Short version: what is the best practice way to access maintain a history for certain messages from both an activity and from a service?
Long version: I have an activity and a service, which both may be running or not. I want to keep a message log (history) in an object an persist it in a file and be able to e.g. delete entries.
When I have such history in the service and one in the activity I run into sync problems. So, any advice, what the best solution would be?
- ideally I could use the methods from the history class in both the service and activity. Probably not possible.
- I could write and read the file in each action. Probably not very efficient in the long run.
- do I really need to setup a service for the history and handle all actions with it via intents?
It is a bit similiar to "proper way to access DB from both Activity and a started Service?", but with just an own class instead of a SQLite DB.
Any advice?
Conclusion: Use a ContentProvider with a SQLite-DB. Short version of the code:
package com.example.history;
import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.Context;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
public class HistoryContentProvider extends ContentProvider {
static final String PROVIDER_NAME = "com.example.HistoryContentProvider";
static final String URL = "content://" + PROVIDER_NAME + "/history";
static final Uri CONTENT_URI = Uri.parse(URL);
static final String id = "id";
static final String normalized_number = "normalized_number";
static final String display_name = "display_name";
static final int uriCode = 1;
static final UriMatcher uriMatcher;
static {
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
uriMatcher.addURI(PROVIDER_NAME, "history", uriCode);
}
@Override
public boolean onCreate() {
Context context = getContext();
DatabaseHelper dbHelper = new DatabaseHelper(context);
db = dbHelper.getWritableDatabase();
if (db != null) {
return true;
}
return false;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
qb.setTables(TABLE_NAME);
Cursor c = qb.query(db, projection, selection, selectionArgs, null, null, sortOrder);
c.setNotificationUri(getContext().getContentResolver(), uri);
return c;
}
@Override
public String getType(Uri uri) {
switch (uriMatcher.match(uri)) {
case uriCode:
return "vnd.android.cursor.dir/history";
default:
throw new IllegalArgumentException("Unsupported URI: " + uri);
} }
@Override
public Uri insert(Uri uri, ContentValues values) {
long rowID = db.insert(TABLE_NAME, "", values);
if (rowID > 0) {
Uri _uri = ContentUris.withAppendedId(CONTENT_URI, rowID);
getContext().getContentResolver().notifyChange(_uri, null);
return _uri;
}
throw new SQLException("Failed to add a record into " + uri);
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
int count = 0;
switch (uriMatcher.match(uri)) {
case uriCode:
count = db.delete(TABLE_NAME, selection, selectionArgs);
getContext().getContentResolver().notifyChange(uri, null);
break;
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
return count;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
int count = 0;
switch (uriMatcher.match(uri)) {
case uriCode:
count = db.update(TABLE_NAME, values, selection, selectionArgs);
getContext().getContentResolver().notifyChange(uri, null);
break;
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
return count;
}
private SQLiteDatabase db;
static final String DATABASE_NAME = "historyDb";
static final String TABLE_NAME = "history";
static final int DATABASE_VERSION = 3;
static final String CREATE_DB_TABLE = " CREATE TABLE " + TABLE_NAME
+ " (id INTEGER PRIMARY KEY AUTOINCREMENT, "
+ normalized_number + " TEXT NOT NULL, "
+ display_name + " TEXT NOT NULL, ";
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_DB_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(db);
}
}
}
