什么是现有的SQLite数据库的完整的Android数据库帮助类？

我试图用现有的SQLite数据库部署一个应用程序。

我已经阅读并试图在网上实现几个样本，但是我发现他们总是缺less一些代码，或者不能像公布的那样进行编译或工作。

有没有人有一个完整的Android数据库助手类在Android上部署现有的SQLite数据库？

Answer 1

这是我想出来的，希望能帮助那些有麻烦的人。

package com.MyPackage; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.UUID; import android.content.Context; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteException; import android.database.sqlite.SQLiteOpenHelper; import android.util.Log; public class AnyDBAdapter { private static final String TAG = "AnyDBAdapter"; private DatabaseHelper mDbHelper; private static SQLiteDatabase mDb; //make sure this matches the //package com.MyPackage; //at the top of this file private static String DB_PATH = "/data/data/com.MyPackage/databases/"; //make sure this matches your database name in your assets folder // my database file does not have an extension on it // if yours does // add the extention private static final String DATABASE_NAME = "data"; //Im using an sqlite3 database, I have no clue if this makes a difference or not private static final int DATABASE_VERSION = 3; private final Context adapterContext; public AnyDBAdapter(Context context) { this.adapterContext = context; } public AnyDBAdapter open() throws SQLException { mDbHelper = new DatabaseHelper(adapterContext); try { mDbHelper.createDataBase(); } catch (IOException ioe) { throw new Error("Unable to create database"); } try { mDbHelper.openDataBase(); } catch (SQLException sqle) { throw sqle; } return this; } //Usage from outside // AnyDBAdapter dba = new AnyDBAdapter(contextObject); //in my case contextObject is a Map // dba.open(); // Cursor c = dba.ExampleSelect("Rawr!"); // contextObject.startManagingCursor(c); // String s1 = "", s2 = ""; // if(c.moveToFirst()) // do { // s1 = c.getString(0); // s2 = c.getString(1); // } while (c.moveToNext()); // dba.close(); public Cursor ExampleSelect(string myVariable) { String query = "SELECT locale, ? FROM android_metadata"; return mDb.rawQuery(query, new String[]{myVariable}); } //Usage // AnyDBAdatper dba = new AnyDBAdapter(contextObjecT); // dba.open(); // dba.ExampleCommand("en-CA", "en-GB"); // dba.close(); public void ExampleCommand(String myVariable1, String myVariable2) { String command = "INSERT INTO android_metadata (locale) SELECT ? UNION ALL SELECT ?"; mDb.execSQL(command, new String[]{ myVariable1, myVariable2}); } public void close() { mDbHelper.close(); } private static class DatabaseHelper extends SQLiteOpenHelper { Context helperContext; DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); helperContext = context; } @Override public void onCreate(SQLiteDatabase db) { } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.w(TAG, "Upgrading database!!!!!"); //db.execSQL(""); onCreate(db); } public void createDataBase() throws IOException { boolean dbExist = checkDataBase(); if (dbExist) { } else { //make sure your database has this table already created in it //this does not actually work here /* * db.execSQL("CREATE TABLE IF NOT EXISTS \"android_metadata\" (\"locale\" TEXT DEFAULT 'en_US')" * ); * db.execSQL("INSERT INTO \"android_metadata\" VALUES ('en_US')" * ); */ this.getReadableDatabase(); try { copyDataBase(); } catch (IOException e) { throw new Error("Error copying database"); } } } public SQLiteDatabase getDatabase() { String myPath = DB_PATH + DATABASE_NAME; return SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); } private boolean checkDataBase() { SQLiteDatabase checkDB = null; try { String myPath = DB_PATH + DATABASE_NAME; checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); } catch (SQLiteException e) { } if (checkDB != null) { checkDB.close(); } return checkDB != null ? true : false; } private void copyDataBase() throws IOException { // Open your local db as the input stream InputStream myInput = helperContext.getAssets().open(DATABASE_NAME); // Path to the just created empty db String outFileName = DB_PATH + DATABASE_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(); } public void openDataBase() throws SQLException { // Open the database String myPath = DB_PATH + DATABASE_NAME; mDb = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE); } @Override public synchronized void close() { if (mDb != null) mDb.close(); super.close(); } } } 

Answer 2

 DatabaseHelper dbHelper = new DatabaseHelper(getApplicationContext()); 

确保在应用程序生命周期中创build一次DatabaseHelper对象并重用它。

阅读数据：

 SQLiteDatabase db = dbHelper.getReadableDatabase(); 

读取/修改数据：

 SQLiteDatabase db = dbHelper.getWritableDatabase(); 

接下来使用SQLiteDatabase对象的insert() ， query() ， update() ， delete()方法：

http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html

你也不应该通过在createNewDatabase方法中直接访问sqlite文件来创build数据库。 在onCreate（…）方法中使用SQLiteDatabase对象的execSQL（）方法。 在那里执行你的CREATE TABLE查询。