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How to Specify Database Files

Here is an example to establishing a connection to a database file C:\work\mydatabase.db (in Windows)

Connection connection = DriverManager.getConnection("jdbc:sqlite:C:/work/mydatabase.db");

Opening a UNIX (Linux, maxOS, etc.) file /home/leo/work/mydatabase.db

Connection connection = DriverManager.getConnection("jdbc:sqlite:/home/leo/work/mydatabase.db");

How to Use Memory Databases

SQLite supports on-memory database management, which does not create any database files. To use a memory database in your Java code, get the database connection as follows:

Connection connection = DriverManager.getConnection("jdbc:sqlite::memory:");

And also, you can create memory database as follows:

Connection connection = DriverManager.getConnection("jdbc:sqlite:");

How to use Online Backup and Restore Feature

Take a backup of the whole database to backup.db file:

// Create a memory database
Connection conn = DriverManager.getConnection("jdbc:sqlite:");
Statement stmt = conn.createStatement();
// Do some updates
stmt.executeUpdate("create table sample(id, name)");
stmt.executeUpdate("insert into sample values(1, \"leo\")");
stmt.executeUpdate("insert into sample values(2, \"yui\")");
// Dump the database contents to a file
stmt.executeUpdate("backup to backup.db");

Restore the database from a backup file:

// Create a memory database
Connection conn = DriverManager.getConnection("jdbc:sqlite:");
// Restore the database from a backup file
Statement stat = conn.createStatement();
stat.executeUpdate("restore from backup.db");

Creating BLOB data

  1. Create a table with a column of blob type: create table T (id integer, data blob)
  2. Create a prepared statement with ? symbol: insert into T values(1, ?)
  3. Prepare a blob data in byte array (e.g., byte[] data = ...)
  4. preparedStatement.setBytes(1, data)
  5. preparedStatement.execute()...

Reading Database Files in classpaths or network (read-only)

To load db files that can be found from the class loader (e.g., db files inside a jar file in the classpath), use jdbc:sqlite::resource: prefix.

For example, here is an example to access an SQLite DB file, sample.db in a Java package org.yourdomain:

Connection conn = DriverManager.getConnection("jdbc:sqlite::resource:org/yourdomain/sample.db");

In addition, external DB resources can be used as follows:

Connection conn = DriverManager.getConnection("jdbc:sqlite::resource:http://www.xerial.org/svn/project/XerialJ/trunk/sqlite-jdbc/src/test/java/org/sqlite/sample.db");

To access db files inside some specific jar file (in local or remote), use the JAR URL:

Connection conn = DriverManager.getConnection("jdbc:sqlite::resource:jar:http://www.xerial.org/svn/project/XerialJ/trunk/sqlite-jdbc/src/test/resources/testdb.jar!/sample.db");

DB files will be extracted to a temporary folder specified in System.getProperty("java.io.tmpdir").

Configure directory to extract native library

sqlite-jdbc extracts a native library for your OS to the directory specified by java.io.tmpdir JVM property. To use another directory, set org.sqlite.tmpdir JVM property to your favorite path.

How to use a specific native library

You can use a specific version of the native library by setting the following JVM properties:

-Dorg.sqlite.lib.path=/path/to/folder
-Dorg.sqlite.lib.name=your-custom.dll

Override detected architecture

If the detected architecture is incorrect for your system, thus loading the wrong native library, you can override the value setting the following JVM property:

-Dorg.sqlite.osinfo.architecture=arm

Configure Connections

SQLiteConfig config = new SQLiteConfig();
// config.setReadOnly(true);   
config.setSharedCache(true);
config.recursiveTriggers(true);
// ... other configuration can be set via SQLiteConfig object
Connection conn = DriverManager.getConnection("jdbc:sqlite:sample.db", config.toProperties());

How to Use Encrypted Databases

Get started with encryption

The main goal of this library is to allow users to encrypt databases they are producing. In this section we will walk through the main aspect to understand to make this library work correctly with your requirements.

The content of this section is mainly extracted from the WxSQLite3 repository.

Introduction

This library is compiled with a modified SQLite native library that support multiple cipher schemes. In order to be used the user must choose a cipher scheme manually. If not using the default one (at the moment the default cipher is CHACHA20) is applied.

Before applying a configuration, choose the encryption scheme you would like to use in the supported cipher list.

The full documentation of the native library used can be found here: https://utelle.github.io/SQLite3MultipleCiphers/

Configuration methods

Configure using SQLiteMCConfig objects

Starting with version 3.32.0 the java implementation has a new configuration object called SQLiteMCConfig that can hold the cipher configuration. The interface allows for very simple and quick configuration of the choosen cipher algorithm.

For each cipher supported a ready to use and a customizable object is present. If you want to go completely custom it is also possible. All parameters are available through setters.

Each conbinaison of paramters presented in previous section are implemented as getDefault (SQLiteMC default) or getDefautls (ex: getV2Defaults() for SQLCipher))

The object names are :

SQLiteMCConfig.Builder; Use this to build a configuration object from scratch
    
SQLiteMCSqlCipherConfig; // Generate a configuration for SQLCipher
SQLiteMCChacha20Config; // Generate a configuration for Chacha20
SQLiteMCWxAES256Config; // Generate a configuration for legacy AES 256 WxSQLite3
SQLiteMCWxAES128Config; // Generate a configuration for legacy AES 128 WxSQLite3
SQLiteMCRC4Config; // Generate a configuration for System.Data.SQLite

To specify the key you just need to use the withKey(String Key) or any of the configuration object. To create the connection it is now very simple:

//Using the SQLiteMC default parameters
Connection connection=DriverManager.getConnection("jdbc:sqlite:file:file.db",new SQLiteMCConfig.Builder().withKey("Key").build().toProperties());
Connection connection=new SQLiteMCConfig.Builder().withKey("Key").build().createConnection("jdbc:sqlite:file:file.db");
//Using Chacha20
Connection connection=DriverManager.getConnection("jdbc:sqlite:file:file.db",SQLiteMCChacha20Config.getDefault().withKey("Key").build().toProperties());
Connection connection=SQLiteMCChacha20Config.getDefault().withKey("Key").build().createConnection("jdbc:sqlite:file:file.db");
Configure using SQL specific SQL functions

Note: See the SQLite3 Multiple Ciphers SQL Documentation for more details.

Configure using URI

Note: See the SQLite3 Multiple Ciphers URI Documentation for more details.

Example: URI query string to select the legacy SQLCipher Version 2 encryption scheme:

file:databasefile?cipher=sqlcipher&legacy=1&kdf_iter=4000

Encryption key manipulations

Several manipulation can be very usefull when encrypting a database. For example you may want to change the password used, remove it, or encrypt a plain database.

Here is what you need to know.

Encrypt a plain database
  1. Open the database file
  2. Set cipher configuration
  3. Apply the key for the first time using the PRAGMA syntax
  4. Use as usual
Open an encrypted DB
  1. Open the database file
  2. set cipher configuration
  3. Apply the corresponding key using the PRAGMA syntax
  4. Use normally
Change the key used for a database
  1. Open the database file
  2. Set cipher configuration
  3. Apply the current key using the PRAGMA key='mykey' syntax (It needs to be adapted if using an hexadecimal key)
  4. Change the key using the PRAGMA rekey='my_new_key' syntax (It needs to be adapted if using an hexadecimal key)
  5. Use normally
Remove the key and go back to plain
  1. Open the database file
  2. Set cipher configuration
  3. Apply the current key using the PRAGMA key='mykey' syntax (It needs to be adapted if using an hexadecimal key)
  4. Change the key to null usingPRAGMA rekey=''
  5. Use normally

Explicit read only transactions (use with Hibernate)

In order for the driver to be compliant with Hibernate, it needs to allow setting the read only flag after a connection has been created.

SQLite has a notion of "auto-upgrading" read-only transactions to read-write transactions. This can cause SQLITE_BUSY exceptions which are difficult to deal with in a JPA/Hibernate/Spring scenario.

For example:

  • open connection
  • query data <--- this uses a read-only transaction in SQLite by default
  • write data <--- this is risky as it promotes the transaction to read-write
  • commit

The approach taken is:

  • open transactions on demand
  • allow setting readOnly only if no statement has been executed yet
  • if readOnly(false) is received, then we quit out of our transaction, and open a new transaction with BEGIN IMMEDIATE. This forces a global lock on the database, preventing SQLITE_BUSY.

You can activate explicit read only support in 2 ways:

  • via SQLiteConfig#setExplicitReadOnly(true):
SQLiteConfig config = new SQLiteConfig();
config.setExplicitReadOnly(true);
  • using the pragma jdbc.explicit_readonly:
DriverManager.getConnection("jdbc:sqlite::memory:?jdbc.explicit_readonly=true");

How to use with Android

Android expects JNI native libraries to be bundled differently than a normal Java application.

You will need to extract the native libraries from our jar (from org/sqlite/native/Linux-Android), and place them in the jniLibs directory:

android-studio-screenshot

The name of directories in our jar and in Android Studio differ, here is a mapping table:

Jar directory Android Studio directory
aarch64 arm64-v8a
arm armeabi
x86 x86
x86_64 x86_64