如果您的应用程序需要一个数据库，并且它带有内置数据，那么交付该应用程序的最佳方式是什么?我应该:
预创建SQLite数据库，并将其包含在。apk? 在应用程序中包含SQL命令，并让它在第一次使用时创建数据库并插入数据?
我所看到的缺点是:
可能的SQLite版本不匹配可能会导致问题，我目前不知道数据库应该去哪里以及如何访问它。 在设备上创建和填充数据库可能需要很长时间。
有什么建议吗?关于任何问题的文档指针将非常感激。
当前回答
我使用ORMLite和下面的代码为我工作
public class DatabaseProvider extends OrmLiteSqliteOpenHelper {
private static final String DatabaseName = "DatabaseName";
private static final int DatabaseVersion = 1;
private final Context ProvidedContext;
public DatabaseProvider(Context context) {
super(context, DatabaseName, null, DatabaseVersion);
this.ProvidedContext= context;
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
boolean databaseCopied = preferences.getBoolean("DatabaseCopied", false);
if (databaseCopied) {
//Do Nothing
} else {
CopyDatabase();
SharedPreferences.Editor editor = preferences.edit();
editor.putBoolean("DatabaseCopied", true);
editor.commit();
}
}
private String DatabasePath() {
return "/data/data/" + ProvidedContext.getPackageName() + "/databases/";
}
private void CopyDatabase() {
try {
CopyDatabaseInternal();
} catch (IOException e) {
e.printStackTrace();
}
}
private File ExtractAssetsZip(String zipFileName) {
InputStream inputStream;
ZipInputStream zipInputStream;
File tempFolder;
do {
tempFolder = null;
tempFolder = new File(ProvidedContext.getCacheDir() + "/extracted-" + System.currentTimeMillis() + "/");
} while (tempFolder.exists());
tempFolder.mkdirs();
try {
String filename;
inputStream = ProvidedContext.getAssets().open(zipFileName);
zipInputStream = new ZipInputStream(new BufferedInputStream(inputStream));
ZipEntry zipEntry;
byte[] buffer = new byte[1024];
int count;
while ((zipEntry = zipInputStream.getNextEntry()) != null) {
filename = zipEntry.getName();
if (zipEntry.isDirectory()) {
File fmd = new File(tempFolder.getAbsolutePath() + "/" + filename);
fmd.mkdirs();
continue;
}
FileOutputStream fileOutputStream = new FileOutputStream(tempFolder.getAbsolutePath() + "/" + filename);
while ((count = zipInputStream.read(buffer)) != -1) {
fileOutputStream.write(buffer, 0, count);
}
fileOutputStream.close();
zipInputStream.closeEntry();
}
zipInputStream.close();
} catch (IOException e) {
e.printStackTrace();
return null;
}
return tempFolder;
}
private void CopyDatabaseInternal() throws IOException {
File extractedPath = ExtractAssetsZip(DatabaseName + ".zip");
String databaseFile = "";
for (File innerFile : extractedPath.listFiles()) {
databaseFile = innerFile.getAbsolutePath();
break;
}
if (databaseFile == null || databaseFile.length() ==0 )
throw new RuntimeException("databaseFile is empty");
InputStream inputStream = new FileInputStream(databaseFile);
String outFileName = DatabasePath() + DatabaseName;
File destinationPath = new File(DatabasePath());
if (!destinationPath.exists())
destinationPath.mkdirs();
File destinationFile = new File(outFileName);
if (!destinationFile.exists())
destinationFile.createNewFile();
OutputStream myOutput = new FileOutputStream(outFileName);
byte[] buffer = new byte[1024];
int length;
while ((length = inputStream.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myOutput.close();
inputStream.close();
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase, ConnectionSource connectionSource) {
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, ConnectionSource connectionSource, int fromVersion, int toVersion) {
}
}
请注意，该代码从资产中的zip文件中提取数据库文件
其他回答
从我所看到的，你应该是一个已经有表设置和数据的数据库。然而，如果你愿意(取决于你拥有的应用程序类型)，你可以允许“升级数据库选项”。然后你要做的就是下载最新的sqlite版本，获得在线托管的文本文件的最新Insert/Create语句，执行这些语句，并从旧的db进行数据传输到新的db。
我使用ORMLite和下面的代码为我工作
public class DatabaseProvider extends OrmLiteSqliteOpenHelper {
private static final String DatabaseName = "DatabaseName";
private static final int DatabaseVersion = 1;
private final Context ProvidedContext;
public DatabaseProvider(Context context) {
super(context, DatabaseName, null, DatabaseVersion);
this.ProvidedContext= context;
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
boolean databaseCopied = preferences.getBoolean("DatabaseCopied", false);
if (databaseCopied) {
//Do Nothing
} else {
CopyDatabase();
SharedPreferences.Editor editor = preferences.edit();
editor.putBoolean("DatabaseCopied", true);
editor.commit();
}
}
private String DatabasePath() {
return "/data/data/" + ProvidedContext.getPackageName() + "/databases/";
}
private void CopyDatabase() {
try {
CopyDatabaseInternal();
} catch (IOException e) {
e.printStackTrace();
}
}
private File ExtractAssetsZip(String zipFileName) {
InputStream inputStream;
ZipInputStream zipInputStream;
File tempFolder;
do {
tempFolder = null;
tempFolder = new File(ProvidedContext.getCacheDir() + "/extracted-" + System.currentTimeMillis() + "/");
} while (tempFolder.exists());
tempFolder.mkdirs();
try {
String filename;
inputStream = ProvidedContext.getAssets().open(zipFileName);
zipInputStream = new ZipInputStream(new BufferedInputStream(inputStream));
ZipEntry zipEntry;
byte[] buffer = new byte[1024];
int count;
while ((zipEntry = zipInputStream.getNextEntry()) != null) {
filename = zipEntry.getName();
if (zipEntry.isDirectory()) {
File fmd = new File(tempFolder.getAbsolutePath() + "/" + filename);
fmd.mkdirs();
continue;
}
FileOutputStream fileOutputStream = new FileOutputStream(tempFolder.getAbsolutePath() + "/" + filename);
while ((count = zipInputStream.read(buffer)) != -1) {
fileOutputStream.write(buffer, 0, count);
}
fileOutputStream.close();
zipInputStream.closeEntry();
}
zipInputStream.close();
} catch (IOException e) {
e.printStackTrace();
return null;
}
return tempFolder;
}
private void CopyDatabaseInternal() throws IOException {
File extractedPath = ExtractAssetsZip(DatabaseName + ".zip");
String databaseFile = "";
for (File innerFile : extractedPath.listFiles()) {
databaseFile = innerFile.getAbsolutePath();
break;
}
if (databaseFile == null || databaseFile.length() ==0 )
throw new RuntimeException("databaseFile is empty");
InputStream inputStream = new FileInputStream(databaseFile);
String outFileName = DatabasePath() + DatabaseName;
File destinationPath = new File(DatabasePath());
if (!destinationPath.exists())
destinationPath.mkdirs();
File destinationFile = new File(outFileName);
if (!destinationFile.exists())
destinationFile.createNewFile();
OutputStream myOutput = new FileOutputStream(outFileName);
byte[] buffer = new byte[1024];
int length;
while ((length = inputStream.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myOutput.close();
inputStream.close();
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase, ConnectionSource connectionSource) {
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, ConnectionSource connectionSource, int fromVersion, int toVersion) {
}
}
请注意，该代码从资产中的zip文件中提取数据库文件
目前还没有办法预先创建一个SQLite数据库来与apk一起发布。最好的方法是将适当的SQL保存为资源，并从应用程序中运行它们。是的，这会导致数据的重复(同样的信息作为资源和数据库存在)，但目前没有其他方法。唯一的缓解因素是apk文件被压缩了。我的经验是908KB压缩到268KB以下。
下面的帖子有我找到的最好的讨论/解决方案，其中有很好的示例代码。
http://groups.google.com/group/android-developers/msg/9f455ae93a1cf152
我把我的CREATE语句存储为一个字符串资源，用Context.getString()读取，并用SQLiteDatabse.execSQL()运行。
我将插入的数据存储在res/raw/inserts中。sql(我创建了sql文件，7000+行)。使用上面链接的技术，我输入了一个循环，逐行读取文件，并将数据连接到“INSERT INTO tbl VALUE”，并执行另一个sqlitedatbase . execsql()。当它们可以连接时，保存7000个“INSERT INTO tbl VALUE”是没有意义的。
在模拟器上大约需要20秒，我不知道在真正的手机上需要多长时间，但它只发生一次，当用户第一次启动应用程序时。
Android已经提供了一种版本感知的数据库管理方法。这种方法已经在Android应用程序的BARACUS框架中得到了利用。
它使您能够在应用程序的整个版本生命周期中管理数据库，能够将sqlite数据库从任何以前的版本更新到当前版本。
此外，它还允许您运行SQLite的热备份和热恢复。
我不是100%确定，但是针对特定设备的热恢复可能使您能够在应用程序中发布准备好的数据库。但我不确定数据库二进制格式，这可能特定于某些设备，供应商或设备代。
因为这些东西是Apache许可证2，所以可以随意重用代码的任何部分，这些代码可以在github上找到
编辑:
如果您只想传送数据，可以考虑在应用程序第一次启动时实例化和持久化pojo。BARACUS有一个内置的支持(内置的键值存储配置信息，例如。"APP_FIRST_RUN"加上一个后上下文引导钩子，以便在上下文上运行后启动操作)。这使得你可以在应用中使用紧密耦合的数据;在大多数情况下，这符合我的用例。
我终于做到了!!我已经使用这个链接帮助在Android应用程序中使用自己的SQLite数据库，但必须稍微改变一下。
If you have many packages you should put the master package name here: private static String DB_PATH = "data/data/masterPakageName/databases"; I changed the method which copies the database from local folder to emulator folder! It had some problem when that folder didn't exist. So first of all, it should check the path and if it's not there, it should create the folder. In the previous code, the copyDatabase method was never called when the database didn't exist and the checkDataBase method caused exception. so I changed the code a little bit. If your database does not have a file extension, don't use the file name with one.
它对我很有用，我希望它对你也有用
package farhangsarasIntroduction;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.HashMap;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DataBaseHelper extends SQLiteOpenHelper{
//The Android's default system path of your application database.
private static String DB_PATH = "data/data/com.example.sample/databases";
private static String DB_NAME = "farhangsaraDb";
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() {
boolean dbExist;
try {
dbExist = checkDataBase();
} catch (SQLiteException e) {
e.printStackTrace();
throw new Error("database dose not exist");
}
if(dbExist){
//do nothing - database already exist
}else{
try {
copyDataBase();
} catch (IOException e) {
e.printStackTrace();
throw new Error("Error copying database");
}
//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();
}
}
/**
* 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.
throw new Error("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{
//copyDataBase();
//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;
File databaseFile = new File( DB_PATH);
// check if databases folder exists, if not create one and its subfolders
if (!databaseFile.exists()){
databaseFile.mkdir();
}
//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();
}
@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) {
}
you to create adapters for your views.
}
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