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我想在后台插入一些使用AsyncTask的数据。我的logcat告诉我，一切进展顺利，数据被插入。但是当我查看table.db时，里面没有数据。我正在使用模拟器来查看table.db。SQLite数据库不会更新数据
这里是我的AsyncTask类：
public class ReadRssBackground extends AsyncTask<Context, Void, Void> {
DatabaseHelper myDB;
Context ctx;
String id, title, link, category;
public ReadRssBackground(Context context) {
ctx = context.getApplicationContext();
}
@Override
protected Void doInBackground(Context... contexts) {
myDB = new DatabaseHelper(ctx);
checkXML(GetData());
return null;
}
public void checkXML(Document data) {
if (data != null) {
Element root = data.getDocumentElement();
Node channel = root.getChildNodes().item(1);
NodeList items = channel.getChildNodes();
for (int i = 0; i < items.getLength(); i++) {
Node currentChild = items.item(i);
if (currentChild.getNodeName().equalsIgnoreCase("item") && count < 5) {
count++;
NodeList itemChilds = currentChild.getChildNodes();
for (int j = 0; j < itemChilds.getLength(); j++) {
Node current = itemChilds.item(j);
if (current.getNodeName().equalsIgnoreCase("title")) {
title = current.getTextContent();
Log.d("Vergleich Title", current.getTextContent());
} else if (current.getNodeName().equalsIgnoreCase("link")) {
link = current.getTextContent();
Log.d("Vergleich Link", current.getTextContent());
} else if (current.getNodeName().equalsIgnoreCase("category")) {
category = current.getTextContent();
Log.d("Vergleich Category", current.getTextContent());
}
}
myDB.insertData(String.valueOf(count),title,link,category);
}
}
}
}
public Document GetData() {
try {
url = new URL(adress);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
InputStream inputStream = connection.getInputStream();
DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = builderFactory.newDocumentBuilder();
Document xmlDoc = builder.parse(inputStream);
return xmlDoc;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
}
在这里，我DatabaseHelper：
public class DatabaseHelper extends SQLiteOpenHelper {
private final Context myContext;
public static final String DATABASE_NAME = "title.db";
public static final String TABLE_NAME = "feed_table";
public static final String COL_1 = "ID";
public static final String COL_2 = "TITLE";
public static final String COL_3 = "LINK";
public static final String COL_4 = "CATEGORY";
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
this.myContext = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT,TITLE TEXT,LINK TEXT)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(db);
}
public boolean insertData(String id, String title, String link, String category) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL_1, id);
contentValues.put(COL_2, title);
contentValues.put(COL_3, link);
contentValues.put(COL_4, category);
Log.d("Vergleich insert check:", contentValues.toString());
long result = db.insert(TABLE_NAME, null, contentValues);
if (result == (-1)) {
Log.d("Vergleich insert:", "DATA INSERTED");
return false;
} else {
Log.d("Vergleich insert:", "NOT");
return true;
}
}
而且logcat的：
> 08-25 04:48:00.102 3244-3309/? D/Vergleich Title: Anhörung in
> Neuseeland: Kim Dotcom wehrt sich gegen Auslieferung 08-25
> 04:48:00.102 3244-3309/? D/Vergleich Link:
> http://www.spiegel.de/netzwelt/web/anhoerung-in-neuseeland-dotcom-wehrt-sich-gegen-auslieferung-a-1109396.html#ref=rss
> 08-25 04:48:00.102 3244-3309/? D/Vergleich Category: Netzwelt 08-25
> 04:48:00.102 3244-3309/? D/Vergleich insert check:: ID=1
> CATEGORY=Netzwelt
> LINK=http://www.spiegel.de/netzwelt/web/anhoerung-in-neuseeland-dotcom-wehrt-sich-gegen-auslieferung-a-1109396.html#ref=rss
> TITLE=Anhörung in Neuseeland: Kim Dotcom wehrt sich gegen Auslieferung
> 08-25 04:48:00.102 3244-3309/? D/Vergleich insert:: DATA INSERTED
> 08-25 04:48:00.102 3244-3309/? D/Vergleich Title: Paisley Park:
> Studios von Prince bald offen für Besucher 08-25 04:48:00.102
> 3244-3309/? D/Vergleich Link:
> http://www.spiegel.de/kultur/musik/paisley-park-studios-von-prince-bald-offen-fuer-besucher-a-1109401.html#ref=rss
> 08-25 04:48:00.102 3244-3309/? D/Vergleich Category: Kultur 08-25
> 04:48:00.102 3244-3309/? D/Vergleich insert check:: ID=2
> CATEGORY=Kultur
> LINK=http://www.spiegel.de/kultur/musik/paisley-park-studios-von-prince-bald-offen-fuer-besucher-a-1109401.html#ref=rss
> TITLE=Paisley Park: Studios von Prince bald offen für Besucher 08-25
> 04:48:00.102 3244-3309/? D/Vergleich insert:: DATA INSERTED
当我得到的反馈，我的数据被插入，为什么表里面什么都没有？我究竟做错了什么？
这里是我的BackgroundService在那里我打电话ReadRssBackground：
public class BackgroundService extends Service {
private boolean isRunning;
private Context context;
private Thread backgroundThread;
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onCreate() {
this.context=this;
this.isRunning=false;
this.backgroundThread = new Thread(myTask);
super.onCreate();
}
private Runnable myTask = new Runnable() {
@Override
public void run() {
//do something in Background
ReadRssBackground readRss = new ReadRssBackground(context);
readRss.execute();
stopSelf();
}
};
@Override
public void onDestroy() {
this.isRunning=false;
super.onDestroy();
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
if(!this.isRunning){
this.isRunning=true;
this.backgroundThread.start();
}
return START_STICKY;
}
}
title.db or table.db？ – Stefan
on'db.insert（）'如果得到-1，则发生错误，如API中所述：https://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#insert%28java .lang.String，％20java.lang.String，％20android.content.ContentValues％29。你切换语句，实际上你得到一个错误 – Opiatefuchs
当'db.insert'操作的结果是'-1'时，你显示'Vergleich insert :: DATA INSERTED'消息 - 这意味着你看到这条消息，因为数据未被插入。你在检查你的日志猫时是否有任何错误？ – ishmaelMakitla