很多时候在应用安装初始化时，需要创建本地数据库，同时为数据库添加数据，之后再从数据库中读取数据。
这里有2个思路
1.先在本地创建一个能支持android使用的sqlite数据库文件,启动时,用现成的sqlite的二进制文件进行直接copy到Android系统的数据库路径
2.可以考虑在第一次启动时,执行数据库初始化的sql文件.
方法1:
1.在本地准备android能使用的sqlite数据库文件
使用sqlite数据库管理工具,看个人爱好(,Navicat Premium,)
打开数据库,创建"android_metadata"数据表
创建其他应用需要的表..此处省略.
2.复制文件到应用中.
把第一步创建的数据库文件复制到应用中的assets文件夹,然后创建DateBaseHelper extends SQLiteOpenHelper的类文件.
代码如下:
public class DataBaseHelper extends SQLiteOpenHelper { //The Android's default system path of your application database. private static String DB_PATH = "/data/data/YOUR_PACKAGE/databases/"; private static String DB_NAME = "myDBName"; private SQLiteDatabase myDataBase; private final Context myContext; /** * Constructor * Takes and keeps a reference of the passed context in order to access to the application assets and resources. * @param context */ public DataBaseHelper(Context context) { super(context, DB_NAME, null, 1); this.myContext = context; } /** * Creates a 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 this method and empty database will be created into the default system path //of your application so we are gonna be able to 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; try { String myPath = DB_PATH + DB_NAME; checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); } catch (SQLiteException e) { //database does't exist yet. } if (checkDB != null) { checkDB.close(); } return checkDB != null ? true : false; } /** * 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(); } public void openDataBase()throws SQLException { //Open the database String myPath = DB_PATH + DB_NAME; myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); } @Override public synchronized void close() { if (myDataBase != null) myDataBase.close(); super.close(); } @Override public void onCreate(SQLiteDatabase db) {} @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {} // Add your public helper methods to access and get content from the database. // You could return cursors by doing "return myDataBase.query(....)" so it'd be easy // to you to create adapters for your views.}
3.现在我们可以创建DateBaseHelper的实现操作了.
createDataBase() //创建
openDataBase()//打开只读数据库
记得要更改"YOUR_PACKAGE"为你的应用的包名
如:com.examplename.myapp
大概代码如下:
...DataBaseHelper myDbHelper = new DataBaseHelper();myDbHelper = new DataBaseHelper(this);try { myDbHelper.createDataBase();} catch (IOException ioe) { throw new Error("Unable to create database");}try { myDbHelper.openDataBase();} catch (SQLException sqle) { throw sqle;}...
转自：http://zhangfan822.iteye.com/blog/1883829