package com.cheng.utils.sqlite;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import com.cheng.utils.file.FileUtil;
/**
* AssetDatabaseOpenHelper
* <ul>
* <li>Auto copy databse form assets to /data/data/package_name/databases</li>
* <li>You can use it like {@link SQLiteDatabase}, use
* {@link #getWritableDatabase()} to create and/or open a database that will be
* used for reading and writing. use {@link #getReadableDatabase()} to create
* and/or open a database that will be used for reading only.</li>
* </ul>
*/
public class AssetDatabaseOpenHelper {
private Context context;
private String databaseName;
public AssetDatabaseOpenHelper(Context context, String databaseName) {
this.context = context;
this.databaseName = databaseName;
}
/**
* Create and/or open a database that will be used for reading and writing.
*
* @return SQLiteDatabase对象
* @throws RuntimeException if cannot copy database from assets
* @throws SQLiteException if the database cannot be opened
*/
public synchronized SQLiteDatabase getWritableDatabase() {
File dbFile = context.getDatabasePath(databaseName);
if (dbFile != null && !dbFile.exists()) {
try {
copyDatabase(dbFile);
} catch (IOException e) {
throw new RuntimeException("Error creating source database", e);
}
}
assert dbFile != null;
return SQLiteDatabase.openDatabase(dbFile.getPath(), null,
SQLiteDatabase.OPEN_READWRITE);
}
/**
* Create and/or open a database that will be used for reading only.
*
* @return SQLiteDatabase对象
* @throws RuntimeException if cannot copy database from assets
* @throws SQLiteException if the database cannot be opened
*/
public synchronized SQLiteDatabase getReadableDatabase() {
File dbFile = context.getDatabasePath(databaseName);
if (dbFile != null && !dbFile.exists()) {
try {
copyDatabase(dbFile);
} catch (IOException e) {
throw new RuntimeException("Error creating source database", e);
}
}
return SQLiteDatabase.openDatabase(dbFile.getPath(), null,
SQLiteDatabase.OPEN_READONLY);
}
/**
* 获取数据库名称
*
* @return the database name
*/
public String getDatabaseName() {
return databaseName;
}
private void copyDatabase(File dbFile) throws IOException {
InputStream stream = context.getAssets().open(databaseName);
FileUtil.writeFile(dbFile, stream);
stream.close();
}
}