我在资产文件夹中有一个 sqlite 文件。我正在使用在其他堆栈溢出帖子中已被引用数千次的数据库管理器类：http ://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/
private void copyDatabase() throws IOException {
// Open your local db as the input stream
InputStream myInput = context.getAssets().open( DB_NAME );
问题在于不断抛出 IOException 的 open() 方法（或 getAssets？）。我的路径和文件名：
private static final String DB_NAME = "attractioninfo";
private static final String DB_PATH = "/data/data/seattle.tourists/";
我的另一个相关问题是关于路径。我已经检查了我的测试手机（三星 Galaxy sII）上的文件，但我没有在任何地方看到 /data/data/mypackagename/...。这在内部存储中到底在哪里？我使用的是安卓 2.2。
编辑：我做了更多测试，我还发现在第一次安装时（这意味着手机内部存储上还没有数据库文件，需要复制到那里）这条线也不起作用（我得到一个SQLite异常）
private boolean checkDatabase() {
SQLiteDatabase checkDB = null;
try {
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase( myPath, null, SQLiteDatabase.OPEN_READONLY );
完整代码：
package seattle.tourists;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.Context;
import android.content.res.AssetManager;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHelper extends SQLiteOpenHelper {
private static final String DB_NAME = "attractioninfo";
private static final String DB_PATH = "/data/data/seattle.tourists/databases/";
private static final int DB_VERSION = 1;
private static final String TABLE_NAME = "ExtraInfo";
private SQLiteDatabase db;
private final Context context;
/**
* Constructor
* @param context application context
*/
public DatabaseHelper( Context context ) {
super( context, DB_NAME, null, DB_VERSION );
this.context = context;
}
/**
* Creates empty database on system and rewrites it with existing database
* @throws IOException
*/
public void createDatabase() throws IOException {
boolean dbExist = checkDatabase();
if ( dbExist ) {
// do nothing, the database already exists;
}
else {
this.getReadableDatabase();
try {
copyDatabase();
}
catch ( IOException e ) {
throw new Error( "Error copying database" );
}
}
}
/**
* Check to see if a database exists
* @return true if database exists, false otherwise;
*/
private boolean checkDatabase() {
SQLiteDatabase checkDB = null;
try {
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase( myPath, null, SQLiteDatabase.OPEN_READONLY );
}
catch ( SQLiteException e ) {
int x = 5;
}
if ( checkDB != null )
checkDB.close();
return checkDB != null ? true : false;
}
/**
* Copes database from assets-folder to system folder, where it can be
* accessed and handled. This is done by transferring byte-stream.
* @throws IOException
*/
private void copyDatabase() throws IOException {
// Open your local db as the input stream
AssetManager assets = context.getAssets();
InputStream myInput = assets.open( DB_NAME );
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 SQLiteDatabase openDataBase() throws SQLException {
// Open the database
String myPath = DB_PATH + DB_NAME;
return db = SQLiteDatabase.openDatabase( myPath, null, SQLiteDatabase.OPEN_READONLY );
}
public synchronized void close() {
if ( db != null )
db.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
// do nothing
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// do nothing
}
}