我有一些代码，当我运行它时会向我的SQLite数据库添加三条记录，这是使用我的MySQLiteHelper类创建的。问题是，每次运行我的应用程序时，三个样本记录都会再次写入数据库，而不会替换它们的相同副本。因此，如果我运行我的应用程序10次，我的数据库中将有30条记录。
MapActivity.java
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map);
MySQLiteHelper db = new MySQLiteHelper(this);
//ADD MAP MARKERS INTO DATABASE (PHASE TWO = FROM CSV FILE)
db.addMapMarker(new MapMarker("Accommodation",
"Cardigan Costal Cottages",
"http://www.cardigan.cc/images/farmhouse/farmhouse.jpg",
"Four star accommodation!",
"Ffrwdwenith Isaf, Felinwyny, Cardigan, SA43 1RW",
"01974 272559",
"http://www.cardigan.cc",
52.2437596, -4.0930263));
db.addMapMarker(new MapMarker("Activity",
"Fforest",
"http://www.coldatnight.co.uk/images/fforestcampcomforts.jpg",
"Offers a full range of half and full day activity packages.",
"1 Cambrian Quay, Cardigan, SA43 2EZ",
"01239 623633",
"http://www.coldatnight.co.uk",
52.1348785, -4.5411973));
db.addMapMarker(new MapMarker("Food & drink",
"Naturally Scrumptious",
"http://www.naturallyscrumptious.co.uk/wp/images/3290f700c749.jpg",
"Delicatessen and cafe bar",
"18 Market Street, Aberaeron, SA46 0AS",
"01545 574733",
"http://www.naturallyscrumptious.co.uk",
52.2424517, -4.2599518));
SQLiteHelper.java
package uk.ac.aber.dwd.util.CeredigionTourism;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
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 MySQLiteHelper extends SQLiteOpenHelper {
//Database Version
private static final int DATABASE_VERSION = 2;
//Database Name
private static final String DATABASE_NAME = "CatalogueDB";
//Catalogue records table name
private static final String TABLE_RECORDS = "records";
//Catalogue records column names
private static final String KEY_ID = "id";
private static final String KEY_GROUP = "category";
private static final String KEY_NAME = "name";
private static final String KEY_IMAGE = "image";
private static final String KEY_DESC = "description";
private static final String KEY_ADDR = "address";
private static final String KEY_TELEPHONE = "telephone";
private static final String KEY_URL = "url";
private static final String KEY_LAT = "latitude";
private static final String KEY_LNG = "longitude";
//Array of Strings used to create database columns
private static final String[] COLUMNS = {KEY_ID, KEY_GROUP, KEY_NAME, KEY_IMAGE, KEY_DESC, KEY_ADDR,
KEY_TELEPHONE, KEY_URL, KEY_LAT, KEY_LNG};
public MySQLiteHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
//SQL statement to create records (map markers) table
String CREATE_RECORDS_TABLE ="CREATE TABLE records (id INTEGER PRIMARY KEY AUTOINCREMENT, " +
"category TEXT, " +
"name TEXT, " +
"image TEXT, " +
"description TEXT, " +
"address TEXT, " +
"telephone TEXT, " +
"url TEXT, " +
"latitude TEXT, " +
"longitude TEXT" + ")";
//Create records (map markers) table
db.execSQL(CREATE_RECORDS_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
//Drop older records table if existed
db.execSQL("DROP TABLE IF EXISTS records");
//create fresh records table
this.onCreate(db);
}
public void addMapMarker(MapMarker marker){
//1. Get reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
//2. Create ContentValues to add key "column"/value
ContentValues values = new ContentValues();
values.put(KEY_GROUP, marker.getGroup());
values.put(KEY_NAME, marker.getName());
values.put(KEY_IMAGE, marker.getImage());
values.put(KEY_DESC, marker.getDescription());
values.put(KEY_ADDR, marker.getAddress());
values.put(KEY_TELEPHONE, marker.getTelephone());
values.put(KEY_URL, marker.getUrl());
values.put(KEY_LAT, marker.getLatitude());
values.put(KEY_LNG, marker.getLongitude());
//3. Insert
db.insert(TABLE_RECORDS, null, values);
db.close();
}
public MapMarker getMapMarker(int id){
//1. Get reference to readable DB
SQLiteDatabase db = this.getReadableDatabase();
//2. Build query
Cursor cursor =
db.query(TABLE_RECORDS,
COLUMNS,
" id = ?",
new String[] {String.valueOf(id)},
null,
null,
null,
null);
//3. If we got result get the first one
if(cursor != null) {
cursor.moveToFirst();
}
//4. Build record object, each column iterates the index value. id = 0, group = 1, etc...
MapMarker marker = new MapMarker();
marker.setId(Integer.parseInt(cursor.getString(0)));
marker.setGroup(cursor.getString(1));
marker.setName(cursor.getString(2));
marker.setImage(cursor.getString(3));
marker.setDescription(cursor.getString(4));
marker.setAddress(cursor.getString(5));
marker.setTelephone(cursor.getString(6));
marker.setUrl(cursor.getString(7));
marker.setLatitude(cursor.getDouble(8));
marker.setLongitude(cursor.getDouble(9));
//5. Return marker
return marker;
}
public List<MapMarker> getAllMapMarkers() {
List<MapMarker> markers = new ArrayList<MapMarker>();
//1. Build the query
String query = "SELECT * FROM " + TABLE_RECORDS;
//2. Get reference to writable DB
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(query, null);
//3. Go over each row, build marker and add it to list
MapMarker marker = null;
if (cursor.moveToFirst()){
do {
marker = new MapMarker();
marker.setId(Integer.parseInt(cursor.getString(0)));
marker.setGroup(cursor.getString(1));
marker.setName(cursor.getString(2));
marker.setImage(cursor.getString(3));
marker.setDescription(cursor.getString(4));
marker.setAddress(cursor.getString(5));
marker.setTelephone(cursor.getString(6));
marker.setUrl(cursor.getString(7));
marker.setLatitude(cursor.getDouble(8));
marker.setLongitude(cursor.getDouble(9));
//Add marker to markers
markers.add(marker);
} while(cursor.moveToNext());
}
cursor.close();
db.close();
//Return markers
return markers;
}
public int updateMapMarker(MapMarker marker) {
//1. Get Reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
//2. Create ContentValues to add key "column"/value
ContentValues values = new ContentValues();
values.put(KEY_GROUP, marker.getGroup());
values.put(KEY_NAME, marker.getName());
values.put(KEY_IMAGE, marker.getImage());
values.put(KEY_DESC, marker.getDescription());
values.put(KEY_ADDR, marker.getAddress());
values.put(KEY_TELEPHONE, marker.getTelephone());
values.put(KEY_URL, marker.getUrl());
values.put(KEY_LAT, marker.getLatitude());
values.put(KEY_LNG, marker.getLongitude());
//3. Updating row
int i = db.update(TABLE_RECORDS, values, KEY_ID + " ?", new String[] {String.valueOf(marker.getId()) });
//4. Close
db.close();
return i;
}
public void deleteMapMarker(MapMarker marker) {
//1. Get reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
//2. Delete
db.delete(TABLE_RECORDS, KEY_ID + " = ?", new String[] {String.valueOf(marker.getId()) });
//3. Close
db.close();
}
}
所以我为SQLiteHelper编写了正确的（我认为！）代码，但每次我的应用程序记录都是重复而不是替换。也许有一种我没有打电话的特殊方法？
答案 0 :(得分：0)
您可以检查数据库中是否已存在记录，并改为调用updateMapMarker。
您确定每次创建活动时都要创建/更新记录吗？听起来很奇怪......