" +");";


    public SQLiteAdapter(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);  
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_TABLE);
        sqLiteDatabase=db;
    }

    /*public void close(){
        sqLiteHelper.close();
    }
     */
    public void insert(String name, String shop, String city, String datee, String orderr){

        try
        {
            ContentValues contentValues = new ContentValues();
            contentValues.put(KEY_NAME, name);
            contentValues.put(KEY_SHOP, shop);
            contentValues.put(KEY_CITY, city);
            contentValues.put(KEY_DATE, datee);
            contentValues.put(KEY_ORDER, orderr);
            sqLiteDatabase.insertOrThrow(TABLE_NAME, KEY_ID, contentValues);
            //sqLiteDatabase.close();
        }
        catch(Exception e)
        {
            e.printStackTrace();
            Log.e("Insertion", e.toString());
        }
    }

    public void deleteAll(){
        sqLiteDatabase.delete(TABLE_NAME, null, null);
    }

    public void delete_byID(int id){
        sqLiteDatabase.delete(TABLE_NAME, KEY_ID+"="+id, null);
    }

    /*public Cursor queueAll(){
        String[] columns = new String[]{KEY_ID, KEY_NAME, KEY_SHOP, KEY_CITY,  KEY_DATE, KEY_ORDER};
        Cursor cursor = sqLiteDatabase.query(TABLE_NAME, columns, 
                null, null, null, null, null);

        return cursor;
    }*/

    public List<NameValuePair> getAllContacts() {
        List<NameValuePair> postParameters = new ArrayList<NameValuePair>();

        String selectQuery = "SELECT  * FROM " + TABLE_NAME;
        sqLiteHelper.getReadableDatabase();
        Cursor cursor = sqLiteDatabase.rawQuery(selectQuery, null);

        if(cursor.moveToFirst()){
            while(!cursor.isAfterLast())
            {
                postParameters.add(new BasicNameValuePair("User", cursor.getString(cursor.getColumnIndex(KEY_NAME))));
                postParameters.add(new BasicNameValuePair("ShopName", cursor.getString(cursor.getColumnIndex(KEY_SHOP))));
                postParameters.add(new BasicNameValuePair("city", cursor.getString(cursor.getColumnIndex(KEY_CITY))));
                postParameters.add(new BasicNameValuePair("OrderDate", cursor.getString(cursor.getColumnIndex(KEY_DATE))));
                postParameters.add(new BasicNameValuePair("OrderDetail", cursor.getString(cursor.getColumnIndex(KEY_ORDER))));
                cursor.moveToNext();
            }

        }
        //cursor.close();
        return postParameters;
    };

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.w(SQLiteAdapter.class.getName(),
                "Upgrading database from version " + oldVersion + " to "
                        + newVersion + ", which will destroy all old data");
        db.execSQL("DROP TABLE IF EXISTS " + CREATE_TABLE);
        onCreate(db);
    }

}

OfflineDataService.java

package com.remote.synchronizer.haris;

import java.util.ArrayList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;
import org.apache.http.NameValuePair;

import android.app.IntentService;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.util.Log;

public class OfflineDataService extends IntentService {

    boolean wifi,edge;
    private Timer timer= new Timer();
    SQLiteDatabase db;
    String un,shop,city,date,order;
    private SQLiteAdapter mySQLiteAdapter;
    Cursor cursor;

    public OfflineDataService() {
        super("OfflineDataService");
    }

    @Override   
    public void onCreate() {

        super.onCreate();

        Log.e("Service", "Service Created.. ");

        mySQLiteAdapter = new SQLiteAdapter(this);
        mySQLiteAdapter.getWritableDatabase();

    }   

    @Override
    protected void onHandleIntent(final Intent intent) {

        final Handler threadHandler;  
        threadHandler = new Handler();

        new Thread(new Runnable(){

            @Override
            public void run() {

                Bundle bundle=intent.getExtras();
                un=bundle.getString("un");
                shop=bundle.getString("shop");
                city=bundle.getString("city");
                date=bundle.getString("date");
                order=bundle.getString("order");

                Log.e("Service Started", "Successful");

                //Inserting New Record
                mySQLiteAdapter.insert(un,shop,city,date,order);

                timer.scheduleAtFixedRate(new TimerTask(){

                    @Override
                    public void run() {

                        //Checking network connectivity
                        wifi=NetworkInfo.Wifi(OfflineDataService.this);
                        edge=NetworkInfo.EDGE(OfflineDataService.this);

                        if(wifi==true||edge==true)
                        {
                            Log.e("Service Network", "Network is online");
                            List<NameValuePair> contacts=new ArrayList<NameValuePair>();

                            contacts=mySQLiteAdapter.getAllContacts();

                            String url="http://10.0.2.2:3325/Product/Create?"; 

                            int response = 0;

                            try 
                            {
                                response = CustomHttpClient.executeHttpPost(url, contacts);

                                if(response==200)
                                {
                                    Log.e("Data Sent", "Response 200");
                                }

                                else{

                                    Log.e("Service Data", "Faield to upload data" );
                                }

                            }
                            catch (Exception e)
                            {
                                Log.e("Data Sending", e.toString());
                                e.printStackTrace();
                            }
                        }
                        else
                        {
                            Log.e("Service Network", "Network is offline");
                        }
                    }

                }, 1000, 5000);

            }

        }).start();
    }

    /*@Override
    public void onDestroy() {

        super.onDestroy();
      //  mySQLiteAdapter.deleteAll();
        Log.e("Service Destroy", "Successful");


    }*/
}

我是否需要使用onStartCommand而不是onHandleIntent，还是需要使用服务而不是IntentService来控制它们？

Answer 1

这可能是问题，我看不到你在哪里保存可读数据库......改变这个：

sqLiteHelper.getReadableDatabase();
Cursor cursor = sqLiteDatabase.rawQuery(selectQuery, null);

对此：

if(sqLiteDatabase == null || !sqLiteDatabase.isOpen()) {
    sqLiteDatabase = sqLiteHelper.getReadableDatabase();
}
Cursor cursor = sqLiteDatabase.rawQuery(selectQuery, null);

<强>加成

对于SQLiteOpenHelper，在创建 new 数据库时，onCreate()仅，而不只是打开现有数据库...将构造函数更改为：

public SQLiteAdapter(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);  
    sqLiteDatabase = this.getWritableDatabase();
}

（并从sqLiteDatabase=db移除onCreate()）

另外，我忘了这是一个两部分的问题。 IntentServices不能无限期运行，您应该使用服务（或切换到使用ContentProvider）。

数据插入SQLite后IntentService停止，插入第二次时给出NULLPOINTER EXCEPTION

1 个答案: