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数据库操作

2024-07-09 09:41:46   228人阅读

1. [代码][Java]代码     
public class Database {
 
private static DbOpenHelper mDbHelper;
private static final int DB_VERSION = 1;
private static final String DB_NAME = "pdf.db";
 
public static void close() {
if(mDbHelper != null) {
mDbHelper.close();
mDbHelper = null;
}
}
 
public static SQLiteDatabase getDb(Context context) {
DbOpenHelper helper = getDbOpenHelper(context);
return helper.getWritableDatabase();
}
 
public static void writeMessageToDb(SQLiteDatabase db, String name, 
String path) {
ContentValues values = new ContentValues();
values.put(PDF.name.name(), name);
values.put(PDF.path.name(), path);
db.insert(PDF.TABLE_NAME, null, values);
}
 
public static HashMap<String, String> loadMessageFromDb(SQLiteDatabase db) {
Cursor cursor = db.query(PDF.TABLE_NAME, null, null, null, null, null, null);
HashMap<String, String> result = new HashMap<String, String>();
while(cursor.moveToNext()) {http://www.huiyi8.com/moban/
String name = cursor.getString(cursor.getColumnIndex(PDF.name.name()));
String path = cursor.getString(cursor.getColumnIndex(PDF.path.name()));
 
 
result.put(name, path);
}
cursor.close();
return result;
}
 
private static DbOpenHelper getDbOpenHelper(Context context) {
if(mDbHelper == null)
mDbHelper = new DbOpenHelper(context, DB_NAME, DB_VERSION);
 
return mDbHelper;
}
 
private static class DbOpenHelper extends SQLiteOpenHelper {
 
public DbOpenHelper(Context context, String name, int version) {
super(context, name, null, version);
}
 
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE " + PDF.TABLE_NAME + " (" +
PDF._id.name() + " INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, " +
PDF.name.name() + " TEXT NOT NULL, " + 
PDF.path.name() + " TEXT NOT NULL" +
");"
);
}
 
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
dropTables(db);html模板
onCreate(db);
}
 
private void dropTables(SQLiteDatabase db) {
db.execSQL("DROP TABLE IF EXISTS " + PDF.TABLE_NAME);
}
}
 
enum PDF {
_id,
name,
path;
 
static final String TABLE_NAME = "PDF";
}
}


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