The ORM Design Pattern Based On ORMLITE JDBC Framework In Java Class Libraries)
ORM design mode based on ORMLITE JDBC framework
ORM (object relationship mapping) is a technique that mapping between the object -oriented programming language and the relational database. It can make developers more conveniently operate the database and eliminate the tedious process of writing SQL statements manually.ORMLITE is a lightweight ORM framework, which provides an easy -to -use API to achieve mapping between the Java class and the database table.
This article will introduce the ORM design pattern based on the ORMLITE JDBC framework, explaining how to use it to simplify the database operation and provide examples of Java code.
1. Introduce the ORMLITE library
First, we need to introduce the ORMLITE library in the Java project.You can add ORMLITE as dependent items to the project construction tool, or manually download the jar file and add it to the project.
2. Create the Java class corresponding to the database table
Next, we need to create the Java class corresponding to the database table.This class should have attributes corresponding to the columns in the table, and use the annotation of ormlite to define the table name, column name, primary key and other information.For example, we create a class called "User" to map the database table named "Users":
@DatabaseTable(tableName = "users")
public class User {
@DatabaseField(generatedId = true)
private int id;
@DatabaseField(columnName = "username")
private String username;
@DatabaseField(columnName = "email")
private String email;
// Other attributes and methods
}
3. Configure database connection
Before using the ORMLITE framework, we need to configure the database connection.You can create a database connection configuration by creating a class called "DataBasehelper" and inheriting the `ORMLITESQLITEOPENHELPER` class provided by Oremlite.In the `databasehelper` class, we need to define the operation of the database name, version number, and initialization database table.The following is an example:
public class DatabaseHelper extends OrmLiteSqliteOpenHelper {
private static final String DATABASE_NAME = "mydatabase.db";
private static final int DATABASE_VERSION = 1;
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase, ConnectionSource connectionSource) {
try {
TableUtils.createTable(connectionSource, User.class);
// Create other tables
} catch (SQLException e) {
e.printStackTrace();
}
}
// Other methods and operations
}
4. Implement CRUD operation
Using the ORMLITE framework can easily achieve additional, deletion and change operations on the database.Here are some examples:
-Colon a user:
public void createUser(User user) {
try {
Dao<User, Integer> userDao = getDao(User.class);
userDao.create(user);
} catch (SQLException e) {
e.printStackTrace();
}
}
-Update a user:
public void updateUser(User user) {
try {
Dao<User, Integer> userDao = getDao(User.class);
userDao.update(user);
} catch (SQLException e) {
e.printStackTrace();
}
}
-Sto a user:
public void deleteUser(User user) {
try {
Dao<User, Integer> userDao = getDao(User.class);
userDao.delete(user);
} catch (SQLException e) {
e.printStackTrace();
}
}
-An query all users:
public List<User> getAllUsers() {
List<User> userList = new ArrayList<>();
try {
Dao<User, Integer> userDao = getDao(User.class);
userList = userDao.queryForAll();
} catch (SQLException e) {
e.printStackTrace();
}
return userList;
}
5. Advantages of using ORM mode
By using the ORM design mode based on the ORMLITE JDBC framework, we can get the following advantages:
-Tmagelessly writing SQL statements to reduce the number of code.
-In the object of operating the database, the readability and maintenance of the code are improved.
-In support automatic creation and update database table structure.
-In rich query operations, including condition query, sorting, paging, etc.
-It can easily handle physical relationships, such as one pair, more pairs, etc.
Summarize:
This article introduces the ORM design mode based on the ORMLITE JDBC framework, and provides the corresponding Java code example.By using the ORM mode, we can more conveniently operate the database to improve the readability and maintenance of code.The use of the ORMLITE framework can simplify the database operation and provide a wealth of query operation operation and physical relationship processing function, making the development process more efficient.
