我有List一些要插入数据库的对象。我在 foreach 循环中创建了插入插入，但它仍然以异常约束失败结束。在我的表中，我创建了 column '_id' INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL。我的插入方法看起来像
public void insertData(List<Item> list) {
dbAdapter = DBAdapter.getDBAdapterInstance(getActivity());
dbAdapter.openDataBase();
for (Itemm item : list) {
ContentValues values = new ContentValues();
values.put("item_id", item.getItemId());
values.put("item_category", item.getItemCategory());
values.put("order_number", item.getOrderNumber());
dbAdapter.insertRecordsInDB("order_list", null, values);
}
dbAdapter.close();
}
这是 DBAdapter 类：
public class DBAdapter extends SQLiteOpenHelper {
private static String DB_PATH = "/data/data/<my_package>/databases/";
private static String DB_NAME = "mydatabase.db";
private static final int DB_VERSION = 1;
private SQLiteDatabase myDataBase;
private final Context myContext;
private static DBAdapter myDBAdapter;
/**
* Constructor Takes and keeps a reference of the passed context in order to
* access to the application assets and resources.
*
* @param context
*/
private DBAdapter(Context context) {
super(context, DB_NAME, null, DB_VERSION);
this.myContext = context;
}
/**
* getting Instance
*
* @param context
* @return DBAdapter
*/
public static synchronized DBAdapter getDBAdapterInstance(Context context) {
if (myDBAdapter == null) {
myDBAdapter = new DBAdapter(context);
}
return myDBAdapter;
}
/**
* Creates an empty database on the system and rewrites it with your own
* database.
**/
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
// do nothing - database already exist
} else {
// By calling following method
// 1) an empty database will be created into
// the default system path of your application
// 2) than we overwrite that database with our database.
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each
* time you open the application.
*
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase() {
//SQLiteDatabase checkdb = null;
boolean checkdb = false;
try{
String myPath = DB_PATH + DB_NAME;
File dbfile = new File(myPath);
//checkdb = SQLiteDatabase.openDatabase(myPath,null,SQLiteDatabase.OPEN_READWRITE);
checkdb = dbfile.exists();
}
catch(SQLiteException e){
System.out.println("Database doesn't exist");
}
return checkdb;
}
/**
* Copies your database from your local assets-folder to the just created
* empty database in the system folder, from where it can be accessed and
* handled. This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException {
// Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
// Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
// transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
// Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
/**
* Open the database
*
* @throws SQLException
*/
public void openDataBase() throws SQLException {
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READWRITE);
if (!myDataBase.isReadOnly()) {
myDataBase.execSQL("PRAGMA foreign_keys=ON;");
}
}
/**
* Close the database if exist
*/
@Override
public synchronized void close() {
if (myDataBase != null)
myDataBase.close();
super.close();
}
/**
* Call on creating data base for example for creating tables at run time
*/
@Override
public void onCreate(SQLiteDatabase db) {
}
/**
* can used for drop tables then call onCreate(db) function to create tables
* again - upgrade
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
// ----------------------- CRUD Functions ------------------------------
/**
* This function used to select the records from DB.
*
* @param tableName
* @param tableColumns
* @param whereClase
* @param whereArgs
* @param groupBy
* @param having
* @param orderBy
* @return A Cursor object, which is positioned before the first entry.
*/
public Cursor selectRecordsFromDB(String tableName, String[] tableColumns,
String whereClase, String whereArgs[], String groupBy,
String having, String orderBy) {
return myDataBase.query(tableName, tableColumns, whereClase, whereArgs,
groupBy, having, orderBy);
}
/**
* select records from db and return in list
*
* @param tableName
* @param tableColumns
* @param whereClase
* @param whereArgs
* @param groupBy
* @param having
* @param orderBy
* @return ArrayList<ArrayList<String>>
*/
public ArrayList<ArrayList<String>> selectRecordsFromDBList(
String tableName, String[] tableColumns, String whereClase,
String whereArgs[], String groupBy, String having, String orderBy) {
ArrayList<ArrayList<String>> retList = new ArrayList<ArrayList<String>>();
ArrayList<String> list = new ArrayList<String>();
Cursor cursor = myDataBase.query(tableName, tableColumns, whereClase,
whereArgs, groupBy, having, orderBy);
if (cursor.moveToFirst()) {
do {
list = new ArrayList<String>();
for (int i = 0; i < cursor.getColumnCount(); i++) {
list.add(cursor.getString(i));
}
retList.add(list);
} while (cursor.moveToNext());
}
if (cursor != null && !cursor.isClosed()) {
cursor.close();
}
return retList;
}
/**
* This function used to insert the Record in DB.
*
* @param tableName
* @param nullColumnHack
* @param initialValues
* @return the row ID of the newly inserted row, or -1 if an error occurred
*/
public long insertRecordsInDB(String tableName, String nullColumnHack,
ContentValues initialValues) {
return myDataBase.insert(tableName, nullColumnHack, initialValues);
}
/**
* This function used to update the Record in DB.
*
* @param tableName
* @param initialValues
* @param whereClause
* @param whereArgs
* @return true / false on updating one or more records
*/
public boolean updateRecordInDB(String tableName,
ContentValues initialValues, String whereClause, String whereArgs[]) {
return myDataBase.update(tableName, initialValues, whereClause,
whereArgs) > 0;
}
/**
* This function used to update the Record in DB.
*
* @param tableName
* @param initialValues
* @param whereClause
* @param whereArgs
* @return 0 in case of failure otherwise return no of row(s) are updated
*/
public int updateRecordsInDB(String tableName, ContentValues initialValues,
String whereClause, String whereArgs[]) {
return myDataBase.update(tableName, initialValues, whereClause,
whereArgs);
}
/**
* This function used to delete the Record in DB.
*
* @param tableName
* @param whereClause
* @param whereArgs
* @return 0 in case of failure otherwise return no of row(s) are deleted.
*/
public int deleteRecordInDB(String tableName, String whereClause,
String[] whereArgs) {
return myDataBase.delete(tableName, whereClause, whereArgs);
}
// --------------------- Select Raw Query Functions ---------------------
/**
* apply raw Query
*
* @param query
* @param selectionArgs
* @return Cursor
*/
public Cursor selectRecordsFromDB(String query, String[] selectionArgs) {
return myDataBase.rawQuery(query, selectionArgs);
}
/**
* apply raw query and return result in list
*
* @param query
* @param selectionArgs
* @return ArrayList<ArrayList<String>>
*/
public ArrayList<ArrayList<String>> selectRecordsFromDBList(String query,
String[] selectionArgs) {
ArrayList<ArrayList<String>> retList = new ArrayList<ArrayList<String>>();
ArrayList<String> list = new ArrayList<String>();
Cursor cursor = myDataBase.rawQuery(query, selectionArgs);
if (cursor.moveToFirst()) {
do {
list = new ArrayList<String>();
for (int i = 0; i < cursor.getColumnCount(); i++) {
list.add(cursor.getString(i));
}
retList.add(list);
} while (cursor.moveToNext());
}
if (cursor != null && !cursor.isClosed()) {
cursor.close();
}
return retList;
}
}
我不知道我做错了什么。如何将列表中的数据插入数据库？感谢您的每一次帮助。谢谢你。