ORMLITE JDBC framework in the Java class library
ORMLITE is a lightweight JDBC framework used in the Java library. It provides simple and easy -to -use API to simplify the interaction with the database.This tutorial will introduce how to use the ORMLite JDBC framework in the Java library and provide some Java code examples.
**Table of contents**
1. Introduce the ORMLITE library
2. Configure database connection
3. Create a data model class
4. Database operation -increase, delete, change, check
4.1 Insert data
4.2 Delete data
4.3 Update data
4.4 Query data
5. Database affairs
6. End language
** 1. Introduce the ORMLITE library **
First, we need to introduce the ORMLITE library into the Java class library project.You can complete the introduction through Maven, Gradle or manually, and imported the ORMLITE JAR file.
** 2. Configure database connection **
Before using Oremlite, we need to configure the database connection.Create a database connection configuration class in the project, as shown below:
import com.j256.ormlite.jdbc.JdbcConnectionSource;
import com.j256.ormlite.support.ConnectionSource;
public class DatabaseConfig {
private static final String DATABASE_URL = "jdbc:mysql://localhost:3306/mydatabase";
private static final String DATABASE_USERNAME = "username";
private static final String DATABASE_PASSWORD = "password";
public static ConnectionSource getConnectionSource() throws SQLException {
return new JdbcConnectionSource(DATABASE_URL, DATABASE_USERNAME, DATABASE_PASSWORD);
}
}
In the above example, we use mysql database and provide database URL, username and password.You can modify it accordingly according to your own situation.
** 3. Create a data model class **
Next, we need to create a data model class to map the database table.Each data model class should have a non -constructor, and uses the relevant injection of ORMLITE to define the table name, field and other attributes.
import com.j256.ormlite.field.DatabaseField;
import com.j256.ormlite.table.DatabaseTable;
@DatabaseTable(tableName = "users")
public class User {
@DatabaseField(generatedId = true)
private int id;
@DatabaseField
private String name;
// Other fields
public User() {
// Oremlite requires an unspeakable constructor
}
// getter and setter method
}
In the above example, we created a table called "Users" and defined the two fields of ID and name.
** 4. Database operation -increase, delete, change, check **
Now we have prepared database connections and data model classes, and we can start performing various database operations.
** 4.1 Insert data **
To insert a new data, we only need to instantiate the data model class and use the ORMLITE's `Dao` interface to operate the database.
import com.j256.ormlite.dao.Dao;
import java.sql.SQLException;
public class UserDao {
private Dao<User, Integer> userDao;
public UserDao(ConnectionSource connectionSource) throws SQLException {
userDao = DaoManager.createDao(connectionSource, User.class);
}
public void createUser() throws SQLException {
User user = new User();
user.setName("John Doe");
userDao.create(user);
// The data insertion is successful
}
}
** 4.2 Delete data **
To delete the data, we need to query the data to be deleted first, and then use ORMLITE's `dao` to perform the delete operation.
public void deleteUser() throws SQLException {
// Query users to delete
User user = userDao.queryForId(userId);
if (user != null) {
userDao.delete(user);
// Data deletion successfully
}
}
** 4.3 Update data **
To update the data, we need to check the data to be updated first, then modify the corresponding field value, and use the `dao` to perform the update operation.
public void updateUser() throws SQLException {
// Query users who want to update
User user = userDao.queryForId(userId);
if (user != null) {
user.setName("Updated Name");
userDao.update(user);
// The data update is successful
}
}
** 4.4 Query data **
To query data, we can use ORMLITE's `dao` or write SQL query statements.
public List<User> getAllUsers() throws SQLException {
return userDao.queryForAll();
}
public User getUserById(int userId) throws SQLException {
return userDao.queryForId(userId);
}
** 5. Database transaction **
ORMLITE also provides the function of transaction management to ensure that a set of operations are either successful or all fails.The following is a simple transaction example:
import com.j256.ormlite.dao.TransactionManager;
import java.sql.SQLException;
public class TransactionExample {
public void performTransaction() throws SQLException {
TransactionManager.callInTransaction(connectionSource, () -> {
// Perform a set of database operations here
return null;
});
}
}
In the above examples, we can perform a set of database operations in the callback method of the `TransactionCalLABLE`, including insertion, deletion and update operations.
** 6. End words **
Through this tutorial, you have learned how to use the ORMLITE JDBC framework in the Java library for database operations.You can easily insert, delete, update and query the simple API provided by Oremlite.Hope this tutorial will help you!
