Java 如何在Android Studio中使用SQLite创建数据库
我基本上想创建一个数据库，我认为这个代码会这样做，但它从来没有创建数据库，因为当我在我的计算机上查找数据库文件时，没有创建数据库。我也不确定数据库是在哪里创建的，所以如果能指出这一点，我们也将不胜感激。我有数据库助手、提供者和登录活动的代码，因为我认为这就是我的问题所在。我也不知道这是否与我使用直接查询有关，因为我在其他部分使用ContentValues，但是如果您想查看其他代码，请告诉我。谢谢大家! 数据库提供者Java 如何在Android Studio中使用SQLite创建数据库,java,android,database,sqlite,Java,Android,Database,Sqlite,我基本上想创建一个数据库，我认为这个代码会这样做，但它从来没有创建数据库，因为当我在我的计算机上查找数据库文件时，没有创建数据库。我也不确定数据库是在哪里创建的，所以如果能指出这一点，我们也将不胜感激。我有数据库助手、提供者和登录活动的代码，因为我认为这就是我的问题所在。我也不知道这是否与我使用直接查询有关，因为我在其他部分使用ContentValues，但是如果您想查看其他代码，请告诉我。谢谢大家! 数据库提供者 public class ChargerPointsProvider exten
public class ChargerPointsProvider extends ContentProvider {
@Override
public boolean onCreate(){
return true;
}
/** URI matcher code for the content URI for the userInfo table */
private static final int USER_INFO = 100;
/** URI matcher code for the content URI for a single user in the userInfo table */
private static final int USER_INFO_ID = 101;
/** URI matcher code for the content URI for the couponInfo table */
private static final int COUPON_INFO = 102;
/** URI matcher code for the content URI for a single coupon in the couponInfo table */
private static final int COUPON_INFO_ID = 103;
/** URI matcher code for the content URI for the points table */
private static final int POINTS_INFO = 104;
/** URI matcher code for the content URI for a single user in the points table */
private static final int POINTS_INFO_ID = 105;
/** URI matcher code for the content URI for the userCouponsInfo table */
private static final int USER_COUPONS_INFO = 106;
/** URI matcher code for the content URI for a single user in the userCouponsInfo table */
private static final int USER_COUPONS_INFO_ID = 107;
/**Tag for the log messages*/
public static final String LOG_TAG = ChargerPointsContract.class.getSimpleName();
private ChargerPointsDbHelper mDbHelper;
/**
* UriMatcher object to match a content URI to a corresponding code.
* The input passed into the constructor represents the code to return for the root URI.
* It's common to use NO_MATCH as the input for this case.
*/
private static final UriMatcher sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
// Static initializer. This is run the first time anything is called from this class.
static {
// The calls to addURI() go here, for all of the content URI patterns that the provider
// should recognize. All paths added to the UriMatcher have a corresponding code to return
// when a match is found.
// The content URI of the form "content://com.example.android.chargerpoints/userInfo" will map to the
// integer code {@link #USER_INFO}. This URI is used to provide access to MULTIPLE rows
// of the userInfo table.
sUriMatcher.addURI(ChargerPointsContract.CONTENT_AUTHORITY, ChargerPointsContract.PATH_USER_INFO, USER_INFO);
// The content URI of the form "content://com.example.android.chargerpoints/userInfo/#" will map to the
// integer code {@link #USER_INFO_ID}. This URI is used to provide access to ONE single row
// of the userInfo table.
//
// In this case, the "#" wildcard is used where "#" can be substituted for an integer.
// For example, "content://com.example.android.chargerpoints/userInfo/3" matches, but
// "content://com.example.android.chargerpoints/userInfo" (without a number at the end) doesn't match.
sUriMatcher.addURI(ChargerPointsContract.CONTENT_AUTHORITY, ChargerPointsContract.PATH_USER_INFO + "/#", USER_INFO_ID);
sUriMatcher.addURI(ChargerPointsContract.CONTENT_AUTHORITY, ChargerPointsContract.PATH_COUPON_INFO, COUPON_INFO);
sUriMatcher.addURI(ChargerPointsContract.CONTENT_AUTHORITY, ChargerPointsContract.PATH_COUPON_INFO + "/#", COUPON_INFO_ID);
sUriMatcher.addURI(ChargerPointsContract.CONTENT_AUTHORITY, ChargerPointsContract.PATH_POINTS_INFO, POINTS_INFO);
sUriMatcher.addURI(ChargerPointsContract.CONTENT_AUTHORITY, ChargerPointsContract.PATH_POINTS_INFO + "/#", POINTS_INFO_ID);
sUriMatcher.addURI(ChargerPointsContract.CONTENT_AUTHORITY, ChargerPointsContract.PATH_USER_COUPONS_INFO, USER_COUPONS_INFO);
sUriMatcher.addURI(ChargerPointsContract.CONTENT_AUTHORITY, ChargerPointsContract.PATH_USER_COUPONS_INFO + "/#", USER_COUPONS_INFO_ID);
}
/**
* Perform the query for the given URI. Use the given projection, selection, selection arguments, and sort order.
*/
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
String sortOrder) {
// Get readable database
SQLiteDatabase database = mDbHelper.getReadableDatabase();
// This cursor will hold the result of the query
Cursor cursor;
// Figure out if the URI matcher can match the URI to a specific code
int match = sUriMatcher.match(uri);
switch (match) {
case USER_INFO:
// For the USER_INFO code, query the userInfo table directly with the given
// projection, selection, selection arguments, and sort order. The cursor
// could contain multiple rows of the userInfo table.
cursor = database.query(ChargerPointsContract.UserInfoEntry.TABLE_NAME, projection, selection, selectionArgs,
null, null, sortOrder);
break;
case USER_INFO_ID:
// For the USER_INFO_ID code, extract out the ID from the URI.
// For an example URI such as "content://com.example.android.chargerpoints/userInfo/3",
// the selection will be "_id=?" and the selection argument will be a
// String array containing the actual ID of 3 in this case.
//
// For every "?" in the selection, we need to have an element in the selection
// arguments that will fill in the "?". Since we have 1 question mark in the
// selection, we have 1 String in the selection arguments' String array.
selection = ChargerPointsContract.UserInfoEntry._ID + "=?";
selectionArgs = new String[] { String.valueOf(ContentUris.parseId(uri)) };
// This will perform a query on the userInfo table where the _id equals 3 to return a
// Cursor containing that row of the table.
cursor = database.query(ChargerPointsContract.UserInfoEntry.TABLE_NAME, projection, selection, selectionArgs,
null, null, sortOrder);
break;
case COUPON_INFO:
cursor = database.query(ChargerPointsContract.CouponInfoEntry.TABLE_NAME, projection, selection, selectionArgs,
null, null, sortOrder);
break;
case COUPON_INFO_ID:
selection = ChargerPointsContract.CouponInfoEntry._ID + "=?";
selectionArgs = new String[] { String.valueOf(ContentUris.parseId(uri)) };
cursor = database.query(ChargerPointsContract.CouponInfoEntry.TABLE_NAME, projection, selection, selectionArgs,
null, null, sortOrder);
break;
case POINTS_INFO:
cursor = database.query(ChargerPointsContract.PointsEntry.TABLE_NAME, projection, selection, selectionArgs,
null, null, sortOrder);
break;
case POINTS_INFO_ID:
selection = ChargerPointsContract.PointsEntry._ID + "=?";
selectionArgs = new String[] { String.valueOf(ContentUris.parseId(uri)) };
cursor = database.query(ChargerPointsContract.PointsEntry.TABLE_NAME, projection, selection, selectionArgs,
null, null, sortOrder);
break;
case USER_COUPONS_INFO:
cursor = database.query(ChargerPointsContract.UserCouponsEntry.TABLE_NAME, projection, selection, selectionArgs,
null, null, sortOrder);
break;
case USER_COUPONS_INFO_ID:
selection = ChargerPointsContract.UserCouponsEntry._ID + "=?";
selectionArgs = new String[] { String.valueOf(ContentUris.parseId(uri)) };
cursor = database.query(ChargerPointsContract.UserCouponsEntry.TABLE_NAME, projection, selection, selectionArgs,
null, null, sortOrder);
break;
default:
throw new IllegalArgumentException("Cannot query unknown URI " + uri);
}
return cursor;
}
/**
* Insert new data into the provider with the given ContentValues.
*/
@Override
public Uri insert(Uri uri, ContentValues contentValues) {
final int match = sUriMatcher.match(uri);
switch (match) {
case USER_INFO:
return insertUserInfo(uri, contentValues);
case COUPON_INFO:
return insertCouponInfo(uri, contentValues);
case USER_COUPONS_INFO:
return insertUserCouponsInfo(uri, contentValues);
case POINTS_INFO:
return insertPointsInfo(uri,contentValues);
default:
throw new IllegalArgumentException("Insertion is not supported for " + uri);
}
}
@Override
public int delete(Uri uri, String s, String[] strings) {
return 0;
}
@Override
public int update(Uri uri, ContentValues contentValues, String s, String[] strings) {
return 0;
}
/**
* Insert a user into the database with the given content values. Return the new content URI
* for that specific row in the database.
*/
private Uri insertUserInfo(Uri uri, ContentValues values) {
// Check that the username is not null
String username = values.getAsString(ChargerPointsContract.UserInfoEntry.COLUMN_USERNAME);
if (username == null) {
throw new IllegalArgumentException("Username Required");
}
// Check that the password is valid
String password = values.getAsString(ChargerPointsContract.UserInfoEntry.COLUMN_PASSWORD);
if (password == null) {
throw new IllegalArgumentException("Password Required");
}
//Get writable database
SQLiteDatabase database = mDbHelper.getWritableDatabase();
//Insert the new user with the given values
long id = database.insert(ChargerPointsContract.UserInfoEntry.TABLE_NAME, null, values);
//If the id is -1, then the insertion failed. Log an error and return null
if (id == -1) {
Log.e(LOG_TAG, "Failed to insert row for " + uri);
return null;
}
// Once we know the ID of the new row in the table,
// return the new URI with the ID appended to the end of it
return ContentUris.withAppendedId(uri, id);
}
/**
* Insert a coupon into the database with the given content values. Return the new content URI
* for that specific row in the database.
*/
private Uri insertCouponInfo(Uri uri, ContentValues values) {
// Check that the coupon is not null
Byte coupon = values.getAsByte(ChargerPointsContract.CouponInfoEntry.COLUMN_COUPON);
if (coupon == null) {
throw new IllegalArgumentException("Coupon Required");
}
//Get writable database
SQLiteDatabase database = mDbHelper.getWritableDatabase();
//Insert the new coupon with the given values
long id = database.insert(ChargerPointsContract.CouponInfoEntry.TABLE_NAME, null, values);
//If the id is -1, then the insertion failed. Log an error and return null
if (id == -1) {
Log.e(LOG_TAG, "Failed to insert row for " + uri);
return null;
}
// Once we know the ID of the new row in the table,
// return the new URI with the ID appended to the end of it
return ContentUris.withAppendedId(uri, id);
}
/**
* Insert a coupon a user has into the database with the given content values. Return the new content URI
* for that specific row in the database.
*/
private Uri insertUserCouponsInfo(Uri uri, ContentValues values) {
// Check that the userId is not null
int userId = values.getAsInteger(ChargerPointsContract.UserCouponsEntry._ID);
if (userId == 0) {
throw new IllegalArgumentException("User ID required");
}
// Check that the name is not null
int couponId = values.getAsInteger(ChargerPointsContract.UserCouponsEntry.COUPON_ID);
if (couponId == 0) {
throw new IllegalArgumentException("Coupon ID required");
}
boolean couponRedeemed = values.getAsBoolean(ChargerPointsContract.UserCouponsEntry.COLUMN_REDEEMED);
if (couponRedeemed == true) {
throw new IllegalArgumentException("Coupon already redeemed");
}
//Get writable database
SQLiteDatabase database = mDbHelper.getWritableDatabase();
//Insert the new pet with the given values
long id = database.insert(ChargerPointsContract.UserCouponsEntry.TABLE_NAME, null, values);
//If the id is -1, then the insertion failed. Log an error and return null
if (id == -1) {
Log.e(LOG_TAG, "Failed to insert row for " + uri);
return null;
}
// Once we know the ID of the new row in the table,
// return the new URI with the ID appended to the end of it
return ContentUris.withAppendedId(uri, id);
}
/**
* Insert a pet into the database with the given content values. Return the new content URI
* for that specific row in the database.
*/
private Uri insertPointsInfo(Uri uri, ContentValues values) {
// Check that the name is not null
int points = values.getAsInteger(ChargerPointsContract.PointsEntry.COLUMN_POINTS);
if (points == 0) {
throw new IllegalArgumentException("Points Required");
}
//Get writable database
SQLiteDatabase database = mDbHelper.getWritableDatabase();
//Insert the new pet with the given values
long id = database.insert(ChargerPointsContract.PointsEntry.TABLE_NAME, null, values);
//If the id is -1, then the insertion failed. Log an error and return null
if (id == -1) {
Log.e(LOG_TAG, "Failed to insert row for " + uri);
return null;
}
// Once we know the ID of the new row in the table,
// return the new URI with the ID appended to the end of it
return ContentUris.withAppendedId(uri, id);
}
/**
* Returns the MIME type of data for the content URI.
*/
@Override
public String getType(Uri uri) {
return null;
}
}
/*Database helper for Charger Points app. Manages database creation and version management.*/
public class ChargerPointsDbHelper extends SQLiteOpenHelper {
public static final String LOG_TAG = ChargerPointsDbHelper.class.getSimpleName();
/* Name of the database file */
private static final String DATABASE_NAME = "chargerPoints.db";
/* Database version. If you change the database schema, you must increment the database version.*/
private static final int DATABASE_VERSION = 1;
/*Constructs a new instance of {@link ChargerPointsDbHelper}. @param context of the app */
public ChargerPointsDbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
/*This is called when the database is created for the first time.*/
@Override
public void onCreate(SQLiteDatabase db) {
// Create a String that contains the SQL statement to create the User Info table
String SQL_CREATE_USER_INFO_TABLE = "CREATE TABLE " + UserInfoEntry.TABLE_NAME + " ("
+ UserInfoEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
+ UserInfoEntry.COLUMN_USERNAME + " TEXT NOT NULL, "
+ UserInfoEntry.COLUMN_PASSWORD + " TEXT NOT NULL);";
// Create a String that contains the SQL statement to create the Coupon Info table
String SQL_CREATE_COUPON_INFO_TABLE = "CREATE TABLE " + CouponInfoEntry.TABLE_NAME + " ("
+ CouponInfoEntry.COUPON_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
+ CouponInfoEntry.COLUMN_COUPON + " BLOB NOT NULL);";
// Create a String that contains the SQL statement to create the Points table
String SQL_CREATE_POINTS_TABLE = "CREATE TABLE " + PointsEntry.TABLE_NAME + " ("
+ PointsEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
+ PointsEntry.COLUMN_POINTS + " INTEGER NOT NULL);";
// Create a String that contains the SQL statement to create the UserCoupons table
String SQL_CREATE_USER_COUPONS_TABLE = "CREATE TABLE " + UserCouponsEntry.TABLE_NAME + " ("
+ UserCouponsEntry._ID + " INTEGER NOT NULL, "
+ UserCouponsEntry.COUPON_ID + " INTEGER NOT NULL, "
+ UserCouponsEntry.COLUMN_REDEEMED + " BOOLEAN NOT NULL);";
// Execute the SQL statement
db.execSQL(SQL_CREATE_USER_INFO_TABLE);
db.execSQL(SQL_CREATE_COUPON_INFO_TABLE);
db.execSQL(SQL_CREATE_POINTS_TABLE);
db.execSQL(SQL_CREATE_USER_COUPONS_TABLE);
}
/*This is called when the database needs to be upgraded.*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// The database is still at version 1, so there's nothing to do be done here.
}
}
尝试卸载应用程序，以便删除创建的数据库。清理并重新安装应用程序，或将数据库版本升级到2。
当我在我的计算机上查找数据库文件时/data/data/…